Estrogen Regulates the Satellite Cell Compartment in Females
Skeletal muscle mass, strength, and regenerative capacity decline with age, with many measures showing greater deterioration in females about the time estrogen levels decrease at menopause. Here we show that maintenance of muscle stem cells, satellite cells, as well as self-renewal and differentiation into muscle fibers, are severely compromised by estrogen deficiency. Mechanistically, by hormone replacement, use of a selective estrogen-receptor modulator (bazedoxifene), and conditional estrogen receptor knockout, we implicate 17{beta}-estradiol and satellite cell expression of estrogen receptor (ER) and show that estrogen signaling through this receptor is necessary to prevent apoptosis of satellite cells. Early data from a biopsy study of women who transitioned from peri-to post-menopause are consistent with the loss of satellite cells coincident with the decline in estradiol in humans. Together, these results demonstrate an important role for estrogen in satellite cell maintenance and muscle regeneration in females.