Alternative Splicing Generates a MONOPTEROS Isoform Required for Ovule Development
Alternative Splicing Generates a MONOPTEROS Isoform Required for Ovule Development
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DOI：
10.1016/j.cub.2020.11.026
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发表时间：
2021-02-22
期刊：
影响因子：
9.2
通讯作者：
Colombo, Lucia
中科院分区：
文献类型：
--
作者：
Cucinotta, Mara;Cavalleri, Alex;Colombo, Lucia
植物激素生长素是器官形成和发育的基本调节因子，通过典型的生长素反应因子(ARF)和生长素/吲哚-3-乙酸(AUX/IAA)组合系统调节基因表达。ARF和AUX/IAA因子相互作用，但在高生长素浓度下，AUX/IAA转录抑制物被降解，允许含有ARF的复合体激活基因表达。ARF5/monopteros(MP)是拟南芥发育过程中生长素信号的重要整合子，在生长素水平升高的细胞中激活基因转录。在这里，我们证明了在胚珠中，MP在生长素水平较低的细胞中表达，并可以激活直接靶基因的表达。我们鉴定并鉴定了MP的一个剪接变体，它编码一个缺乏AUX/IAA相互作用结构域的生物功能异构体。这种MP11ir异构体能够弥补MP突变体的花序、花和胚珠发育缺陷，表明它是完全功能的。我们的发现描述了一种新的场景，其中ARF转录后调控控制异构体的形成，该异构体可以作为阈值下生长素浓度区域的转录激活因子。
The plant hormone auxin is a fundamental regulator of organ patterning and development that regulates gene expression via the canonical AUXIN RESPONSE FACTOR (ARF) and AUXIN/INDOLE-3-ACETIC ACID (Aux/IAA) combinatorial system. ARF and Aux/IAA factors interact, but at high auxin concentrations, the Aux/IAA transcriptional repressor is degraded, allowing ARF-containing complexes to activate gene expression. ARF5/MONOPTEROS (MP) is an important integrator of auxin signaling in Arabidopsis development and activates gene transcription in cells with elevated auxin levels. Here, we show that in ovules, MP is expressed in cells with low levels of auxin and can activate the expression of direct target genes. We identified and characterized a splice variant of MP that encodes a biologically functional isoform that lacks the Aux/IAA interaction domain. This MP11ir isoform was able to complement inflorescence, floral, and ovule developmental defects in mp mutants, suggesting that it was fully functional. Our findings describe a novel scenario in which ARF post-transcriptional regulation controls the formation of an isoform that can function as a transcriptional activator in regions of subthreshold auxin concentration.