Tissue culture studies of muscle disorders: Part 1. Techniques, cell growth, morphology, cell surface

Abstract

Tissue culture has been used extensively in studies of human inherited disorders, and its application in the field of the neuromuscular disorders has increased rapidly in recent years. This review, covering the period 1977 to 1984, deals with tissue culture studies of both human and animal muscle disorders, although Duchenne muscular dystrophy (DMD) figures prominently because of the overwhelming interest in that disorder. The review is in two parts. In the first part, I discuss technical innovations in the field, the morphology and growth of cells, and a variety of studies related to the cell surface. Important findings in relation to DMD include reports of abnormal growth rates and reduced lifespan of DMD cells, hypersensitivity to DNA-damaging agents, abnormal cell-to-cell and cell-to-substratum adhesion, and a more "fluid" cell membrane. However, these findings are controversial or have so far been reported only by single laboratories.

Acetylcholine Receptors in Innervated Muscles of DystrophicmdxMice Degrade as after Denervation

“…If the steady-state AChR density is indeed unaffected in md x animals as reported by Lyons and Slater (1991), the fast degradation rate of AChRs in innervated md x muscles must be compensated for by an increased synthesis of AChRs. In fact, total protein turnover has been reported to be elevated in md x muscles (Witkowski, 1986;MacLennan and Edwards, 1990;MacLennan et al, 1991;Kämper and Rodemann, 1992). Future studies on the distribution and insertion rates of AChRs on md x muscles should help resolve this issue.…”

“…6). Thus the adenylate cyclase pathway for stabilizing Rs was f unctioning in md x muscles, although as suggested by Witkowski (1986), the sensitivity to all factors may not be as in controls.…”

“…Although adenylate cyclase can be activated by forskolin, it may not respond to some relevant neurotrophic factors, just as it is insensitive to catecholamines and sodium fluorides (Witkowski, 1986). One such possible neurotrophic factor is calcitonin gene-related peptide (CGRP), a 37 amino acid peptide that elevates intracellular cAMP Changeux, 1987, 1989;Miles et al, 1989;Crook and Yabu, 1992).…”

“…Earlier reports had indeed suggested that adenylate cyclase in dystrophic muscles were insensitive to stimulation by catecholamines or sodium fluoride (Witkowski, 1986). We therefore tested the effect of the adenylate cyclase activator forskolin on the degradation rate of the receptors in denervated diaphragm muscles.…”

Molecular and functional analysis of the muscle-specific promoter region of the Duchenne muscular dystrophy gene.

“…Prior to the cloning of the DMD gene, it was not clear whether the primary defect in this disease was expressed in myogenic cell cultures, since observations relating to growth, morphology, and membrane function were often inconsistent and contradictory (70). A number of reports * Corresponding author.…”