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

描述（由申请人提供）：佩吉特病（PD）是一种慢性骨病，其特征为局灶性区域高度夸张和紊乱的骨重建。PD的病因一直难以定义，因为有明确的遗传和环境的疾病的贡献。最近，在家族性和散发性PD的病例中，已经在SQSTM 1/p62基因中鉴定出疾病相关突变，并且该基因的突变可能与高达30%的所有佩吉特病例相关。SQSTM 1/p62基因编码一种62 kDa的蛋白质，该蛋白质在参与正常破骨细胞生成的多种信号转导途径中发挥作用，包括RANKL、TNF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一种或多种这些途径的激活增加，从而导致破骨细胞生成增加和对后续PD发展的易感性。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，并增加了新骨形成对破骨细胞活性增加的反应。为了研究这些假设，我们通过将P394 L突变（类似于人类佩吉特相关的P392 L突变）引入内源性小鼠p62基因，建立了p62突变佩吉特患者的小鼠模型。我们现在提出了一系列互补的体内和体外实验，采用这种新开发的小鼠模型，以确定这种突变在多大程度上有助于完整的pagetic表型，并确定这种突变对调节破骨细胞和成骨细胞形成，功能和生存的信号通路的影响。这种独特的小鼠模型将使我们能够确定p62突变促进PD发展的具体机制，也将作为一种有价值的研究工具，用于确定其他环境和遗传因素对PD的影响。公共卫生相关性：PD是仅次于骨质疏松症的第二大常见骨疾病，并导致佩吉特患者的显著疼痛、畸形、骨折易感性增加和各种神经系统并发症。然而，尽管PD的患病率，它是相对不足的研究，其起源是知之甚少。拟议的研究应导致更好地了解PD，因此可能有助于开发更好的治疗方法。

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.