Study On The A20 Gene

During the postischemia period, focal cerebral ischemia can cause typical apoptosis in neural cells in various parts of brain. A body of data shows that TNF and other inflammatory cytokines play an important role in neuronal apoptosis in vitro and in vivo as a result of brain injury. Caspase pathways are important signal pathways in such apoptosis mediated by TNF. A20 is a TNF-induced primary response gene which encodes a novel zinc finger protein which can inhibit TNF-mediated apoptosis in many cell lines. But little work has been done in central nervous system. To determine the neuroprotective effect of A20 gene, liposome-mediated gene delivery of A20 and transplantation of primary rat hippocampal neurons transfected with human A20 into brains of MCAO rats were performed in present study. Gene transfer of A20 resulted in improvement of neural deficit, decrease of infarct volume and reduction of NO production in MCAO rats. A20 also could enhance the viability of transplanted neurons in penumbra zone of ischemic brain. We further analyzed the antiapoptotic function of A20 against TNF-αinduced apoptosis in vitro. Results of flow cytometry, TUNEL and DNA agarose gel electrophoresis all indicated that A20 could inhibit TNF-αinduced apoptosis both in primary rat hippocampal neurons and SH-SY5Y cells. Moreover, we found A20 targeted the TNF apoptotic pathway by inhibiting proteolytic cleavage of caspase 8 and caspase 3 in SH-SY5Y cells. These data demonstrated that A20 gene could effectively protect neurons from postischemia apoptosis and may function partly by inhibiting death receptor caspase pathway. Gene transfer of A20 may be a promising approach for gene therapy of cerebral ischemia in the future.