Evolving enhancer-promoter interactions within the tinman complex of the flour beetle, Tribolium castaneum
Evolving enhancer-promoter interactions within the tinman complex of the flour beetle, Tribolium castaneum
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DOI：
10.1242/dev.038034
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发表时间：
2009-09-15
期刊：
影响因子：
4.6
通讯作者：
Levine, Michael
中科院分区：
文献类型：
--
作者：
Cande, Jessica Doran;Chopra, Vivek S.;Levine, Michael
顺式调节DNA的修饰，特别是增强子，是动物进化过程中基因表达变化的基础。在这里，我们提出了一个独特的机制的监管演变的证据，从而产生一种新的模式的基因表达改变基因靶向的保守增强子。Tinman基因复合体（Tin-C）控制着果蝇背侧中胚层组织（包括背侧血管或心脏）的图案形成。尽管广泛的保护锡-C基因的表达模式在面粉甲虫（赤拟谷盗），蜜蜂（蜜蜂）和果蝇（果蝇），一个关键的心包决定因素，瓢虫的表达，是缺席的背侧中胚层的赤拟谷盗胚胎。有证据表明，这种损失的表达被C15，在复杂的相邻基因的表达所取代。这种从瓢虫到C15的表达转换似乎是由tinman复合物内的倒位引起的，该倒位重定向保守的瓢虫3'增强子以调节C15。在果蝇中，这种增强子未能激活C15的表达，由于在干预瓢虫早期启动子的绝缘体的活动。相比之下，在赤拟谷盗中，染色体倒位允许心脏增强子绕过瓢虫绝缘子。鉴于昆虫基因组重排的频率很高，这种增强子转换可能会广泛用于节肢动物的多样化。
Modifications of cis-regulatory DNAs, particularly enhancers, underlie changes in gene expression during animal evolution. Here, we present evidence for a distinct mechanism of regulatory evolution, whereby a novel pattern of gene expression arises from altered gene targeting of a conserved enhancer. The tinman gene complex (Tin-C) controls the patterning of dorsal mesodermal tissues, including the dorsal vessel or heart in Drosophila. Despite broad conservation of Tin-C gene expression patterns in the flour beetle (Tribolium castaneum), the honeybee (Apis mellifera) and the fruit fly (Drosophila melanogaster), the expression of a key pericardial determinant, ladybird, is absent from the dorsal mesoderm of Tribolium embryos. Evidence is presented that this loss in expression is replaced by expression of C15, the neighboring gene in the complex. This switch in expression from ladybird to C15 appears to arise from an inversion within the tinman complex, which redirects a conserved ladybird 3' enhancer to regulate C15. In Drosophila, this enhancer fails to activate C15 expression owing to the activity of an insulator at the intervening ladybird early promoter. By contrast, a chromosomal inversion allows the cardiac enhancer to bypass the ladybird insulator in Tribolium. Given the high frequency of genome rearrangements in insects, it is possible that such enhancer switching might be widely used in the diversification of the arthropods.