Insufficient folding of type IV collagen and formation of abnormal basement membrane-like structure in embryoid bodies derived from Hsp47-null embryonic stem cells
Insufficient folding of type IV collagen and formation of abnormal basement membrane-like structure in embryoid bodies derived from Hsp47-null embryonic stem cells
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DOI：
10.1091/mbc.e04-01-0050
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发表时间：
2004-10-01
影响因子：
3.3
通讯作者：
Nagata, K
中科院分区：
文献类型：
--
作者：
Matsuoka, Y;Kubota, H;Nagata, K
热休克蛋白47是一种分子伴侣，特异性识别内质网中的前胶原。Hsp 47-null小鼠胚胎产生未成熟的I型胶原，并形成不连续的基底膜。我们建立了Hsp 47（-/-）胚胎干细胞系，并检查了形成的基底膜和生产的IV型胶原在胚状体，模型植入后的卵筒期胚胎。Hsp 47（-/-）胚状体周围的内脏内胚层细胞层往往是混乱的，这一结果表明，内脏内胚层下的基膜功能异常。Hsp 47（-/-）细胞分泌IV型胶原的速率比Hsp 47（+/+）细胞低4倍。此外，从Hsp 47（-/-）细胞分泌的IV型胶原蛋白比从Hsp 47（-/-）细胞分泌的IV型胶原蛋白对蛋白酶消化更敏感，这表明在不存在Hsp 47的情况下IV型胶原蛋白中的三螺旋形成不足或不正确。这些结果首次表明，热休克蛋白47是所需的IV型胶原蛋白的分子成熟，并建议，错误折叠的IV型胶原蛋白引起异常形态的胚状体。
Hsp47 is a molecular chaperone that specifically recognizes procollagen in the endoplasmic reticulum. Hsp47-null mouse embryos produce immature type I collagen and form discontinuous basement membranes. We established Hsp47(-/-) embryonic stem cell lines and examined formation of basement membrane and production of type IV collagen in embryoid bodies, a model for postimplantation egg-cylinder stage embryos. The visceral endodermal cell layers surrounding Hsp47(-/-) embryoid bodies were often disorganized, a result that suggested abnormal function of the basement membrane under the visceral endoderm. Rate of type IV collagen secretion by Hsp47(-/-) cells was fourfold lower than that of Hsp47(+/+) cells. Furthermore, type IV collagen secreted from Hsp47(-/-) cells was much more sensitive to protease digestion than was type IV collagen secreted from Hsp47(-/-) cells, which suggested insufficient or incorrect triple helix formation in type IV collagen in the absence of Hsp47. These results indicate for the first time that Hsp47 is required for the molecular maturation of type IV collagen and suggest that misfolded type IV collagen causes abnormal morphology of embryoid bodies.