Chronic binge alcohol consumption alters myogenic gene expression and reduces in vitro myogenic differentiation potential of myoblasts from rhesus macaques

Abstract

Chronic alcohol abuse is associated with skeletal muscle myopathy. Previously, we demonstrated that chronic binge alcohol (CBA) consumption by rhesus macaques accentuates skeletal muscle wasting at end-stage of simian immunodeficiency virus (SIV) infection. A proinflammatory, prooxidative milieu and enhanced ubiquitin proteasome activity were identified as possible mechanisms leading to loss of skeletal muscle. The possibility that impaired regenerative capacity, as reflected by the ability of myoblasts derived from satellite cell (SCs) to differentiate into myotubes has not been examined. We hypothesized that the inflammation and oxidative stress in skeletal muscle from CBA animals impair the differentiation capacity of myoblasts to form new myofibers in in vitro assays. We isolated primary myoblasts from the quadriceps femoris of rhesus macaques that were administered CBA or isocaloric sucrose (SUC) for 19 mo. Proliferation and differentiation potential of cultured myoblasts were examined in vitro. Myoblasts from the CBA group had significantly reduced PAX7, MYOD1, MYOG, MYF5, and MEF2C expression. This was associated with decreased myotube formation as evidenced by Jenner-Giemsa staining and myonuclei fusion index. No significant difference in the proliferative ability, cell cycle distribution, or autophagy was detected between myoblasts isolated from CBA and SUC groups. Together, these results reflect marked dysregulation of myoblast myogenic gene expression and myotube formation, which we interpret as evidence of impaired skeletal muscle regenerative capacity in CBA-administered macaques. The contribution of this mechanism to alcoholic myopathy warrants further investigation.

Behavioral, Metabolic, and Immune Consequences of Chronic Alcohol or Cannabinoids on HIV/AIDs: Studies in the Non-Human Primate SIV Model

“…Moreover, they show a marked decrease in skeletal muscle mass (SAIDS wasting) and dysfunctional skeletal muscle phenotype, which we found were associated with accelerated time to end-stage disease, relative to isocaloric sucrose SIV-infected animals (Molina et al 2006). Our findings indicate that the mechanisms underlying (and preceding) accentuated SAIDS wasting include the amplification of localized skeletal muscle inflammation, profound depletion of skeletal muscle anti-oxidant capacity (oxidative stress), increased proteasomal activity, and decreased myoblast differentiation potential (LeCapitaine et al 2011; Simon et al 2014). …”

Chronic Binge Alcohol Administration Accentuates Expression of Pro‐Fibrotic and Inflammatory Genes in the Skeletal Muscle of Simian Immunodeficiency Virus–Infected Macaques

“…The pro-inflammatory milieu present in the SKM of the CBA-SIV animals potentially contributes to the up-regulation of pro-fibrotic gene expression and favors collagen expression, which we predict is likely to impair satellite cell (resident SKM stem cells) function and muscle regeneration. Recent studies from our laboratory have demonstrated that myogenic gene expression is markedly altered in satellite cells isolated from CBA animals and this is associated with impaired myotube formation (Simon et al, 2014). In addition, the down-regulation of genes that code for proteins involved in anabolic signaling suggests that the overall loss in SKM is likely the result of combined enhancement of proteolysis and suppression of anabolic mechanisms.…”

HEMA 3 Staining: A Simple Alternative for the Assessment of Myoblast Differentiation

“…Differentiating myoblasts can be fixed, stained, and visualized, and indices of differentiation can be quantified. Using the protocols described herein, we have previously found that myoblasts isolated from simian immunodeficiency virus–infected male rhesus macaques subjected to chronic binge alcohol administration have reduced myoblast differentiation potential compared to those who were not administered alcohol (Simon et al., ; Simon, Ford, et al., ). The use of these protocols to assess differentiation provide support for hypothesized mechanisms underlying alcoholic myopathy (Molina, Simon, Amedee, Welsh, & Ferguson, ; Simon, Jolley, & Molina, ).…”

“…Growth and repair of skeletal muscle tissue requires satellite cells to be activated, proliferated, differentiated, and fused with existing muscle fibers in a process termed myogenesis (Yin, Price, & Rudnicki, ). Some stimuli, such as resistance or high‐force exercise and anabolic hormones, promote myogenesis (Bellamy et al., ; Goh et al., ; Sinha‐Hikim, Cornford, Gaytan, Lee, & Bhasin, ), whereas stimuli such as alcohol and catabolic hormones impair myogenesis (Dong, Pan, & Zhang, ; McCroskery, Thomas, Maxwell, Sharma, & Kambadur, ; Simon et al., ; Simon, Ford, et al., ). Myogenesis can be studied in vitro using myoblasts isolated from skeletal muscle cultured first in high‐serum medium to promote myoblast proliferation and then in low‐serum medium to promote differentiation and fusion.…”