Studies on the role of microtubules in myofibrillogenesis

Abstract

Go-localization of microtubnle (MT) and muscle myosin (MHC) myofibril immunofluoreseoneo in developing myotubes of chicken skeletal muscle cultures was observed by using double staining of tubulin and MHC indirect immunofluorescence. 12-o-tetradecanoyl-phorbol-13-acetate (TPA) selectively and reversibly blocks myofibrillogenesis and alters the morphology of myotubes into myosacs where MTs are present in radiating pattern. When the arrested myogenic cells recover and start myofibrillogenesis after released from TPA, prior to the emergence of myofibrils, the pro-existing MTs become bipolarly aligned eoineidontly with the tubular restoration of cell shape. Single nascent myofibrils overlapping with MTs extend into the base of growth tips where MTs go farther to the end of the tips. That MT might act as scaffold in guiding the bipolar elongation of the growing myofibrils was suggested. Taxol and eoleomid disturbed MT polymerization and disposition, and interfered with the normal spatial assembly of myofibrils in developing myotubos.