| Budget Amount *help |
¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1989: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1988: ¥1,700,000 (Direct Cost: ¥1,700,000)
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| Research Abstract |
Heat shock protein of molecular weight 47,000 D, HSP47, binds to native and denatured collagen including type I, type III, or type IV. We examined the localization of HSP47 as well as collagen type I,II,III, and IV in various tissues from chicken embryos and adults by immunohistochemical and immuno- electronmicroscopical methods. In adult chicks, HSP47 is located on fibrocytes or fibroblasts in the connective tissue in various organs, chondrocytes in the cartilage, smooth muscle cells in the gastrointestinal tract and blood vessels, vitamin A storage cells in sinusoidal area of liver, and epithelial cells of renal glomeruli and tubules. These cells also co-express a certain type of collagen molecules. Further, in developing embryos the expression of HSP47 in periosteal fibroblasts surrounding vertebral bone or in chondrocytes within scleral cartilage is coupled to the expression of collagen type I or type II, respectively.
When chick embryo fibroblasts (CEF) were cultured in the condition that the hydroxylation of pro-alpha chains of collagen was inhibited, such as deficiency of ascorbate or addition of 2-2'-dipyridyl, procollagen was retained within ER in the granular pattern because of inhibition of triple-helix formation, and HSP47 was co-localized with procollagen. Enough level of hydroxylation induced the formation of triple-helix and the transportation of procollagen molecules from ER to Golgi apparatus to change the distribution of HSP47 to reticular networks. Even if enough ascorbate was added to the cultures, heat shock treatment of the cells induced the retention of procollagen molecules in ER because the helix formation was inhibited at high temperature over melting point of procollagen. The distribution of HSP47 was also coincided to that of retained procollagen.
These results indicate that HSP47 indeed binds to collagen molecules in vivo, and that it may play an important role in the transportation of procollagen molecules from ER to Golgi.
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