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12 pages, 970 KiB  
Review
The MET Family of Receptor Tyrosine Kinases Promotes a Shift to Pro-Tumor Metabolism
by James C. Davis and Susan E. Waltz
Genes 2024, 15(7), 953; https://doi.org/10.3390/genes15070953 - 20 Jul 2024
Viewed by 923
Abstract
The development and growth of cancer is fundamentally dependent on pro-tumor changes in metabolism. Cancer cells generally shift away from oxidative phosphorylation as the primary source of energy and rely more heavily on glycolysis. Receptor tyrosine kinases (RTKs) are a type of receptor [...] Read more.
The development and growth of cancer is fundamentally dependent on pro-tumor changes in metabolism. Cancer cells generally shift away from oxidative phosphorylation as the primary source of energy and rely more heavily on glycolysis. Receptor tyrosine kinases (RTKs) are a type of receptor that is implicated in this shift to pro-tumor metabolism. RTKs are important drivers of cancer growth and metastasis. One such family of RTKs is the MET family, which consists of MET and RON (MST1R). The overexpression of either MET or RON has been associated with worse cancer patient prognosis in a variety of tumor types. Both MET and RON signaling promote increased glycolysis by upregulating the expression of key glycolytic enzymes via increased MYC transcription factor activity. Additionally, both MET and RON signaling promote increased cholesterol biosynthesis downstream of glycolysis by upregulating the expression of SREBP2-induced cholesterol biosynthesis enzymes via CTTNB1. These changes in metabolism, driven by RTK activity, provide potential targets in limiting tumor growth and metastasis via pharmacological inhibition or modifications in diet. This review summarizes pro-tumor changes in metabolism driven by the MET family of RTKs. In doing so, we will offer our unique perspective on metabolic pathways that drive worse patient prognosis and provide suggestions for future study. Full article
(This article belongs to the Section Molecular Genetics and Genomics)
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<p><b>MET and RON promote glycolysis and cholesterol biosynthesis leading to increased metastasis.</b> RON and MET activate MYC transcription factor activity which increases the expression and activity of glycolytic enzymes. RON and MET both signal through CTTNB1 to induce SREBP2-mediated cholesterol biosynthesis.</p>
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<p><b>The effect of Vitamins on MET activity.</b> Vitamin K1 and sorafenib inhibit MET-mediated RAF activity, decreasing tumor growth. Vitamin C lowers ROS and limits SP transcription factor activity leading to less production of MET RNA while FASN inhibits the degradation of MET RNA. Vitamin D inhibits CTTNB1 via VDR leading to an inhibition of tumor growth.</p>
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23 pages, 6816 KiB  
Article
Characterization and Expression Analysis of Sugar Transporters through Partial Least Square Structural Equation Model (PLS-SEM) Revealed Their Role in Pepper (Capsicum annuum L.)
by Pan Xia, Shiyong Zhou, Xiaoxue Zhao and Changling Zhao
Plants 2024, 13(13), 1825; https://doi.org/10.3390/plants13131825 - 3 Jul 2024
Viewed by 624
Abstract
Pepper (Capsicum annuum L.) is one of the most important economic crops in the world. By controlling the transport and distribution of photosynthetic products between cells and organs, sugar transporters are widely involved in growth and development, environmental adaptation, and microbial interactions. [...] Read more.
Pepper (Capsicum annuum L.) is one of the most important economic crops in the world. By controlling the transport and distribution of photosynthetic products between cells and organs, sugar transporters are widely involved in growth and development, environmental adaptation, and microbial interactions. The present study was carried out at the genome-wide level to systematically characterize sugar transporters. As a result, 50 MST, 3 SUT, and 29 SWEET genes were identified and classified. The expression pattern of sugar transporters in pepper was analyzed by transcriptomic data. The expression properties of sugar transporters were further explored in pepper varieties with significant differences in weight, shape, and pungency. It was shown that the pepper sugar transporter genes had obvious spatiotemporal specific expression characteristics and exhibited variety-specific expression preferences. We focus on analyzing candidate genes that may be involved in fruit development and expansion. We further explore the response of pepper sugar transporters to adversity stress using a structural equation model. Finally, we found that the MST, SUT, and SWEET families are collectively involved in balancing pepper resistance to abiotic stress by coordinating the expression strengths of different family members. Our study may contribute to the functional study of pepper sugar transporter genes and create the prospect of utilizing sugar transporter gene resources to improve pepper variety. Full article
(This article belongs to the Section Horticultural Science and Ornamental Plants)
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<p>Distribution of the sugar transporter on the chromosome in pepper (<span class="html-italic">Capsicum annuum</span>). (<b>A</b>) All sugar transporter members were located on chromosomes. (<b>B</b>) Distribution of genes on the double strand. The chromosome numbers and sizes (Mb) are indicated at the bottom of each chromosome, respectively.</p>
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<p>Duplication and synteny analysis of sugar transporter genes. (<b>A</b>) Schematic representations for the chromosomal distribution and inter-chromosomal relationships of pepper sugar transporter genes. (<b>B</b>) Synteny analysis of sugar transporter genes between pepper and eggplant, rice, and maize. The red lines highlight the synteny sugar transporter gene pairs.</p>
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<p>Heatmap of sugar transporter genes during different pepper fruits. (<b>A</b>) Expression profile of sugar transporter genes in six domesticated (AS, JE, ST, CM, CW, ZU) and four wild (SR, SY, CO, QU) varieties, (<b>B</b>) ten pepper varieties, (<b>C</b>) and pepper fruit developmental stages (0DAA, 10DAA, 20DAA, 30DAA, 40DAA, 50DAA, 60DAA; DAA: days after anthesis) [<a href="#B33-plants-13-01825" class="html-bibr">33</a>]. The values in the image of heatmap are the averages of three biological replicates (log2(TMM + 1)). The images depicted in the manuscript are only representative of the sample’s appearance, and they are not to scale.</p>
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<p>Expression profile of sugar transporter genes in SJ11-3 and 06g19-1-1-1. (<b>A</b>) Heatmap of sugar transporter genes and (<b>B</b>) pepper fruit developmental stages (20DAA, 30DAA, 40DAA, 50DAA; DAA: the day after anthesis) [<a href="#B34-plants-13-01825" class="html-bibr">34</a>]. The values in the image of heatmap are the averages of three biological replicates. The images depicted in the manuscript are only representative of the sample’s appearance, and they are not to scale.</p>
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<p>Expression profile of sugar transporter genes in BB3 and Chiltepin. (<b>A</b>) Heatmap of sugar transporter genes and (<b>B</b>) pepper fruit developmental stages (11DAP; 22DAP; 33DAP; 55DAP; DAP: the day after pollination) [<a href="#B35-plants-13-01825" class="html-bibr">35</a>]. The values in the image of heatmap are the averages of three biological replicates. The images depicted in the manuscript are only representative of the sample’s appearance, and they are not to scale.</p>
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<p>Heatmap of transcriptome expression of sugar transporter genes of pepper (CM334) leaves under abiotic stress (heat, cold, salinity, and osmotic) [<a href="#B36-plants-13-01825" class="html-bibr">36</a>]. Each differently colored rectangle of the heatmap represents one gene. The values in the image are the averages of three biological replicates. Leaves were harvested at 3, 6, 12, 24, and 72 h after treatment. Plants (at the six-true-leaf stage) were treated with 50 mL of a 400 mM solution.</p>
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<p>Identification of modules associated with the development periods. (<b>A</b>) Heatmap of the correlation between the module eigengenes and development periods of pepper fruit. (<b>B</b>) Dendrogram of all expressed genes clustered based on the measurement of dissimilarity (1-TOM). The color band shows the results obtained from the automatic single-block analysis. (<b>C</b>) Hierarchical clustering among all repeat samples based on all expressed genes.</p>
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<p>Mantel test analysis of the three sugar transporter families. (<b>A</b>) Correlation between <span class="html-italic">SUT</span>, <span class="html-italic">SWEET</span>, and <span class="html-italic">MST</span> gene families based on expression data of pepper fruit in different varieties. (<b>B</b>) Correlation between <span class="html-italic">SUT</span>, <span class="html-italic">SWEET</span>, and <span class="html-italic">MST</span> gene families based on expression data of pepper leaf in CM334 under stresses. Edge width corresponds to Mantel’s r statistic for the corresponding distance correlations, and edge color denotes the statistical significance. Pairwise comparisons of intestinal <span class="html-italic">MST</span> family members are shown, with a color gradient denoting Pearson’s correlation coefficient.</p>
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<p>PLS-SEM analysis of pepper sugar transporters and the expression of manifest variables. (<b>A</b>) PLS-SEM analysis of pepper sugar transporters. The brown ovals represent latent variables, and the number on the arrows indicates the path coefficient. (<b>B</b>) The expression of manifest variables. Genes expressed in all samples (leaf) under treatments were selected for PLS-SEM analysis (Partial Least Squares Structural Equation Modeling). Each gene is considered as a manifest variable. The 10 genes with the highest expression levels under mannitol treatment were selected for qPCR analysis (*: <span class="html-italic">p</span> ≤ 0.05; **: <span class="html-italic">p</span> ≤ 0.01; ns: <span class="html-italic">p</span> &gt; 0.05). The values in the image are the averages of three biological replicates. Plants (at the six-true-leaf stage) were treated with 400 mM mannitol solution, and water was applied to the corresponding control group. Leaves were harvested at 24 h after treatment.</p>
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14 pages, 323 KiB  
Article
Whole-Exome Sequencing in Family Trios Reveals De Novo Mutations Associated with Type 1 Diabetes Mellitus
by Mira Mousa, Sara Albarguthi, Mohammed Albreiki, Zenab Farooq, Sameeha Sajid, Sarah El Hajj Chehadeh, Gihan Daw ElBait, Guan Tay, Asma Al Deeb and Habiba Alsafar
Biology 2023, 12(3), 413; https://doi.org/10.3390/biology12030413 - 7 Mar 2023
Cited by 1 | Viewed by 2871
Abstract
Type 1 diabetes mellitus (T1DM) is a chronic autoimmune disease characterized by insulin deficiency and loss of pancreatic islet β-cells. The objective of this study is to identify de novo mutations in 13 trios from singleton families that contribute to the genetic basis [...] Read more.
