Fibroblasts that proliferate near denervated synaptic sites in skeletal muscle synthesize the adhesive molecules tenascin(J1), N-CAM, fibronectin, and a heparan sulfate proteoglycan.

摘要: Four adhesive molecules, tenascin(J1), N-CAM, fibronectin, and a heparan sulfate proteoglycan, accumulate in interstitial spaces near synaptic sites after denervation of rat skeletal muscle (Sanes, J. R., M. Schachner, Covault. 1986. Cell Biol. 102:420-431). We have now asked which cells synthesize these how this synthesis is regulated. Electron microscopy revealed that mononucleated selectively perisynaptic beginning 2 d denervation. These were identified as fibroblasts by ultrastructural immunohistochemical criteria; [3H]thymidine autoradiography their accumulation results from local proliferation. microscopic immunohistochemistry demonstrated N-CAM associated with the surface fibroblasts, while tenascin(J1) collagen fibers abut fibroblasts. Using immunofluorescence immunoprecipitation methods, we found isolated regions denervated proteoglycan vitro. Thus, proliferate are likely to be cellular source deposits molecules muscle. To elucidate factors might regulate vivo, analyzed expression fibronectin cultured Fibroblasts synapse-free muscle, well skin, lung, 3T3 high levels culture, showing not unique regard. However, when they first placed bear more than innervated indicating molecule regulated muscle's state innervation; difference no longer apparent few days culture. In cells, proliferating cultures, depressed confluent reactivated stimulated replating at low density or wounding monolayer. parallel mitotic activity. contrast, increase less dramatically similar quiescent cells.(ABSTRACT TRUNCATED AT 400 WORDS)