Project 2: The role of the HSP47/FKBP65 chaperone complex in osteogenesis imperfecta

项目2摘要 -- 我们小组的遗传学研究表明，编码两种I型前胶原蛋白之一的基因突变 伴侣，FKBP10(编码FKBP65蛋白)或SERPINH1(编码HSP47)，产生 严重的隐性遗传性OI。此外，我们已经确定这两种蛋白质形成了一种复合体 作用于内质网(ER)中的I型前胶原三聚体，其功能对正常是必不可少的 I型前胶原生物发生。复杂功能的取消会导致细胞表型的改变 扩张的内质网，细胞内I型前胶原聚集体，伴侣复合体成分的隔离和 异常的PLOD2依赖的交联物。通过使用突变的FKBP65和HSP47细胞系，我们已经 确定PLOD2也是这个新发现的伴侣复合体的成员，并确定了伴侣 功能障碍是OI新的发病机制。这些研究将主要使用新产生的小鼠 模型，辅以对人类OI组织的研究，以建立一种目前未被认识的机制 I型前胶原合成的范式和对OI是如何由这一缺陷导致的详细理解 进程。这是我们对I型前胶原合成的理解的一个范式转变，从如何 LH2修饰或能够接触到I型前胶原，并提供了对OI如何伴挛缩的洞察，也称为 作为Bruck综合征，可以由FKBP10或PLOD2的突变引起。建议的实验是 意义重大，因为它们有可能对我们对 端肽交联在功能性细胞外基质的产生中起作用，并将是必不可少的 在骨基质改变对骨下游功能影响的背景下理解和定制治疗方法 以及相关的组织。

Project 2 Summary   Genetic studies from our group has shown that mutations in the genes encoding either of two type I procollagen chaperones, FKBP10 (which encodes the FKBP65 protein) or SERPINH1 (which encodes HSP47), produce severe, recessively inherited forms of OI. Furthermore, we have determined that the two proteins form a complex acting on type I procollagen trimers in the endoplasmic reticulum (ER) and whose function is essential for normal type I procollagen biogenesis. Abrogation of the complex function leads to an altered cellular phenotype with dilated ER, aggregates of intracellular type I procollagen, sequestering of chaperone complex components and abnormal PLOD2-dependent cross-linking. Through the use of mutant FKBP65 and HSP47 cell lines, we have established that PLOD2 is also a member of this newly identified chaperone complex and identifies chaperone dysfunction as a new mechanism of disease in OI. These studies will primarily use newly generated mouse models, complemented by studies in human OI tissues to establish a currently unappreciated mechanistic paradigm for type I procollagen synthesis and a detailed understanding of how OI results from defects in this process. This is a paradigm shift in our understanding of type I procollagen synthesis from the viewpoint of how LH2 modifies or has access to type I procollagen and provides insight into how OI with contractures, also known as Bruck syndrome, can result from mutations in either FKBP10 or PLOD2. The proposed experiments are significant because they have the potential to have an extensive impact on our understanding of the role of telopeptide cross-linking plays in the generation of a functional extracellular matrix and will be essential to understanding and tailoring therapeutics in the context of altered bone matrix on downstream function of bone and associated tissues.