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型前胶原蛋白的基因突变， 分子伴侣FKBP10（编码FKBP65蛋白）或SERPINH1（编码HSP 47）产生 严重的复发性遗传性OI。此外，我们已经确定这两种蛋白质形成复合物， 作用于内质网（ER）中的I型前胶原三聚体，其功能对于正常的 I型前胶原生物合成。复杂功能的消除导致改变的细胞表型， 扩张的ER、细胞内I型前胶原的聚集、伴侣蛋白复合物组分的隔离以及 异常PLOD 2依赖性交联。通过使用突变的FKBP 65和HSP 47细胞系，我们已经 确定PLOD 2也是这种新鉴定的伴侣蛋白复合物的成员，并鉴定伴侣蛋白 功能障碍作为OI疾病的新机制。这些研究将主要使用新产生的小鼠 模型，并辅以人体OI组织研究，以建立一个目前尚未认识到的机制， I型前胶原合成的范例，并详细了解OI是如何从这种缺陷中产生的。 过程这是一个范式的转变，我们的理解I型前胶原合成的观点，如何 LH2修饰或接近I型前胶原，并提供了对OI与挛缩如何发生的深入了解， 如Bruck综合征，可能由FKBP 10或PLOD 2突变引起。建议的实验是 重要的是，它们有可能对我们理解人类的作用产生广泛的影响。 端肽交联在功能性细胞外基质的产生中起作用， 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 和相关组织。

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.