The Arabidopsis MOS4-Associated Complex Promotes MicroRNA Biogenesis and Precursor Messenger RNA Splicing

In Arabidopsis thaliana, the MOS4-ASSOCIATED COMPLEX (MAC) is required for defense and development. The evolutionarily conserved, putative RNA helicase MAC7 is a component of the Arabidopsis MAC, and the human MAC7 homolog, Aquarius, is implicated in pre-mRNA splicing. Here, we show that mac7-1, a p...

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Published in:The Plant cell 2017-10, Vol.29 (10), p.2626-2643
Main Authors: Jia, Tianran, Zhang, Bailong, You, Chenjiang, Zhang, Yong, Zeng, Liping, Li, Shengjun, Johnson, Kaeli C.M., Yu, Bin, Li, Xin, Chen, Xuemei
Format: Article
Language:English
Subjects:
Arabidopsis
Arabidopsis - genetics
Arabidopsis - metabolism
Arabidopsis Proteins - genetics
Arabidopsis Proteins - metabolism
Biosynthesis
DNA helicase
Gene Expression Regulation, Plant
Homology
Immunoprecipitation
Localization
MicroRNAs
MicroRNAs - genetics
MicroRNAs - metabolism
miRNA
Mutants
Precursors
Ribonucleic acid
RNA
RNA helicase
RNA processing
RNA Processing, Post-Transcriptional
RNA Splicing - genetics
RNA, Messenger - genetics
Splicing
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Summary:In Arabidopsis thaliana, the MOS4-ASSOCIATED COMPLEX (MAC) is required for defense and development. The evolutionarily conserved, putative RNA helicase MAC7 is a component of the Arabidopsis MAC, and the human MAC7 homolog, Aquarius, is implicated in pre-mRNA splicing. Here, we show that mac7-1, a partial loss-of-function mutant in MAC7, and two other MAC subunit mutants, mac3a mac3b and prl1 prl2 (pleiotropic regulatory locus), exhibit reduced microRNA (miRNA) levels, indicating that MAC promotes miRNA biogenesis. The mac7-1 mutant shows reduced primary miRNA (pri-miRNA) levels without affecting miRNA gene (MIR) promoter activity or the half-life of pri-miRNA transcripts. As a nuclear protein, MAC7 is not concentrated in dicing bodies, but it affects the localization of HYPONASTIC LEAVES1 (HYL1), a key protein in pri-miRNA processing, to dicing bodies. Immunoprecipitation of HYL1 retrieved 11 known MAC subunits, including MAC7, indicating association between HYL1 and MAC. We propose that MAC7 links MIR transcription to pri-miRNA processing. RNA-seq analysis showed that downregulated genes in MAC subunit mutants are mostly involved in plant defense and stimulus responses, confirming a role of MAC in biotic and abiotic stress responses. We also discovered global intron retention defects in mutants in three subunits of MAC, thus linking MAC function to splicing in Arabidopsis.
ISSN:1040-4651
1532-298X
DOI:10.1105/tpc.17.00370