Genome-wide comparative analysis of type-A Arabidopsis response regulator genes by overexpression studies reveals their diverse roles and regulatory mechanisms in cytokinin signaling
Genome-wide comparative analysis of type-A Arabidopsis response regulator genes by overexpression studies reveals their diverse roles and regulatory mechanisms in cytokinin signaling
复制标题
通过过表达研究对 A 型拟南芥反应调节基因进行全基因组比较分析，揭示了它们在细胞分裂素信号传导中的不同作用和调节机制
DOI：
10.1038/cr.2009.88
复制
发表时间：
2009-10-01
期刊：
影响因子：
44.1
通讯作者：
Zuo, Jianru
中科院分区：
文献类型：
--
作者：
Ren, Bo;Liang, Yan;Zuo, Jianru
细胞分裂素是植物生长发育的重要生长调节因子。在拟南芥中，细胞分裂素信号传导由基于双组分系统的磷酸化传递介导，该磷酸化传递将信号从受体通过组氨酸磷酸转移蛋白传递到下游反应调节因子（ARR）。在这些ARR中，A型ARR基因，其转录可以被细胞分裂素快速诱导，充当细胞分裂素信号传导的负调节子。然而，由于A型ARR基因在植物生长发育中存在功能冗余，通过分析功能缺失突变体还不能很好地了解其功能。在这项研究中，我们进行了比较功能研究的所有10个A型ARR基因，通过分析过表达这些ARR基因融合到MYC表位标签的转基因植物。ARR基因的过表达导致多种细胞分裂素相关表型。值得注意的是，不同ARR转基因的过表达导致不同的表型，甚至在遗传学上密切相关的基因对之间，例如在ARR 3-ARR 4和ARR 5-ARR 6对内。我们发现，一个子集的ARR蛋白（ARR 3，ARR 5，ARR 7，ARR 16和ARR 17;可能ARR 8和ARR 15）的积累增加了MG 132，一个特定的蛋白酶体抑制剂，表明这些蛋白质的稳定性调节蛋白酶体降解。此外，类似于先前表征的ARR 5、ARR 6和ARR 7，ARR 16和ARR 17（可能包括ARR 8和ARR 15）的稳定性受细胞分裂素调节。这些结果表明，A型ARR蛋白的调控组合机制，涉及细胞分裂素和蛋白酶体途径，从而执行独特的功能，在植物的生长和发育。
Cytokinin is a critical growth regulator for various aspects of plant growth and development. In Arabidopsis, cytokinin signaling is mediated by a two-component system-based phosphorelay that transmits a signal from the receptors, through histidine phosphotransfer proteins, to the downstream response regulators (ARRs). Of these ARRs, type-A ARR genes, whose transcription can be rapidly induced by cytokinin, act as negative regulators of cytokinin signaling. However, because of functional redundancy, the function of type-A ARR genes in plant growth and development is not well understood by analyzing loss-of-function mutants. In this study, we performed a comparative functional study on all ten type-A ARR genes by analyzing transgenic plants overexpressing these ARR genes fused to a MYC epitope tag. Overexpression of ARR genes results in a variety of cytokinin-associated phenotypes. Notably, overexpression of different ARR transgenes causes diverse phenotypes, even between phylogenetically closely-related gene pairs, such as within the ARR3-ARR4 and ARR5-ARR6 pairs. We found that the accumulation of a subset of ARR proteins (ARR3, ARR5, ARR7, ARR16 and ARR17; possibly ARR8 and ARR15) is increased by MG132, a specific proteasomal inhibitor, indicating that stability of these proteins is regulated by proteasomal degradation. Moreover, similar to that of previously characterized ARR5, ARR6 and ARR7, stability of ARR16 and ARR17, possibly including ARR8 and ARR15, is regulated by cytokinin. These results suggest that type-A ARR proteins are regulated by a combinatorial mechanism involving both the cytokinin and proteasome pathways, thereby executing distinctive functions in plant growth and development.