Department of Cardiology, First Affiliated Hospital of Nanjing Medical University, 300 Guangzhou Road, Nanjing, Jiangsu, China.
Curr Mol Med. 2013 Jul;13(6):993-9. doi: 10.2174/15665240113139990053.
Genetic mutations in GATA4, a transcriptional factor, have been found to cause congenital heart diseases. The underlying mechanism, however, remains largely unknown. We previously reported 7 heterozygous variants in patients with ventricular septal defects (VSD). Here we functionally characterized a de novo mutation p.S335X and demonstrated that this mutation led to the pre-termination of its translation, producing a truncated GATA4 lacking a conservative region at C-terminus. Truncated GATA4 did not disturb its subcellular localization; however, it delayed the cardiomyocyte differentiation in P19cl6 model and prohibited Bcl2 expression that led to apoptosis proved by fragmented genomic DNA and positive TUNEL staining in H9C2 cells. By ChIP assay, we showed that GATA4 without C-terminus reduced its DNA binding affinity and suppressed the expressions of its target genes. These findings suggest that C-terminus of GATA4 is critical to maintain DNA binding, and genetic mutations in this region may affect genes important for myocyte apoptosis and differentiation associated with congenital heart defects.
GATA4 是一种转录因子，其基因突变已被发现可导致先天性心脏病。然而，其潜在机制在很大程度上仍不清楚。我们之前在患有室间隔缺损 (VSD) 的患者中报道了 7 种杂合变异体。在这里，我们对一个新发生的突变 p.S335X 进行了功能表征，并证明该突变导致其翻译提前终止，产生一个缺乏 C 末端保守区域的截断 GATA4。截断的 GATA4 不会干扰其亚细胞定位；然而，它在 P19cl6 模型中延迟了心肌细胞分化，并抑制了 Bcl2 表达，导致 H9C2 细胞中出现基因组 DNA 片段化和 TUNEL 染色阳性的凋亡。通过 ChIP 检测，我们表明没有 C 末端的 GATA4 降低了其 DNA 结合亲和力，并抑制了其靶基因的表达。这些发现表明 GATA4 的 C 末端对于维持 DNA 结合至关重要，该区域的基因突变可能会影响与先天性心脏病相关的肌细胞凋亡和分化的重要基因。
