Mechanisms and Treatment of Hajdu Cheney Syndrome

项目摘要/摘要 Notch受体在细胞命运的决定和骨重建的调节中起着关键作用 直接或通过诱导其靶基因，即分裂毛发增强器(Hes)和Hes相关基因 YRPW主题(嘿)。Hajdu Cheney综合征(HCS)是一种破坏性疾病，其特征是 发育异常、顶骨溶解和伴有骨折的骨丢失。人巨细胞瘤与基因突变有关 NOTCH2的外显子34位于PEST结构域的上游，导致NOTCH2的稳定和功能增益。我们 建立了HCS(Notch2tm1.1Ecan)的小鼠模型，由于增强的骨量减少 破骨细胞发生与骨吸收。这些事件是继发性的，因为受体激活剂增加 核因子-kappaB配体(RANKL)对成骨细胞系细胞的影响及NOTCH2的直接作用 髓系细胞。在这个谱系中，HES1的表达是由NOTCH2和 破骨细胞系中Hes1的失活逆转了HCS突变体的体外和体内表型。 此外，HES1直接诱导破骨细胞生成，导致体内骨量减少。这揭示了一种 HES1在破骨细胞分化中的未知功能和功能将作为一部分进行探索 这项拟议的研究。这项拟议工作的另一个目标是开发纠正骨骼的方法 通过使用Notch2反义寡核苷酸(ASO)靶向突变来表现HCS，这一策略 也适用于骨骼的其他遗传性疾病。我们的具体目标是：目标1)确定 HES1在破骨细胞形成中的作用我们的目标是诱导和灭活Hes1，特别是在 破骨细胞谱系确定其在破骨细胞分化和骨重建中的作用 通过显微计算机断层扫描和组织形态计量学；目的2)确定Notch2tm1.1 Ecan突变可以 成为靶子。我们将确定Notch2tm1.1Ecan突变是否可以具体下调，以及 Notch2tm1.1Ecan骨骼表型通过给予针对该基因的反义寡核苷酸来改善 Notch26955C&GT；T突变；目的3)验证HCS表型和ASO的发病机制 Notch2突变诱导的多能(IPS)细胞。为此，我们建立了NOTCH2HCS突变型iPS细胞系 研究突变对破骨细胞生成的影响及ASOS的下调作用 Notch2突变等位基因。拟议工作的目标是了解机制并开发 特异性反义技术治疗一种破坏性NOTCH2相关的骨骼表现 疾病。

PROJECT SUMMARY/ABSTRACT Notch receptors play a critical role in cell fate decisions and in the regulation of bone remodeling, either directly or through the induction of their target genes, namely Hairy Enhancer of Split (Hes) and Hes-related with YRPW motif (Hey). Hajdu Cheney Syndrome (HCS) is a devastating disease characterized by developmental abnormalities, acroosteolysis and bone loss with fractures. HCS is associated with mutations in exon 34 of NOTCH2 upstream of the PEST domain leading to NOTCH2 stabilization and gain-of-function. We created a mouse model of HCS (Notch2tm1.1Ecan) that presents with osteopenia due to enhanced osteoclastogenesis and bone resorption. These events are secondary to an increase in receptor activator of nuclear factor Kappa B ligand (RANKL) by cells of the osteoblast lineage, and to direct effects of NOTCH2 in cells of the myeloid lineage. In this lineage, the expression of HES1 is induced by NOTCH2 and the inactivation of Hes1 in the osteoclast lineage reverses the in vitro and in vivo phenotype of HCS mutants. Moreover, HES1 induces osteoclastogenesis directly and as a result causes osteopenia in vivo. This reveals a previously unrecognized function of HES1 in osteoclast differentiation and function that will be explored as part of the proposed research. An additional goal of the proposed work is to develop ways to correct the skeletal manifestations of HCS by targeting the mutation with Notch2 antisense oligonucleotides (ASO), a strategy that would be applicable to other genetic disorders of the skeleton. Our specific aims are: Aim 1) To determine the role of HES1 in osteoclastogenesis. Our goals are to induce and inactivate Hes1 specifically in cells of the osteoclast lineage to determine its contribution to osteoclast differentiation and bone remodeling as determined by microcomputed tomography and histomorphometry; Aim 2) To establish that the Notch2tm1.1Ecan mutation can be targeted. We will determine whether the Notch2tm1.1Ecan mutation can be downregulated specifically and the Notch2tm1.1Ecan skeletal phenotype ameliorated by the administration of antisense oligonucleotides targeting the Notch26955C>T mutation; and Aim 3) To validate the mechanisms of the HCS phenotype and ASO approach in NOTCH2 mutant-induced pluripotent (iPS) cells. To this end, we created NOTCH2HCS mutant iPS cell lines to study the impact of the mutation on osteoclastogenesis and the efficacy of ASOs in downregulating NOTCH2 mutant alleles. The goals of the proposed work are to understand the mechanisms and develop specific antisense technology to treat the skeletal manifestations of a devastating NOTCH2-associated disease.