Type 1 diabetes mellitus (T1DM) is a chronic autoimmune disease characterized by insulin deficiency and loss of pancreatic islet β-cells. The objective of this study is to identify de novo mutations in 13 trios from singleton families that contribute to the genetic basis of T1DM through the application of whole-exome sequencing (WES). Of the 13 families sampled for this project, 12 had de novo variants, with Family 7 having the highest number (nine) of variants linked to T1DM/autoimmune pathways, whilst Family 4 did not have any variants past the filtering steps. There were 10 variants of 7 genes reportedly associated with T1DM (MST1; TDG; TYRO3; IFIHI; GLIS3; VEGFA; TYK2). There were 20 variants of 13 genes that were linked to endocrine, metabolic, or autoimmune diseases. Our findings demonstrate that trio-based WES is a powerful approach for identifying new candidate genes for the pathogenesis of T1D. Genotyping and functional annotation of the discovered de novo variants in a large cohort is recommended to ascertain their association with disease pathogenesis. Full article
9 pages, 1906 KiB  
Article
The Promoter Region of the Proto-Oncogene MST1R Contains the Main Features of G-Quadruplexes Formation
by Coralie Robert, Julien Marquevielle and Gilmar F. Salgado
Int. J. Mol. Sci. 2022, 23(21), 12905; https://doi.org/10.3390/ijms232112905 - 26 Oct 2022
Cited by 4 | Viewed by 1748
Abstract
MST1R (RON) is a receptor of the MET tyrosine kinase receptor family involved in several cancers such as pancreas, breast, ovary, colon, and stomach. Some studies have shown that overexpression of MST1R increases the migratory and invasive properties of cancer cells. The promoter [...] Read more.
MST1R (RON) is a receptor of the MET tyrosine kinase receptor family involved in several cancers such as pancreas, breast, ovary, colon, and stomach. Some studies have shown that overexpression of MST1R increases the migratory and invasive properties of cancer cells. The promoter region of the oncogene MST1R is enriched in guanine residues that can potentially form G-quadruplexes (G4s), as it was observed in other oncogenic promoters such as KRAS and c-MYC. There is abundant literature that links the presence of G4s in promoter regions of oncogenes to diverse gene regulation processes that are not well understood. In this work, we have studied the reverse and forward sequence of MST1R promoter region using the G4Hunter software and performed biophysical studies to characterize the best scored sequences. Full article
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Graphical abstract

Graphical abstract
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<p>(<b>A</b>) Schematic representation of the G-quadruplexes formed within MST1R promoter region and their potential role on transcription. (<b>B</b>) Downstream signaling pathways after MST1R activation by dimerization and phosphorylation upon binding of MSP ligand.</p>
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<p>(<b>A</b>) CD spectra of reverse and forward MST1R G4 forming sequences at 37 °C exhibiting parallel (R2, R4, R5, F1 and F5), antiparallel (F2), hybrid conformation (F3, F4) and a partial antiparallel or mixture (R1 and R3). (<b>B</b>) UV-melting spectra of reverse and forward MST1R G-quadruplexes forming sequences at 295 nm from 10 °C to 90 °C. All experiments were performed in buffer 1× (50 mM KCl; 10 mM KPi; pH 6.6).</p>
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<p>Native gel electrophoresis experiment of reverse sequences R1, R2, R3, R4, R5 and forward sequences F1, F2, F3, F4, F5 compared to a low molecular weight DNA ladder. R3, R4, F2 and F4 seem to form intramolecular G-quadruplexes whereas all other sequences form intermolecular structures. Native gel experiments were performed at 4 °C with 15% acrylamide/bisacrylamide (19:1 ratio) gels.</p>
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<p>MST1R reverse and forward sequences imino region at 37 °C showing results in agreement with native gel experiment. R1, F2 and F4 exhibit spectra with quite well-resolved peak supporting the formation of three-tetrad G-quadruplexes. Looking to the medium-broad 1D NMR profile, some monomeric species seems to be in equilibrium between different conformers (R3 and F4), whereas the other seems to form higher molecular weight complexes. R1 seems to form a bimolecular quadruplex. All experiments were performed in buffer 1× (50 mM KCl; 10 mM KPi; pH 6.6).</p>
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15 pages, 737 KiB  
Article
Mediating Effects of Discipline Approaches on the Relationship between Parental Mental Health and Adolescent Antisocial Behaviours: Retrospective Study of a Multisystemic Therapy Intervention
by Leartluk Nuntavisit and Mark Porter
Int. J. Environ. Res. Public Health 2022, 19(20), 13418; https://doi.org/10.3390/ijerph192013418 - 17 Oct 2022
Viewed by 2340
Abstract
Poor parental mental health is one of the risk factors for child emotional and behavioural problems because it reduces caregiver’s ability to provide appropriate care for their child. This study aimed to measure changes in parenting factors and adolescent behaviours after Multisystemic Therapy [...] Read more.
Poor parental mental health is one of the risk factors for child emotional and behavioural problems because it reduces caregiver’s ability to provide appropriate care for their child. This study aimed to measure changes in parenting factors and adolescent behaviours after Multisystemic Therapy (MST), and to explore the mediating role of discipline approaches on the relationship between parental mental health and adolescent behavioural problems. This retrospective study extracted data collected from 193 families engaged with the MST research program during 2014–2019. Data was collected at different time points (pre-treatment, post-treatment, 6- and 12-months follow-up). Statistically significant changes were found in adolescent behaviours and parenting factors following the MST intervention and these positive changes were maintained over the following 12 months. Results of the parallel multiple mediator model analysis confirmed mediating effects of discipline approaches on the relationship between parental mental health and adolescent’s behavioural problems. The findings suggested that parental mental well-being significantly contributes to effectiveness of parenting, which resulted in positive changes in adolescent’s behavioural problems. It is recommended caregiver’s parental skills and any mental health issues are addressed during the intervention to enhance positive outcomes in adolescent behaviour. Full article
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<p>A conceptual diagram of the parallel multiple mediator model.</p>
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<p>% of caregivers who reported DASS in clinical range at baseline, post-treatment, 6-month and 12 month follow-up (<span class="html-italic">n</span> = 193).</p>
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<p>Parental discipline approaches and monitoring skill as mediators of the relationship between parental mental health and adolescent behavioural problems. Note: <span class="html-italic">c</span> = total effect, <span class="html-italic">c’</span> = direct effect, * <span class="html-italic">p &lt;</span> 0.05, ** <span class="html-italic">p</span> &lt; 0.01.</p>
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12 pages, 236 KiB  
Article
The Multilevel Pathway in MSTs for the Evaluation and Treatment of Parents and Minor Victims of ACEs: Qualitative Analysis of the Intervention Protocol
by Luna Carpinelli, Daniela D’Elia and Giulia Savarese
Children 2022, 9(3), 358; https://doi.org/10.3390/children9030358 - 4 Mar 2022
Cited by 1 | Viewed by 2276
Abstract
Background: Adverse childhood experiences (ACEs) may be an important risk factor for the onset of developmental psychopathological disorders. Families involved in ACEs are often the subject of social or welfare policies aimed solely at the victim, without a proper consideration of family functionality. [...] Read more.
Background: Adverse childhood experiences (ACEs) may be an important risk factor for the onset of developmental psychopathological disorders. Families involved in ACEs are often the subject of social or welfare policies aimed solely at the victim, without a proper consideration of family functionality. Methods: We describe the results of an Italian intervention project, which aimed to reinforce both the local networking of the Campania region, and the skills of the operators involved in actions to prevent and combat ACEs. The project was characterized by different phases and two actions, namely: (1) diagnosis and therapy aimed at child victims of ACEs and their families; (2) supervision of the operators of the multidisciplinary specialized teams (MSTs). Results: 99% of the cases under review were characterized by intra-family violence; 34% suffered psychological abuse, 33% neglect, 23% inappropriate care, 4% sexual abuse, 3% excessive care and 3% physical abuse. Conclusions: Thanks to the interventions carried out, severe and chronic ACE situations were recognized, and processes of de-institutionalization and the construction of life projects were carried out in accordance with the territorial services. This offered child victims and their families an opportunity to restore the conditions of well-being, both for the growth of the individual and the family system. Full article
12 pages, 1006 KiB  
Article
Deciphering Promoter Hypermethylation of Genes Encoding for RASSF/Hippo Pathway Reveals the Poor Prognostic Factor of RASSF2 Gene Silencing in Colon Cancers
by Marc Riffet, Yassine Eid, Maxime Faisant, Audrey Fohlen, Benjamin Menahem, Arnaud Alves, Fatéméh Dubois, Guénaelle Levallet and Céline Bazille
Cancers 2021, 13(23), 5957; https://doi.org/10.3390/cancers13235957 - 26 Nov 2021
Cited by 3 | Viewed by 1994
Abstract
The aims of this study were to assess the frequency of promoter hypermethylation of the genes encoding the Ras associated domain family (RASSF)/Hippo pathway, as well as the impact on overall (OS) and progression-free survival (PFS) in a single-center retrospective cohort of 229 [...] Read more.
