Anatomy of a homeoprotein revealed by the analysis of human MODY3 mutations
Anatomy of a homeoprotein revealed by the analysis of human MODY3 mutations
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DOI：
10.1074/jbc.274.50.35639
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发表时间：
1999-12-10
影响因子：
4.8
通讯作者：
Pontoglio, M
中科院分区：
文献类型：
--
作者：
Vaxillaire, M;Abderrahman, A;Pontoglio, M
肝细胞核因子1 α (HNF1 α)是一种非典型的二聚体同源结构域蛋白，在肝、肠、胃、肾和胰腺中表达。HNF1 α基因突变与常染色体显性非胰岛素依赖型糖尿病有关，称为青年成熟型糖尿病（MODY3）。到目前为止，已经发现了80多种不同的突变，其中许多涉及脊椎动物HNF1 α中高度保守的氨基酸残基。在目前的工作中，我们研究了MODY3突变影响HNF1 α功能的分子机制。为此，我们分析了10个导致氨基酸取代或蛋白质截断的突变体的特性。一些突变体的蛋白质稳定性降低，而另一些突变体要么是DNA结合缺陷，要么是其内在反式激活电位受损。三个突变体的特点是完全失去反式激活，当转染野生型蛋白时表现为显性阴性。这些数据明确了MODY3突变与HNF1 α反式激活的功能缺陷之间的因果关系。此外，我们的分析揭示了在胰腺细胞功能中起关键作用的同型蛋白的结构。
Hepatocyte nuclear factor 1 alpha (HNF1 alpha) is an atypical dimeric homeodomain-containing protein that is expressed in liver, intestine, stomach, kidney, and pancreas. Mutations in the HNF1 alpha gene are associated with an autosomal dominant form of non-insulin-dependent diabetes mellitus called maturity-onset diabetes of the young (MODY3). More than 80 different mutations have been identified so far, many of which involve highly conserved amino acid residues among vertebrate HNF1 alpha. In the present work, we investigated the molecular mechanisms by which MODY3 mutations could affect HNF1 alpha function. For this purpose, we analyzed the properties of 10 mutants resulting in amino acid substitutions or protein truncation. Some mutants have a reduced protein stability, whereas others are either defective in the DNA binding or impaired in their intrinsic trans-activation potential. Three mutants, characterized by a complete loss of trans-activation, behave as dominant negatives when transfected with the wildtype protein. These data define a clear causative relationship between MODY3 mutations and functional defects in HNF1 alpha trans-activation. In addition, our analysis sheds new light on the structure of a homeoprotein playing a key role in pancreatic beta cell function.