Sirt2 deficiency aggravates intramuscular adipose tissue infiltration and impairs myogenesis with aging in male mice.

Sarcopenia, closely associated with other diseases such as diabetes, metabolic syndrome, and osteoporosis, significantly impacts aging populations. It is characterized by muscle atrophy, increased intramuscular adipose tissue, impaired myogenesis, chronic low-grade inflammation, and reduced muscle function. The mechanisms behind aging muscle remain incompletely understood. This study aims to elucidate the role of Sirt2 in the aging process of skeletal muscles and enhance our understanding of the underlying mechanisms. Sirt2 expression was reduced in aging muscle of male mice by 40%, compared to young muscle. Aged male Sirt2 knockout mice exhibit increased intramuscular adipose tissue infiltration by 8.5-fold changes. Furthermore, the deletion of Sirt2 exacerbated myogenesis impairment in aged muscle by decreasing the expression of Pax7 (50%) and NogoA (80%), compared to age- and sex- matched counterparts, emphasizing the role of Sirt2 in pathology of aging muscle. Additionally, long-term Sirt2 deletion affected other Sirtuin subfamily members, with decreased expressions of Sirt1 (65%), Sirt4 (94%), and Sirt5 (71%), and increased expressions of Sirt6 (4.6-fold) and Sirt7 (2.8-fold) in old male Sirt2 knockout mice, while there was no difference of these gene expression in young male mice. This study underscores the critical need for a deeper investigation into Sirt2, promising new insights that could lead to targeted therapies for sarcopenia, ultimately improving the quality of life in the elderly.