STAT1基因变异及转录结合与人类骨质疏松的关联和在斑马鱼骨骼发育中的功能研究

Osteoporosis is a systemic disease characterized with low bone mineral density (BMD) and the prevalence increases in China, causing fractures and serious damage. Previously, we launched the osteoporosis studies on differential expression profiling of monocytes, genome-wide linkage analysis, genome-wide asociation study and signaling pathway analysis, indicating that STAT1 gene is significantly associated with human osteoporosis, but its mechanism is mainly unknown. In the present project, we aim to identify the function loci associated with BMD with common and rare variations in exons of STAT1 in Chinese population with exon re-sequencing strategies. Chromatin immuno-precipitation combined with parallel sequencing (ChIP SEQ) is used to screen STAT1 binding sites in whole genome in monocytes treated by interferon-γ in the high and low BMD groups. The significant different binding sites and important candidate genes with STAT1 are validated using ChIP qPCR. In zebrafish with knockdown of stat1a and stat1b genes,the expression of important regulators to skeleton development, the activities of osteoblasts and osteoclasts, bone mass and BMD are all investigated. This project will systematically set out the molecular biological mechanism of STAT1 gene for human osteoporosis.

骨质疏松是一种全身性疾病,表现为较低的骨密度，在我国发病率不断增加,引起骨折危害严重。前期我们开展了骨质疏松的单核细胞差异表达、连锁分析和全基因组关联分析及信号通路分析，发现STAT1基因与骨质疏松显著关联，但其作用机制不清楚。本项目应用外显子重测序策略，在中国人群随机样本中鉴定STAT1基因与骨密度关联的常见变异和罕见变异的功能位点。结合先进的染色质免疫沉淀测序（ChIP seq）技术筛选不同骨密度人群干扰素γ处理的单核细胞中STAT1转录因子的转录结合差异，并对显著性差异的结合位点和重要骨质疏松候选基因的转录结合活性采用ChIP qPCR验证。敲降斑马鱼stat1a、stat1b基因,研究其骨骼发育中重要调节因子表达、成骨细胞和破骨细胞活性、骨量及骨密度的变化规律。本项目将较为系统阐明STAT1基因的骨质疏松分子生物学机制。

前期我们开展了骨质疏松的单核细胞差异表达、连锁分析和全基因组关联分析及信号通路分析，发现STAT1基因与骨质疏松显著关联，但其作用机制不清楚。本项目应用外显子重测序，发现在101个中国人群随机样本中STAT1基因功能变异位点45个，次等位基因频率极低，通过罕见变异关联分析策略并没有发现与骨密度关联，这有待更大的样本和高功效的统计策略。通过表达相关及ChIP SEQ分析，发现STAT1基因与UBE2L6基因在单核细胞中表达高度相关，且UBE2L6基因在高低骨密度人群中显著性差异表达，STAT1在UBE2L6基因内含子1区域存在结合调控区域。发现miR-140-5p突变对斑马鱼软骨发育的影响，miR-140-5p可能通过抑制STAT1激活起作用。采用CRISPR/Cas9基因敲除技术分别获得斑马鱼stat1a、stat1b基因稳定遗传突变品系，stat1a突变斑马鱼早期生长加快，stat1b突变斑马鱼脊柱畸形明显。stat1a与stat1b基因敲除后的斑马鱼发育过程中基因组表达调控规律通过单细胞扩增及RNA-Seq高通量技术研究进行解析，由于单细胞扩增技术的难度及基因网络大数据分析挑战性，stat1a与stat1b基因表达调控分析仍在进行中。本项目较为系统阐明STAT1基因在骨骼发育中的调控作用。