Parallel regulation of procollagen I and colligin, a collagen-binding protein and a member of the serine protease inhibitor family.
A potential regulatory linkage between the biosynthesis of colligin, a collagen-binding protein of the ER, and procollagen I was examined under a variety of experimental conditions. Cell lines which did not produce a significant amount of procollagen I mRNA also lacked the capacity to produce colligin mRNA. Anchorage-dependent cell lines like L6 myoblasts and normal rat kidney fibroblasts produced both colligin and procollagen I mRNA, but the level of both was concurrently reduced considerably in their ras-transformed counterparts. Similarly, during the differentiation of L6 myoblasts, levels of both colligin and procollagen declined together. Treatment of myoblasts by dexamethasone or EGF led to a decrease in the steady-state levels of procollagen I mRNA, and this was, again, accompanied by a decrease in colligin mRNA synthesis. On the other hand, when the rate of procollagen I synthesis was stimulated by treatment of myoblasts with TGF beta, it led to the concurrent augmentation of both the mRNA and protein levels of colligin. A linkage between the regulation of synthesis of procollagen I and colligin thus seems to exist. The only exception to this generalization is provided by the heat induction behavior of the two proteins. Treatment of myoblasts for a very short period leads to an increase in the synthesis of both the mRNA and protein levels of colligin. This, however, is not accompanied by a change in the mRNA levels of procollagen I. These studies establish that colligin and procollagen are generally tightly co-regulated except after heat shock, suggesting an important functional linkage.
Clarke
E P
EP
Department of Biochemistry, University of Western Ontario, London, Canada.
Jain
N
N
Brickenden
A
A
Lorimer
I A
IA
Sanwal
B D
BD
D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism*; D002454:Cell Differentiation; D002478:Cells, Cultured; D003094:Collagen / Q000096:biosynthesis / Q000378:metabolism*; D003907:Dexamethasone / Q000494:pharmacology; D004815:Epidermal Growth Factor / Q000502:physiology; D006023:Glycoproteins; D006360:Heat-Shock Proteins / Q000378:metabolism; D006801:Humans; D051379:Mice; D009132:Muscles / Q000166:cytology / Q000378:metabolism; D011347:Procollagen / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D015842:Serine Proteinase Inhibitors / Q000378:metabolism*; D016212:Transforming Growth Factor beta / Q000502:physiology
D002352:Carrier Proteins; D006023:Glycoproteins; D006360:Heat-Shock Proteins; D011347:Procollagen; D012333:RNA, Messenger; D015842:Serine Proteinase Inhibitors; D016212:Transforming Growth Factor beta; C046289:colligin; D004815:Epidermal Growth Factor; D003907:Dexamethasone; D003094:Collagen