MITF: Regulating Osteoclast Gene Expression and Function

 描述（由申请人提供）：NFATc 1、NF κ B B、cFOS、PU. 1/SPI 1和MITF是从髓样前体分化破骨细胞所必需的转录因子（TF）。然而，我们对这些TF之间的相互作用以及这种相互作用如何促进破骨细胞分化和功能的理解仍存在很大的差距。重要的是，关键的问题是如何动态TF调节有助于人类骨相关疾病的临床结果尚未解决。在该资助的最后一个周期中，我们使用了新的功能基因组方法和新的生物信息学方法来开发一个分层网络模型，该模型解释了这些因素之间的相互作用及其在破骨细胞分化中的相对作用。基于这个模型，我们最重要的假设是， PU.1和MITF位于破骨细胞及其髓样前体中破骨细胞转录因子网络的顶点，其响应于从局部微环境接收的信号启动并维持分化状态。在目前的建议中，我们的目标是使用体内和体外实验来测试这种模型，重要的是将这些研究扩展到正常人破骨细胞和类风湿关节炎患者的循环破骨细胞前体。此外，我们将在类风湿性关节炎的临床前小鼠模型中测试该网络和相关因素的重要性，使用遗传靶向Pu.1或使用小分子抑制剂靶向前破骨细胞中PU.1/MITF依赖性表观遗传变化的方法。通过结合我们的努力和专业知识，我们的多学科团队将专注于了解控制破骨细胞分化和功能的机制，以及这些因素在人类破骨细胞中的相关性。

 DESCRIPTION (provided by applicant): NFATc1, NFB, cFOS, PU.1/SPI1 and MITF are transcription factors (TFs) essential for osteoclast differentiation from myeloid precursors. However, large gaps still remain in our understanding of the interplay between these TFs and how this interplay contributes to osteoclast differentiation and function. Importantly, critical questions about how the dynamics of TF regulation contributes to clinical outcome of human bone related diseases are unresolved. During the last cycle of this grant we used newly available functional genomic approaches and new bioinformatics approaches to develop a hierarchical network model that explains the interactions between these factors and their relative roles in osteoclast differentiation. Based on this model our overriding hypothesis is that PU.1 and MITF are at the apex of an osteoclast transcription factor network in osteoclasts and their myeloid precursors that initiates and maintains the differentiated state in response to signals received from the local microenvironment. In the current proposal, we aim to test this model using both in vivo and in vitro experiments and importantly to extend these studies into normal human osteoclasts and circulating osteoclast precursors from rheumatoid arthritis patients. Further we will test the importance of this network and associated factors in a preclinical mouse model for rheumatoid arthritis, using approaches that genetically target Pu.1 or use small molecule inhibitors to target PU.1/MITF-dependent epigenetic changes in pre-osteoclasts. By combining our efforts and expertise, our multidisciplinary team will focus on the task of understanding the mechanisms that govern osteoclast differentiation and function, and the relevance of these factors in human osteoclasts.