IMPACT OF MUTANT COMP ON SECRETION IN CHONDROCYTES

突变体 COMP 对软骨细胞分泌的影响

• 批准号: 6375156
• 负责人: HANS PETER BACHINGER
• 金额: $ 19.03万
• 依托单位: OREGON HEALTH & SCIENCE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-09-30 至 2003-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6375156
• 关键词: SDS polyacrylamide gel electrophoresis; achondroplasia; affinity chromatography; analytical ultracentrifugation; bone development disorder; calcium; cartilage; chondrocytes; circular dichroism; collagen; disulfide bond; endoplasmic reticulum; extracellular matrix proteins; gene mutation; high performance liquid chromatography; ion exchange chromatography; molecular pathology; molecular sieving; protein binding; protein folding; protein structure; secretion; sedimentation equilibrium; thrombospondins; tissue /cell culture

Two human dwarfing disorders, pseudoachondroplasia (PSACH) and multiple epiphyseal dysplasia (MED), are caused by mutations in cartilage oligomeric matrix protein (COMP). In PSACH chondrocytes, mutations in COMP lead to the formation of abnormally large rough endoplasmic reticulum (RER) with a unique fingerprint appearance. Located within these vesicles are COMP and type IX collagen. These abnormal vesicles are not found in tendon fibroblasts, although these cells secrete COMP. This proposal is aimed at elucidating the molecular mechanism behind the abnormal retention of COMP and type IX collagen in chondrocytes but not in tendon fibroblasts. The following hypotheses were developed from recent studies: Mutant COMP molecules are retained in the RER of chondrocytes because the type III repeats do not fold properly, which leads to the formation of non-native disulfide bonds. These molecules are then interacting with either chondrocyte specific RER molecules and/or with native type IX collagen and/or type IX collagen chains in the process of assembly. This non-native complex cannot be secreted and leads to the accumulation in lamellar structures within the RER of chondrocytes. Secretion of mutant COMP occurs in fibroblasts and dedifferentiated chondrocytes, because these cells do not synthesize type IX collagen or do not contain chondrocyte specific RER proteins. Specific aims are proposed to determine the structure of normal and mutant thrombospondin type III repeats, to define the disulfide linkages in these repeats and the effects of calcium on structure, and to test binding interactions of mutant COMP with type IX collagen and unfolded type IX collagen chains and with REER proteins of chondrocytes.

两种人类矮小的疾病，假牙性脑（PSACH）和多个另一张力性发育不良（MED）是由软骨寡聚基质基质蛋白（COMP）突变引起的。 在PSACH软骨细胞中，COMP中的突变导致形成异常大的粗糙内质网（RER），具有独特的指纹外观。 位于这些囊泡内是Comp和IX型胶原蛋白。这些异常囊泡在肌腱成纤维细胞中未发现，尽管这些细胞分泌。 该建议旨在阐明在软骨细胞中的COMP和IX型胶原蛋白异常保留背后的分子机制，而不是在肌腱成纤维细胞中。 从最近的研究中提出了以下假设：突变体COMP分子保留在软骨细胞的RER中，因为III型重复不能正确折叠，从而导致形成非本性二硫化物键。 然后，在组装过程中，这些分子与软骨细胞特异性RER分子和/或与天然IX胶原蛋白和/或IX型胶原链相互作用。 这种非本地复合物不能分泌，并导致软骨细胞层中层状结构的积累。 突变comp的分泌发生在成纤维细胞和去分化的软骨细胞中，因为这些细胞不合成IX型胶原蛋白或不包含软骨细胞特异性RER蛋白。 提出具体目的是为了确定正常和突变体血小板蛋白III型重复序列的结构，以定义这些重复序列中的二硫键以及钙对结构的影响，并测试突变体与IX胶原型和未折叠的IX胶原链链的结合相互作用，以及与Chondorocytes的reer蛋白的结合相互作用。

项目成果

Selective intracellular retention of extracellular matrix proteins and chaperones associated with pseudoachondroplasia.

• DOI: 10.1016/s0945-053x(01)00148-2
• 发表时间: 2001-11
• 期刊: Matrix biology : journal of the International Society for Matrix Biology
• 作者: Janice A. Vranka;Asawari Mokashi;Asawari Mokashi;D. Keene;S. Tufa;G. Corson;M. Sussman;W. Horton;W. Horton;Kerry Maddox;Kerry Maddox;L. Sakai;L. Sakai;H. Bächinger;H. Bächinger