The aims of this study were to assess the frequency of promoter hypermethylation of the genes encoding the Ras associated domain family (RASSF)/Hippo pathway, as well as the impact on overall (OS) and progression-free survival (PFS) in a single-center retrospective cohort of 229 patients operated on for colon cancers. Hypermethylation status was investigated by methylation-specific PCR on the promoters of the RASSF1/2, STK4/3 (encoding Mammalian Ste20-like protein 1 and 2 (MST1 and 2), respectively), and LATS1/2 genes. Clinicopathological characteristics, recurrence-free survival, and overall survival were analysed. We found the RASSF/Hippo pathway to be highly silenced in colon cancer, and particularly RASSF2 (86%). The other promoters were hypermethylated with a lesser frequency of 16, 3, 1, 10 and 6%, respectively for RASSF1, STK4, STK3, LATS1, and LATS2 genes. As the hypermethylation of one RASSF/Hippo family member was by no means exclusive from the others, 27% of colon cancers displayed the hypermethylation of at least two RASSF/Hippo member promotors. The median overall survival of the cohort was 60.2 months, and the median recurrence-free survival was 46.9 months. Survival analyses showed a significantly poorer overall survival of patients when the RASSF2 promoter was hypermethylated (p = 0.03). The median OS was 53.5 months for patients with colon cancer with a hypermethylated RASSF2 promoter versus still not reached after 80 months follow-up for other patients, upon univariate analysis (HR = 1.86, [95% CI: 1.05–3.3], p < 0.03). Such difference was not significant for relapse-free survival as in multivariate analysis. A logistic regression model showed that RASSF2 hypermethylation was an independent factor. In conclusion, RASSF2 hypermethylation is a frequent event and an independent poor prognostic factor in colon cancer. This biomarker could be investigated in clinical practice. Full article
(This article belongs to the Collection New Treatment for Colorectal Cancer)
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<p>Heat map of RASSF/Hippo signaling pathway data decryption by staging.</p>
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<p><span class="html-italic">RASSF2</span> gene promoter hypermethylation predicts worse overall survival in 229 patients with colon cancer. (<b>A</b>) Methylation analysis in 10 colon cancer cases. Lane U: amplified product with primers recognizing unmethylated sequence; Lane M: amplified product with primers recognizing methylated sequence. Control “M”: positive control for hypermethylation; Control “U”: positive control for unmethylation (lymphocyte DNA); H<sub>2</sub>O: negative control. The ladder (L) saw at the first lane is 50 bp. (<b>B</b>) Diagram of the consequences of the silencing of <span class="html-italic">RASSF2</span> on the nuclear expression of YAP and TAZ in colonic cancer cells. (<b>C</b>) <span class="html-italic">RASSF2</span> gene promoter hypermethylation impact on overall survival in patients with colon cancer.</p>
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22 pages, 3012 KiB  
Article
Insight into the Binding and Hydrolytic Preferences of hNudt16 Based on Nucleotide Diphosphate Substrates
by Magdalena Chrabąszczewska, Maria Winiewska-Szajewska, Natalia Ostrowska, Elżbieta Bojarska, Janusz Stępiński, Łukasz Mancewicz, Maciej Łukaszewicz, Joanna Trylska, Michał Taube, Maciej Kozak, Edward Darżynkiewicz and Renata Grzela
Int. J. Mol. Sci. 2021, 22(20), 10929; https://doi.org/10.3390/ijms222010929 - 10 Oct 2021
Cited by 7 | Viewed by 2338
Abstract
Nudt16 is a member of the NUDIX family of hydrolases that show specificity towards substrates consisting of a nucleoside diphosphate linked to another moiety X. Several substrates for hNudt16 and various possible biological functions have been reported. However, some of these reports contradict [...] Read more.
Nudt16 is a member of the NUDIX family of hydrolases that show specificity towards substrates consisting of a nucleoside diphosphate linked to another moiety X. Several substrates for hNudt16 and various possible biological functions have been reported. However, some of these reports contradict each other and studies comparing the substrate specificity of the hNudt16 protein are limited. Therefore, we quantitatively compared the affinity of hNudt16 towards a set of previously published substrates, as well as identified novel potential substrates. Here, we show that hNudt16 has the highest affinity towards IDP and GppG, with Kd below 100 nM. Other tested ligands exhibited a weaker affinity of several orders of magnitude. Among the investigated compounds, only IDP, GppG, m7GppG, AppA, dpCoA, and NADH were hydrolyzed by hNudt16 with a strong substrate preference for inosine or guanosine containing compounds. A new identified substrate for hNudt16, GppG, which binds the enzyme with an affinity comparable to that of IDP, suggests another potential regulatory role of this protein. Molecular docking of hNudt16-ligand binding inside the hNudt16 pocket revealed two binding modes for representative substrates. Nucleobase stabilization by Π stacking interactions with His24 has been associated with strong binding of hNudt16 substrates. Full article
(This article belongs to the Special Issue The Role of Hydrolases in Biology and Xenobiotics Metabolism)
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<p>HPLC chromatograms for the hydrolysis of GppG catalyzed by hNudt16. (<b>A</b>) GppG in buffer (without hNudt16), (<b>B</b>) after 2 min reaction with hNudt16, (<b>C</b>) after 8 min reaction with hNudt16. Substrate concentration was 20 µM, enzyme concentration 0.002 µM. Chromatogram (<b>A</b>) was obtained after five-minute substrate incubation at 95 °C to show that heat inactivation of the enzyme in the assay buffer does not lead nonenzymatic degradation of GppG.</p>
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<p>(<b>A</b>) CD spectra for wild-type hNudt16 and studied mutants. (<b>B</b>) Contribution of secondary structures in the polypeptide chain obtained from CD measurements (calculated in BeStSel) in comparison to the corresponding crystal structure.</p>
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<p>Representative MST pseudo-titration data for binding of GppG to hNudt16E76Q. Squares represent experimental points, solid lines represent results of fitting for two independent binding sites model, and gray area bounded by a dashed line represents 95% confidence bands for this model. See <a href="#app1-ijms-22-10929" class="html-app">Figure S4</a> for other ligands data.</p>
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<p>Comparison of the free energy associated with the dissociation of the complex (ΔG<sub>diss</sub>) calculated for stronger binding site (with K<sub>d1</sub> obtained from MST) with ΔT<sub>m</sub> obtained from dye-free and DSF with dye measurements for tested hNudt16E76Q-ligand pairs.</p>
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<p>SAXS data analysis for hNudt16: (<b>A</b>) Comparison of experimental SAXS data for hNudt16 in solution with a fit for all crystal structures of hNudt16 dimer available in the PDB database. Theoretical scattering curves for PDB structures and discrepancy χ value (compared to SAXS data) were obtained in CRYSOL. PDB: 2XSQ had the lowest discrepancy with experimental SAXS data; (<b>B</b>) pair distance distribution function (<span class="html-italic">p</span>(R)) determined based on SAXS scattering curve for the hNudt16 (calculated in GNOM software). The calculated structural parameters were R<sub><span class="html-italic">g</span></sub> = 24.16 Å and D<sub>max</sub> = 79.22 Å; (<b>C</b>) superposition of low-resolution 3D model of hNudt16 in solution (semitransparent shape) with the crystal structure of dimeric hNudt16 PDB: 2XSQ in projections along the two axes of the molecule. Monomer-like subunits of 2XSQ dimer are marked with different colors (light and dark blue). Figures obtained in PyMOL.</p>
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<p>Top: IDP and GppG bound to hNudt16 in docking (<b>A</b>) mode 1 and (<b>B</b>) mode 2. Bottom: Schematic illustration of IDP interactions in (<b>C</b>) mode 1 and (<b>D</b>) mode 2.</p>
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<p>(<b>A</b>,<b>B</b>) Conformations of GppG and AppA bound to hNudt16 in mode 1. GppG remains in its active conformation, whereas adenine positions are less stabilized and one of the AppA adenines either stays inside (<b>A</b>) or flips out (<b>B</b>) of the pocket (marked with three residues, His24, Phe57 and Gln170 in ball and stick representation in gray). (<b>C</b>,<b>D</b>) Schematic illustration of GppG and AppA interactions in active conformations of mode 1 (ligand conformations as in (<b>A</b>)). (<b>E</b>) Comparison of the ligand positions in active conformations of mode 1: a very good hNudt16 substrate, GppG, vs. the conformation of a poor substrate, ADPr (ADPr position is from the PDB:5W6X structure). (<b>F</b>) Schematic illustration of ADPr interactions with hNudt16.</p>
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9 pages, 801 KiB  
Article
Saliva Molecular Testing for SARS-CoV-2 Surveillance in Two Italian Primary Schools
by Daniela Carmagnola, Gaia Pellegrini, Elena Canciani, Dolaji Henin, Mariachiara Perrotta, Federica Forlanini, Lucia Barcellini and Claudia Dellavia
Children 2021, 8(7), 544; https://doi.org/10.3390/children8070544 - 24 Jun 2021
Cited by 8 | Viewed by 1927
Abstract
Background: No evidence has so far proven a significant role of schools in SARS-CoV-2 transmission, while the negative effects of their closure on children and adolescents are well documented. Surveillance, by means of frequent students and staff testing, has been advocated in order [...] Read more.
