Table 1

Primers sequence used in this study"

Fig.1

Morphology of gastrocnemius muscle and changes in P21 and P53 expression in young， adult， and aged miceA. HE staining of gastrocnemius muscle in young， adult， and aging mice （bar=100 μm）； B， C. Immunofluorescence detection and quantification of P21 expression in mouse gastrocnemius muscle of different ages （in Fig.B， bar=200 μm）； D， E. Immunofluorescence detection and quantification of P53 expression in mouse gastrocnemius muscle of different ages （in Fig.D， bar=200 μm）. *. P<0.05， **. P < 0.01， ***. P<0.001"

Fig.2

With the increase of age， the expression of PPARα in the gastrocnemius muscle of mice decreased at both mRNA and protein levelsA. PCR detection of PPARα expression in skeletal muscle （M. DL500 DNA marker； 1. Negative control， DEPC water； 2. Positive control， liver tissue cDNA； 3. Target band， gastrocnemius cDNA）； B. Real-time quantitative PCR was used to detect the expression of PPARα； C， D. Western blot to detect the expression level and quantitative analysis of PPARα protein； E， F. Immunofluorescence was used to detect the expression and quantification of PPARα in gastrocnemius muscle at different developmental stages （in Fig.E， bar=100 μm）. *. P<0.05， **. P<0.01， ***. P<0.001， ****. P<0.000 1"

Fig.3

Knockout of PPARα reduces myofiber area and the expression of MyoD and MyoGA. HE staining of WT and PPARα-/- mouse gastrocnemius muscles （bar=100 μm）；B. Cross-sectional area analysis of gastrocnemius muscle of WT and PPARα-/- mice；C. Body composition analysis of WT and PPARα-/- mice；D. qRT-PCR was used to detect genes related to skeletal muscle development in WT and PPARα-/- mice； E. Western blot was used to detect the expressions of PPARα， MyoD and MyoG in the gastrocnemius muscle of WT and PPARα-/- mice； F. Relative quantitative statistics of PPARα， MyoD， and MyoG in panel E. *. P<0.05， **. P<0.01， ***. P<0.001"

Fig.4

Knockdown of PPARα significantly reduces the positive areas of MyoD and Pax7 in the gastrocnemius muscleA， B. Immunofluorescence detection and quantification of MyoD in the gastrocnemius muscle of WT and PPARα-/- mice （bar=100 μm）； C， D. Immunofluorescence detection and quantification of Pax7 in gastrocnemius muscle of WT and PPARα-/- mice （bar=100 μm）. *. P<0.05， **. P<0.01"

Fig.5

PPARα knockdown activates P38 and AMPK phosphorylation levelsA. Western blot was used to detect the expression and quantification of P38 and AMPK in the gastrocnemius muscle of WT and PPARα-/- mice； B. Quantification of protein bands in panel A. *. P<0.05， **. P<0.01"