Functional Dissection of the MARK3 GWAS Locus for Bone Mineral Density

摘要/摘要 骨密度(BMD)是骨质疏松性骨折(REF)的高度遗传性预测因子。大规模基因组 广谱关联研究已经确定了数十个含有变异(SNPs)的遗传基因座 与BMD有关。这些基因座构成了关于新的骨骼调节的未开发信息的宝库 基因和控制其功能的可遗传基因组元素。然而，尽管它们有可能告知 骨生物学，由和靶基因确定的确切原因变异还没有明确地确定为 甚至是一个单一的轨迹。使用一种新开发的策略将与BMD GWA相关的基因映射到骨骼上 表达网络，我们预测了30个基因座的因果基因。位于染色体上的一个基因座 14q32.32包含与股骨颈骨密度高度相关的SNP(P=5.0x10-16)，我们预测 该基因座的五个基因之一Mark3是因果关系。Mark3编码已知的保守的丝氨酸/苏氨酸激酶 调节不同的过程，包括不对称的细胞分裂和神经元分化，但其潜力 在骨骼中的作用尚不清楚。对Mark3基因缺陷小鼠的临时评估，无论是全局的还是有条件的 (成骨细胞)表现出非常相似的骨骼表型。基于这些令人兴奋的发现，我们开发了一种 确定与Mark3相关联的精确因果变量(S)并确定活动如何的综合方法 成骨细胞中这种激酶的含量控制着骨量。研究分为三个目标：具体目标1：明确 该基因座的致病遗传机制可能与该基因座有关。具体目标2：确定 Mark3在骨特异性靶蛋白3中的作用：体内调节性单核苷酸多态性的功能测试(S)。这个项目 由约翰·霍普金斯大学的托马斯·克莱门斯和查尔斯·法伯共同领导 在弗吉尼亚大学，在多重PI安排的主持下。他们免费赠送的协同效应 在以前的项目中已经建立了研究计划。我们坚信，这种方法 将定义受突变影响的生物网络将大大有助于理解它们 病理改变，为干预提供重要靶点。

SUMMARY/ABSTRACT Bone mineral density (BMD) is a highly heritable predictor of osteoporotic fracture (ref). Large-scale genome wide association studies (GWAS) have identified dozens of genetic loci harboring variants (SNPs) robustly associated with BMD. These loci constitute a treasure trove of untapped information on novel skeletal regulatory genes and the heritable genomic elements that control their function. However, despite their potential to inform bone biology, the precise causal variants identified by and target genes have not been definitively identified for even a single locus. Using a strategy newly developed to map genes implicated by BMD GWAS onto a bone co- expression network, we predicted causal genes for 30 of 64 GWAS loci. One locus located on chromosome 14q32.32 contained SNPs highly associated with femoral neck BMD (P=5.0 x 10-16) and we predicted that MARK3, one of five genes in the locus, was causal. MARK3 encodes a conserved serine/threonine kinase known to regulate diverse processes including asymmetric cell division, and neuronal differentiation, but its potential role in bone was unknown. Provisional assessment of mice deficient in Mark3 either globally or conditionally (osteoblast) revealed closely similar skeletal phenotypes. Based on these exciting findings, we developed a comprehensive approach to identify the precise causal variant(s) linked to MARK3 and determine how the activity of this kinase in osteoblasts controls bone mass. The studies are divided into three aims: Specific Aim 1: Define the causal genetic mechanism underlying the Chr14q32.32 BMD GWAS locus. Specific Aim 2: Determine how Mark3 functions in bone Specific Aim 3: Test function of the regulatory SNP(s) in vivo. This project was conceived and will be jointly headed by Thomas Clemens at Johns Hopkins University and Charles Farber at the University of Virginia under the auspices of a Multi PI arrangement. The synergy of their complimentary research programs has already been established in previous projects. We strongly believe that the approach will define the biological networks impacted by mutation will contribute substantially to the understanding of their pathology and provide important targets for intervention.