GENETIC BASES FOR DISEASES OF THE RANK SIGNALING PATHWAY

描述（由申请人提供）：少年佩吉特病（JPD）是一种常染色体隐性骨病，以快速重塑编织骨、骨质减少、骨折和进行性骨骼畸形为特征，在年轻成年时可能是致命的。编码骨保护素（OPG）的TNFRSF11B基因的纯合子缺失被确定为两个纳瓦霍家族JPD的原因。此前，核因子受体激活因子（RANK）的缺陷？-B)基因被确定为家族性扩张性骨溶解（FEO）相关疾病的原因。因此，参与OPG/RANKL/RANK/NF-？B信号通路与JPD及骨转换相关疾病有关。本研究的长期目标是确定OPG/RANKL/RANK/NF-？并利用体外细胞建模系统评估这些突变的下游效应，阐明这些疾病的病理生物学。该项目的具体目标是：1：确定和评估全球范围内患有少年佩吉特病（JPD）、家族性扩张性骨溶解（FEO）和相关疾病的其他患者。特定目标2：在JPD， FEO和相关疾病的新患者中，确定导致这些骨骼疾病的遗传缺陷。特异性目标3：表征突变体OPG、RANK和其他OPG/RANKL/RANK/NF-？B信号通路对破骨细胞形成及其作用。将确定其他患者，并进行放射学、生化学和分子学评估。DNA和RNA样本将筛选编码OPG的TNFRSF11B，编码RANK的TNFRSF11A和编码RANKL的TNFSF11突变，采用PCR和毛细管DNA测序，以及RT-PCR。我们还将使用基于微阵列的拷贝数分析来确定这些患者的潜在基因组缺陷，并确定新的候选基因。对于没有OPG、RANK或RANKL基因突变的患者，大规模Solexa测序将用于搜索OPG/RANKL/RANK/NF-？B信号通路的致病突变，包括SQSTM1、VCP、TRAF6、aPKC、NIK等。还将研究RANK信号的调节剂，包括TRAIL、IL-1、MCSF、c-FMS和其他细胞因子及其同源受体。体外破骨细胞培养试验将用于确定突变对破骨细胞形成和功能的下游影响。这些研究将进一步阐明由OPG/RANKL/RANK/NF-?缺陷引起的JPD、FEO及相关骨转换疾病的遗传基础。B信号通路，这对破骨细胞的形成和作用至关重要。

DESCRIPTION (provided by applicant): Juvenile Paget's disease (JPD), an autosomal recessive osteopathy, features rapidly remodeling woven bone, osteopenia, fractures, and progressive skeletal deformity that can be fatal by young adult life. Homozygous deletion of the TNFRSF11B gene, encoding osteoprotegerin (OPG), was identified as the cause of JPD in two Navajo families. Previously, a defect in the RANK (receptor activator of nuclear factor ?-B) gene was determined to be the cause of a related disorder, familial expansile osteolysis (FEO). Hence, mutations in genes involved in the OPG/RANKL/RANK/NF-?B signaling pathway are responsible for JPD and related disorders of bone turnover. The long-range goal of this study is to identify other mutations in members of the OPG/RANKL/RANK/NF-?B pathway that cause JPD and related diseases in newly-ascertained patients, and to use in vitro cell modeling systems to assess the downstream effects of these mutations, to elucidate the pathobiology of these disorders. The Specific Aims of this project are: Specific Aim 1: Ascertain and evaluate additional patients worldwide with juvenile Paget's disease (JPD), familial expansile osteolysis (FEO), and related disorders. Specific Aim 2: In new patients with JPD, FEO, and related disorders, identify the genetic defects that cause these skeletal diseases. Specific Aim 3: Characterize the downstream effects of mutant OPG, RANK, and other members of the OPG/RANKL/RANK/NF-?B signaling pathway on osteoclast formation and action. Additional patients will be ascertained, and evaluated radiographically, biochemically, and molecularly. DNA and RNA samples will be screened for mutations in TNFRSF11B, encoding OPG, TNFRSF11A, encoding RANK, and TNFSF11, encoding RANKL, using PCR and capillary DNA sequencing, and RT-PCR. We will also use a microarray-based copy number analysis to identify potential genomic defects in these patients, and identify new candidate genes. For patients without mutations in the OPG, RANK, or RANKL genes, large-scale Solexa sequencing will be used to search other candidate genes in the OPG/RANKL/RANK/NF-?B signaling pathway for disease-causing mutations, including SQSTM1, VCP, TRAF6, aPKC, NIK, and others. Modulators of RANK signaling will also be examined, including TRAIL, IL-1, MCSF, c-FMS and additional cytokines and their cognate receptors. In vitro osteoclast culture assays will be used to determine downstream effects of mutations on osteoclast formation and function. These studies will further elucidate the genetic bases for JPD, FEO, and related disorders of bone turnover, caused by defects in the OPG/RANKL/RANK/NF-?B signaling pathway, which is critical for osteoclast formation and action.