摘要
目的对小睑裂综合征（BPES）患者进行FOXL2基因突变筛选，并对基因突变前后的蛋白质结构进行预测，研究基因突变对编码蛋白一、二级结构的影响，探讨该病发生的分子机制。方法以临床确诊的7例BPES患者为研究对象，取外周血进行基因组DNA抽提，PCR扩增FOXL2开放性阅读框及5’非翻译区，产物直接或克隆后测序。用PDH和ExPASy软件包对正常及发生突变后的蛋白质结构进行预测，分析比较它们一、二级结构的差异。结果我们在1个Ⅱ型小家系的2个患者和1例散发患者中发现了FOXL2 901-930重复插入突变，而在正常人对照中，没有发现该突变。一级结构分析显示，FOXL2突变前后蛋白质相对分子质量发生了明显的改变，但蛋白质等电点没有发生改变。二级结构分析显示，FOXL2为一跨膜蛋白，其聚丙氨酸肽段包含1个α-螺旋区，该螺旋区域位于跨膜区内；发生突变后，聚丙氨酸扩增，螺旋区域长度增加，从而使α-螺旋占整个蛋白质二级结构的比例较突变前增加了4．1％，而β折叠与无规卷曲的比例相应下降。结论经查实FOXL2 901-930重复插入突变是一新的突变，该突变导致了聚丙氨酸肽段的扩增（222-232插入10）；蛋白质结构预测显示突变前后其编码蛋白二级结构存在显著差异，这可能与BPES发病密切相关。（中华腰群杂志,2007，43：535-539）
Objective The aim of this study was to investigate the effect of mutations of the forkhead transcription factor 2 （FOXL2） gene on the primary and secondary structure of the coded protein and seek for the molecular mechanism of blepharophimosis-ptosis-epicanthus inversus syndrome （BPES）. Methods The genomic DNA was extracted from peripheral blood of 7 clinically diagnosed BPES patients, PCR amplification of FOXL2 coding region and 5＇ untranslated region were performed, Sequence analysis was performed using the PCR or cloning products. The structure of the protein was predicted with PDH and ExPASy software, and the difference between the normal and the mutational protein was analyzed. Results A 901-930dup 30 mutation of FOXL2 was found in two patients from a BPES family of type Ⅱ and a sporadic ease, and no any mutations were detected in normal control. Analysis of the primary structure displayed that the molecular weight of the protein coded by the mutated gene was greater than the normal, but both have the same isoelectric point. Analysis of the secondary structure showed that FOXL2 was a transmembrane protein with a polyalanine tract which contained a α-helix. When the polyalanine tract expanded, the helix region extended, as a result, the proportion of α-helix increased by 4. 1%, but the proportions of β-pleated sheet and random coil decreased correspondingly. Conclusion Our results suggest that the 901-930 dup30 mutation of FOXL2 is a novel finding. Moreover, this mutation causes great changes in the primary and secondary structure of the coded protein, which may be the molecular pathogenesis of BPES. （Chin J Ophthalmol , 2007,43 .535-539）
出处
《中华眼科杂志》
CAS
CSCD
北大核心
2007年第6期535-539,共5页
Chinese Journal of Ophthalmology
基金
山东省教育厅重点资助项目（J02K06）
关键词
睑裂狭小
突变
蛋白质构象
DNA结合蛋白质类
转录因子
Blepharophimosis
Mutation
Protein conformation
DNA-binding proteins
Transcription factors
