Loss of function and inhibitory effects of human CSX/NKX2.5 homeoprotein mutations associated with congenital heart disease
Loss of function and inhibitory effects of human CSX/NKX2.5 homeoprotein mutations associated with congenital heart disease
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DOI：
10.1172/jci9860
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发表时间：
2000-07-01
影响因子：
15.9
通讯作者：
Izumo, S
中科院分区：
文献类型：
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作者：
Kasahara, H;Lee, B;Izumo, S
CSX/NKX2.5是一种进化上保守的含同源结构域（含HD）的转录因子，对早期心脏发育至关重要。最近，在以常染色体显性遗传方式传播的先天性心脏病患者中发现了10种不同的杂合CSX/NKX2.5突变。为了确定这些突变的后果，我们分析了突变CSX/NKX2.5蛋白的核定位、DNA结合、转录激活和二聚化。所有的突变体蛋白质翻译和本地：艾德到细胞核，除了一个剪接供体位点突变体的蛋白质不积累在细胞中。所有在HD中具有截短或错义突变的突变体具有严重降低的DNA结合活性和很少或没有转录激活功能。相反，具有完整HD的突变体表现出与单体结合位点的正常DNA结合，但与二聚体结合位点的DNA结合减少了三至九倍。保留同源二聚化能力的HD错义突变抑制了野生型CSX/NKX2.5对心钠素的激活。虽然我们的研究没有描述这10种人类突变的基因型-表型关系，但它们确定了CSX/NKX2.5功能的特异性异常，这些功能对靶基因的反式激活至关重要。
CSX/NKX2.5 is an evolutionarily conserved homeodomain-containing (HD-containing) transcription factor that is essential for early cardiac development. Recently, ten different heterozygous CSX/NKX2.5 mutations were found in patients with congenital heart defects that are transmitted in an autosomal dominant fashion. To determine the consequence of these mutations, we analyzed nuclear localization, DNA binding, transcriptional activation, and dimerization of mutant CSX/NKX2.5 proteins. All mutant proteins were translated and local:ed to the nucleus, except one splice-donor site mutant whose protein did not accumulate in the cell. All mutants that had truncation or missense mutations in the HD had severely reduced DNA binding activity and little or no transcriptional activation function. In contrast, mutants with intact HDs exhibit normal DNA binding to the monomeric binding site but had three- to ninefold reduction ill DNA binding to the dimeric binding sites. HD missense mutations that preserved homodimerization ability inhibited the activation of atrial natriuretic factor by wild-type CSX/NKX2.5. Although our studies do not characterize the genotype-phenotype relationship of the ten human mutations, they identify specific abnormalities of CSX/NKX2.5 function essential for transactivation of target genes.