Functional characterization of GATA3 mutations causing the hypoparathyroidism-deafness-renal (HDR) dysplasia syndrome: insight into mechanisms of DNA binding by the GATA3 transcription factor
Functional characterization of GATA3 mutations causing the hypoparathyroidism-deafness-renal (HDR) dysplasia syndrome: insight into mechanisms of DNA binding by the GATA3 transcription factor
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DOI：
10.1093/hmg/ddl454
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发表时间：
2007-02-01
影响因子：
3.5
通讯作者：
Thakker, Rajesh V.
中科院分区：
文献类型：
--
作者：
Ali, Asif;Christie, Paul T.;Thakker, Rajesh V.
甲状旁腺功能减退-耳聋-肾（HDR）发育不良综合征是由双锌指转录因子GATA 3突变引起的常染色体显性遗传疾病。我们调查了21例HDR先证者和14例孤立性甲状旁腺功能减退症患者的GATA 3异常。在HDR患者中鉴定了13种不同的杂合生殖系突变。这些包括三个无义突变，六个移码缺失，两个移码插入，一个错义（Leu 348 Arg）突变和一个受体剪接位点突变。剪接位点突变被证明会导致前mRNA加工异常，导致在正常位点下游8 bp处使用替代受体位点，导致移码和过早终止的蛋白质。电泳迁移率变动分析（EMSA）揭示了三类GATA 3突变：导致DNA结合丧失的突变，其占所有突变的90%以上，并且涉及羧基末端锌指的丧失;导致DNA结合亲和力降低的突变;和那些（例如Leu 348 Arg）这并不改变DNA结合或亲和力，但可能改变了构象变化，发生在结合过程中的DNA大沟，如预测的，三维建模这些结果进一步阐明了这种锌指转录因子突变体功能改变的分子机制及其在导致这种发育异常中的作用。在孤立性甲状旁腺功能减退患者中未发现突变，从而表明GATA 3异常更可能导致HDR综合征的两种或多种表型特征，而不是一种，如孤立性甲状旁腺功能减退。
The hypoparathyroidism-deafness-renal (HDR) dysplasia syndrome is an autosomal dominant disorder caused by mutations of the dual zinc finger transcription factor, GATA3. We investigated 21 HDR probands and 14 patients with isolated hypoparathyroidism for GATA3 abnormalities. Thirteen different heterozygous germline mutations were identified in patients with HDR. These consisted of three nonsense mutations, six frameshifting deletions, two frameshifting insertions, one missense (Leu348Arg) mutation and one acceptor splice site mutation. The splice site mutation was demonstrated to cause a pre-mRNA processing abnormality leading to the use of an alternative acceptor site 8 bp downstream of the normal site, resulting in a frameshift and prematurely terminated protein. Electrophoretic mobility shift assays (EMSAs) revealed three classes of GATA3 mutations: those that lead to a loss of DNA binding which represent over 90% of all mutations, and involved a loss of the carboxy-terminal zinc finger; those that resulted in a reduced DNA-binding affinity; and those (e.g. Leu348Arg) that did not alter DNA binding or the affinity but likely altered the conformational change that occurs during binding in the DNA major groove as predicted by a three-dimensional modeling. These results elucidate further the molecular mechanisms underlying the altered functions of mutants of this zinc finger transcription factor and their role in causing this developmental anomaly. No mutations were identified in patients with isolated hypoparathyroidism, thereby indicating that GATA3 abnormalities are more likely to result in two or more of the phenotypic features of the HDR syndrome and not in one, such as isolated hypoparathyroidism.