Abstract
It has long been assumed that the wide reprogramming of gene expression that modulates plant response to unfavorable environmental conditions is mainly controlled at the transcriptional level. A growing body of evidence, however, indicates that posttranscriptional regulatory mechanisms also play a relevant role in this control. Thus, the LSMs, a family of proteins involved in mRNA metabolism highly conserved in eukaryotes, have emerged as prominent regulators of plant tolerance to abiotic stress. Arabidopsis contains two main LSM ring-shaped heteroheptameric complexes, LSM1-7 and LSM2-8, with different subcellular localization and function. The LSM1-7 ring is part of the cytoplasmic decapping complex that regulates mRNA stability. On the other hand, the LSM2-8 complex accumulates in the nucleus to ensure appropriate levels of U6 snRNA and, therefore, correct pre-mRNA splicing. Recent studies reported unexpected results that led to a fundamental change in the assumed consideration that LSM complexes are mere components of the mRNA decapping and splicing cellular machineries. Indeed, these data have demonstrated that LSM1-7 and LSM2-8 rings operate in Arabidopsis by selecting specific RNA targets, depending on the environmental conditions. This specificity allows them to actively imposing particular gene expression patterns that fine-tune plant responses to abiotic stresses. In this review, we will summarize current and past knowledge on the role of LSM rings in modulating plant physiology, with special focus on their function in abiotic stress responses.
Highlights
Due to their sessile nature, plants have evolved sophisticated adaptive mechanisms to correctly decipher external signals and deploy the corresponding adequate responses
Transcriptional control has attracted most of the attention so far and numerous transcription factors and cis-acting elements functioning in plant adaptation to abiotic stresses have been described (Khan et al, 2018)
In order to situate the LSM complexes into their own context, we will provide a general view about the RNA metabolic pathways in which they participate, discussing the implication of their corresponding intermediates in plant response to abiotic stresses
Summary
Due to their sessile nature, plants have evolved sophisticated adaptive mechanisms to correctly decipher external signals and deploy the corresponding adequate responses. Recent studies evidenced that both LSM rings actively participate in regulating plant responses to abiotic stress conditions (Perea-Resa et al, 2016; Carrasco-López et al, 2017), which constitutes an unanticipated novel function for the eukaryotic LSMs. In this review, we will summarize the current state of the art knowledge on the activity of LSM proteins, paying special attention to their role in modulating abiotic stress responses. In order to situate the LSM complexes into their own context, we will provide a general view about the RNA metabolic pathways in which they participate (i.e., the exonucleolytic mRNA decay and the pre-mRNA splicing), discussing the implication of their corresponding intermediates in plant response to abiotic stresses. We will propose and comment on future research directions to better understand the role of LSM complexes as master integrators of plant adaptation to their ever-changing environment
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