• The Korean Journal of Zoology
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• v.38 no.1
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• pp.78-86
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• 1995

Our previous report has suggested that the decrease of fibronectin level during mvogenesis is due to the decreased Bvailabilitv of receptor (matrix assembly receptor) for 29-kDa fragment of fibronectin. In the present study, we demonstrate that G protein and adenvlate cvclase system are involved in the regulation of fibronectin matrix assembly and that when fibronectin level in extracellular matrix decreases, the postmitotic fusion-capable cells emerge more frequently from the proliferative population. This proposal is based on the following observations. (1) Cholers toxin, which increases intracellular CAMP, caused a decrease in the ability of mvoblasts to incorporate fibronectin into extracellular matrix. (2) Cholera toxin decreased the proliferation of mvoblasts and Induced the precocious fusion. (3) decAMP, which was found to induce the precocious fusion and decrease the proliferation of myoblasts, decreased the fibronectin level in extracellular matrix and matrix assembly receptor for fibronectin- (4) RGOS, whlh inhibits the incorporation of fibronectin into extracellular matrix, induced the precocious fusion and reduced the proliferaton of mvoblasts. These results suggest that CAMP regulates the fibronectin levels in extracellular matrix and that the alteration of fibronectin level is involved in regulation of the proliferation and differentiation of chick embryonic mvoblasts.