Estradiol deficiency reduces the satellite cell pool by impairing cell cycle progression

Abstract

The size of the satellite cell pool is reduced in estradiol (E2)-deficient female mice and humans. Here, we use a combination of in vivo and in vitro approaches to identify mechanisms whereby E2 deficiency impairs satellite cell maintenance. By measuring satellite cell numbers in mice at several early time points post-ovariectomy (Ovx), we determine that satellite cell numbers decline by 33% between 10 and 14 days post-Ovx in tibialis anterior and gastrocnemius muscles. At 14 days post-Ovx, we demonstrate that satellite cells have a reduced propensity to transition from G0/G1 to S and G2/M phases, compared to cells from ovary-intact mice, associated with changes in two key satellite cell cycle regulators, ccna2 and p16INK4a. Further, freshly isolated satellite cells treated with E2 in vitro have 62% greater cell proliferation and require less time to complete the first division. Using clonal and differentiation assays, we measured 69% larger satellite cell colonies and enhanced satellite cell-derived myoblast differentiation with E2 treatment compared to vehicle-treated cells. Together, these results identify a novel mechanism for preservation of the satellite cell pool by E2 via promotion of satellite cell cycling.

The chemokine receptor CXCR4 regulates satellite cell activation, early expansion, and self-renewal, in response to skeletal muscle injury

“…Following imaging, data were exported as individual TIFFs for each position and time point. ImageJ was used to concatenate TIFF images from each location and time to first division was determined for each as previously described ( Larson et al, 2022 ).…”

Influence of sexual dimorphism on satellite cell regulation and inflammatory response during skeletal muscle regeneration

“…Interestingly, postmenopausal women using hormonal (Kitajima & Ono, 2016;Seko et al, 2020). Use of phenol red, as an indicator of bacterial contaminations, which is also known as a selective modulator of ER-β due to its structure very close to that of non-steroidal E2 (Berthois et al, 1986;Welshons et al, 1988) Use phenol-free medium and charcoal stripped serum to avoid interactions between medium components and estrogens (Larson et al, 2022) Characterization of cell types/status Lack of specificity of markers used to characterize leukocyte infiltration Use of specific markers for immunostaining Omic approaches (single-cell/single-nucleus RNA seq, spatial transcriptomics) to identify a subpopulation of myogenic/inflammatory cells and/or specific transcriptomic signature…”

“…A consensus is emerging illustrating that OVX‐induced hormonal deficiency affects the number of SCs at steady‐state and after damage (Collins et al, 2019 ; Enns & Tiidus, 2008 ; Kitajima & Ono, 2016 ; Seko et al, 2020 ; Velders et al, 2012 ). The total number of SCs assessed by flow cytometry (i.e., CD31 − ,CD45 − ,VCAM + ,α7‐integrin + ) or by immunostaining (i.e., Pax7 + cells) was reduced in several uninjured muscles, such as tibialis anterior , extensor digitorum longus , gastrocnemius and diaphragm , after ovarian hormone deficiency lasting from 14 days to 7 months (Collins et al, 2019 ; Kitajima & Ono, 2016 ; Larson et al, 2022 ). On the contrary, the SC content of the slower soleus muscle was unaffected, suggesting that OVX could specifically affect SC number of the fast muscles (Collins et al, 2019 ).…”

“…Interestingly, SCs obtained from isolated myofibers and cultured for 3 days showed reduced self‐renewal and differentiating capacities after OVX (Kitajima & Ono, 2016 ). In addition, SCs from OVX mice showed a reduced capacity to transition from G0/G1 to S and G2/M phases as compared with SCs extracted from intact female mice (Larson et al, 2022 ). This was associated with an upregulated gene expression of ccna2 and p16 INK4a , known as key cell cycle regulators.…”

Decreased Neuromuscular Function and Muscle Quality along with Increased Systemic Inflammation and Muscle Proteolysis Occurring in the Presence of Decreased Estradiol and Protein Intake in Early to Intermediate Post-Menopausal Women

“…Because of the antioxidant properties of E2 [ 3 ], the reduction in endogenous E2 associated with menopause leads to oxidative stress and a subsequent increase in the expression of the pro-inflammatory mediators, tumor necrosis factor-α (TNF-α) [ 4 ] and nuclear factor kappa кB (NF-кB) [ 5 ], which can detrimentally impact muscle mass and function [ 6 ]. There is evidence demonstrating that a reduction in E2 triggers the release of TNF-α, suggesting that the decline in E2 associated with menopause can mediate inflammatory-regulated sarcopenia, thereby negatively impacting muscle quality (MQ) and muscular function [ 7 ].…”