Abstract
Identifying the genes relevant for muscle development is pivotal to improve meat production and quality in pigs. Insulin-degrading enzyme (IDE), a thiol zinc-metalloendopeptidase, has been known to regulate the myogenic process of mouse and rat myoblast cell lines, while its myogenic role in pigs remained elusive. Therefore, the current study aimed to identify the effects of IDE on the proliferation and apoptosis of porcine skeletal muscle stem cells (PSMSCs) and underlying molecular mechanism. We found that IDE was widely expressed in porcine tissues, including kidney, lung, spleen, liver, heart, and skeletal muscle. Then, to explore the effects of IDE on the proliferation and apoptosis of PSMSCs, we subjected the cells to siRNA-mediated knockdown of IDE expression, which resulted in promoted cell proliferation and reduced apoptosis. As one of key transcription factors in myogenesis, MYOD, its expression was also decreased with IDE knockdown. To further elucidate the underlying molecular mechanism, RNA sequencing was performed. Among transcripts perturbed by the IDE knockdown after, a downregulated gene myostatin (MSTN) which is known as a negative regulator for muscle growth attracted our interest. Indeed, MSTN knockdown led to similar results as those of the IDE knockdown, with upregulation of cell cycle-related genes, downregulation of MYOD as well as apoptosis-related genes, and enhanced cell proliferation. Taken together, our findings suggest that IDE regulates the proliferation and apoptosis of PSMSCs via MSTN/MYOD pathway. Thus, we recruit IDE to the gene family of regulators for porcine skeletal muscle development and propose IDE as an example of gene to prioritize in order to improve pork production.
Highlights
Skeletal myogenesis is an important and complex process during muscle development, which sequentially involves the proliferation of myoblasts, withdrawal from cell cycle, differentiation into mononucleated myocytes, fusion of myocytes into multinucleated myotubes, and maturation of myotubes into mature muscle fibers (Chal and Pourquié, 2017)
We aim to explore the role of Insulin-degrading enzyme (IDE) in porcine skeletal muscle stem cells (PSMSCs)
We determined the expression of IDE in pig different tissues. mRNA was isolated from kidney, lung, spleen, liver, heart, and skeletal muscle of adult large white pigs and subjected to Real-time quantitative polymerase chain reaction (RT-qPCR)
Summary
Skeletal myogenesis is an important and complex process during muscle development, which sequentially involves the proliferation of myoblasts, withdrawal from cell cycle, differentiation into mononucleated myocytes, fusion of myocytes into multinucleated myotubes, and maturation of myotubes into mature muscle fibers (Chal and Pourquié, 2017). Thereafter, MYOG expression further controls the differentiation process, and lastly MRF4, which is involved in myotube maturation (Rawls et al, 1998; Kitzmann and Fernandez, 2001; Yamamoto et al, 2018) Of these four MRFs, MYOD was the first one identified as a myogenic factor since forced expression of MYOD converted fibroblasts to stable myoblasts and activated muscle-specific genes (Davis et al, 1987; Weintraub et al, 1989). MYOG was identified as a factor regulating myogenesis, since transfection of MYOG into mesenchymal cell line produced cells expressing musclespecific markers (Wright et al, 1989) Both Myf and MRF4 act upstream of MYOD to direct embryonic multipotent cells into the myogenic lineage (Kassar-Duchossoy et al, 2004), demonstrating the importance of MYOD as a downstream effector in myogenesis
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