Vesicular transport system in myotubes: ultrastructural study and signposting with vesicle-associated membrane proteins

Abstract

Myofibers have characteristic membrane compartments in their cytoplasm and sarcolemma, such as the sarcoplasmic reticulum, T-tubules, neuromuscular junction, and myotendinous junction. Little is known about the vesicular transport that is believed to mediate the development of these membrane compartments. We determined the locations of organelles in differentiating myotubes. Electron microscopic observation of a whole myotube revealed the arrangement of Golgi apparatus, rough endoplasmic reticulum, autolysosomes, mitochondria, and smooth endoplasmic reticulum from the perinuclear region toward the end of myotubes and the existence of a large number of vesicles near the ends of myotubes. Vesicles in myotubes were further characterized using immunofluorescence microscopy to analyze expression and localization of vesicle-associated membrane proteins (VAMPs). VAMPs are a family of seven proteins that regulate post-Golgi vesicular transport via the fusion of vesicles to the target membranes. Myotubes express five VAMPs in total. Vesicles with VAMP2, VAMP3, or VAMP5 were found near the ends of the myotubes. Some of these vesicles are also positive for caveolin-3, suggesting their participation in the development of T-tubules. Our morphological analyses revealed the characteristic arrangement of organelles in myotubes and the existence of transport vesicles near the ends of the myotubes.

Release of VAMP5‐positive extracellular vesicles by retinal Müller glia in vivo

“…Our finding that VAMP5 is associated with EVs is supported by several lines of evidence. Electron microscopic inspection of muscle cell lines revealed its localization at the plasma membrane, in vesicular structures, and in multivesicular bodies (Tajika et al, 2014;Zeng et al, 1998) in line with our immunogold data. Moreover, VAMP5 was detected in EVs of the murine lung (Choudhary et al, 2021), from cultured myotubes (Forterre et al, 2014), mesenchymal stem cells (Salomon et al, 2013) and tumoural Jurkat T cells (Bosque et al, 2016).…”

Release of VAMP5-positive extracellular vesicles by retinal Müller gliain vivo

“…Our finding that VAMP5 is associated with EVs is supported by several lines of evidence. Electron microscopic inspection of muscle cell lines revealed its localization at the plasma membrane, in vesicular structures, and in multivesicular bodies (Tajika et al, 2014;Zeng et al, 1998) in line with our immunogold data. Moreover, VAMP5 was detected in EVs of the murine lung (Choudhary et al, 2021), from cultured myotubes (Forterre et al, 2014), mesenchymal stem cells (Salomon et al, 2013) and tumoral Jurkat T cells (Bosque et al, 2016).…”

The Evaluation and Validation of Blood-Derived Novel Biomarkers for Precise and Rapid Diagnosis of Tuberculosis in Areas With High-TB Burden

“…Vesicle-associated membrane protein 5 (VAMP5) is a member of the SNARE protein family, which regulates the docking and fusion of intracellular membrane vesicles ( Hong, 2005 ) and is involved in the development or function of the respiratory system ( Ikezawa et al, 2018 ). VAMP5 controls intracellular transport events, including endocytosis, exocytosis, and internal recycling ( Tajika et al, 2014 ). SERPING1-encoded serpin peptidase Inhibitor (C1Inh), a member of a large family of serine proteases, can influence the complement C1q levels which can mark active disease in human tuberculosis ( Cai et al, 2014 ; Horwitz et al, 2019 ).…”