Anabolic effects of feeding β 2-adrenergic agonists on rainbow trout muscle proteases and proteins (original) (raw)
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PloS one, 2017
Proteolytic systems exert an important role in vertebrate muscle controlling protein turnover, recycling of amino acids (AA) or its use for energy production, as well as other functions like myogenesis. In fish, proteolytic systems are crucial for the relatively high muscle somatic index they possess, and because protein is the most important dietary component. Thus in this study, the molecular profile of proteolytic markers (calpains, cathepsins and ubiquitin-proteasome system (UbP) members) were analyzed during gilthead sea bream (Sparus aurata) myogenesis in vitro and under different AA treatments. The gene expression of calpains (capn1, capn3 and capns1b) decreased progressively during myogenesis together with the proteasome member n3; whereas capn2, capns1a, capns1b and ubiquitin (ub) remained stable. Contrarily, the cathepsin D (ctsd) paralogs and E3 ubiquitin ligases mafbx and murf1, showed a significant peak in gene expression at day 8 of culture that slightly decreased afte...
Mechanisms of stress-related muscle atrophy in fish: An ex vivo approach
Mechanisms of Development, 2018
Muscle development involves coordinated molecular events leading to cell proliferation, fusion, differentiation, sarcomere assembly, and myofibrogenesis. However, under physiological or pathological stress, energy requirements and secretion of glucocorticoids increase, resulting in muscle atrophy because of the depletion of energy reserves. Glucocorticoids induce muscular atrophy by two main mechanisms, protein degradation through the ubiquitin-proteasome system, and inhibition of protein synthesis through the negative regulation of the IGF1-Akt-mTOR signaling pathway. Other signaling pathways (such as the myostatin-activin-smad pathway) involved in muscle atrophy by glucocorticoid exposure are unclear. In fish, the role of glucocorticoids in muscle atrophy has not been fully elucidated. The aim of the present study was to evaluate the mechanisms of muscle atrophy induced by a synthetic glucocorticoid (dexamethasone, DEX) in an ex vivo muscle culture system of a marine fish (Lutjanus guttatus). Results showed that DEX was able to induce the expression of myostatin-1, and the expression of the transcription factor foxo3b. Myostatin-1 silencing by RNAi produced a decrease in the expression of foxo3b and murf1, and increased the expression of mtor, myod-2 and myogenin. These results suggest that in fish skeletal muscle, myostatin-1 signaling participates in glucocorticoid-induced muscle wasting through the negative regulation of genes involved in muscle growth, such as mtor, myod-2 and myogenin, and the induction of atrophy genes like foxo3b and murf1.
American journal of physiology. Regulatory, integrative and comparative physiology, 2017
Swimming activity primarily accelerates growth in fish by increasing protein synthesis and energy efficiency. The role of muscle in this process is remarkable and especially important in teleosts, where muscle represents a high percentage of body weight, and by the continuous growth that many fish species present. The aim of this work was to characterize the effects of five weeks of moderate and sustained swimming in gene and protein expression of myogenic regulatory factors, proliferation markers and proteolytic molecules in two muscle regions (anterior and caudal) of gilthead sea bream fingerlings. Western blot results showed an increase in the proliferation marker PCNA, proteolytic systems' members CAPN1 and CTSD, as well as vascular-endothelial growth factor protein expression. Moreover, quantitative real-time PCR data showed that exercise increased the gene expression of proteases: calpains, cathepsins and members of the ubiquitin-proteasome system in the anterior muscle re...