Defective Ca2+ metabolism in Duchenne muscular dystrophy: effects on cellular and viral growth.

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Abstract
Normal [human] fibroblasts in medium containing 0.02 mM CaCl2 arrested growth within 24 h, whereas Duchenne muscular dystrophy fibroblasts contained to grow for 5 days, albeit at 40% of their rate in standard medium (1.8 mM CaCl2). Moreover, Duchenne cells in Ca-deficient medium showed an enhanced rate of protein synthesis (60% over the rate in standard medium), whereas normal cells were unaffected. Previously a general assay was described for detection of mutant cells by using herpes simplex virus I replication as a probe of cellular function. By altering the growth medium, one can elicit changes in viral DNA replication that depend upon cellular differences. Duchenne fibroblasts in Ca-deficient loss-serum (0.5%) medium supported viral replication at a rate 7- to 10-fold greater than did normal cells infected under the same conditions. Using this viral assay, all 10 samples of a blind coded set of Duchenne muscular dystrophy, normal and heterozygote cells were successfully identified. In addition, differences of a lower magnitude were found between these cell strains as measured by cellular growth or protein synthesis. Therefore, a cell''s ability to grow and support viral replication in Ca-deficient medium can be used to readily distinguish Duchenne muscular dystrophy fibroblasts from normal ones. The viral assay could be used as a prenatal diagnostic test. A defect related to Ca metabolism may be functional to this disease.