Knockdown of Ski decreased the reactive astrocytes proliferation in vitro induced by oxygen-glucose deprivation/reoxygenation

Glia scar is a pathological marker in late phase of brain ischemia disease, which constitutes a major physical biochemical barrier to impede axonal regrowth. Astrocytes are known to be critically involved in the formation of glial scar. However, their response to ischemia and their role in neuroprotection after central nervous system (CNS) injury are not completely clear. Recently, we have demonstrated for the first time that Ski was up-regulated in reactive astrocytes after spinal cord injury in vivo and in vitro, which indicates Ski may be a new molecule that control astrocytes biologic properties after CNS injury. However, its role in the process of reactive astrogliosis after cerebral ischemia and its definite mechanism still remains unknown. This study is to elucidate the role of Ski in reactive astrocytes induced by oxygen-glucose deprivation/reoxygenation (OGD/R) model in vitro. The expression of Ski was proved to be up-regulated in OGD/R model. Meanwhile, Up-regulation of Ski was accompanied with high ratio of EdU (+) cells and up-expression of related proteins including GFAP, PCNA, CDK4, and CyclinD1, which demonstrated the distinct activation and proliferation of astrocytes after stimulation by OGD/R. Astrocytes were transfected with Ski-specific siRNA to knockdown Ski expression and subsequently attenuated OGD-induced astrocyte proliferation. Our results also showed that Ski down-regulation could suppress the activity of the Ras-Raf-ERK1/2 signaling pathway. Together, knockdown of Ski can effectively inhibit the proliferation of reactive astrogliosis via suppressing the Ras-Raf-ERK1/2 pathway. These findings indicated that maybe Ski is a promising therapeutic target for cerebral ischemic injury.