PKA

Polymer hydrogels have been widely explored as therapeutic delivery matrices because of their ability to present sustained, localized and controlled release of bioactive factors. Bioactive factor delivery from injectable biopolymer hydrogels provides a versatile approach to treat a wide variety of diseases, to direct cell function and to enhance tissue regeneration. The innovative development and modification of both natural-(e.g., alginate (ALG), chitosan, hyaluronic acid (HA), gelatin, heparin (HEP), etc.) and synthetic-(e.g., polyesters, polyethyleneimine (PEI), etc.) based polymers has resulted in a variety of approaches to design drug delivery hydrogel systems from which loaded therapeutics are released. This review presents the state-of-the-art in a wide range of hydrogels that are formed though self-assembly of polymers and peptides, chemical crosslinking, ionic crosslinking and biomolecule recognition. Hydrogel design for bioactive factor delivery is the focus of the first s...

Modifications of neuronal circuits allow the brain to adapt and change with experience. This plasticity manifests during development and throughout life, and can be remarkably long lasting. Evidence has linked activity-regulated gene expression to the long-term structural and electrophysiological adaptations that take place during developmental critical periods, learning and memory, and alterations to sensory map representations in the adult. In all these cases, the cellular response to neuronal activity integrates multiple tightly coordinated mechanisms to precisely orchestrate long-lasting, functional and structural changes in brain circuits. Experience-dependent plasticity is triggered when neuronal excitation activates cellular signaling pathways from the synapse to the nucleus that initiate new programs of gene expression. The protein products of activity-regulated genes then work via a diverse array of cellular mechanisms to modify neuronal functional properties. Synaptic stre...

The basolateral region of the amygdala (BLA) plays a crucial role in making significant experiences memorable. There is extensive evidence that stress hormones and other neuromodulatory systems activated by arousing training experiences converge in regulating noradrenaline-receptor activity within the BLA. Such activation of the BLA modulates memory consolidation via BLA projections to many brain regions involved in consolidating lasting memory, including the hippocampus, caudate nucleus, nucleus basalis and cortex. Investigation of the involvement of BLA projections to other brain regions is essential for understanding influences of the amygdala on different aspects and forms of memory.

Log P values have been measured for twenty phenyl and benzyl five membered heterocycles and alicyclic analogs that might function as acidic bioisosteres. pKa's have been measured by potentiometric titration in water and 1:1 dioxane-water. From this experimental data, twelve missing fragmental CLOGP values are derived for use in calculating Log P values according to the Pomona College MedChem program. Log P values of some of the simple benzyl and phenyl heterocycles are compared to those measured for four clinically used drugs containing the same acidic moieties. Sulfonyl urea and acyl sulfonamide moieties have similar pKa and Log P values suggesting that these groups might be explored as bioisosteres.

The purine nucleoside adenosine acts via four distinct adenosine receptor subtypes: the adenosine A(1), A(2A), A(2B), and A(3) receptor. They are all G protein-coupled receptors (GPCR) coupling to classical second messenger pathways such as modulation of cAMP production or the phospholipase C (PLC) pathway. In addition, they couple to mitogen-activated protein kinases (MAPK), which could give them a role in cell growth, survival, death and differentiation. Although each of the adenosine receptors can activate one or more of the MAPKs, the mechanisms appear to differ substantially, both between receptor subtypes in the same cell type and between the same receptor in different cell types.

Mammalian AMP-activated protein kinase (AMPK) is a heterotrimeric serine/threonine protein kinase that acts as a sensor of cellular energy status. It interacts with a great variety of different substrates leading to short-term (i.e. regulation of the activity of different enzymes by direct phosphorylation) and long-term effects (i.e. regulation of transcriptional activity of different transcription factors). In this work, we describe the use of the yeast two-hybrid technology to identify additional proteins that interact with the different subunits of AMPK. We have performed three yeast two-hybrid screenings of a human skeletal muscle cDNA library using three different baits: a constitutively active form of AMPKalpha2 (LexA-AMPKalpha2-T172D) co-expressed with AMPKgamma1, LexA-AMPKbeta2 and LexA-AMPKgamma3. Our results identify novel interaction partners of AMPK in human skeletal muscle. We also further characterize the interaction of AMPK with one of these novel interacting proteins...

Background and purpose:  Protein kinase (PK) A and the ε isoform of PKC (PKCε) are involved in the development of hypernociception (increased sensitivity to noxious or innocuous stimuli) in several animal models of acute and persistent inflammatory pain. The present study evaluated the contribution of PKA and PKCε to the development of prostaglandin E2 (PGE2)-induced mechanical hypernociception.Experimental approach:  Prostaglandin E2-induced mechanical hypernociception was assessed by constant pressure rat paw test. The activation of PKA or PKCε was evaluated by radioactive enzymic assay in the dorsal root ganglia (DRG) of sensory neurons from the hind paws.Key results:  Hypernociception induced by PGE2 (100 ng) by intraplantar (i.pl.) injection, was reduced by i.pl. treatment with inhibitors of PKA [A-kinase-anchoring protein St-Ht31 inhibitor peptide (AKAPI)], PKCε (PKCεI) or adenylyl cyclase. PKA activity was essential in the early phase of the induction of hypernociception, whereas PKC activity was involved in the maintenance of the later phase of hypernociception. In the DRG (L4-L5), activity of PKA increased at 30 min after injection of PGE2 but PKC activity increased only after 180 min. Moreover, i.pl. injection of the catalytic subunit of PKA induced hypernociception which was markedly reduced by pretreatment with an inhibitor of PKCε, while the hypernociception induced by paw injection of PKCε agonist was not affected by an inhibitor of PKA (AKAPI).Conclusions and implications:  Taken together, these findings are consistent with the suggestion that PKA activates PKCε, which is a novel mechanism of interaction between these kinases during the development of PGE2-induced mechanical hypernociception.

cAMP-dependent protein kinase (PKA) mediates key cellular processes via compartmentalized activity, and the ability to track its activity in living cells should help increase our understanding of this precise regulation. Here, through systematic testing of new fluorescent proteins, we developed a new FRET-based A-kinase activity reporter (AKAR), AKAR3, with a dynamic range of 31-41%, twice that of predecessors. Visualization of PKA activity at plasma membrane, cytoplasm, nucleus, and mitochondria was achieved. Targeting AKAR3 to outer mitochondrial membrane revealed that basal PKA activity at mitochondria differs from that in the cytoplasm, indicating differential regulation of PKA activity at different subcellular locations.