Involvement of collagen in the aggregation of acetylcholine receptors on cultured muscle cells.

Abstract

The role of collagen macromolecules in the aggregation of acetylcholine receptors on the surface of cultured rat muscle cells was investigated. Both the synthesis and secretion of collagen, as well as acetylcholine receptor aggregation were stimulated by treatment of muscle cultures with an embryonic brain extract. Treatments with cis-hydroxyproline or monensin, which interfere with collagen synthesis and secretion, significantly reduced the number of acetylcholine receptor aggregates detected. Incubation of the cultures with embryonic brain extract induced a decrease in extractability of acetylcholine receptors. This effect could be reversed by treating the cells with bacterial collagenase. In addition, affinity purified antibodies against collagen of types I and IV inhibited the aggregation of acetylcholine receptors by stimulated brain extract. These data suggest that neurotrophic factor(s) present in embryonic nerve tissue have the ability to induce collagen production; the collagen formed plays a role in the formation and/or stabilization of acetylcholine receptor aggregates and possibly also of synaptic connections.