Kuhn J M, Hugouvieux V, Schroeder J I
Division of Biological Sciences, Cell and Developmental Biology Section, University of California San Diego, La Jolla, CA 92093-0116, USA.
Curr Top Microbiol Immunol. 2008;326:139-50. doi: 10.1007/978-3-540-76776-3_8.
The plant hormone abscisic acid (ABA) intricately regulates a multitude of processes during plant growth and development. Recent studies have established a connection between genes participating in various steps of cellular RNA metabolism and the ABA signal transduction machinery. In this chapter we focus on the plant nuclear mRNA cap binding proteins, CBP20 and CBP80. We summarize and report recent findings on their effects on cellular signal transduction networks and mRNA processing events. ABA hypersensitive 1 (abh1) harbors a gene disruption in the Arabidopsis CBP80 gene. Loss-of-function mutation of ABH1 can also result in an early flowering phenotype in the Arabidopsis accession C24. abh1 revealed noncoding cis-natural antisense transcripts (cis-NATs) at the CONSTANS locus in wild-type plants with elevated cis-NAT expression in the mutant. abh1 also revealed an influence on the splicing of the MADS box transcription factor Flowering Locus C pre-mRNA, which may result in the regulation of flowering time. Furthermore, new experiments analyzing complementation of cpb20 with site-directed cpb20 mutants provide evidence that the CAP binding activity of CBP20 is essential for the observed cbp-associated phenotypes. In conclusion, mutants in genes participating in RNA processing provide excellent tools to uncover novel molecular mechanisms for the regulation of RNA metabolism and of signal transduction networks in wild-type plants.
植物激素脱落酸（ABA）在植物生长发育过程中复杂地调控着众多过程。最近的研究已在参与细胞RNA代谢各个步骤的基因与ABA信号转导机制之间建立了联系。在本章中，我们聚焦于植物核mRNA帽结合蛋白CBP20和CBP80。我们总结并报告了关于它们对细胞信号转导网络和mRNA加工事件影响的最新发现。ABA超敏1（abh1）在拟南芥CBP80基因中存在基因破坏。ABH1的功能缺失突变也会导致拟南芥C24生态型出现早花表型。abh1在野生型植物的CONSTANS位点揭示了非编码顺式天然反义转录本（cis-NATs），且在突变体中cis-NAT表达升高。abh1还揭示了对MADS盒转录因子开花位点C前体mRNA剪接的影响，这可能导致开花时间的调控。此外，分析定点cpb20突变体对cpb20进行互补的新实验提供了证据，表明CBP20的帽结合活性对于观察到的cpb相关表型至关重要。总之参与RNA加工的基因突变体为揭示野生型植物中RNA代谢和信号转导网络调控的新分子机制提供了出色的工具。
