Figure 1.

ANGPTL2 levels increase in skeletal muscle of aging mice. a, relative transcript levels of cellular senescence-associated (p16, p19, p21, and p57) and pro-inflammatory (Il-1β and Il-6) genes in musculus gastrocnemius and musculus soleus of adult (8-month-old) and aging (18-month-old) female wildtype mice (n = 4 per group). b, absolute muscle mass and body weight as well as tibia length normalized muscle mass in adult and aging mice (n = 7–10 per group). c, representative Western blot of 4-HNE-adducted proteins, a product of oxidative stress, in musculus soleus of adult and aging mice. Asterisks indicate increased levels of 4-HNE-adducted proteins in aging mice. d–f, relative expression of genes encoding antioxidant enzymes (catalase, Sod1, Sod2, and Gpx1) (d) or Cd34, Pax3, and Pax7 (e), or Angptl2 (f) transcripts in musculus gastrocnemius and musculus soleus of adult and aging mice (n = 4 per group). g, representative Western blot and the quantifications of ANGPTL2 and PAX7 proteins in musculus gastrocnemius and musculus soleus of adult and aging mice. h, representative Western blot of ANGPTL2 in SMC-rich or stromal cells-rich fractions isolated from musculus gastrocnemius of adult and aging mice. Myosin light chain (MYL) serves as a skeletal myocyte marker. Relative mRNA expression was normalized to 18S mRNA (a, d, e, and f). Hsc70 and CBB staining serves as an internal loading control (c, g, and h). Values in adult mice were set to 1 (a and d–g). All data are presented as means ± S.D. (a, b, and d–f) or means ± S.E. g, statistical significance was determined by Student's t test. *, p < 0.05; **, p < 0.01; †, p < 0.001.