Ryanodine receptor 3 impacts on the expression of aminopeptidase in mammalian skeletal muscle cells during myogenic differentiation

In mammalian skeletal muscle, ryanodine receptor (Ryr) expresses in the membrane of sarcoplasmic reticulum (SR), and is known as Ca 2+ -releasing channel. Ryr in mammalian skeletal muscle consists of 2 isoforms, Ryr1 and Ryr3. Ryr1 is coupled with dihydropyridine receptors (DHPRs) in transverse tubules, and Ca 2+ release is a key step for the excitation-contraction coupling (E-C coupling). However, a physiological role of ryr3 is still unclear. Recently, we confirmed that Ryr3 knockdown induces abnormal myotube formation of C2C12 cells. Further, it is reported that the abnormal shape of C2C12 myotubes were observed by the knockdown of puromycin-sensitive aminopeptidase, a selective hydrolyze of amino acid residue from the N-terminus of peptide and proteins. In the present study, we investigated that the molecular mechanisms for the abnormal myotube formation of C2C12 cells following the knockdown of Ryr3. Aggregation of phalloidin-stained actin fibers were observed in Ryr3-knockdown myotubes. On the other hand, a significantly decrease in the mRNA expression level of puromycin-sensitive aminopeptidase and endoplasmic reticulum aminopeptidase 1 was observed in Ryr3-knockdown C2C12 cells (p<0.05). Therefore, Ryr3 may play a crucial role in the quality control of proteins and peptides during myogenic differentiation via the up-regulation of puromycin-sensitive aminopeptidase and endoplasmic reticulum aminopeptidase 1. This study was partially supported by JSPS KAKENHI (18H03160, K.G.; 19K22825, K.G.; 19KK0254, K.G., S.Y., T.E.; 22H03474, K.G., T.E.; 22K19722, K.G., T.E.; 22H03319, K.G., T.E.; 22K18413, K.G., T.E.), a grant from Graduate School of Health Science, Toyohashi SOZO University (K.G.), and a research grant from Toyohashi SOZO university (K.G.). All authors declare that they have no conflicts of interest. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.