Mechanisms and Treatment of Hajdu Cheney Syndrome

项目总结/摘要 Notch受体在细胞命运决定和骨重建调节中起着关键作用， 直接或通过诱导它们的靶基因，即分裂的毛增强子（Hes）和Hes相关的 YRPW Motif（嘿）Hajdu切尼综合征（HCS）是一种毁灭性的疾病，其特征在于 发育异常、肢端骨质溶解和骨折引起的骨丢失。HCS与以下基因突变相关： PEST结构域上游的NOTCH 2的外显子34，导致NOTCH 2稳定和功能获得。我们 创建了HCS小鼠模型（Notch2tm1.1Ecan），该模型由于增强的 破骨细胞生成和骨吸收。这些事件是继发于受体激活剂的增加， 核因子κ B配体（RANKL）的作用，以及NOTCH 2在成骨细胞中的直接作用。 骨髓细胞在该谱系中，HES 1的表达由NOTCH 2诱导，而HES 1的表达由NATCH 2诱导。 破骨细胞谱系中Hes 1的失活逆转了HCS突变体的体外和体内表型。 此外，HES 1直接诱导破骨细胞生成，结果导致体内骨质减少。这揭示了一个 HES 1在破骨细胞分化中的功能以前未被认识， 的拟议研究。拟议工作的另一个目标是开发矫正骨骼的方法。 通过用Notch 2反义寡核苷酸（阿索）靶向突变来治疗HCS的表现，这是一种 也适用于骨骼的其他遗传疾病。我们的具体目标是：目标1）确定 HES 1在破骨细胞生成中的作用。我们的目标是诱导和特异性地在细胞中表达Hes 1。 破骨细胞谱系，以确定其对破骨细胞分化和骨重建的贡献， 目的2）确定Notch2tm1.1Ecan突变可以导致Notch2tm1.1Ecan突变， 成为目标。我们将确定Notch2tm1.1Ecan突变是否可以特异性下调， Notch2tm1.1Ecan的骨骼表型通过施用靶向Notch2tm1.1Ecan的反义寡核苷酸而得到改善。 目的3）验证HCS表型和阿索方法在Notch 26955 C>T突变中的作用机制。 N 0 TCH 2突变体诱导的多能（iPS）细胞。为此，我们创建了NOTCH 2 HCS突变iPS细胞系， 研究该突变对破骨细胞生成的影响以及ASO在下调破骨细胞生成中的作用。 NOTCH 2突变等位基因。拟议工作的目标是了解机制， 特异性反义技术治疗破坏性NOTCH 2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.