The effects of pregnancy and SMTNL1 deletion on ER and PR expression in skeletal muscle.
A and B, SMTNL1 deletion and pregnancy (PRE) induce expression of PR-B (A) and ERα (B) in SKM comparing to non-pregnant (NP) animals. Data are the mean ± S. E. for n = 4, GLM with Tukey's test; different letters indicate significant differences. p < 0.05. C, analysis of PR-B (red) in MHC2a (co-staining for SMTNL1 (green)) and MHC2b (red, staining for MHC2b) in plantaris. Scale bars = 20 μm. D, immunohistochemistry shows discrete expression of ERα (red) in type2b fibers in plantaris muscle. Scale bars = 20 μm. E, SMTNL1 and ERα localization in human skeletal muscle. Shown is localization of SMTNL1 (green) in type2a (red) and ERα (green) in type2b fibers (red) in human skeletal muscle by confocal microscopy. Scale bars represent 20 μm. F, SMTNL1 expression in plantaris of ERα−/− and ERβ−/− mice. Plantaris muscle of ERα/β+/+, ERα−/−, and ERβ−/− were lysed and analyzed by WB analysis using SMTNL1 antibody and anti-tubulin for loading control. Data were normalized, and values are relative changes compared with that obtained in ERα/β+/+. Data are the mean ± S.E., n = 4 each group. GLM: *, p > 0.05. G, SMTNL1 binds to PR-B but not to ERα in vivo in skeletal muscle. SMTNL, PR-B, and ERα were immunoprecipitated from skeletal muscle and uterine muscle (see positive control as shown in Ref. 12) extracts.