Pathogenic Mechanisms of Craniometaphyseal Dysplasia

项目摘要/摘要 研究罕见孟德尔疾病的致病机制不仅对确定治疗方法具有重要意义 不仅要了解终生衰弱疾病的战略，而且还要了解基本的生物机制。在这 更新应用，我们建议对颅干骺端发育不良(CMD)进行机制和翻译研究。 一种未被充分研究的以颅面部终生进行性骨质增生症为特征的颅管骨病 骨骼和长骨的异常形状。慢性骨质疏松症患者持续的骨积聚会导致疼痛 头痛、失明、耳聋和面瘫。严重病例可能危及生命。CMD患者是 在需要矫正面部畸形或严重畸形时进行重复、昂贵和危险的手术 神经症状就会出现。进行性强直蛋白(Ankh)和连接蛋白43(Cx43)的突变 分别被确定为常染色体显性遗传性和隐性遗传性CMD的病因。为了研究CMD，我们 已经产生了最先进的研究工具，其中包括携带CMD突变的小鼠模型，同基因 有或无CMD突变的人诱导多能干细胞(HiPSCs)和骨吸收细胞 (破骨细胞)来源于这些HiPSCs。在过去的资助期，我们发现了快速的退化 突变的Ankh(人)/ANK(鼠)蛋白的表达，并研究了突变的Ankh/ANK对细胞的负性影响。 细胞骨架，它决定细胞的形状、大小和极性。我们还发现了差异表达的 CMD破骨细胞中的蛋白质和突变的ANK蛋白的优先结合伙伴。然而，CMD 发病机制还不完全清楚，潜在的治疗方法也没有被探索。 我们的长期目标是利用我们的研究成果来确定潜在的治疗目标，以减少或 防止颅面部骨骼终生骨沉积。在接下来的5年里，我们将使用动物模型和 分子和细胞方法，我们已经开发了专注于机械研究和 为未来的临床研究做好准备。基于我们的初步数据和以前的出版物，我们提出了三个 明确的目标。我们将研究CMD突变的ANK对破骨细胞细胞酸化的影响(目标1)和 关于细胞骨架与能量代谢调节剂之间的双向调节(目标2)。 这些可能是导致CMD的ANK突变体的新的显性功能。在目标3中，我们将识别生物标记物 这可以用来监测患者和小鼠模型的疾病进展。我们还将评估班次 在我们的模型系统中，生物标记物的表达对实验性治疗方案的反应。我们期待着 拟议的研究将使人们对CMD的致病机制有更深入的了解，需要的知识 发现治疗学的候选靶点。与疾病进展或治疗相对应的生物标志物 疗效将是未来临床研究的基础。

Project Summary/Abstract Investigating pathogenic mechanisms for rare Mendelian disorders is important not only to identify therapeutic strategies for lifelong debilitating diseases but also to understand fundamental biological mechanisms. In this renewal application, we propose mechanistic and translational studies for craniometaphyseal dysplasia (CMD), an understudied craniotubular bone disorder characterized by lifelong progressing hyperostosis of craniofacial bones and abnormal shape of long bones. Continued bone accrual in CMD can lead to excruciating headaches, blindness, deafness, and facial palsy. Severe cases can be life-threatening. CMD patients are treated with repetitive, costly and risky surgeries when corrections of facial deformity are needed or severe neurological symptoms occur. Mutations in the progressive ankylosis protein (ANKH) and connexin 43 (Cx43) have been identified as causes for autosomal dominant and recessive CMD, respectively. To study CMD, we have generated state-of-the-art research tools, which include mouse models carrying CMD mutations, isogenic human induced pluripotent stem cells (hiPSCs) with or without CMD mutations, and bone resorbing cells (osteoclasts) derived from these hiPSCs. In the past funding period, we have discovered the rapid degradation of mutant ANKH(Human)/ANK(Mouse) protein and studied negative effects of mutant ANKH/ANK on the cytoskeleton, which determinates cell shape, size, and polarity. We also identified differentially expressed proteins in CMD osteoclasts and preferential binding partners for mutant ANK protein. However, CMD pathogenesis is not fully understood and potential therapeutics have not been explored. Our long-term goal is to utilize our research findings for identifying potential therapeutic targets to reduce or prevent the lifelong bone deposition in craniofacial bones. In the next 5 years, we will use animal models and molecular and cellular methodologies that we have developed to focus on mechanistic investigations and prepare for future clinical studies. Based on our preliminary data and previous publications we propose three specific aims. We will study the impact of CMD-mutant ANK on cellular acidification of osteoclasts (Aim 1) and on the bi-directional regulation between the cytoskeleton and an energy metabolism regulator in CMD (Aim 2). These are likely novel dominant functions of mutant ANK leading to CMD. In Aim 3 we will identify biomarkers that can be used to monitor the disease progression in patients and mouse models. We will also evaluate shifts in biomarker expression in response to experimental treatment regimen in our model systems. We expect that the proposed studies will give deeper insight into pathogenic mechanisms of CMD, knowledge needed to discover candidate targets for therapeutics. Biomarkers that correspond to disease progression or treatment efficacy will be the basis for future clinical studies.