Selenium Status Affects Hypertrophic Growth of Skeletal Muscle in Growing Zebrafish by Mediating Protein Turnover.

Abstract

Selenium (Se) status is closely related to skeletal muscle physiological status. However, its influence on skeletal muscle growth has not been well studied. This study aimed to analyze the impacts of overall Se status (deficient, adequate, and high) on skeletal muscle growth using a growing zebrafish model. Zebrafish (1.5-mo-old) were fed graded levels of Se (deficient: 0.10mg Se/kg; marginally deficient: 0.22mg Se/kg; adequate: 0.34mg Se/kg; high: 0.44, 0.57, and 0.69mg Se/kg) as Se-enriched yeast for 30 d. Zebrafish growth, and Se accumulation, selenoenzyme activity, selenotranscriptome profiles, and oxidative status in the whole body, and selenotranscriptome profiles, histological characteristics, biochemicals, and gene and protein expression profiles related to muscle growth in the skeletal muscle were analyzed by model fitting and/or 1-factor ANOVA. Se status biomarkers within the whole body and skeletal muscle indicated that 0.34mg Se/kg was adequate for growing zebrafish. For biomarkers related to skeletal muscle growth, compared with 0.34mg Se/kg, 0.10mg Se/kg decreased the white muscle cross-sectional area (WMCSA) and the mean diameter of white muscle fibers (MDWMF) by 14.4%-15.1%, inhibited protein kinase B-target of rapamycin complex 1 signaling by 63.7%-68.5%, and stimulated the autophagy-lysosome pathway by 1.07 times and the ubiquitin-proteasome pathway (UPP) by 96.0% (P <0.05), whereas 0.22mg Se/kg only decreased the WMCSA by 7.8% (P <0.05); furthermore, 0.44mg Se/kg had no clear effects on skeletal muscle biomarkers, whereas 0.57-0.69mg Se/kg decreased the WMCSA and MDWMF by 6.3%-25.9% and 5.1%-21.3%, respectively, and stimulated the UPP by 2.23 times (P <0.05). A level of 0.34mg Se/kg is adequate for the growth of zebrafish skeletal muscle, whereas ≤0.10 and ≥0.57mg Se/kg are too low or too high, respectively, for maintaining efficient protein accretion and normal hypertrophic growth.