Liu Jian-Min, Cui Ya-Zhou, Zhang Geng-Lin, Zhou Xiao-Yan, Pang Jing-Xiang, Wang Xue-Zheng, Han Jin-Xiang
National Laboratory for Bio Drugs of Ministry of Health, Provincial Laboratory for Modern Medicine and Technology of Shandong, Research Center for Medicinal Biotechnology, Shandong Academy of Medical Sciences, Jinan, Shandong 250062, China.
Chin Med J (Engl). 2016 Mar 20;129(6):657-64. doi: 10.4103/0366-6999.177972.
Ankylosing spondylitis (AS) is the most common rheumatic condition that is slowly progressive and predominantly affects adolescents. Pathological bone formation associated with AS is an important cause of disability. The aim of the study was to investigate the possible involvement of the genes related to endochondral ossification and ectopia ossification in genetic susceptibility to AS in a Chinese Han population.
Sixty-eight single nucleotide polymorphisms (SNPs) from 13 genes were genotyped in discovery cohorts including 300 AS patients and 180 healthy controls. The rs10019009 in dentin matrix protein 1 (DMP1) gene shown as association with AS after multiple testing corrections in discovery cohorts was replicated in a validation independent cohort of 620 AS patients and 683 healthy controls. The rs10019009 was assessed with bioinformatics including phylogenetic context, F-SNP and FastSNP functional predictions, secondary structure prediction, and molecular modeling. We performed a functional analysis of rs10019009 via reverse transcription-polymerase chain reaction, alkaline phosphatase (ALP) activity in human osteosarcoma U 2 OS cells.
Interestingly, the SNP rs10019009 was associated with AS in both the discovery cohort (P = 0.0012) and validation cohort (P = 0.0349), as well as overall (P = 0.0004) in genetic case-control association analysis. After a multivariate logistic regression analysis, the effect of this genetic variant was observed to be independent of linkage disequilibrium. Via bioinformatics analysis, it was found that the amino acid change of the rs10019009 led to changes of SNP function, secondary structure, tertiary conformation, and splice mode. Finally, functional analysis of rs10019009 in U 2 OS cells demonstrated that the risk T allele of the rs10019009 increased enzymatic activity of ALP, compared to that of the nonrisk allele (P = 0.0080).
These results suggested that the DMP1 gene seems to be involved in genetic predisposition to AS, which may contribute to the ectopic mineralization or ossification in AS. In addition, DMP1 gene may be a promising intervention target for AS in the future.
强直性脊柱炎（AS）是最常见的风湿性疾病，呈缓慢进展，主要影响青少年。与AS相关的病理性骨形成是导致残疾的重要原因。本研究旨在探讨软骨内成骨和异位骨化相关基因在中国汉族人群AS遗传易感性中的可能作用。
在包括300例AS患者和180例健康对照的发现队列中，对13个基因的68个单核苷酸多态性（SNP）进行基因分型。在发现队列中经多次检验校正后显示与AS相关的牙本质基质蛋白1（DMP1）基因中的rs10019009，在一个独立的验证队列（620例AS患者和683例健康对照）中进行重复验证。使用包括系统发育背景、F-SNP和FastSNP功能预测、二级结构预测和分子建模在内的生物信息学方法对rs10019009进行评估。通过逆转录-聚合酶链反应、人骨肉瘤U 2 OS细胞中的碱性磷酸酶（ALP）活性，对rs10019009进行功能分析。
有趣的是，SNP rs10019009在发现队列（P = 0.0012）和验证队列（P = 0.0349）中均与AS相关，在遗传病例对照关联分析中总体上也相关（P = 0.0004）。经过多变量逻辑回归分析，观察到该基因变异的作用独立于连锁不平衡。通过生物信息学分析发现，rs10019009的氨基酸变化导致SNP功能、二级结构、三级构象和剪接模式的改变。最后，在U 2 OS细胞中对rs10019009进行功能分析表明，与非风险等位基因相比，rs10019009的风险T等位基因增加了ALP的酶活性（P = 0.0080）。
这些结果表明，DMP1基因似乎参与了AS的遗传易感性，这可能导致AS中的异位矿化或骨化。此外，DMP1基因可能是未来AS的一个有前景的干预靶点。
