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In mammalian skeletal muscle, ryanodine receptor (Ryr) expresses in the membrane of sarcoplasmic reticulum (SR), and is known as Ca2+-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 Ca2+ 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 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.

Mechanical stimuli such as stretch and resistance training are essential to regulate growth and function of skeletal muscle. However, the molecular mechanisms involved in sensing mechanical stress during muscle formation remain unclear. Here, we investigate the role of the mechano-sensitive ion channel Piezo1 during myogenic progression. Direct manipulation of Piezo1 in muscle stem cells alters their myogenic progression. Indeed, Piezo1 knockdown suppresses myoblast fusion leading to smaller myotubes. Such event is accompanied by significant downregulation of the fusogenic protein Myomaker. In parallel, while Piezo1 knockdown also lowers Ca2+ influx in response to stretch, Piezo1 activation increases Ca2+ influx in response to stretch and enhances myoblasts fusion. We believe these findings may help understand molecular defects present in some muscle diseases. Altogether our study shows that Piezo1 is essential for terminal muscle differentiation acting on myoblast fusion, suggesting that Piezo1 deregulation may have implications in muscle aging and degenerative diseases including muscular dystrophies.

International audience; Highly moisture-​resistant optical adhesives need to be developed for optical devices to ensure that they can be used reliably in optical devices for outside environment use. Further, a principal aim is that these adhesives have less toxicity impact on the environment and also on humans, so they need to be eco-​friendly. A Vegetable Oil Based Epoxidized Thermoset (VOBET) derived from linseed, was tested as an optical adhesive after being cured with different hardeners. A conventional optical adhesive, the petroleum-​based, Epotek 353ND was used as a ref. material. With increasing humidity the ref. material's shear strength decreased significantly and interface peeling was obsd. for all samples, while VOBET samples maintained a certain level of strength. One particular VOBET formulation showed exceptional reliability. A comparison of shear strength before and after a pressure cooker test of thermally cured VOBET samples and Epotek 353ND samples showed that the strength of the latter decreased significantly while the former maintained a certain ratio of the initial strength. Furthermore, one particular VOBET formulation that was successfully cured at room temp. showed ∼7.2 MPa shear strength, which is comparable to that of Epotek 353ND.

We report the adhesion properties between glass plates and silicon chips by measuring compression shear strength changes of silane modified optical adhesives, Y-41, Y-42, Y-43, and Y-45R after various reliability tests, with the goal to apply these adhesives to the newly emerging Si-photonics area.