GSK3β and ERK regulate the expression of 78 kDa SG2NA and ectopic modulation of its level affects phases of cell cycle.

摘要: Striatin and SG2NA are essential constituents of the multi-protein STRIPAK assembly harbouring protein phosphatase PP2A several kinases. has isoforms generated by mRNA splicing editing. While expression striatin is largely restricted to striatum in brain, that SG2NAs ubiquitous. In NIH3T3 cells, only 78 kDa isoform expressed. When cells enter into S phase, level increases; reaches maximum at G2/M phase declines thereafter. Downregulation extends G1 its overexpression G2. Ectopic 35 kDa no effects on cell cycle. Relative abundance phospho-SG2NA high microsome cytosol nucleus but low mitochondria. Okadoic acid, an inhibitor PP2A, increases which further enhanced upon inhibition proteasomal activity. Phospho-SG2NA thus more stable than dephosphorylated form. Inhibition GSK3β LiCl reduces level, ERK PD98059 it. Thus, decreases inhibiting GSK3β. depleted from shRNA, levels pGSK3β pERK reduced, suggesting these kinases regulate each other’s expression.