FRZB PROFILES AS OSTEOARTHRITIS BIOMARKERS

描述（申请人提供）： 越来越多的证据表明，wnt、frizzled [fzd]、分泌型frizzled-1相关蛋白[SFRP]和LDL受体相关蛋白[LRP 1基因家族的产物在关节和骨骼的发育和维持中起关键作用。因此，改变蛋白质表达或功能的这些基因的多态性是骨关节炎[OA]易感性和进展的潜在生物标志物候选者。本项目的总体目标是证实这一假设。家族性OA的一些先前的遗传学研究已经将主要易感基因定位于染色体2 q31，该区域编码FRZB [也称为SFRP 3]，SFRP家族成员拮抗wnt信号传导。我们实验室与牛津大学的John Loughlin合作进行的初步实验表明，与女性对照组相比，家族性和散发性女性髋关节OA患者中FRZB基因的特定突变明显更常见。在转染实验中，与野生型基因相比，突变的FRZB基因具有减弱的wnt抑制功能。过量的wnt信号可以增加软骨下骨密度，并可能增加骨软骨连接处的软骨细胞代谢活性。事实上，其他初步实验使用表面增强激光解吸和电离质谱分析的OA血清已显示增加浓度的阴离子蛋白与分子量对应的几个wnt相关的蛋白质。因此，我们假设FRZB突变体是女性髋关节OA的生物标志物，并且它们改变了wnt调节蛋白的血清浓度。为了验证这一假设，我们的目标是[1]确认在UCSF的Nancy Lane和Michael Nevitt描述的髋关节OA女性患者中观察到的FRZB突变的相关性，[2]评估这些女性中FRZB突变体与髋骨密度增加之间的相关性，[3]比较表达模式和水平，通过表面增强激光解吸电离质谱法和免疫测定法，对具有确定的FRZB多态性的OA患者和对照组血液中wnt诱导蛋白的含量进行了测定。这些研究的结果将有助于并将利用OA生物标志物联盟的资源。

DESCRIPTION(Provided by Applicant): Accumulating evidence has demonstrated that the products of the wnt, frizzled [fzd], secreted frizzled- Irelated protein [SFRP] and LDL receptor-related protein [LRP1 gene families play a critical role in the ]development and maintenance of joints and bones. Consequently, polymorphisms of these genes that alter protein expression or function are potential biomarker candidates for osteoarthritis [OA] susceptibility and progression. The overall goal of this project is to confirm this hypothesis. Several prior genetic studies of familial OA have mapped a major susceptibility locus to chromosome 2q31, a region that encodes FRZB [also known as SFRP3], a SFRP family member that antagonizes wnt signaling. Preliminary experiments from our laboratory, performed in collaboration with John Loughlin of the University of Oxford, have demonstrated that a specific mutation of the FRZB gene is significantly more common in both familial and sporadic female patients with hip OA, than in female controls. In transfecfion experiments, the mutated FRZB genes have diminished wnt-inhibitory function compared to wild type genes. Excessive wnt signaling can increase subchondral bone density and possibly chondrocyte metabolic activity at the bonecartilage junctions. Indeed, other preliminary experiments using surface enhanced laser desorption and ionization mass spectrometric analysis of OA sera have revealed increased concentrations of anionic proteins with molecular masses corresponding to several wnt-associated proteins. Accordingly, we postulate that the FRZB mutants are biomarkers for hip OA in women, and that they alter the serum concentrations of wnt-regulated proteins. To test this hypothesis, we aim [1] to confirm the association of the observed FRZB mutations in an additional series of female patients with hip OA characterized by Nancy Lane and Michael Nevitt at UCSF, [2] to assess the association between the FRZB mutants and increased hip bone density in these women, and [3] to compare the patterns of expression, and the levels, of wnt-inducible proteins in the blood of OA patients with defined FRZB polymorphisms, and of controls, by surface-enhanced laser desorption and ionization mass spectrometry, and by immunoassay. The results of these studies will both contribute to, and will utilize, the resources of the OA biomarker consortium.