monensin and Muscular-Dystrophies

The spreading on glass of monensin-treated normal and Duchenne fibroblasts has been investigated with the intention of extending this approach to a study of the comparative spreading of these cells on differing substrata. Untreated normal and Duchenne fibroblasts varied considerably in their ability to spread on glass. The spreading properties of normal and DMD fibroblasts treated in four different ways were compared: (1) pre-incubated and plated without monensin; (2) pre-incubated with, but plated without monensin; (3) pre-incubated without, but plated with monensin; (4) pre-incubated and plated with monensin. The response to plating with monensin (and pre-incubation/plating with monensin) also varied from patient to patient, but no statistically significant differences in the degree of spreading between the four treatment groups were observed in pooled data for either normal or dystrophic fibroblasts. Our data thus do not substantiate the previous finding of Pizzey et al. (1984) that Duchenne fibroblasts spread less well than normal fibroblasts after pre-incubation or plating with monensin, and possible explanations for this are discussed. The observations made are, however, consistent with the recent report that dystrophin is effectively not expressed in fibroblasts, and with the idea that the abnormal behaviour of endomysial fibroblasts in Duchenne dystrophy is a secondary consequence of their proximity to degenerating muscle.

Topics: Cell Adhesion; Fibroblasts; Glass; Humans; In Vitro Techniques; Monensin; Muscular Dystrophies

Cultured skin fibroblasts from patients with Duchenne muscular dystrophy (DMD) are more sensitive than normal cells to prolonged exposure to the ionophore monensin. In a cell spreading assay in which cells were preincubated with monensin and subsequently allowed to adhere to and spread on a glass substratum in serum-free medium for 100 min, the mean transformed cell area of normal and DMD cells was 5.97 +/- 0.11 and 5.29 +/- 0.03, respectively. Cultured fibroblasts from carriers of DMD yielded a value of 5.59 +/- 0.03, which is intermediate between, and significantly different from, the values for both normal and DMD cultures. This result would be predicted on the basis of random X-chromosome inactivation in female carriers of this disorder. However, comparison of DMD carrier cell spreading data with data obtained from pooled and summated measurements taken from separate experiments using either normal or DMD fibroblasts suggest a more complex situation. Examination of the variance of the means of cell area for the true carrier population and the summated normal and DMD population provides evidence suggesting that some form of cellular interaction may occur between the two cell genotypes in culture.

Topics: Cell Adhesion; Cells, Cultured; Fibroblasts; Heterozygote; Humans; Monensin; Muscular Dystrophies; Skin

Measurements of aggregation kinetics using couette viscometry show that freshly trypsinized skin fibroblasts from patients with Duchenne muscular dystrophy have values of intercellular adhesiveness approx. 40% those of normal cells. If cells are allowed to recover from the effects of trypsinization (by incubation for 2 h at 37 degrees C in serum-containing medium) the intercellular adhesiveness of both cell types increases, and normal and Duchenne cells aggregate to the same extent. Exposure to the ionophore monensin during the recovery phase leads to suppression of recovery in both cell types, and this effect of the drug is greater in Duchenne fibroblasts. These results are discussed in relation to other data on the reported differential effects of trypsin and monensin on normal and Duchenne fibroblasts.

Topics: Cell Aggregation; Fibroblasts; Furans; Humans; Monensin; Muscular Dystrophies; Skin; Trypsin

Cultured skin fibroblasts from normal individuals and from patients with Duchenne muscular dystrophy spread equally rapidly when seeded on a glass substratum. Exposure to the ionophore monensin substantially suppresses normal and dystrophic fibroblast spreading in serum-free media for up to at least 100 min. Preincubation of normal fibroblasts with monensin causes a further reduction in cell spreading. Dystrophic fibroblasts fail to spread as well as normal cells after monensin preincubation. Such findings indicate that there is a delay in the secretion of functional adhesive surface proteins in monensin-preincubated normal fibroblasts and that this lag period is significantly longer in dystrophic fibroblasts. These data are consistent with findings of altered adhesive and secretory properties of fibroblasts from patients with Duchenne muscular dystrophy.

Topics: Cell Adhesion; Cell Movement; Cells, Cultured; Furans; Humans; Monensin; Muscular Dystrophies