特发性矮小症患者SHOX基因启动子突变的功能分析

A functional analysis of short stature homeobox （SHOX） gene promoter mutation in idiopathic short stature

目的研究矮身材同源盒基因（SHOX）启动子-372G—A突变对其转录活性的影响及机制。方法构建含SHOX基因启动子野生型-372G和-372A纯合突变的荧光素酶报告基因载体，在鸡的软骨细胞中检测其转录活性；PCR扩增产生-372G及-372A转录活性的双链DNA探针，凝胶电泳迁移率（EMSA）检测结合在-400／-290片段的转录因子。结果报告基因结果显示$HOX基因启动子-372A转录活性高于-372G30％（P〈0．01）。EMSA结果显示-372A突变的DNA片段不能与核蛋白结合。结论SHOX基因-372A突变降低核转录因子与其启动子的结合力，增加了启动子的活性，可能与特发性矮小症患者长骨的生长障碍有关。

Objective To investigate the effect of short stature homeobox （SHOX） gene promoter -372G →A mutation on the promoter activity and its mechanism. Methods The luciferase report gene vectors containing human SHOX gene promoter -372G or -372A were contructed. Their transcription activities were detected in chicken chondrocytes. Double-stranded DNA probes containing -372G or -372A were produced by PCR, and used for detecting the affinity with nuclear transcription factors by electrophoretic mobility shift assay （EMSA）. Results The transcription activity in a -372A promoter construct was significantly higher than that in the wild type -372G （ P〈0.01 ）. The result of EMSA showed that -372A gene mutation resulted in loss of the binding affinity to nuclear transcription factors. Conclusion The -372A mutation increases SHOX promoter activity with decreased DNA binding affinity to transcription factors, which may contribute to impaired long bone growth in patients with idiopathic short stature.