Figure 2. Knocking down of HSP90 or STAT3 prevented C2C12 myotubes from C26 CM-induced atrophy.
(a) The expression levels of Atrogin-1, MuRF-1, MHC, HSP90, Myostatin, and phosphorylated STAT3 in the skeletal muscle from C26 CM treated C2C12 myotubes were detected by western blot. (b) The lysates of C2C12 cells treated with C26 CM or DMEM (control) were immunoprecipitated with the STAT3 antibody, the HSP90 antibody, or control rabbit IgG. The immunopellets were detected by immunoblot analysis with the anti-HSP90 antibody and the anti-STAT3 antibody.(c) Representative hematoxylin and eosin (HE)-stained C2C12 treated with C26 CM and transfected with the HSP90 siRNA or the STAT3 siRNA. (d) The histogram represents the average myotube diameter (μm) (d, left part) . qRT-PCR analysis of atrogin-1 and MuRF-1 in the gastrocnemius muscles of mice (d, right part) .(e) Atrophy markers in C2C12 were tested by WB analysis when the expression of HSP90 or STAT3 was knocked down by siRNA. Data represent the mean ± standard deviation (SD). *p<0.05, **p<0.01 denotes compared to control; #p<0.05, ##p<0.01 denotes compared to C26 CM treated myotubes.