Figure 13.

A hypothetical model illustrating the function and mechanism of ischemia-induced astrocytic cpg15 on the neurological recovery after cerebral ischemia. The expression of cpg15, a neuronal-specific expressed protein, is increased significantly in astrocytes after cerebral ischemia. The cpg15 secreted as the soluble form from ischemia-stimulated astrocytes and promoted neuroprotection and recovery of neuronal neurite outgrowth probably via adhering to the surface of neurons. The upregulation of cpg15 expression in astrocytes may be activated via MAPK, PI3K, or TrkA signal pathways, and phosphorylation of CREB transcription factor. The astrocyte-secreted cpg15 protein probably interacts with BAIAP2 and LRFN2 proteins in neurons that might mediate the intracellular signal and regulate the expression of downstream genes in neuronal cells, such as genes of GAP20, GAP22, GAP29, and EP400, and therefore participate in promoting neurite outgrowth and inhibiting neuronal injury.