PP2A-Bδ holoenzyme regulates cytoskeleton dynamics via the RhoGTPase Rac1.a Rac1 activity was measured by GST pull-down assay in control (shCTL) and Bδ-knocked down (shBδ) C2C12 myoblasts at the indicated time points during the differentiation process. Values are mean ± SD from at least three experiments. Unpaired t-test, two-tailed, *P < 0.05. b Western blot analysis of phospho-Pak1,2 (α-pPAK1,2) and total Pak 1,2 (α-PAK1,2) in control (shCTL) and Bδ-knocked down (shBδ) C2C12 myoblasts at the indicated time points during the differentiation process. Images are representative of two independent experiments. c Confocal analysis of F-actin (phalloidin, gray) in control (shCTL) and Bδ-knocked down (shBδ) C2C12 myoblasts treated ( + ) or not (−) with a Rac1 inhibitor (NSC23766). Imaging was done at the indicated time points during the differentiation process. Representative cells from two independent experiments are shown. Scale bars are 10 µm. d Major/minor cell axis ratio in control Bδ-KD (shBδ) C2C12 myoblasts treated or not with the NSC23766 Rac1 inhibitor. Analysis was performed at day 2 during the differentiation process. Cells from 2 independent experiments for each condition were analyzed (n = 570 for shBδ and n = 585 for shBδ + Rac inhibitor). Mann–Witney’s test ****P < 0.0001. e Analysis of Abl, CrkII, and FAK activation by western blot in control (shCTL) and Bδ-KD (shBδ) C2C12 myoblasts during differentiation using antibodies against the phosphorylated forms of their activation sites, i.e., Y412 (α-pAbl (Y412)), (α-pCrkII (Y221)), and (α-pFAK (S273)), respectively. In total, Abl, CrkII, and FAK were used as loading controls. Images are representative of at least two experiments
|