Background: No evidence has so far proven a significant role of schools in SARS-CoV-2 transmission, while the negative effects of their closure on children and adolescents are well documented. Surveillance, by means of frequent students and staff testing, has been advocated in order to implement school safety. Our aim was to report the results of a school surveillance program for the early detection of SARS-CoV-2 infection in pre- and asymptomatic subjects, by means of molecular salivary testing (MST). Methods: School surveillance in two schools in Milan, Italy, was carried out for six weeks. Each participant received a saliva collection kit, to be self-performed. Results: 401 students and 12 teachers were enrolled, and 5 positive children in 5 different classes were observed. All the cases were asymptomatic. Their nasopharyngeal swab was positive on the same day in four cases, while in one case it resulted negative on the same day and positive 3 days later. In one positive case, the whole family was set under surveillance. The positive child did not develop symptoms and no family member was infected. Conclusions: MST might represent an efficient way to actively survey communities in order to detect asymptomatic cases, thus limiting SARS-CoV-2 transmission. Full article
(This article belongs to the Section Global Pediatric Health)
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<p>Picture of the cotton roll inserted under the tongue to collect and promote saliva production (<b>A</b>) and in the lower vestibular space (<b>B</b>).</p>
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<p>Overview of the COVID-19-related quarantine trend during the first school term. The graphic shows the number of classes, students and teachers starting and ending the 14 days quarantine. In the red boxes, a photo of the situation at the beginning of the surveillance. At the left of the red boxes the quarantine and transmission status before the start of the surveillance, and at the right the status after.</p>
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23 pages, 5261 KiB  
Article
Effect of Posttranslational Modifications on the Structure and Activity of FTO Demethylase
by Michał Marcinkowski, Tomaš Pilžys, Damian Garbicz, Jan Piwowarski, Damian Mielecki, Grzegorz Nowaczyk, Michał Taube, Maciej Gielnik, Maciej Kozak, Maria Winiewska-Szajewska, Ewa Szołajska, Janusz Dębski, Agnieszka M. Maciejewska, Kaja Przygońska, Karolina Ferenc, Elżbieta Grzesiuk and Jarosław Poznański
Int. J. Mol. Sci. 2021, 22(9), 4512; https://doi.org/10.3390/ijms22094512 - 26 Apr 2021
Cited by 2 | Viewed by 3203
Abstract
The FTO protein is involved in a wide range of physiological processes, including adipogenesis and osteogenesis. This two-domain protein belongs to the AlkB family of 2-oxoglutarate (2-OG)- and Fe(II)-dependent dioxygenases, displaying N6-methyladenosine (N6-meA) demethylase activity. The aim of [...] Read more.
The FTO protein is involved in a wide range of physiological processes, including adipogenesis and osteogenesis. This two-domain protein belongs to the AlkB family of 2-oxoglutarate (2-OG)- and Fe(II)-dependent dioxygenases, displaying N6-methyladenosine (N6-meA) demethylase activity. The aim of the study was to characterize the relationships between the structure and activity of FTO. The effect of cofactors (Fe2+/Mn2+ and 2-OG), Ca2+ that do not bind at the catalytic site, and protein concentration on FTO properties expressed in either E. coli (ECFTO) or baculovirus (BESFTO) system were determined using biophysical methods (DSF, MST, SAXS) and biochemical techniques (size-exclusion chromatography, enzymatic assay). We found that BESFTO carries three phosphoserines (S184, S256, S260), while there were no such modifications in ECFTO. The S256D mutation mimicking the S256 phosphorylation moderately decreased FTO catalytic activity. In the presence of Ca2+, a slight stabilization of the FTO structure was observed, accompanied by a decrease in catalytic activity. Size exclusion chromatography and MST data confirmed the ability of FTO from both expression systems to form homodimers. The MST-determined dissociation constant of the FTO homodimer was consistent with their in vivo formation in human cells. Finally, a low-resolution structure of the FTO homodimer was built based on SAXS data. Full article
(This article belongs to the Section Molecular Toxicology)
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<p>FTO architecture, specificity and functions. (<b>A</b>) Physiological functions affected by FTO. Green—physiological processes. Red—defects caused by FTO over-activity. Purple—defects caused by deficit of FTO activity; (<b>B</b>) demethylation reaction performed by FTO; (<b>C</b>) <span class="html-italic">N</span><sup>6</sup>-meA<sub>m</sub>—the preferred FTO substrate (description in the text); (<b>D</b>) domain architecture of FTO protein.</p>
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<p>Purification and characterization of FTO proteins. (<b>A</b>) SDS-PAGE analysis of <sup>EC</sup>FTO and <sup>BSE</sup>FTO purification. <span class="html-italic">E. coli</span> BL21 carrying empty pET-28a(+) plasmid is a negative control. L—7.5 µL of cell lysate, M—molecular marker, P—purified <sup>EC</sup>FTO (42 µg), <sup>BES</sup>FTO (17 µg), or negative control. (<b>B</b>) Enzymatic activity of <sup>EC</sup>FTO, <sup>BES</sup>FTO and <sup>EC</sup>FTO<sup>S256D</sup> mutant based on chemiluminescence assay. <span class="html-italic">N</span><sup>6</sup>-meA was used as a substrate. Relative activity is referenced to activity of 1 µg of <sup>EC</sup>FTO (100%). Data are represented as points and means with whiskers showing standard deviation. n—number of samples. ** <span class="html-italic">p</span> &lt; 0.05. (<b>C</b>) NanoDSF analysis of the thermal stability of purified <sup>EC</sup>FTO and <sup>BES</sup>FTO in the absence (apo) or presence of Mn<sup>2+</sup> and 2-OG (holo). Left and middle, ratio of emissions (bold lines) and first derivative (thin lines) curves as a function of temperature. All four protein samples display two unfolding transitions (red dots): one (T<sub>m1</sub>) less prominent, at a lower temperature, and the second (T<sub>m2</sub>) clearer at a higher temperature. Right, gathered data represented as boxplots. The box represents the interquartile range. Whiskers show the highest and the lowest data points. The horizontal line within a box represents the median value. n—number of samples. ** <span class="html-italic">p</span> &lt; 0.05.</p>
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<p>Location of phosphoserines identified in <sup>BES</sup>FTO. The modifications (green) are located only in the N-terminal domain (blue); the C-terminal domain is in orange. The FTO protein structure was modelled basing on the PDB4IE5 record.</p>
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<p>The effect of Ca<sup>2+</sup> on FTO parameters. (<b>A</b>) DSF analysis of the Ca<sup>2+</sup> effect on the thermal stability of <sup>BES</sup>FTO in the absence (apo) or presence of Mn<sup>2+</sup> and 2-OG (holo). Left, ratio of emissions (bold lines) and first derivative (thin lines) curves are shown as a function of temperature. All four protein samples display one distinct unfolding transition (red dots). Data gathered on the right are shown as boxplots. Box represents the interquartile range. Whiskers show the highest and lowest data points. The horizontal line within a box represents the median of the data. n—number of samples. A. U.—arbitrary units. ** <span class="html-italic">p</span> &lt; 0.05. (<b>B</b>) HDX analysis of the Ca<sup>2+</sup> effect on the solvent accessibility of <sup>BES</sup>FTO after 1-h incubation with deuterium water. Differences between the exchange levels of individual peptides (each rectangle with whiskers represent one peptide) in samples with and without calcium are shown. Statistically significant differences (<span class="html-italic">p</span> &lt; 0.05) in peptide accessibility are marked in purple. Two regions of <sup>BES</sup>FTO are more stable in Ca<sup>2+</sup> presence, comprising residues 120–155 and 240–310. Each experimental setup was repeated four times. (<b>C</b>) Location of Ca<sup>2+</sup>-stabilized regions in the FTO molecule colored according to HDX data. Regions with significant exchange are marked in red and purple; the Ca<sup>2+</sup> binding part of the first region is marked in pink. The two protein regions stabilized by Ca<sup>2+</sup> lie close to each other in the structure. The FTO protein structure was modelled based on the PDB4IE5 record.</p>
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<p>Effect of Ca<sup>2+</sup> on enzymatic activity of FTO by chemiluminescence assay. Relative activity is referenced to the activity of 1 µg <sup>EC</sup>FTO (<b>A</b>) or <sup>BES</sup>FTO (<b>B</b>) (100%). The <span class="html-italic">N</span><sup>6</sup>-meA was used as a substrate. Data are represented as points and means, with the whiskers showing sample standard deviation. n—number of samples. ** <span class="html-italic">p</span> &lt; 0.05, * <span class="html-italic">p</span> &lt; 0.1.</p>
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<p>Gel filtration chromatography of <sup>EC</sup>FTO (blue) and <sup>BES</sup>FTO (orange) in the presence of 0.5 mM Mn<sup>2+</sup> and 1 mM 2-OG. Chromatograms show the presence of both versions of FTO in fractions corresponding to two state of the protein: the one clearly monomeric (peak around 50 kDa) and the second one (peak around 80 kDa) where the dynamic dimer/monomer equilibrium occurs.</p>
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<p>SAXS structural analysis of FTO homodimer. (<b>A</b>) Low resolution (~12–20 Å) model of the <sup>BES</sup>FTO homodimer and its parameters obtained from SAXS data: MW—molecular weight of molecule, Rg Guinier—radius of gyration, Rg P(r)—radius pair distance distribution, Dmax—maximum dimension (<b>B</b>) Fitting of scattering data to ten best dimer structures generated in silico by SymmDock server. I—scattering intensity, Q—scattering vector. (<b>C</b>,<b>D</b>) The two best-fitting models of the FTO dimer, with monomers interacting via their C-terminal domains (<b>C</b>) or N-terminal domains (<b>D</b>), generated in silico with the SymmDock server (orange–blue ribbon structures) superimposed on the low resolution experimental structure (light blue).</p>
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<p>FTO dimer selection based on HDX data. (<b>A</b>) HDX profile of <sup>BES</sup>FTO in the presence of Fe<sup>2+</sup> and 2-OG, showing distribution of peptides (rectangles) colored according to the hydrogen exchange extent after 1 h. Two regions are substantially less solvent-accessible than the rest of the protein, residues 130–160 and 330–420. (<b>B</b>) Model of FTO homodimer connected through C-domains presented in <a href="#ijms-22-04512-f007" class="html-fig">Figure 7</a>C, colored according to HDX exchange ratio.</p>
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<p>MST analysis of <sup>EC</sup>FTO (blue) and <sup>BES</sup>FTO (orange) dimerization in the presence of Fe<sup>2+</sup> and 2-OG. The difference between the <span class="html-italic">K</span><sub>D</sub> values for <sup>EC</sup>FTO and <sup>BES</sup>FTO is not statistically significant. The plot represents the dimer level of the labeled protein at a given FTO concentration for each separate sample (data points) and for modeled equilibrium between monomer and dimer (straight lines). <span class="html-italic">K</span><sub>D</sub> are shown as estimated value ± standard deviation. n—number of repetitions.</p>
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14 pages, 930 KiB  
Review
Hippo Signaling Pathway in Gliomas
by Konstantin Masliantsev, Lucie Karayan-Tapon and Pierre-Olivier Guichet
Cells 2021, 10(1), 184; https://doi.org/10.3390/cells10010184 - 18 Jan 2021
Cited by 67 | Viewed by 8341
Abstract
The Hippo signaling pathway is a highly conserved pathway involved in tissue development and regeneration that controls organ size through the regulation of cell proliferation and apoptosis. The core Hippo pathway is composed of a block of kinases, MST1/2 (Mammalian STE20-like protein kinase [...] Read more.
