UORFs: Important Cis-Regulatory Elements in Plants.

Ting Zhang,Anqi Wu,Yaping Yue,Yu Zhao

doi:10.3390/ijms21176238

Ting Zhang, Anqi Wu + Show 2 more

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https://doi.org/10.3390/ijms21176238

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Abstract

Gene expression is regulated at many levels, including mRNA transcription, translation, and post-translational modification. Compared with transcriptional regulation, mRNA translational control is a more critical step in gene expression and allows for more rapid changes of encoded protein concentrations in cells. Translation is highly regulated by complex interactions between cis-acting elements and trans-acting factors. Initiation is not only the first phase of translation, but also the core of translational regulation, because it limits the rate of protein synthesis. As potent cis-regulatory elements in eukaryotic mRNAs, upstream open reading frames (uORFs) generally inhibit the translation initiation of downstream major ORFs (mORFs) through ribosome stalling. During the past few years, with the development of RNA-seq and ribosome profiling, functional uORFs have been identified and characterized in many organisms. Here, we review uORF identification, uORF classification, and uORF-mediated translation initiation. More importantly, we summarize the translational regulation of uORFs in plant metabolic pathways, morphogenesis, disease resistance, and nutrient absorption, which open up an avenue for precisely modulating the plant growth and development, as well as environmental adaption. Additionally, we also discuss prospective applications of uORFs in plant breeding.

Highlights

Plant growth and development is a precise and highly regulated process, which is controlled at multiple steps, including mRNA transcription, splicing, stability, and translation
A comparative study that explored AtPAO orthologous in 24 plant genomes indicated that PAO transcripts have one or more upstream open reading frames (uORFs). These findings demonstrate that the translational regulation of PA-related genes mediated by uORFs might be conserved in plants
A conserved uORF (CPuORF30) has been identified in the 5 -UTR of AtXIPOTL1 mRNA, which results in the translational repression of major ORFs (mORFs) just when PCho is at a physiological concentration, without significantly altering its mRNA levels [73]

Summary

Introduction

Plant growth and development is a precise and highly regulated process, which is controlled at multiple steps, including mRNA transcription, splicing, stability, and translation. It has been predicted and reported that there are 10,104 uORFs in Arabidopsis [31], 21,915 uORFs in maize [32], 1329 uORFs in tomatoes [33], 10,226 in yeast [34], and 35,735 uORFs in Drosophila melanogaster [35] and that uORF-containing mRNAs in human, mouse, and zebrafish, respectively, account for about 49%, 44%, and 50% of their total mRNAs [36,37,38] These findings suggest that uORFs are widespread cis-elements in eukaryotic protein-coding genes (Table 1), and these uORF identifications will further advance our understanding of translational control mechanisms in eukaryotes

Classification of uORFs

Regulatory Roles of uORFs in Plant Morphogenesis

Regulatory Functions of uORFs in Disease Resistance and Nutrient Absorption

Prospect of uORFs in Plant Breeding

Findings

Conclusions