Collagens of Cartilage and the Intervertebral Disc

描述（由申请人提供）：本项目采用先进的蛋白质分析方法，研究构成软骨细胞外基质的胶原和相关蛋白的复杂聚合组装。稳定网络的共价交联机制和驱动组装的非共价蛋白质-蛋白质相互作用特别令人感兴趣。我们的目的是了解IX型胶原分子与II型胶原原纤维交联的机制，以及异型聚合物的另一组分XI型胶原在其中的作用。基于交联残基的位置，胶原ix -胶原11相互作用的分子模型正在得到完善。与透明软骨的长型相比，用于椎间盘的短型胶原IX分子的特性正在被确定。这包括研究两条胶原IX链（由COL9A2和COL9A3编码）中含有色氨酸(W)的等位基因变异（多态性）如何导致与这些基因型相关的椎间盘退变风险增加。对w等位基因阳性的人软骨和椎间盘组织的基因分型样本进行分析，以确定表达的胶原IX是否在翻译后发生改变，从而可能导致加速椎间盘退变和/或神经根刺激。在椎间盘中表达的胶原V和XI基因产物和剪接变异体的特征是根据所代表的分子种类的数量，以及它们在基质和n -前肽结构域结合相互作用中的共价交联伙伴。matrilin-3的结合位点，一种选择性结合胶原网络成分的蛋白质，正在胶原亚基中被定义。胶原蛋白网络中任何其他共价键合的分子组分也将被识别。

DESCRIPTION (provided by applicant): This project is using advanced methods in protein analysis to study the complex polymeric assembly of collagens and associated proteins that frame the extracellular matrix of cartilages. Covalent cross-linking mechanisms that stabilize the network and non-covalent protein-protein interactions that drive the assembly are of particular interest. We aim to understand the mechanism of cross-linking of the type IX collagen molecule onto the type II collagen fibril, and the role in this of type XI collagen, another component of the heterotypic polymer. A molecular model of the collagen IX-collagen 11 interaction is being refined based on the placement of cross-linking residues. The properties of the short variant of the collagen IX molecule used in the intervertebral disc, compared with the long form of hyaline cartilage, are being determined. This includes studying how tryptophan (W)-containing allelic variants (polymorphisms) of two of the collagen IX chains (encoded by COL9A2 and COL9A3) can cause the reported increased risk of disc degeneration associated with these genotypes. Genotyped samples of human cartilage and disc tissue positive for the W-alleles are being analyzed to determine if the expressed collagen IX becomes post-translationally altered such that it could lead to accelerated disc degeneration and/or nerve root irritation. Collagen V and XI gene products and splicing variants expressed in the intervertebral disc are being characterized in terms of number of molecular species represented, for their covalent cross-linking partners in the matrix and N-propeptide domain binding interactions. The binding sites for matrilin-3, a protein that selectively binds to components of the collagen network, are being defined in the collagen subunits. Any additional covalently bonded molecular components of the collagen network will also be identified. The clinical significance of the work is in providing a basis in molecular structure for understanding processes through which articular cartilages and intervertebral discs may be at risk of being degraded during adult life. Since mechanical failure of the collagen framework of both tissues is a key, irreversible feature of age-related joint degeneration, new insights on molecular mechanisms may offer the basis of therapeutic advances.