Salt Stress and CTD PHOSPHATASE-LIKE 4 Mediate the Switch Between Production of Small Nuclear RNAs and mRNAs.

Phosphorylation of the RNA polymerase II (Pol II) C-terminal domain (CTD) regulates transcription of protein-coding mRNAs and non-coding RNAs (ncRNAs). CTD function in transcription of protein-coding RNAs has been studied extensively, but its role in plant ncRNA transcription remains obscure. Here, using Arabidopsis thaliana CTD PHOSPHATASE-LIKE 4 knock-down lines (CPL4RNAi), we showed that CPL4 functions in genome-wide, conditional production of 3'-extensions of small nuclear RNAs (snRNAs) and biogenesis of novel transcripts from protein-coding genes downstream of the snRNAs (snRNA-Downstream Protein-coding Genes, snR-DPGs). Production of snR-DPGs required the Pol II snRNA promoter (PIIsnR), and CPL4RNAi plants showed increased read-through of the snRNA 3'-end processing signal, leading to continuation of transcription downstream of the snRNA gene. We also discovered an unstable, intermediate-length RNA from the SMALL SCP1-LIKE PHOSPHATASE 14 locus (imRNASSP14), whose expression originated from the 5' region of a protein-coding gene. Expression of the imRNASSP14 was driven by a PIIsnR and was conditionally 3'-extended to produce an mRNA. In wild type, salt stress induced the snRNA-to-snR-DPG switch, which was associated with alterations of Pol II-CTD phosphorylation at the target loci. The snR-DPG transcripts occur widely in plants, suggesting that the transcriptional snRNA-to-snR-DPG switch may be a ubiquitous mechanism to regulate plant gene expression in response to environmental stresses. © 2017 American Society of Plant Biologists. All rights reserved.

Citation

Akihito Fukudome, Di Sun, Xiuren Zhang, Hisashi Koiwa. Salt Stress and CTD PHOSPHATASE-LIKE 4 Mediate the Switch Between Production of Small Nuclear RNAs and mRNAs. The Plant cell. 2017 Nov 01

PMID: 29093215

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