Neonatal and Adult Myosin Heavy Chain Isoforms in a Nerve-Muscle Culture System

• Published in: The Journal of cell biology Vol. 103; no. 3; pp. 995 - 1005
• Main Authors: Ecob-Prince, Marion S., Jenkison, Margaret, Butler-Browne, Gillian S., Whalen, Robert G.
• Format: Journal Article
• Language: English
• Published: New York, NY Rockefeller University Press 01.09.1986; The Rockefeller University Press
• Subjects: Adults; Age Factors; Animals; Animals, Newborn; Antibodies; Biological and medical sciences; Bungarotoxins - pharmacology; Cell interactions, adhesion; Embryonic Induction; Fundamental and applied biological sciences. Psychology; Innervation; Mice; Molecular and cellular biology; Morphogenesis; Muscle Contraction - drug effects; Muscle fibers; Muscles; Muscles - analysis; Muscles - ultrastructure; Myosins - analysis; Nerves; Organ Culture Techniques; Protein isoforms; Rats; Skeletal muscle; Spinal cord; Spinal Cord - analysis; Spinal Cord - embryology; Vertebrata; Mixed cell culture; Regulation(control); Mammalia; Neuron; Mouse; Rodentia; Myosin; Contractile protein; Biosynthesis; Myotube; Striated muscle
• ISSN: 0021-9525; 1540-8140
• DOI: 10.1083/jcb.103.3.995

When adult mouse muscle fibers are cocultured with embryonic mouse spinal cord, the muscle regenerates to form myotubes that develop cross-striations and contractions. We have investigated the myosin heavy chain (MHC) isoforms present in these cultures using polyclonal antibodies to the neonatal, adult fast, and slow MHC isoforms of rat (all of which were shown to react specifically with the analogous mouse isoforms) in an immunocytochemical assay. The adult fast MHC was absent in newly formed myotubes but was found at later times, although it was absent when the myotubes myotubes were cultured without spinal cord tissue. When nerve-induced muscle contractions were blocked by the continuous presence of α-bungarotoxin, there was no decrease in the proportion of fibers that contained adult fast MHC. Neonatal and slow MHC were found at all times in culture, even in the absence of the spinal cord, and so their expression was not thought to be nerve-dependent. Thus, in this culture system, the expression of adult fast MHC required the presence of the spinal cord, but was probably not dependent upon nerve-induced contractile activity in the muscle fibers.