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AGO-unbound cytosolic pool of mature miRNAs in plant cells reveals a novel regulatory step at AGO1 loading.

ABSTRACT: RNA interference (RNAi) is mediated by small, 20-24-nt-long, non-coding regulatory (s)RNAs such as micro (mi) and small interfering (si) RNAs via the action of ARGONAUTE (AGO) proteins. High-throughput sequencing of size-separated sRNA pools of plant crude extracts revealed that the majority of the canonical miRNAs were associated with high molecular weight RNA-induced silencing complexes co-migrating with AGO1 (HMW RISC). In contrast, the majority of 24-nt-long siRNAs were found in association with low molecular weight complexes co-migrating with AGO4 (LMW RISC). Intriguingly, we identified a large set of cytoplasmic sRNAs, including mature miRNA sequences, in the low molecular size range corresponding to protein-unbound sRNAs. By comparing the RISC-loaded and protein-unbound pools of miRNAs, we identified miRNAs with highly different loading efficiencies. Expression of selected miRNAs in transient and transgenic systems validated their altered loading abilities implying that this process is controlled by information associated with the diverse miRNA precursors. We also showed that the availability of AGO proteins is a limiting factor determining the loading efficiency of miRNAs. Our data reveal the existence of a regulatory checkpoint determining the RISC-loading efficiencies of various miRNAs by sorting only a subset of the produced miRNAs into the biologically active RISCs.

SUBMITTER: Dalmadi A

PROVIDER: S-EPMC6765109 | biostudies-literature | 2019 Oct

REPOSITORIES: biostudies-literature

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AGO-unbound cytosolic pool of mature miRNAs in plant cells reveals a novel regulatory step at AGO1 loading.

Dalmadi Ágnes Á Gyula Péter P Bálint Jeannette J Szittya György G Havelda Zoltán Z

Nucleic acids research 20191001 18

RNA interference (RNAi) is mediated by small, 20-24-nt-long, non-coding regulatory (s)RNAs such as micro (mi) and small interfering (si) RNAs via the action of ARGONAUTE (AGO) proteins. High-throughput sequencing of size-separated sRNA pools of plant crude extracts revealed that the majority of the canonical miRNAs were associated with high molecular weight RNA-induced silencing complexes co-migrating with AGO1 (HMW RISC). In contrast, the majority of 24-nt-long siRNAs were found in association ...[more]

PMID: 31392979

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Project description:MicroRNAs (miRNAs) are a class of small RNAs which typically function by guiding cleavage of target messenger RNAs. They have been shown to play major roles in a variety of plant processes including development, and responses to pathogens and environmental stresses. To identify new miRNAs and regulation in Arabidopsis thaliana, 27 small RNA libraries were constructed and sequenced from various tissues, stresses and small RNA biogenesis mutants, resulting in 95 million genome-matched sequences. The use of rdr2 to enrich the miRNA population greatly enhanced this analysis and led to the discovery of 44 new miRNAs arising from both known and new precursors. Parallel Analysis of RNA Ends (PARE) data provide evidence that the majority guide target cleavage. The inclusion of novel stress/tissue conditions, such as submergence-stressed flowers, enabled identification of new stress regulation of both miRNAs and their targets, all of which were validated in wild type plants. By combining small RNA expression analysis with ARGONAUTE (AGO) immunoprecipitation data and global target cleavage data from PARE, a much more complete picture of Arabidopsis miRNAs was obtained. This combinatorial approach led to the discovery of AGO loading and target cleavage biases, which gave important insights into tissue-specific expression patterns, pathogen responses and the role of sequence variation among closely related miRNA family members. Examination of various tissues, stresses and small RNA biogenesis mutants in Arabidopsis by high-throughput sequencing for small RNA profiling. We have used AGO-IP and PARE data from the published data, which were downloaded from NCBI GEO with the following accession number. AGO-IP from GSM253622, GSM707682, GSM642335, GSM642336, GSM512703, GSM512702, GSM707683, GSM707684, GSM707685, GSM149080, GSM253623, GSM304283, GSM642337, GSM642338, GSM253624, GSM415788, GSM707686, GSM707687, GSM707688, GSM707689, GSM415787, GSM149081, GSM253625, GSM415789, GSM415790, GSM304285, GSM415791, GSM415792 PARE sequencing data from xrn4 flowers were obtained from Gene Expression Omnibus with accession number GSM280227.

Dataset Information

AGO-unbound cytosolic pool of mature miRNAs in plant cells reveals a novel regulatory step at AGO1 loading.

Publications

AGO-unbound cytosolic pool of mature miRNAs in plant cells reveals a novel regulatory step at AGO1 loading.

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