Institut de Biologie du Développement de Marseille Luminy, IBDML, UMR7288, CNRS, AMU, Parc Scientifique de Luminy, Case 907, Marseille, France.
PLoS Biol. 2012;10(6):e1001351. doi: 10.1371/journal.pbio.1001351. Epub 2012 Jun 26.
Hox transcription factors control a number of developmental processes with the help of the PBC class proteins. In vitro analyses have established that the formation of Hox/PBC complexes relies on a short conserved Hox protein motif called the hexapeptide (HX). This paradigm is at the basis of the vast majority of experimental approaches dedicated to the study of Hox protein function. Here we questioned the unique and general use of the HX for PBC recruitment by using the Bimolecular Fluorescence Complementation (BiFC) assay. This method allows analyzing Hox-PBC interactions in vivo and at a genome-wide scale. We found that the HX is dispensable for PBC recruitment in the majority of investigated Drosophila and mouse Hox proteins. We showed that HX-independent interaction modes are uncovered by the presence of Meis class cofactors, a property which was also observed with Hox proteins of the cnidarian sea anemone Nematostella vectensis. Finally, we revealed that paralog-specific motifs convey major PBC-recruiting functions in Drosophila Hox proteins. Altogether, our results highlight that flexibility in Hox-PBC interactions is an ancestral and evolutionary conserved character, which has strong implications for the understanding of Hox protein functions during normal development and pathologic processes.
Hox 转录因子借助 PBC 类蛋白控制着许多发育过程。体外分析已经确立，Hox/PBC 复合物的形成依赖于一个短的保守的 Hox 蛋白基序，称为六肽 (HX)。这个范例是绝大多数专门用于研究 Hox 蛋白功能的实验方法的基础。在这里，我们使用双分子荧光互补 (BiFC) 测定法质疑 HX 对 PBC 募集的独特和通用用途。该方法允许在体内和全基因组范围内分析 Hox-PBC 相互作用。我们发现，在大多数研究的果蝇和小鼠 Hox 蛋白中，HX 对于 PBC 的募集是可有可无的。我们表明，存在 Meis 类共因子会揭示出与 HX 无关的相互作用模式，这一特性也在刺胞动物海葵 Nematostella vectensis 的 Hox 蛋白中观察到。最后，我们揭示了果蝇 Hox 蛋白中，种系特异性基序具有主要的 PBC 募集功能。总之，我们的研究结果表明，Hox-PBC 相互作用的灵活性是一种古老的和进化保守的特征，这对理解正常发育和病理过程中 Hox 蛋白功能具有重要意义。
