MUTANT p62 AND THE ROLE OF THE BONE MICROENVIRONMENT IN PAGET'S DISEASE

描述(申请人提供)：帕吉特病(PD)是一种慢性骨病，以局部高度夸大和紊乱的骨重建为特征。帕金森病的病因很难定义，因为显然有遗传和环境两方面的因素导致了这种疾病。最近，在家族性和散发性帕金森病中都发现了与疾病相关的SQSTM1/p62基因突变，该基因的突变可能与高达30%的Paget‘s病例有关。SQSTM1/p62基因编码一个62 kDa的蛋白，参与正常破骨细胞形成的多种信号转导途径，包括RANKL、肿瘤坏死因子和IL-1激活的信号转导途径。我们假设，p62突变导致破骨细胞前体中的一个或多个途径的激活增加，导致破骨细胞生成增加，并对随后发生帕金森病的易感性增加。我们进一步假设，突变型p62在成骨细胞或骨髓基质细胞中的表达增强了它们支持破骨细胞生成的能力，并随着破骨细胞活性的增加而增加新骨形成。为了研究这些假设，我们通过将P394L突变(类似于人类Paget相关的P392L突变)引入内源性小鼠p62基因，建立了p62突变的Paget患者的小鼠模型。我们现在提出了一系列补充的体内和体外实验，利用这个新开发的小鼠模型来确定这种突变在多大程度上影响了完整的Pagtic表型，并确定了这种突变对调控破骨细胞和成骨细胞形成、功能和存活的信号通路的影响。这一独特的小鼠模型将使我们能够确定p62突变促进帕金森病发生的具体机制，也将成为识别其他环境和遗传因素导致帕金森病的有价值的研究工具。公共卫生相关性：帕金森病是仅次于骨质疏松症的第二种最常见的骨骼疾病，在Paget‘s患者中会导致严重的疼痛、畸形、骨折易感性增加和各种神经并发症。然而，尽管帕金森病很普遍，但对其研究相对较少，其起源也鲜为人知。建议的研究应该有助于更好地了解帕金森病，因此可能会促进改进治疗方法的发展。

DESCRIPTION (provided by applicant): Paget's disease (PD) is a chronic bone disease characterized by focal regions of highly exaggerated and disordered bone remodeling. The etiology of PD has been difficult to define, as there are clearly both genetic and environmental contributions to the disease. Recently, disease-associated mutations have been identified in the SQSTM1/p62 gene in cases of both familial and sporadic PD, and mutations of this gene may be linked to up to 30% of all Paget's cases. The SQSTM1/p62 gene encodes a 62 kDa protein that functions in multiple signal transduction pathways involved in normal osteoclastogenesis, including those activated by RANKL, TNF, and IL-1. We hypothesize that p62 mutations lead to increased activation of one or more of these pathways in osteoclast precursors, resulting in increased osteoclastogenesis and susceptibility to the subsequent development of PD. We further hypothesize that expression of mutant p62 in osteoblasts or bone marrow stromal cells enhances their capacity to support osteoclastogenesis as well as increase new bone formation in response to the increased osteoclast activity. To investigate these hypotheses, we have developed a mouse model of Paget's patients with p62 mutations by introducing a P394L mutation (analogous to the human Paget's-associated P392L mutation) into the endogenous mouse p62 gene. We now propose a series of complementary in vivo and in vitro experiments employing this newly developed mouse model to determine the extent to which this mutation contributes to the full pagetic phenotype, and to determine the effect of this mutation on the signaling pathways that regulate both osteoclast and osteoblast formation, function, and survival. This unique mouse model will allow us to determine the specific mechanisms by which p62 mutation contributes to the development of PD, and will also serve as a valuable research tool for identifying other environmental and genetic factors contributing to PD. PUBLIC HEALTH RELEVANCE: PD is the second most common bone disease after osteoporosis, and results in significant pain, deformity, increased susceptibility to fractures, and a variety of neurological complications in Paget's patients. However, despite the prevalence of PD, it is relatively understudied and its origin is poorly understood. The proposed studies should lead to a better understanding of PD, and may therefore facilitate the development of improved therapeutic approaches.