The Hippo signaling pathway is a highly conserved pathway involved in tissue development and regeneration that controls organ size through the regulation of cell proliferation and apoptosis. The core Hippo pathway is composed of a block of kinases, MST1/2 (Mammalian STE20-like protein kinase 1/2) and LATS1/2 (Large tumor suppressor 1/2), which inhibits nuclear translocation of YAP/TAZ (Yes-Associated Protein 1/Transcriptional co-activator with PDZ-binding motif) and its downstream association with the TEAD (TEA domain) family of transcription factors. This pathway was recently shown to be involved in tumorigenesis and metastasis in several cancers such as lung, breast, or colorectal cancers but is still poorly investigated in brain tumors. Gliomas are the most common and the most lethal primary brain tumors representing about 80% of malignant central nervous system neoplasms. Despite intensive clinical protocol, the prognosis for patients remains very poor due to systematic relapse and treatment failure. Growing evidence demonstrating the role of Hippo signaling in cancer biology and the lack of efficient treatments for malignant gliomas support the idea that this pathway could represent a potential target paving the way for alternative therapeutics. Based on recent advances in the Hippo pathway deciphering, the main goal of this review is to highlight the role of this pathway in gliomas by a state-of-the-art synthesis. Full article
(This article belongs to the Special Issue Molecular and Cellular Mechanisms of Cancers: Glioblastoma)
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<p>Canonical Hippo signaling pathway in mammals.</p>
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<p>Modulations of Hippo signaling in gliomas.</p>
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17 pages, 1745 KiB  
Article
The Impact of Antimicrobial Substances on the Methanogenic Community during Methane Fermentation of Sewage Sludge and Cattle Slurry
by Izabela Koniuszewska, Małgorzata Czatzkowska, Monika Harnisz and Ewa Korzeniewska
Appl. Sci. 2021, 11(1), 369; https://doi.org/10.3390/app11010369 - 1 Jan 2021
Cited by 11 | Viewed by 2879
Abstract
This study showed the effect of amoxicillin (AMO), and oxytetracycline (OXY) at a concentration of 512 µg mL−1, and sulfamethoxazole (SMX), and metronidazole (MET) at a concentration of 1024 µg mL−1 on the efficiency of anaerobic digestion (AD) of sewage [...] Read more.
This study showed the effect of amoxicillin (AMO), and oxytetracycline (OXY) at a concentration of 512 µg mL−1, and sulfamethoxazole (SMX), and metronidazole (MET) at a concentration of 1024 µg mL−1 on the efficiency of anaerobic digestion (AD) of sewage sludge (SS) and cattle slurry (CS). The production of biogas and methane (CH4) content, and the concentration of volatile fatty acids (VFAs) was analyzed in this study. Other determinations included the concentration of the mcrA gene, which catalyzes the methanogenesis, and analysis of MSC and MST gene concentration, characteristic of the families Methanosarcinaceae and Methanosaetaceae (Archaea). Both substrates differed in the composition of microbial communities, and in the sensitivity of these microorganisms to particular antimicrobial substances. Metronidazole inhibited SS fermentation to the greatest extent (sixfold decrease in biogas production and over 50% decrease in the content of CH4). The lowest concentrations of the mcrA gene (106 gD−1) were observed in CS and SS digestates with MET. A decline in the number of copies of the MSC and MST genes was noted in most of the digestate samples with antimicrobials supplementation. Due to selective pressure, antimicrobials led to a considerably lowered efficiency of the AD process and induced changes in the structure of methanogenic biodiversity. Full article
(This article belongs to the Special Issue Intensified Conversion of Organic Waste into Biogas)
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<p>Heatmap with the logged values of methane production (L kg<sup>−1</sup> VS) and VFAs concentrations (g L<sup>−1</sup>) in process and control bioreactors with sewage sludge (SS) and cattle slurry (CS). (SSC) control samples of sewage sludge, (CSC) control samples of cattle slurry.</p>
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<p>Average concentrations of <span class="html-italic">mcr</span>A, <span class="html-italic">MSC</span> and <span class="html-italic">MST</span> genes in 1 g<sub>D</sub><sup>−1</sup> of sewage sludge samples (<b>A</b>,<b>C</b>,<b>E</b>, respectively) from the process and control bioreactors and cattle slurry samples (<b>B</b>,<b>D</b>,<b>F</b>, respectively) from the process and control bioreactors. (SSC) control samples of sewage sludge, (CSC) control samples of cattle slurry, (*) indicates statistically significant differences compared to the proper control (<span class="html-italic">p</span> &lt; 0.05).</p>
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<p>Principal component analysis (PCA) based on the distribution of the analyzed genes characteristic of methanogens and parameters of methane fermentation in bioreactors with sewage sludge (SS) and cattle slurry (CS). (SSC) control samples of sewage sludge, (CSC) control samples of cattle slurry.</p>
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<p>Heatmap with the logged concentrations (number of copies in g<sub>D</sub><sup>−1</sup>) of <span class="html-italic">MST</span>, <span class="html-italic">MSC</span> and <span class="html-italic">mcr</span>A genes in process and control bioreactors with sewage sludge (SS) and cattle slurry (CS). (SSC) control samples of sewage sludge, (CSC) control samples of cattle slurry.</p>
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17 pages, 2691 KiB  
Article
Human DDX17 Unwinds Rift Valley Fever Virus Non-Coding RNAs
by Corey R. Nelson, Tyler Mrozowich, Sean M. Park, Simmone D’souza, Amy Henrickson, Justin R. J. Vigar, Hans-Joachim Wieden, Raymond J. Owens, Borries Demeler and Trushar R. Patel
Int. J. Mol. Sci. 2021, 22(1), 54; https://doi.org/10.3390/ijms22010054 - 23 Dec 2020
Cited by 18 | Viewed by 4269
Abstract
Rift Valley fever virus (RVFV) is a mosquito-transmitted virus from the Bunyaviridae family that causes high rates of mortality and morbidity in humans and ruminant animals. Previous studies indicated that DEAD-box helicase 17 (DDX17) restricts RVFV replication by recognizing two primary non-coding RNAs [...] Read more.
Rift Valley fever virus (RVFV) is a mosquito-transmitted virus from the Bunyaviridae family that causes high rates of mortality and morbidity in humans and ruminant animals. Previous studies indicated that DEAD-box helicase 17 (DDX17) restricts RVFV replication by recognizing two primary non-coding RNAs in the S-segment of the genome: the intergenic region (IGR) and 5′ non-coding region (NCR). However, we lack molecular insights into the direct binding of DDX17 with RVFV non-coding RNAs and information on the unwinding of both non-coding RNAs by DDX17. Therefore, we performed an extensive biophysical analysis of the DDX17 helicase domain (DDX17135–555) and RVFV non-coding RNAs, IGR and 5’ NCR. The homogeneity studies using analytical ultracentrifugation indicated that DDX17135–555, IGR, and 5’ NCR are pure. Next, we performed small-angle X-ray scattering (SAXS) experiments, which suggested that DDX17 and both RNAs are homogenous as well. SAXS analysis also demonstrated that DDX17 is globular to an extent, whereas the RNAs adopt an extended conformation in solution. Subsequently, microscale thermophoresis (MST) experiments were performed to investigate the direct binding of DDX17 to the non-coding RNAs. The MST experiments demonstrated that DDX17 binds with the IGR and 5’ NCR with a dissociation constant of 5.77 ± 0.15 µM and 9.85 ± 0.11 µM, respectively. As DDX17135–555 is an RNA helicase, we next determined if it could unwind IGR and NCR. We developed a helicase assay using MST and fluorescently-labeled oligos, which suggested DDX17135–555 can unwind both RNAs. Overall, our study provides direct evidence of DDX17135–555 interacting with and unwinding RVFV non-coding regions. Full article
(This article belongs to the Special Issue Non-coding RNAs in Pathogen-Host Interaction)
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<p>(<b>A</b>) Schematic representation of DDX17 highlighting individual domains. DDX17<sub>135–555</sub>, which contains the Q motif, ATP binding domain, DEAD-box, and the helicase domain, was used in downstream studies. (<b>B</b>) The chromatogram from the size exclusion purification (Superdex 200 Increase gl 10/300) of DDX17<sub>135–555</sub>, suggesting that DDX17<sub>(135–555)</sub> can be purified to ~68% homogeneity (~16 mL). The y-axis represents absorbance at 260 nm while the x-axis represents elution volume. We collected peak fractions from 15.5 to 16.5 mL for subsequent analysis. The inset to <a href="#ijms-22-00054-f001" class="html-fig">Figure 1</a>B represents the SDS-PAGE analysis of DDX17<sub>135–555</sub> (48.45 kDa) following size exclusion chromatography. (<b>C</b>) Sedimentation coefficient distribution of DDX17<sub>135–555</sub> obtained from analytical ultracentrifugation sedimentation velocity (SV-AUC) experiment. The peak at ~3.16S represents monodispersed DDX17<sub>135–555</sub>. Sedimentation coefficient values are corrected to standard solvent conditions (20 °C in water).</p>
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<p>Purification and hydrodynamic characterization of in vitro transcribed Rift Valley fever virus RNA. (<b>A</b>) Size exclusion chromatogram of the elution profile of both Rift Valley fever virus (RVFV) 5’ intergenic region (IGR) and RVFV 5’ non-coding region (NCR). The y-axis represents absorbance at 260 nm while the x-axis represents elution volume. An inset to <a href="#ijms-22-00054-f002" class="html-fig">Figure 2</a>A represents the urea-PAGE (7.5%) analysis of RVFV IGR and 5’ NCR after size exclusion chromatography. Each well represents 10 µL of a 500 µL elution fraction from size exclusion chromatography. The gel was run for 25 min, at 300 V in 0.5× TBE (Tris-Borate-EDTA) running buffer and was visualized using Sybr Safe dye. (<b>B</b>) Sedimentation coefficient distribution profiles for RVFV 5’ IGR (green) and RVFV 5’ NCR (blue) from SV-AUC. The primary SV peaks for each RNA are 4.07 S and 4.18 S for IGR and 5’ NCR, respectively, and represent the monomeric form. Sedimentation coefficient values were corrected to standard conditions (20 °C in water).</p>
