Endosperm breakdown in Arabidopsis requires heterodimers of the basic helix-loop-helix proteins ZHOUPI and INDUCER OF CBP EXPRESSION 1
Endosperm breakdown in Arabidopsis requires heterodimers of the basic helix-loop-helix proteins ZHOUPI and INDUCER OF CBP EXPRESSION 1
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DOI：
10.1242/dev.103531
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发表时间：
2014-03-15
期刊：
影响因子：
4.6
通讯作者：
Ingram, Gwyneth
中科院分区：
文献类型：
--
作者：
Denay, Gregoire;Creff, Audrey;Ingram, Gwyneth
在拟南芥种子中，胚的生长与胚乳的破裂是协调的。胚乳特异性基因ZHOUPI（ZESTO）编码一种独特的碱性螺旋-环-螺旋（bHLH）转录因子，突变体具有异常的胚乳，在整个种子发育过程中持续存在，显著阻碍胚生长。在这里，我们表明，bHLH编码基因诱导CBP表达1（ICE 1）的功能丧失导致相同的胚乳持久性表型。我们发现，ZE 3和ICE 1在胚乳中共表达，并通过它们的bHLH结构域在酵母中相互作用。我们表明，无论是在遗传和异源植物系统，尽管事实上，这两个ZERTAGE和ICE 1可以在酵母中形成同源二聚体，他们在胚乳分解的作用需要他们的异源二聚体。与这一结论相一致，我们证实，ZERO和ICE 1调节发育胚乳中共同靶基因的表达。最后，我们表明，ZERO和ICE 1的异源二聚化可能是必要的，他们的结合到特定的目标，而不是为他们的核定位在胚乳。通过比较我们的研究结果与范式的bHLH功能和动物系统中的进化，我们提出，ZERO/ICE 1复合体可能有古老的起源，获得新的巨配子体特异性功能的异孢子陆地植物，被保存在被子植物胚乳。
In Arabidopsis seeds, embryo growth is coordinated with endosperm breakdown. Mutants in the endosperm-specific gene ZHOUPI (ZOU), which encodes a unique basic helix-loop-helix (bHLH) transcription factor, have an abnormal endosperm that persists throughout seed development, significantly impeding embryo growth. Here we show that loss of function of the bHLH-encoding gene INDUCER OF CBP EXPRESSION 1 (ICE1) causes an identical endosperm persistence phenotype. We show that ZOU and ICE1 are co-expressed in the endosperm and interact in yeast via their bHLH domains. We show both genetically and in a heterologous plant system that, despite the fact that both ZOU and ICE1 can form homodimers in yeast, their role in endosperm breakdown requires their heterodimerization. Consistent with this conclusion, we confirm that ZOU and ICE1 regulate the expression of common target genes in the developing endosperm. Finally, we show that heterodimerization of ZOU and ICE1 is likely to be necessary for their binding to specific targets, rather than for their nuclear localization in the endosperm. By comparing our results with paradigms of bHLH function and evolution in animal systems we propose that the ZOU/ICE1 complex might have ancient origins, acquiring novel megagametophyte-specific functions in heterosporous land plants that were conserved in the angiosperm endosperm.