Calreticulin, PDI, Grp94 and BiP chaperone proteins are associated with retained COMP in pseudoachondroplasia chondrocytes
Calreticulin, PDI, Grp94 and BiP chaperone proteins are associated with retained COMP in pseudoachondroplasia chondrocytes
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DOI：
10.1016/s0945-053x(01)00136-6
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发表时间：
2001-07-01
期刊：
影响因子：
6.9
通讯作者：
Duke, PJ
中科院分区：
文献类型：
--
作者：
Hecht, JT;Hayes, E;Duke, PJ
软骨寡聚基质蛋白（COMP）是一种大的五聚体糖蛋白，是细胞外蛋白中血小板反应蛋白（TSP）组的成员，存在于软骨细胞周围的软骨基质中。超过50种独特的COMP突变已被确定为导致两种骨骼发育不良：假性软骨发育不全（PRACH）和多发性骨骺发育不良（EDM 1）。最近的研究表明，钙结合和钙诱导的蛋白质折叠之间的野生型和突变体蛋白质，和异常加工的突变COMP蛋白有助于特征性的扩大板层出现rER池在体内和体外的PSACH和Escherichia软骨细胞。为了阐明PSACH和Escherichia coli的发病机制，检查了在藻酸盐珠中培养的体内PSACH生长板和体外PSACH软骨细胞，以鉴定和定位参与PSACH rER中保留的细胞外基质蛋白的加工的伴侣蛋白。聚集蛋白聚糖定位于rER池和基质，而COMP和IX型胶原仅在rER中发现。II型胶原仅在ECM中发现，表明其与其他保留的ECM蛋白不同地加工和转运。五种伴侣蛋白：BiP（Grp78）;钙网蛋白（CRT）;蛋白质二硫化物（PDI）; ERp72;和Grp 94，在来自体内和体外样品的软骨细胞的扩大的PSACH池和短的rER通道中表现出免疫反应性。伴侣蛋白聚集在扩大的rER池内的电子致密物质周围。CRT、PDI和GRP 94 AB-金颗粒似乎与COMP密切相关。免疫沉淀和Western印迹以及荧光共振能量转移（FRET）分析表明，PDI和GRP 94与正常和突变型COMP非常接近，BiP与突变型COMP非常接近。这些结果表明，这些蛋白在正常软骨细胞中加工和转运野生型COMP以及在软骨细胞中保留野生型COMP中发挥作用。PSACH软骨细胞中突变COMP的表达。(C)2001 Elsevier Science B.V./国际矩阵生物学学会。All rights reserved.
Cartilage oligomeric matrix protein (COMP), a large pentameric glycoprotein and member of the thrombospondin (TSP) group of extracellular proteins, is found in the territiorial matrix surrounding chondrocytes. More than 50 unique COMP mutations have been identified as causing two skeletal dysplasias: pseudoachondroplasia (PSACH); and multiple epiphyseal dysplasia (EDM1). Recent studies suggest that calcium-binding and calcium-induced protein folding differ between wild type and mutant proteins, and abnormal processing of the mutant COMP protein contributes to the characteristic enlarged lamellar appearing rER cisternae in PSACH and EDMI chondrocytes in vivo and in vitro. Towards the goal of delineating the pathogenesis of PSACH and EDMI, in-vivo PSACH growth plate and in-vitro PSACH chondrocytes cultured in alginate beads were examined to identify and localize the chaperone proteins participating in the processing of the retained extracellular matrix proteins in the PSACH rER. Aggrecan was localized to both the rER cisternae and matrix while COMP and type IX collagen were only found in the rER. Type II collagen was solely found in the ECM suggesting that it is processed and transported differently from other retained ECM proteins. Five chaperone proteins: BiP (Grp78); calreticulin (CRT); protein disulfide (PDI); ERp72; and Grp94, demonstrated immunoreactivity in the enlarged PSACH cisternae and the short rER channels of chondrocytes from both in-vivo and in-vitro samples. The chaperone proteins cluster around the electron dense material within the enlarged rER cisternae. CRT, PDI and GRP94 AB-gold particles appear to be closely associated with COMP. Immunoprecipitation and Western blot, and Flourescence Resonance Energy Transfer (FRET) analyses indicate that CRT, PDI and GRP94 are in close proximity to normal and mutant COMP and BiP to mutant COMP. These results suggest that these proteins play a role in the processing and transport of wild type COMP in normal chondrocytes and in the retention of mutant COMP in PSACH chondrocytes. (C) 2001 Elsevier Science B.V./International Society of Matrix Biology. All rights reserved.