The evolution of Runx genes II. The C-terminal Groucho recruitment motif is present in both eumetazoans and homoscleromorphs but absent in a haplosclerid demosponge.
The evolution of Runx genes II. The C-terminal Groucho recruitment motif is present in both eumetazoans and homoscleromorphs but absent in a haplosclerid demosponge.
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DOI：
10.1186/1756-0500-2-59
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发表时间：
2009-04-17
影响因子：
1.8
通讯作者：
Coffman JA
中科院分区：
文献类型：
--
作者：
Robertson AJ;Larroux C;Degnan BM;Coffman JA
Runt DNA 结合域 (Runx) 定义了后生动物序列特异性转录因子家族，在动物个体发育和基于干细胞的发育中发挥重要作用。根据顺式调控背景，Runx 蛋白介导转录激活或抑制。在许多情况下，Runx 介导的抑制是由 Groucho/TLE 进行的，Groucho/TLE 通过 C 端 WRPY 序列基序招募到转录复合物，该基序被发现编码在所有迄今为止已知的 Runx 基因中。在最近测序的系统发育多样化的后生动物基因组中鉴定出了全长 Runx 基因，这些后生动物包括长生动物和海绵动物，它们是该分支中最基本的分支成员。在领鞭毛虫 Monosiga brevicollis 的基因组中没有发现与 Runt 结构域显着相似的序列，证实 Runx 是后生动物的无性型。由单孔海绵类 Aphimedon queenslandica 的基因组序列组装而成的重叠群被用来构建来自该物种 AmqRunx 的单个 Runx 基因的模型，其准确性通过表达序列得到证实。来自同型海绵 Oscarella carmella 的 Runx 蛋白 OscRunx 的编码序列也从组装的 EST 中获得。值得注意的是，之前在脊椎动物中报道过的 Runx 和 Supt3h 之间的同线性联系在 A. queenslandica 中得到了保留。 OscRunx 编码 C 端 Groucho 招募基序，而 AmqRunx 则不编码，尽管在 A. queenslandica 基因组中发现了 Groucho 同源物。我们的结果与海绵是并系群的假设一致，并表明 Runx-WRPY 介导 Groucho 募集到顺式调控序列，这些序列起源于真后生动物的祖先，在它们与海绵动物分化后。
The Runt DNA binding domain (Runx) defines a metazoan family of sequence-specific transcription factors with essential roles in animal ontogeny and stem cell based development. Depending on cis-regulatory context, Runx proteins mediate either transcriptional activation or repression. In many contexts Runx-mediated repression is carried out by Groucho/TLE, recruited to the transcriptional complex via a C-terminal WRPY sequence motif that is found encoded in all heretofore known Runx genes. Full-length Runx genes were identified in the recently sequenced genomes of phylogenetically diverse metazoans, including placozoans and sponges, the most basally branching members of that clade. No sequences with significant similarity to the Runt domain were found in the genome of the choanoflagellate Monosiga brevicollis, confirming that Runx is a metazoan apomorphy. A contig assembled from genomic sequences of the haplosclerid demosponge Amphimedon queenslandica was used to construct a model of the single Runx gene from that species, AmqRunx, the veracity of which was confirmed by expressed sequences. The encoded sequence of the Runx protein OscRunx from the homoscleromorph sponge Oscarella carmella was also obtained from assembled ESTs. Remarkably, a syntenic linkage between Runx and Supt3h, previously reported in vertebrates, is conserved in A. queenslandica. Whereas OscRunx encodes a C-terminal Groucho-recruitment motif, AmqRunx does not, although a Groucho homologue is found in the A. queenslandica genome. Our results are consistent with the hypothesis that sponges are paraphyletic, and suggest that Runx-WRPY mediated recruitment of Groucho to cis-regulatory sequences originated in the ancestors of eumetazoans following their divergence from demosponges.