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<p>Small-angle X-ray scattering (SAXS) characterization of RVFV RNA (IGR and NCR) and DDX17<sub>135–555</sub>. (<b>A</b>) Merged scattering data of RVFV RNA and DDX17<sub>135–555</sub> showing scattering intensity (log I(q)) vs. scattering angle (q = 4πsinθ/λ). (<b>B</b>) Guinier plots allowing for the determination of R<sub>g</sub> from low-angle region data and representing the homogeneity of samples. (<b>C</b>) Dimensionless Kratky plots (I(q)/I(0)*(q*R<sub>g</sub>)<sup>2</sup> vs. q*R<sub>g</sub>) of RVFV RNA and DDX17<sub>135–555</sub>, demonstrating extended structures for RVFV RNA and a more compact structure for DDX17<sub>135–555</sub>. (<b>D</b>) Pair distance distribution (P(r)) plots for RVFV RNA and DDX17<sub>135–555</sub> which allow for the determination of R<sub>g</sub> from the entire SAXS dataset, and maximal particle dimension (D<sub>max</sub>).</p>
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<p>Low-resolution structure determination via SAXS for RVFV 5’ NCR and RVFV 5’ IGR, indicating that these RNA molecules adopt an extended solution structure. (<b>A</b>,<b>B</b>) Three structures representing sequential 90° rotational angles from the top panel structure. Dimensions represent the D<sub>max</sub> obtained from P(r) analysis.</p>
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<p>Structural modeling of DDX17<sub>135–555</sub>. (<b>A</b>) Low-resolution SAXS structure indicating that DDX17<sub>135–555</sub> adopts an extended globular conformation in solution. The bottom panel represents a 90° rotation of the x-axis from the top panel. Dimensions represent the D<sub>max</sub> from P(r) analysis. (<b>B</b>) CORAL-derived models of DDX17<sub>135–555</sub>, suggesting a linker (purple/gray chain) between the ATP-binding domain (blue ribbon), and the helicase domain (yellow/brown ribbon), allowing them to adopt different orientations. (<b>C</b>) SAXS envelope overlayed with the CORAL-derived representative model highlighting an agreement between high- and low-resolution models.</p>
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<p>Interaction studies of DDX17<sub>135–555</sub> with IGR and 5’ NCR. (<b>A</b>) Microscale thermophoresis (MST) traces indicating the change in fluorescence when exposed to the infrared laser. Each trace represents a different concentration of DDX17<sub>135–555</sub> and is used to assess how the change in concentration affects the fluorescently labeled RNA migration. The blue highlight is the “cold” region and the red highlight is the “hot” region. The difference between these regions is used to calculate the ΔF<sub>norm</sub>. (<b>B</b>) The MST binding curves for the IGR and 5’ NCR RVFV RNAs (n = 3). RNA was used at a concentration of 40 nM while DDX17<sub>135–555</sub> was titrated up to a maximum concentration of 55 µM. The y-axis ΔF<sub>norm</sub> is the change in fluorescent migration normalized to 0. The dissociation constant for DDX17<sub>135–555</sub> and the IGR was determined to be 5.78 ± 0.15 µM (reduced Χ<sup>2</sup> = 0.967, Std. error of regression = 0.702) while for DDX17<sub>135–555</sub> and the 5’ NCR was determined to be 9.85 ± 0.11 µM (reduced Χ<sup>2</sup> = 0.996, Std. error of regression = 0.351). We used polyU RNA as a negative control (black diamonds) that did not bind to DDX17<sub>135–555</sub>.</p>
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<p>DDX17<sub>135–555</sub> helicase assays performed using MST. (<b>A</b>) Representation of helicase assay using MST. The helicase assay was performed by combining the RNAs, fluorescently labeled DNA oligo, DDX17<sub>135–555</sub>, and ATP. DDX17<sub>135–555</sub> hydrolyzes the ATP and unwinds the RNA, giving the oligo access to the newly opened complimentary site. The fluorescently labeled DNA oligo hybridized to the RNA can be measured in the MST by detecting the change in migration. This is compared to a control that uses bovine serum albumin (BSA) instead of DDX17<sub>135–555</sub>, and a change in the migration indicates that the RNA has been unwound by DDX17. (<b>B</b>) Signal to noise ratios of different comparative assays (n = 3). Control compared a reaction mix without protein to BSA, signal to noise did not meet the threshold of 5 and was not significant, unpaired <span class="html-italic">t</span>-test (<span class="html-italic">p</span> = 0.9350, N.S.). DDX17<sub>135–555</sub> caused a significant change in the IGR (<span class="html-italic">p</span> &lt; 0.0001, ****), with the signal to noise ratio reaching 12.5. The 5’ NCR also experienced a significant shift in the presence of DDX17<sub>135–555</sub> (<span class="html-italic">p</span> &lt; 0.0001, ****), having a signal to noise ratio of 9.17. Gray bar represents including ATP vs. not including ATP in the reaction mixture, showing ATP causes a significant change in fluorescent migration, having a signal to noise of 8.70 (<span class="html-italic">p</span> = 0.0059, **).</p>
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35 pages, 2614 KiB  
Review
MOB: Pivotal Conserved Proteins in Cytokinesis, Cell Architecture and Tissue Homeostasis
by Inês L. S. Delgado, Bruno Carmona, Sofia Nolasco, Dulce Santos, Alexandre Leitão and Helena Soares
Biology 2020, 9(12), 413; https://doi.org/10.3390/biology9120413 - 24 Nov 2020
Cited by 8 | Viewed by 4008
Abstract
The MOB family proteins are constituted by highly conserved eukaryote kinase signal adaptors that are often essential both for cell and organism survival. Historically, MOB family proteins have been described as kinase activators participating in Hippo and Mitotic Exit Network/ Septation Initiation Network [...] Read more.
The MOB family proteins are constituted by highly conserved eukaryote kinase signal adaptors that are often essential both for cell and organism survival. Historically, MOB family proteins have been described as kinase activators participating in Hippo and Mitotic Exit Network/ Septation Initiation Network (MEN/SIN) signaling pathways that have central roles in regulating cytokinesis, cell polarity, cell proliferation and cell fate to control organ growth and regeneration. In metazoans, MOB proteins act as central signal adaptors of the core kinase module MST1/2, LATS1/2, and NDR1/2 kinases that phosphorylate the YAP/TAZ transcriptional co-activators, effectors of the Hippo signaling pathway. More recently, MOBs have been shown to also have non-kinase partners and to be involved in cilia biology, indicating that its activity and regulation is more diverse than expected. In this review, we explore the possible ancestral role of MEN/SIN pathways on the built-in nature of a more complex and functionally expanded Hippo pathway, by focusing on the most conserved components of these pathways, the MOB proteins. We discuss the current knowledge of MOBs-regulated signaling, with emphasis on its evolutionary history and role in morphogenesis, cytokinesis, and cell polarity from unicellular to multicellular organisms. Full article
(This article belongs to the Section Cell Biology)
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<p>Comparison between Hippo and MEN/SIN pathways. (<b>A</b>) Schematic representation of the Hippo pathway in <span class="html-italic">Drosophila melanogaster</span> (orange) and in <span class="html-italic">Homo sapiens</span> (blue). (<b>B</b>) Schematic representation of the Mitotic Exit Network (MEN) in <span class="html-italic">Saccharomyces cerevisiae</span> (orange) and Septation Initiation Network (SIN) in <span class="html-italic">Schizosaccharomyces pombe</span> (blue). In these pathways, ortholog proteins are represented with oval nodes of the same color (yellow, Salvador/SAV1/Tem1/Spg1; green, Hippo/MST1/2/Cdc15/Cdc7; blue, Mats/MOB1/Mob1; orange, Warts/LATS1/2/Dbf2). * There are some controversies in the literature regarding whether to consider Cdc15 and Hippo as orthologous. This scheme is in accordance with Hergovich, 2017 [<a href="#B17-biology-09-00413" class="html-bibr">17</a>].</p>
