Research Paper Advance Articles

Figure 6. Aging-related changes in the gene or protein expression levels of cellular senescence and senescence-associated secretory phenotype (SASP) markers in the gastrocnemius muscles of female mice. The protein expression levels of the cellular senescence marker, p21, in the gastrocnemius muscles of 6- and 24-month-old female mice with PAI-1 gene deficiency (PAI-1^−/−) and their wild-type counterparts (PAI-1^+/+) are shown (A) (n = 8−10 in each group). Results of Western blot analysis for p21 are expressed as a ratio to GAPDH. Moreover, the gene expression levels of the SASP markers (B), IL-1β, TNFα, and IL-6, in the gastrocnemius muscles of 6- and 24-month-old female PAI-1^+/+ and PAI-1^−/− mice are shown (n = 9−10 in each group). Results of real-time PCR analyses for IL-1β, TNFα, and IL-6 mRNA are expressed as a ratio to 18S rRNA. The protein expression levels of IL-6, expressed as a ratio to GAPDH, in the gastrocnemius muscles of 6- and 24-month-old PAI-1^+/+ and PAI-1^−/− female mice are shown (C) (n = 4 in each group). Plasma IL-6 levels in 6- and 24-month-old PAI-1^+/+ and PAI-1^−/− female mice are shown (D) (n = 9−10 in each group). Data are presented as mean ± standard error of the mean. ^*P < 0.05.