SOD1 stimulates lamellipodial protrusions in Neuro 2A cell lines

We here investigated the effects of overexpressed superoxide dismutase (SOD)1 and amyotrophic lateral sclerosis (ALS)-linked SOD1 mutants G93A and G147S in Neuro 2A (N2A) cell lines, and found a three-fold increase in lamellipodia either in cells cultured under differentiated or undifferentiated growth conditions. In undifferentiated N2A cells, SOD1 constructs promoted lamellipodial protrusions to similar extent as the overexpression of Rac1, and SOD1-mediated lamellipodia were prevented by coexpression of the N17 dominant-negative form of Rac1, or shRNA for a downstream effector of Rac1, the insulin receptor tyrosine kinase substrate p53 (IRSp53) or its binding partner LIN7. Moreover, no additive effect was measured by coexpression of the SOD1 constructs with Rac1, IRSp53 or LIN7. Collectively these data support a role for SOD1 in the regulation of Rac1-mediated lamellipodia pathway, a property fully retained by the two SOD1 mutants.

本研究探究了过表达超氧化物歧化酶（superoxide dismutase, SOD）1以及与肌萎缩侧索硬化症（amyotrophic lateral sclerosis, ALS）相关的SOD1突变体G93A和G147S在Neuro 2A（N2A）细胞系中的效应，结果显示：无论细胞处于分化还是未分化的培养条件下，片状伪足（lamellipodia）的数量均增加至三倍。在未分化的N2A细胞中，SOD1过表达载体促进片状伪足突起的效果与Rac1过表达相当；共表达Rac1的N17显性负性突变体，或靶向Rac1下游效应分子胰岛素受体酪氨酸激酶底物p53（insulin receptor tyrosine kinase substrate p53, IRSp53）及其结合伴侣LIN7的短发夹RNA（short hairpin RNA, shRNA），可阻断SOD1介导的片状伪足形成。此外，将SOD1过表达载体与Rac1、IRSp53或LIN7共表达时，未检测到加性效应。综上，本研究数据证实SOD1参与调控Rac1介导的片状伪足通路，且这一功能在两种SOD1突变体中均完整保留。