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<p>Metazoan MOB proteins present extensive regulation between isotypes. The canonical Hippo pathway is activated by upstream signals resulting in MST1/2 phosphorylation (which may be mediated by SAV1) and MOB1-LATS1/2 activation, causing YAP/TAZ phosphorylation and cytoplasm retention. The lack of YAP/TAZ transcriptional signaling results in a tumor suppressing effect. However, MOB proteins present several activities beyond canonical Hippo signaling. These include non-canonical Hippo signaling through different interactions with GCKII STE20 or NDR kinases, direct MOB stimulation by upstream signals and direct stimulation by MOBs of non-Hippo proteins. This intricate network results in direct and indirect MOB to MOB regulation. PLK1 regulates mitotic spindle orientation through NDR1 phosphorylation which results in NDR1 binding shifting from MOB1 to MOB2, favoring canonical Hippo activation [<a href="#B48-biology-09-00413" class="html-bibr">48</a>]. NDR1/2 also regulate P21 and RABIN8 [<a href="#B49-biology-09-00413" class="html-bibr">49</a>,<a href="#B50-biology-09-00413" class="html-bibr">50</a>]. MOB3 is a MOB1 antagonist by inhibiting MST1 [<a href="#B36-biology-09-00413" class="html-bibr">36</a>]. MOB4/Phocein-MST4, part of the STRIPAK complex, also antagonizes MOB1, by disrupting MOB1-MST1/1 binding [<a href="#B34-biology-09-00413" class="html-bibr">34</a>]. MOB1 interacts in a HsMOB1-PPP6R1/2/3-ANKRD28 complex which appears to inhibit MOB1 mediated Hippo activation and in a DOCK6/7/8-CRLF3-LRCH3/4 complex, in a phosphorylation dependent manner [<a href="#B51-biology-09-00413" class="html-bibr">51</a>,<a href="#B52-biology-09-00413" class="html-bibr">52</a>]. Both PP6 phosphatase and DOCK6-8 promote actin cytoskeleton polarization signaling via RAC1. The FERMT2-PRAJA2 complex inhibits Hippo signaling by promoting MOB1 ubiquitin-proteasome degradation [<a href="#B40-biology-09-00413" class="html-bibr">40</a>]. MOB1 is stimulated by GSK3β, a signaling hub involved in Wnt, mTOR, and Notch signaling [<a href="#B53-biology-09-00413" class="html-bibr">53</a>]. MOB2 interacts with RAD50 stimulating the DNA damage response [<a href="#B54-biology-09-00413" class="html-bibr">54</a>]. MOB2-SAV1 interaction was detected in <span class="html-italic">G. gallus</span> [<a href="#B42-biology-09-00413" class="html-bibr">42</a>]. Notably, PP6, DOCK6, FERMT2 and GSK3 are proteins involved in cell-cell junctions. Colored boxes represent Hippo pathway members while other proteins are represented by non-colored boxes. Protein complexes are identified by an interrupted box with dashes and dots lines. Arrows represent activation while dashes represent inhibition. Lack of arrow or dash indicates an uncertain effect. Full lines represent well-established interactions. Interrupted lines represent less documented interactions.</p>
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<p>Different MOB isotypes present similar functions. MOB functions were divided into 4 categories: tissue homeostasis, morphogenesis, differentiation and cell cycle progression (includes mitosis, meiosis, cytokinesis, and centrosome biology). Circle areas are proportional to the number of proteins counted in the literature related to these functions, as is illustrated in the protein count examples at the bottom right. MOB protein isotypes for each organism were counted only once per function category (variants within protein isotypes were not considered). It is obvious that there is no one MOB isotype responsible for a particular function. Various MOB isotypes present similar functions, be it in distinct species or in distinct tissues in the same species. In fungi, NcMOB1, ChMOB2, and SmMOB4/Phocein, all participate in conidiation, ascosporogenesis, and meiosis [<a href="#B3-biology-09-00413" class="html-bibr">3</a>,<a href="#B4-biology-09-00413" class="html-bibr">4</a>,<a href="#B23-biology-09-00413" class="html-bibr">23</a>]. In <span class="html-italic">M. musculus,</span> MmMOB1, MmMOB2, and MmMOB4/Phocein are necessary for neuronal development while MmMOB1 also promotes lung morphogenesis [<a href="#B25-biology-09-00413" class="html-bibr">25</a>,<a href="#B53-biology-09-00413" class="html-bibr">53</a>,<a href="#B62-biology-09-00413" class="html-bibr">62</a>,<a href="#B64-biology-09-00413" class="html-bibr">64</a>]. The data also evidence a higher abundance of studies on MOB1 proteins, which are the more represented in each category, except morphogenesis. Colors representing MOB isotypes: 1—blue, 2—green, 3—red, 4—orange.</p>
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<p>Evolutionary analysis of MOB proteins in unicellular organisms and the multicellular fungi <span class="html-italic">Neurospora crassa.</span> The evolutionary history of MOB proteins was inferred by using the Maximum Likelihood method and Le_Gascuel_2008 model [<a href="#B171-biology-09-00413" class="html-bibr">171</a>]. The tree with the highest log likelihood (-9063.20) is shown. The percentage of trees in which the associated taxa clustered together is shown next to the branches. Initial tree(s) for the heuristic search were obtained automatically by applying Neighbor-Join and BioNJ algorithms to a matrix of pairwise distances estimated using the JTT model, and then selecting the topology with superior log likelihood value. A discrete Gamma distribution was used to model evolutionary rate differences among sites (5 categories (+<span class="html-italic">G</span>, parameter = 3.0458)). The rate variation model allowed for some sites to be evolutionarily invariable ([+<span class="html-italic">I</span>], 0.60% sites). The tree is drawn to scale, with branch lengths measured in the number of substitutions per site. This analysis involved 36 amino acid sequences. All positions with less than 95% site coverage were eliminated, i.e., fewer than 5% alignment gaps, missing data, and ambiguous bases were allowed at any position (partial deletion option). A total of 168 positions was included in the final dataset. Evolutionary analyses were conducted in MEGA X [<a href="#B172-biology-09-00413" class="html-bibr">172</a>]. The sequences included predicted MOB proteins from the chosen unicellular organisms plus the sequences from the multicellular fungus <span class="html-italic">Neurospora crassa</span>. Blue rectangle highlights predicted MOB1-like proteins based on &gt;50% amino acid identity among the amino acids conserved in MOB1 proteins [<a href="#B169-biology-09-00413" class="html-bibr">169</a>]. Green rectangle highlights yeast Mob2 proteins. Orange rectangle highlights predicted Phocein-like proteins based on &lt;50% amino acid identity among the amino acids conserved in non-Phocein MOB proteins [<a href="#B169-biology-09-00413" class="html-bibr">169</a>]. The MOB protein sequences for the analysis were obtained for the following organisms: <span class="html-italic">Amphimedon queenslandica; Arabidopsis thaliana; Branchiostoma floridae; Caenorhabditis elegans; Capsaspora owczarzaki; Chlamydomonas reinhardtii; Ciona intestinalis; Cryptosporidium parvum; Danio rerio; Drosophila melanogaster; Emericella nidulans; Giardia intestinalis; Hammondia hammondi; Homo sapiens; Leishmania major; Monosiga brevicollis; Naegleria gruberi; Nematostella vectensis; Neospora caninum; Neurospora crassa; Paramecium tetraurelia; Saccharomyces cerevisiae; Schizosaccharomyces pombe; Strongylocentrotus purpuratus; Tetrahymena thermophila; Toxoplasma gondii; Trichoplax adhaerens; Trypanosoma brucei; Trypanosoma cruzi.</span></p>
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<p>Localization of MOB proteins in different unicellular organisms in comparison to human cells. (<b>A</b>) In the ciliate <span class="html-italic">Tetrahymena</span> Mob1 accumulates in basal bodies at the posterior pole of the cell forming a gradient through the anterior–posterior axis. During cell division Mob1 is recruited to the basal bodies at the equatorial zone where the cleavage furrow will be established [<a href="#B7-biology-09-00413" class="html-bibr">7</a>]. Mob1 depletion causes the abnormal establishment of the cell division plane and cytokinesis is arrested [<a href="#B7-biology-09-00413" class="html-bibr">7</a>]. (<b>B</b>) In <span class="html-italic">T. gondii</span>, TgMOB1 protein shows a punctate cytoplasmic localization that is excluded from the apical pole (Delgado et al., unpublished). TbMOB1 in the bloodstream form of <span class="html-italic">T. brucei</span> presents a punctate distribution in the cytoplasm throughout the cell cycle. TbMOB1 was shown to be essential in both bloodstream and procyclic life cycle stages of the protozoan. Down-regulation of TbMOB1 in the bloodstream form results in a delay in cytokinesis and leads to a de-regulation of the cell cycle (not shown in the scheme) [<a href="#B159-biology-09-00413" class="html-bibr">159</a>]. In the procyclic form, it affects the accuracy of cytokinesis, presenting mispositioning of the cleavage furrow and incorrect cytokinesis [<a href="#B159-biology-09-00413" class="html-bibr">159</a>]. AP—apical pole; PP—posterior pole. (<b>C</b>) In budding yeast Mob1p localizes diffusely to the cytoplasm in G1, S, and G2 phases. In mitotic cells Mob1p first localizes to the spindle pole bodies during mid-anaphase and to a ring at the bud neck just before and during cytokinesis. Mob1p is required for cytokinesis in addition to mitotic exit [<a href="#B108-biology-09-00413" class="html-bibr">108</a>]. Cultures of mutant mob1 strains present cellular chains indicating the role of Mob1p in cytokinesis [<a href="#B108-biology-09-00413" class="html-bibr">108</a>]. In mitotic cells Mob2p first localizes to the growing bud tip and to the bud neck and the daughter nucleus in late mitosis. Mob2p is required for maintenance of polarized cell growth and for mother/daughter separation after cytokinesis. mob2Δ strains grow as clumps of round cells joined at certain regions [<a href="#B131-biology-09-00413" class="html-bibr">131</a>]. (<b>D</b>) In human HeLa cells HsMOB1 localizes to the centrosome and this staining pattern remains until the centrioles duplicate and centrosomes separate [<a href="#B55-biology-09-00413" class="html-bibr">55</a>]. In late telophase cells with two separated centrioles, HsMOB1 is detected just in the stronger GFP-centrin signal (probably mother centriole), often the one closer to the midbody. Depletion of HsMOB1A and HsMOB1B by RNAi causes abscission failure and increases cell motility after cytokinesis inducing persistent centriole separation in G1 phase [<a href="#B55-biology-09-00413" class="html-bibr">55</a>].</p>
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Article
Membrane Phospholipids and Polyphosphates as Cofactors and Binding Molecules of SERPINA12 (vaspin)
by Catherine A. Tindall, Sebastian Dommel, Veronika Riedl, David Ulbricht, Stefanie Hanke, Norbert Sträter and John T. Heiker
Molecules 2020, 25(8), 1992; https://doi.org/10.3390/molecules25081992 - 24 Apr 2020
Cited by 4 | Viewed by 3695
Abstract
Visceral adipose tissue derived serine protease inhibitor (vaspin) is a member of the serpin family and has been shown to have beneficial effects on glucose tolerance, insulin stability as well as adipose tissue inflammation, parameters seriously affected by obesity. Some of these effects [...] Read more.
