Sex differences in constitutive autophagy

Abstract

Sex bias has been described nowadays in biomedical research on animal models, although sexual dimorphism has been confirmed widely under pathological and physiological conditions. The main objective of our work was to study the sex differences in constitutive autophagy in spinal cord and skeletal muscle tissue from wild type mice. To examine the influence of sex on autophagy, mRNA and proteins were extracted from male and female mice tissues. The expressions of microtubule-associated protein 1 light chain 3 (LC3) and sequestosome 1 (p62), markers to monitor autophagy, were analyzed at 40, 60, 90, and 120 days of age. We found significant sex differences in the expression of LC3 and p62 in both tissues at these ages. The results indicated that sex and tissue specific differences exist in constitutive autophagy. These data underlined the need to include both sexes in the experimental groups to minimize any sex bias.

Figure 1

LC3 and p62 mRNA expression in the spinal cord and the skeletal muscle. (a) The transcript levels in the spinal cord of males (black bars) and females (grey bars) from mice at P60, P90, and P120 are shown. Relative expression values are females compared with males (set at 1) at each age. (b) The transcript levels in skeletal muscles of male (black bars) and female (grey bars) mice at P40, P60, P90, and P120 are shown as in (a). Each data point represents the mean ± SEM of twelve mice. Asterisks denote a student t-test p value <0.05 (*), <0.01 (**), and <0.001 (***).

Figure 2

LC3-II and p62 protein expression in the spinal cord. Western blot for LC3-II and p62 proteins in spinal cord tissue from male (black bars) and female (grey bars) mice and its quantitative analysis relative to GAPDH. The representative blots for each age, sex, and protein are shown at the bottom. Data show mean ± SEM of twelve mice. p value <0.05 (*) and <0.001 (***).

Figure 3

LC3-II and p62 protein expression in the skeletal muscle. Western blot for LC3-II, LC3-I, and p62 proteins in muscle tissue from male (black bars) and female (grey bars) mice and its quantitative analysis relative to GAPDH. Data show mean ± SEM of twelve mice. p value <0.05 (*) and <0.001 (***).