RT Journal Article SR Electronic T1 Gain-of-function dynamin-2 mutations linked to centronuclear myopathy impair Ca2+-induced exocytosis in human myoblasts JF bioRxiv FD Cold Spring Harbor Laboratory SP 2022.08.31.506089 DO 10.1101/2022.08.31.506089 A1 Lucas Bayonés A1 María José Guerra-Fernández A1 Fernando Hinostroza A1 Ximena Báez-Matus A1 Jacqueline Vásquez-Navarrete A1 Luciana I. Gallo A1 Sergio Parra A1 Agustín D. Martínez A1 Arlek González-Jamett A1 Fernando D. Marengo A1 Ana M. Cárdenas YR 2022 UL http://biorxiv.org/content/early/2022/09/03/2022.08.31.506089.abstract AB Gain-of-function mutations of dynamin-2, a mechano-GTPase that remodels membrane and actin filaments, cause centronuclear myopathy (CNM), a congenital disease that mainly affects skeletal muscle tissue. Among these mutations, the variants p.A618T and p.S619L lead to gain of function and cause a severe neonatal phenotype. By using total internal reflection fluorescence microscopy (TIRFM) in immortalized human myoblasts expressing the pH-sensitive fluorescent protein (pHluorin) fused to the insulin-responsive aminopeptidase IRAP as reporter of the GLUT4 vesicle-trafficking, we measured single pHluorin signals to investigate how p.A618T and p.S619L mutations influence exocytosis. We show here that both dynamin-2 mutations significantly reduced the number and durations of pHluorin signals induced by 10 μM ionomycin, indicating that in addition to impair exocytosis, they also affect the fusion pore dynamics. These mutations also disrupt the formation of actin filaments, a process that reportedly favors exocytosis. This altered exocytosis might importantly disturb the plasmalemma expression of functional proteins such as the glucose transporter GLUT4 in skeletal muscle cells, impacting the physiology of the skeletal muscle tissue and contributing to the CNM disease.Competing Interest StatementThe authors have declared no competing interest.