Mechanistic and Therapeutic Studies of Initiation and Expansion for Genetic and Acquired Heterotopic Ossification

项目摘要/摘要 异位骨化是指常见的骨外病理性骨形成。 损伤后的并发症或特殊遗传性疾病的表现。然而，受贫困的限制， 对潜在的细胞和分子机制的了解，目前还没有有效的治疗方法和 手术驱逐往往会导致复发。该项目的总体目标是研究细胞和分子 HO启动和扩展的机制，并确定潜在的遗传性和 后天获得的何某。我们的初步数据表明，在进行性骨质疏松症(POH)的小鼠模型中， 一种由编码GαS的GNA零突变引起的人类疾病，异位骨进行性扩张 是由于周围野生型细胞的招募。GNAS-/-间充质细胞分化的机制 通过激活YAP，一种调节成骨的转录因子，招募野生型细胞形成骨 表达Sonic hedgehog(Shh)，它编码HH家族中的一种分泌型配体。隐秘的SHH进一步 诱导YAP激活，从而导致额外的Shh表达和成骨细胞分化 周围的野生型细胞。在获得性HO的人类样本中，上调的YAP和HH信号也 这表明了我们发现的临床重要性。在我们未发表的初步研究中，我们发现 上调Wnt5a在体外GNAS-/-SMPS和体内POH小鼠模型HO损伤中的表达。WNT5A 不仅调节干细胞的增殖和促进再繁殖，而且在长骨中也起着至关重要的作用。 以及胚胎发育过程中的软骨发育。重要的是，我们发现Wnt5a表达也是 受YAP激活控制，是遗传性和获得性HO所必需的。这些发现导致了 中心假设YAP和WNT5A在正反馈环路中被激活，以招募祖细胞 软组织中的成骨细胞分化，从而促进遗传性和获得性HO小鼠HO的形成 模特们。我们将在三个目标上检验这些假设。第一个目的是澄清YAP和 Wnt5A在POH异位成骨中的表达及YAP与Wnt5A是否存在正相互作用 反馈环路。第二个目的是阐明YAP和WNT5A在水稻中的反应分子机制。 异位成骨。第三个目的是研究WNT5A在兔异位骨形成中的作用。 进行性骨化性纤维发育不良(FOP)和创伤性HO模型。综合来看，这些建议 研究将对共同的细胞和分子机制产生新的见解 扩展不同的HO形式，并强调罕见遗传病研究在识别 共同的核心病理机制是一类疾病的基础。

Project Summary/Abstract Heterotopic ossification (HO) refers to extraskeletal pathological bone formation that occurs as a common complication after injury or as a manifestation of particular genetic disorders. However, limited by poor understanding of the underlying cellular and molecular mechanisms, there is currently no effective treatment and surgical eviction often results in recurrence. The overall goal of the project is to investigate cellular and molecular mechanisms underlying HO initiation and expansion and identify potential treatment targets for genetic and acquired HO. Our preliminary data suggests that in mouse models of progressive osseous heteroplasia (POH), a human disease caused by null mutations in GNAS that encodes Gαs, progressive expansion of ectopic bone was due to recruitment of surrounding wild-type cells. Mechanistically, Gnas-/- mesenchymal cells differentiate into osteoblasts and recruit wild-type cells to form bone by activating YAP, a transcription factor that regulates expression of Sonic hedgehog (Shh), which encodes a secreted ligand in the Hh family. Secreted SHH further induces YAP activation, thereby resulting in additional Shh expression and osteoblast differentiation in surrounding wild type cells. In human samples with acquired HO, upregulated YAP and HH signaling were also found, indicating the clinical importance of our findings. In our unpublished preliminary studies, we found upregulated Wnt5a expression in Gnas-/- SMPs in vitro and in HO lesions of POH mouse models in vivo. WNT5a not only regulates stem cell proliferation and enhances repopulation, but also plays an essential role in long bone and cartilage development during embryogenesis. Importantly, we found that Wnt5a expression was also controlled by YAP activation and was required for HO in both genetic and acquired HO. These findings lead to a central hypothesis that YAP and WNT5a are activated in a positive feedback loop to recruit progenitor cells for osteoblast differentiation in soft tissues, thereby promoting HO formation in both genetic and acquired HO mouse models. We will test these hypotheses in three aims. The first aim is to clarify the relationship between YAP and Wnt5a expression in ectopic bone formation in POH and test whether YAP and WNT5a interact in a positive feedback loop. The second aim is to illuminate the molecular mechanism in response to YAP and WNT5a in ectopic bone formation. The third aim is to investigate the contribution of WNT5a to ectopic bone formation in fibrodysplasia ossificans progressiva (FOP) and trauma-induced HO models. Taken together, these proposed studies will yield novel insights into a common cellular and molecular mechanism underlying initiation and expansion of distinct HO forms and highlight the importance of rare genetic disease studies in identifying a shared core pathological mechanism underlying a class of diseases.