FRZB PROFILES AS OSTEOARTHRITIS BIOMARKERS

描述(由申请人提供)： 越来越多的证据表明，WNT、FrizzleD[fzd]、分泌型FrizzleD相关蛋白[SFRP]和低密度脂蛋白受体相关蛋白[LRP1]基因家族的产物在关节和骨骼的发育和维持中起着至关重要的作用。因此，这些改变蛋白表达或功能的基因的多态性是骨关节炎[OA]易感性和进展的潜在生物标记物候选。该项目的总体目标是证实这一假设。先前对家族性骨性关节炎的几项遗传学研究已将一个主要易感基因定位于染色体2q31，该区域编码FRZB[也称为sFRP3]，FRZB[也称为sFRP3]是一个SFRP家族成员，可拮抗WNT信号。我们实验室与牛津大学的John Loughlin合作进行的初步实验表明，FRZB基因的特定突变在患有髋关节骨性关节炎的家族性和散发性女性患者中明显比女性对照组更常见。在转基因实验中，突变的FRZB基因与野生型基因相比，对WNT的抑制作用减弱。过多的WNT信号可增加软骨下骨密度，并可能增加骨关节处软骨细胞的代谢活性。事实上，使用表面增强激光解吸和电离质谱分析OA血清的其他初步实验已经揭示了阴离子蛋白质的浓度增加，其分子质量对应于几个WNT相关蛋白质。因此，我们推测FRZB突变是女性髋关节骨性关节炎的生物标记物，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]确认观察到的FRZB突变与加州大学旧金山分校的Nancy Lane和Michael Nigitt所描述的另外一组女性髋关节骨性关节炎患者的相关性，[2]评估FRZB突变与这些女性髋骨密度增加之间的关联，以及[3]通过表面增强激光解吸和电离质谱仪以及免疫分析，比较具有明确FRZB基因多态性的骨性关节炎患者和对照组血液中WNT诱导蛋白的表达模式和水平。这些研究的结果将有助于并将利用OA生物标记物联盟的资源。

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.