Aberrant signal peptide cleavage of collagen X in Schmid metaphyseal chondrodysplasia - Implications for the molecular basis of the disease
Aberrant signal peptide cleavage of collagen X in Schmid metaphyseal chondrodysplasia - Implications for the molecular basis of the disease
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DOI：
10.1074/jbc.m003361200
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发表时间：
2001-03-16
影响因子：
4.8
通讯作者：
Cheah, KSE
中科院分区：
文献类型：
--
作者：
Chan, D;Ho, MSP;Cheah, KSE
施密德干骺端软骨发育不良是由胶原X （COL10A1）基因突变引起的。除了两种情况外，已知的突变集中在胶原X的c端非螺旋（NC1）结构域。体外和细胞培养研究表明，NC1突变导致胶原X三聚体的组装和分泌受损。在另外两个案例中，发现了在假定的信号肽切割位点-1位置改变Gly（18）的错义突变（Ikegawa， S., Nakamura, K ., Nagano， A., Haga, N ., and Nakamura， Y. (1997) Hum, Mutat. 9,131 -135）。为了研究它们对胶原X生物合成的影响，在存在微粒体的体外无细胞翻译和细胞转染实验中，通过位点定向诱变在COL10A1中产生了这两个突变。数据表明，突变体α 1(X)前链易位进入微粒体不受影响，但信号肽的切割被抑制，突变体链仍然锚定在微粒体的膜上。细胞的无细胞翻译和转染研究表明，突变体链结合成三聚体，但不能形成三螺旋，信号肽切割和螺旋构型的缺乏共同影响分泌。因此，尽管X胶原中NC1和信号肽突变的性质不同，但两者都导致X胶原分泌受损，可能随后是细胞内突变链的保留和降解，并导致Schmid干骺端chandrodyplasia表型。
Schmid metaphyseal chondrodysplasia results from mutations in the collagen X (COL10A1) gene. With the exception of two cases, the known mutations are clustered in the C-terminal nonhelical (NC1) domain of the collagen X. In vitro and cell culture studies have shown that the NC1 mutations result in impaired collagen X trimer assembly and secretion. In the two other cases, missense mutations that alter Gly(18) at the -1 position of the putative signal peptide cleavage site were identified (Ikegawa, S., Nakamura, K,, Nagano, A., Haga, N,, and Nakamura, Y. (1997) Hum, Mutat. 9, 131-135). To study their impact on collagen X biosynthesis using in vitro cell-free translation in the presence of microsomes, and cell transfection assays, these two mutations were created in COL10A1 by site-directed mutagenesis. The data suggest that translocation of the mutant pre-alpha1(X) chains into the microsomes is not affected, but cleavage of the signal peptide is inhibited, and the mutant chains remain anchored to the membrane of microsomes, Cell-free translation and transfection studies in cells showed that the mutant chains associate into trimers but cannot form a triple helix, The combined effect of both the lack of signal peptide cleavage and helical configuration is impaired secretion. Thus, despite the different nature of the NC1 and signal peptide mutations in collagen X, both result in impaired collagen X secretion, probably followed by intracellular retention and degradation of mutant chains, and causing the Schmid metaphyseal chandrodysplasia phenotype.