Visceral adipose tissue derived serine protease inhibitor (vaspin) is a member of the serpin family and has been shown to have beneficial effects on glucose tolerance, insulin stability as well as adipose tissue inflammation, parameters seriously affected by obesity. Some of these effects require inhibition of target proteases such as kallikrein 7(KLK7) and many studies have demonstrated vaspin-mediated activation of intracellular signaling cascades in various cells and tissues. So far, little is known about the exact mechanism how vaspin may trigger these intracellular signaling events. In this study, we investigated and characterized the interaction of vaspin with membrane lipids and polyphosphates as well as their potential regulatory effects on serpin activity using recombinant vaspin and KLK7 proteins and functional protein variants thereof. Here, we show for the first time that vaspin binds to phospholipids and polyphosphates with varying effects on KLK7 inhibition. Vaspin binds strongly to monophosphorylated phosphatidylinositol phosphates (PtdInsP) with no effect on vaspin activation. Microscale thermophoresis (MST) measurements revealed high-affinity binding to polyphosphate 45 (KD: 466 ± 75 nM) and activation of vaspin in a heparin-like manner. Furthermore, we identified additional residues in the heparin binding site in β-sheet A by mutating five basic residues resulting in complete loss of high-affinity heparin binding. Finally, using lipid overlay assays, we show that these residues are additionally involved in PtdInsP binding. Phospholipids play a major role in membrane trafficking and signaling whereas polyphosphates are procoagulant and proinflammatory agents. The identification of phospholipids and polyphosphates as binding partners of vaspin will contribute to the understanding of vaspins involvement in membrane trafficking, signaling and beneficial effects associated with obesity. Full article
(This article belongs to the Special Issue Protein-Peptide and Protein-Small Molecule Interactions)
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Figure 1

Figure 1
<p>Vaspin affinity for immobilized membrane lipids. Shown are lipid overlay assays analyzing binding of vaspin to a variety of membrane lipids with 100 pmol/spot of lipid immobilized on each spot and 1 µg/mL vaspin was used for incubation of (<b>A</b>) membrane lipid and sphingo lipid strips, (<b>B</b>) PtdIns lipid strip and (<b>C</b>) PtdIns array with serial dilutions of different PtdInsPs from 100 pmol down to 1.56 pmol/spot as indicated. TG: triglyceride, DAG: diacylglycerol, PA: phosphatidic acid, PS: phosphatidylserine, PE: phosphatidylethanolamine, PC: phosphatidylcholine, PG: phosphatidylglycerol, CL: cardiolipin, SG: sphingosine, S1P: sphingosine-1-phosphate, PSG: phytosphingosine, C: ceramide, SM: sphingomyelin, SPC: sphingosylphosphorylcholine, LPA: lysophosphatidic acid, Myr: myriosine, M-GM1: monosialoganglioside-GM1, D-GD3: disiaganglioside-GD3, S: sulfatide, P: psychosine, Ch: cholesterol, PtdIns: phosphatidylinositol, PtdIns(3)P: phosphatidylinositol (3)-phosphate, PtdIns(4)P: phosphatidylinositol (4)-phosphate, PtdIns(5)P: phosphatidylinositol (5)-phosphate, PtdIns(3,4)P<sub>2</sub>: phosphatidylinositol (3,4)-bisphosphate, PtdIns(3,5)P<sub>2</sub>: phosphatidylinositol (3,5)-bisphosphate, PtdIns(4,5)P<sub>2</sub>: phosphatidylinositol (2,4)-bisphosphate, PtdIns(3,4,5)P<sub>3</sub>: phosphatidylinositol (3,4,5)-trisphosphate.</p>
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<p>Influence of PtdInsPs on vaspin/KLK7 complex formation and KLK7 activity. (<b>A</b>) SDS-PAGE analysis of vaspin/KLK7 complex formation. Vaspin wt was incubated with x-fold excess of PtdInsPs (0.1, 1 and 10-fold) or unfractionated heparin (ufh, 10-fold) as indicated. Notable and indicated bands are: 1-vaspin-protease complex; 2-full-length vaspin; 3-<span class="html-italic">N</span>-terminally cleaved vaspin; 4-RCL- and <span class="html-italic">N</span>-terminally cleaved vaspin; 5-KLK7. KLK7 was incubated with vaspin (at a molar ratio 3:1) for 2 min. C<sub>0</sub>: control reaction after t = 0 min. (<b>B</b>) Densitometric quantification of complex formation with and without PtdInsPs or ufh. Presented is the relative increase of complex band intensity as x-fold over control (vaspin without PtdInsP). (<b>C</b>) Inhibition of KLK7 by vaspin was measured under pseudo-first-order conditions (ligand/serpin ratio of 10). Presented is the relative increase in second-order rate constant as x-fold over control (without PtdInsP or heparin). (<b>D</b>) KLK7 activity was measured in presence of 10 or 100-fold excess of PtdInsPs. Presented is the relative KLK7 activity as x-fold over control (without PtdInsPs). Data are presented as means ± SEM. Statistical significance was determined by one-way ANOVA followed by Dunnett’s post-hoc test. * <span class="html-italic">p</span> &lt; 0.05, *** <span class="html-italic">p</span> &lt; 0.001.</p>
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<p>Influence of polyphosphates on complex formation. (<b>A</b>) Shown is complex formation of vaspin with KLK7 (protease/serpin molar ratio 3:1) with increasing concentrations of polyP<sub>3</sub> and polyP<sub>45</sub> (0.8−400-fold as indicated) after 1 min. Notable and indicated bands are: 1-vaspin-protease complex; 2-full-length vaspin; 3-<span class="html-italic">N</span>-terminally cleaved vaspin; 4-RCL- and <span class="html-italic">N</span>-terminally cleaved vaspin; 5-KLK7. (<b>B</b>) Densitometric quantification of complex band intensities in relation to ligand/vaspin ratio of SDS gels. (<b>C</b>) Inhibition of KLK7 by vaspin under pseudo first-order conditions in presence of polyP<sub>45</sub> (polyP/serpin ratio of 10:1). Presented is the second-order rate constant as x–fold over control (without polyP). (<b>D</b>) Binding of polyP<sub>45</sub> to fluorescently labeled vaspin in submicromolar range. The curve was derived from the measurement of the thermophoretic mobility after titration of polyP<sub>45</sub> to a constant vaspin concentration. Data are presented as means ± SEM. Statistical significance was determined by Student’s two-tailed <span class="html-italic">t</span>-test. ** <span class="html-italic">p</span> &lt; 0.01.</p>
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<p>Investigation of the PtdInsP binding site using a non-heparin binding (NHB) vaspin variant. (<b>A</b>) Thermal stability of wt vaspin and NHB variant (K188A/K131A/R211A/K359A/R363A). Denaturation was observed by nanoDSF plotting the intrinsic tryptophan and tyrosine fluorescence ratio of 350 nm/330 nm against temperature. (<b>B</b>) Complex formation of wt vaspin, R211A/K359A and NHB variant in the absence (−) and presence of heparin (+; heparin/vaspin ratio of 10:1) for 1 min. Notable and indicated bands are: 1-vaspin-protease complex; 2-full-length vaspin; 3-<span class="html-italic">N</span>-terminally cleaved vaspin; 4-RCL- and <span class="html-italic">N</span>-terminally cleaved vaspin; 5-KLK7. (<b>C</b>) Binding of the low-molecular weight heparin clexane to wt vaspin, R211A/K359A and NHB variant. Data from the wt and R211A/K359A was originally published in the Journal of Biological Chemistry: Ulbricht D, Oertwig K, Arnsburg K, Saalbach A, Pippel J, Strater N and Heiker JT. Basic Residues of β-Sheet A Contribute to Heparin Binding and Activation of Vaspin (Serpin A12). <span class="html-italic">J Biol Chem</span>. 2017, 292, 994–1004, © the American Society for Biochemistry and Molecular Biology. Curves were derived from changes in fluorescence (wt or R211A/K359A) or thermophoretic mobility (NHB) after titration of enoxaparin to a constant vaspin concentration. (<b>D</b>) Lipid strips incubated with wt vaspin (alone (−) or in presence of heparin, with a molar ratio serpin/heparin of 1:1 or 10:1 as indicated) and vaspin variants. NHB: non-heparin binding variant, con: control, ufh: unfractionated heparin.</p>
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<p>Heparin and phosphate ion binding site of vaspin. (<b>A</b>,<b>B</b>) Electrostatic potential at the molecular surface of vaspin (PDB 4IF8) [<a href="#B7-molecules-25-01992" class="html-bibr">7</a>] as viewed from the opposite sides. A large area of strong positive potential is visible in the orientation depicted in (<b>B</b>). Potential values &lt; −8 kT/e are colored in red and values &gt; +8 kT/e in blue. The electrostatic potential was generated with the program APBS [<a href="#B35-molecules-25-01992" class="html-bibr">35</a>]. The protein orientation in (<b>B</b>) is the same as that of (<b>C</b>), showing the protein fold and the basic residues generating the strong positive electrostatic potential. The reactive center loop (RCL, red) is flexible in the crystal structure and modeled here for orientation. Five basic resides are present in the area of the distinct positive potential (<b>C</b>) and a sulfate ion is coordinated by three side chains (<b>D</b>).</p>
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