Figure 2.

SGK-1-KO increases CKD–induced muscle wasting and activation of Atrogin1 and MuRF1. (A) Western blot analysis of SGK-1 expression in TA muscle in WT and SGK-1-KO mice (n=5). (B) Changes in body weight of WT and SGK-1-KO mice over 4 weeks after creation of CKD. *P<0.05 versus WT mice. (C and D) Weights of (C) TA and (D) gastrocnemius muscle from WT and SGK-1-KO mice after 4 weeks after creation of CKD (n=5). (E) Myofiber sizes (cross-sectional areas [CSAs]) in WT and SGK-1-KO mice, including sham and CKD mice, were studied. (E, upper panels) Cross-sections of TA muscles of WT and SGK-1-KO mice were immunostained with antilaminin. (E, lower panels) The distribution of myofiber sizes was calculated as the percentage of the number of myofibers in a designated area divided by the total number of myofibers in the area. (F) E3 ubiquitin ligases Atrogin1 and MuRF1 mRNAs in TA muscles were determined in WT and SGK-1-KO mice, including both control and CKD mice (n=5 pairs of mice). (G and H) C2C12 cells were (G) transfected with control scrambled or SGK-1 siRNA for 72 hours or (H) infected with adenovirus expressing SGK-1. Cells were treated with cytokine cocktail (IL-6 at 2 ng/ml, TNF-α at 2 ng/ml, and TGF-β1 at 2 ng/ml) for 24 hours. The expressions of Atrogin1 and MuRF1 were detected by RT-PCR. Representative data are shown from three repeated experiments. CTL, control; GAPDH, glyceraldehyde-3-phosphate dehydrogenase; GFP, green fluorescent protein; siRNA, short interfering RNA. *P<0.05 versus no treatment; ^#P<0.05 versus CTL siRNA or AdGFP (n=3).