Knockdown of integrin beta4 in primary cultured mouse neurons blocks survival and induces apoptosis by elevating NADPH oxidase activity and reactive oxygen species level.

Recently, the specific roles of integrin beta4 in the signaling networks that drive pathological angiogenesis and tumor progression have been revealed. Our previous study showed that integrin beta4 might be involved in neuron survival signal transduction. To further our study on the role of integrin beta4 in the survival and apoptosis of primary cultured mouse neurons, we inhibited the expression of integrin beta4 by its specific small interfering RNA. Viability of the cells remarkably declined, and neurons underwent apoptosis with down-regulation of integrin beta4. Next, we investigated the effect of siRNA-mediated down-regulation of integrin beta4 on the level of intracellular reactive oxygen species and the activities of NADPH oxidase and superoxide dismutase. The level of reactive oxygen species in the neurons was elevated significantly, the activities of manganese-dependent superoxide dismutase and copper/zinc-dependent superoxide dismutase were not altered, but the activity of NADPH oxidase was increased. Furthermore, inhibition of NADPH oxidase by its specific inhibitor dibenziodolium chloride attenuated the neuronal death induced by integrin beta4 knockdown. The data suggest that integrin beta4 is a key factor in neuron survival and apoptosis and indicate that this integrin subunit might perform its action through regulating NADPH oxidase and the level of reactive oxygen species in neuronal survival and apoptosis.