UC San Diego

Ischemic stroke is a condition characterized by loss of brain function due to interruption of blood supply to the brain. A central core of dead cells, the infarct, forms and expands over time. Thus, the extent of ischemic injury is not defined immediately following the stroke event. Prevention of lesion expansion can then limit neurological deficit, making determination of the mechanism of ischemia -induced cell death of great importance. Using an in vitro model of the penumbral rim, the dynamic border between the dead cells of the infarct core and the unaffected healthy tissue, we studied the expression of CCRL2 in relation to ischemic cell death via potential intracellular mediators. CCRL2 is a novel chemokine receptor, previously reported to have no signaling function. However, CCRL2 has yet to be studied in an ischemic context, and a microarray of mouse brain tissue slices treated with IS for 2 hours, reveal CCRL2 to be one of the most highly up-regulated genes. Western blots reveal CCRL2 to be up-regulated after 14 hours of IS treatment along with JNK and activated caspase-3, a hallmark of apoptotic cell death. In CCRL2- deficient murine tissue, the level of activated caspase-3 decreases to half of the level in wild-type tissue. Additionally, PI staining shows significantly less PI uptake in CCRL2 KO tissue, denoting less cell death, suggesting CCRL2 promotes cell death in ischemia. In vivo, CCRL2 was found to be expressed on neurons subjected to MCAO, but not expressed on astrocytes an microglia