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Parallel Regulation of Procollagen I and Colligin, a Collagen-Binding Protein and a Member of the Serine Protease Inhibitor Family

Elke P. Clarke, Neeraj Jain, Anne Brickenden, Ian A. Lorimer and Bishnu D. Sanwal
The Journal of Cell Biology
Vol. 121, No. 1 (Apr., 1993), pp. 193-199
Stable URL: http://www.jstor.org/stable/1615726
Page Count: 7
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Parallel Regulation of Procollagen I and Colligin, a Collagen-Binding Protein and a Member of the Serine Protease Inhibitor Family
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Abstract

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 TGFβ, 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.

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