Figure 4

Expression of atrophy related genes in denervated gastrocnemius muscles from WT and MST1 KO mice. A-D. Quantitative PCR results showed three days after denervation, Atrogin-1 mRNA levels in WT and MST1 deficient gastrocnemius muscle were both increased (by 4.57 ± 0.70 folds and 2.68 ± 0.28 folds of the contralateral level, respectively). The increases in mRNA levels of LC-3 (1.76 ± 0.35 and 1.54 ± 0.15, WT vs. MST1 KO) and Bnip-3 were both less than two-fold and there is no significant difference in the WT and MST1 deficient muscles. MuRF-1 mRNA levels were upregulated to 9.51 ± 0.88 and 24.07 ± 7.68 folds in WT and MST1 deficient muscles, respectively. E-H. At Day 7 after denervation, the mRNA levels of muscle atrophy-related genes were significantly increased in both WT and MST1 deficient denervated muscles. The mRNA levels of Atrogin-1 and LC3 in denervated WT muscles (4.45 ± 0.47 and 4.43 ± 0.26 folds increased, respectively) were both significantly higher than that of MST1 KO mice (1.82 ± 0.12 folds and 2.91 ± 0.06 folds, respectively). Bnip-3 and MuRF-1 mRNA levels were also increased in denervated WT and MST1 deficient muscles but showed no differences between the genotypes. I-L. The protein levels of total LC3 and lapidated form (LC3 II) were both increased in MST1 deficient and WT muscles. Total LC3 protein was increased at 3.95 ± 0.37 folds in WT denervated muscle and 2.65 ± 0.48 folds in MST1 deficient denervated muscles. The LC3 II protein level in WT denervated muscle was increased 3.95 ± 0.31 folds and 2.44 ± 0.54 folds in MST1 deficient muscles, respectively. The ratio of LC3 II/LC3 I was 1.68 ± 0.20 and 1.31 ± 0.12 in WT and MST1 deficient muscles after denervation. * P < 0.05 by two-tailed Student's test.