Serum response factor, an enriched cardiac mesoderm obligatory factor, is a downstream gene target for Tbx genes
Serum response factor, an enriched cardiac mesoderm obligatory factor, is a downstream gene target for Tbx genes
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DOI：
10.1074/jbc.m412408200
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发表时间：
2005-03-25
影响因子：
4.8
通讯作者：
Schwartz, RJ
中科院分区：
文献类型：
--
作者：
Barron, MR;Belaguli, NS;Schwartz, RJ
我们测试的想法，T盒因子直接血清反应因子（SRF）基因活性在发展的早期。SRF-LacZ“敲入”小鼠的分析显示，在早期胚胎心脏和骨骼肌中胚层和神经外胚层中的表达高度受限。通过连接启动子和5 '-侧翼序列（高达5.5 kb）检查SRF基因的调节区，未能将LacZ转基因活性靶向心脏和尾前体间充质。然而，一个最小的SRF启动子与SRF 3 '-非翻译区（UTR）的连接，淹没了多聚体T-box结合位点（TBE），恢复了强大的报告基因活性胚胎心脏和尾巴。将3 '-UTR更精细地切割成一小簇TBE也刺激了心脏形成区和尾部中的转基因活性，然而，当这些DNA序列中包含的TBE突变时，阻止了Tbx结合，转基因活性丧失。Tbx 2、Tbx 5和心脏富集的MYST家族组蛋白乙酰转移酶TIP 60被观察到通过TIP 60锌指和Tbx因子的T-box是相互作用的辅因子。在SRF缺失ES细胞中，TIP 60、Tbx 2和Tbx 5足以刺激共转染的SRF报告基因活性，然而该活性需要SRF 3 '-UTR的存在。SRF基因反式激活被两种不同的TIP 60突变体阻断，其中组蛋白乙酰转移酶结构域被失活或锌指蛋白结合结构域被切除。我们的研究支持了SRF胚胎心脏基因表达依赖于SRF 3 '-UTR增强子、Tbx 2、Tbx 5和TIP 60组蛋白乙酰转移酶活性的观点。
We tested the idea that T-box factors direct serum response factor (SRF) gene activity early in development. Analysis of SRF-LacZ "knock-in" mice showed highly restricted expression in early embryonic cardiac and skeletal muscle mesoderm and neuroectoderm. Examination of the SRF gene for regulatory regions by linking the promoter and 5'-flanking sequences, up to 5.5 kb, failed to target LacZ transgene activity to the heart and the tail pre-somitic mesenchyme. However, linkage of a minimal SRF promoter with the SRF 3'-untranslated region (UTR), inundated with multimeric T-box binding sites (TBEs), restored robust reporter gene activity to embryonic heart and tail. Finer dissection of the 3'-UTR to a small cluster of TBEs also stimulated transgene activity in the cardiac forming region and the tail, however, when the TBEs contained within these DNA sequences were mutated, preventing Tbx binding, transgene activity was lost. Tbx2, Tbx5, and the cardiac-enriched MYST family histone acetyltransferase TIP60, were observed to be mutual interactive cofactors through the TIP60 zinc finger and the T-box of the Tbx factors. In SRF-null ES cells, TIP60, Tbx2, and Tbx5 were sufficient to stimulate co-transfected SRF reporter activity, however this activity required the presence of the SRF 3'-UTR. SRF gene transactivation was blocked by two distinct TIP60 mutants, in which either the histone acetyltransferase domain was inactivated or the Zn finger-protein binding domain was excised. Our study supports the idea that SRF embryonic cardiac gene expression is dependent upon the SRF 3'-UTR enhancer, Tbx2, Tbx5, and TIP60 histone acetyltransferase activity.