Dataset Information

HOS1 regulates Argonaute1 by promoting transcription of the microRNA gene MIR168b in Arabidopsis.

ABSTRACT: Proper accumulation and function of miRNAs is essential for plant growth and development. While core components of the miRNA biogenesis pathway and miRNA-induced silencing complex have been well characterized, cellular regulators of miRNAs remain to be fully explored. Here we report that High Expression Of Osmotically Responsive Genes1 (HOS1) is a regulator of an important miRNA, mi168a/b, that targets the Argonaute1 (AGO1) gene in Arabidopsis. HOS1 functions as an ubiquitin E3 ligase to regulate plant cold-stress responses, associates with the nuclear pores to regulate mRNA export, and regulates the circadian clock and flowering time by binding to chromatin of the flowering regulator gene Flowering Locus C (FLC). In a genetic screen for enhancers of sic-1, we isolated a loss-of-function Arabidopsis mutant of HOS1 that is defective in miRNA biogenesis. Like other hos1 mutant alleles, the hos1-7 mutant flowered early and was smaller in stature than the wild-type. Dysfunction in HOS1 reduced the abundance of miR168a/b but not of other miRNAs. In hos1 mutants, pri-MIR168b and pre-MIR168b levels were decreased, and RNA polymerase II occupancy was reduced at the promoter of MIR168b but not that of MIR168a. Chromatin immunoprecipitation assays revealed that HOS1 protein is enriched at the chromatin of the MIR168b promoter. The reduced miR168a/b level in hos1 mutants results in an increase in the mRNA and protein levels of its target gene, AGO1. Our results reveal that HOS1 regulates miR168a/b and AGO1 levels in Arabidopsis by maintaining proper transcription of MIR168b.

SUBMITTER: Wang B

PROVIDER: S-EPMC4355216 | biostudies-literature | 2015 Mar

REPOSITORIES: biostudies-literature

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HOS1 regulates Argonaute1 by promoting transcription of the microRNA gene MIR168b in Arabidopsis.

Wang Bangshing B Duan Cheng-Guo CG Wang Xingang X Hou Yueh-Ju YJ Yan Jun J Gao Caiqiu C Kim Jin-Hong JH Zhang Huiming H Zhu Jian-Kang JK

The Plant journal : for cell and molecular biology 20150219 6

Proper accumulation and function of miRNAs is essential for plant growth and development. While core components of the miRNA biogenesis pathway and miRNA-induced silencing complex have been well characterized, cellular regulators of miRNAs remain to be fully explored. Here we report that High Expression Of Osmotically Responsive Genes1 (HOS1) is a regulator of an important miRNA, mi168a/b, that targets the Argonaute1 (AGO1) gene in Arabidopsis. HOS1 functions as an ubiquitin E3 ligase to regulat ...[more]

PMID: 25619693

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Project description:Flowering in the appropriate season is critical for successful reproduction in angiosperms. The orchid species, Dendrobium nobile, requires vernalization to achieve flowering in the spring, but the underlying regulatory network has not been identified to date. The MADS-box transcription factor DnAGL19 was previously identified in a study of low-temperature treated D. nobile buds and was suggested to regulate vernalization-induced flowering. In this study, phylogenetic analysis of DnAGL9 and the MADS-box containing proteins showed that DnAGL19 is phylogenetically closely related to the SOC1-like protein from orchid Dendrobium Chao Parya Smile, DOSOC1. The orchid clade closed to but is not included into the SOC1-1/TM3 clades associated with either eudicots or monocots, suggesting that DnAGL19 is an SOC1-1/TM3-like ortholog. DnAGL19 was found to be highly expressed in pseudobulbs, leaves, roots, and axillary buds but rarely in flowers, and to be substantially upregulated in axillary buds by prolonged low-temperature treatments. Overexpression of DnAGL19 in Arabidopsis thaliana resulted in a small but significantly reduced time to bolting, suggesting that flowering time was slightly accelerated under normal growth conditions. Consistent with this, the A. thaliana APETELA1 (AP1) gene was expressed at an earlier stage in transgenic lines than in wild type plants, while the FLOWERING LOCUS T (FT) gene was suppressed, suggesting that altered regulations on these transcription factors caused the weak promotion of flowering. HIGH EXPRESSION OF OSMOTICALLY RESPONSIVE GENE 1 (HOS1) was slightly activated under the same conditions, suggesting that the HOS1-FT module may be involved in the DnAGL19-related network. Under vernalization conditions, FT expression was significantly upregulated, whereas HOS1 expression in the transgenic A. thaliana has a level similar to that in wild type. Taken together, these results suggest that DnAGL19 controls the action of the HOS1-FT module depending on temperature cues, which could contribute to regulation of D. nobile flowering time. These data provide insights into how flowering is fine-tuned in D. nobile to acclimate the plant to seasonal changes in temperature.

Dataset Information

HOS1 regulates Argonaute1 by promoting transcription of the microRNA gene MIR168b in Arabidopsis.

Publications

HOS1 regulates Argonaute1 by promoting transcription of the microRNA gene MIR168b in Arabidopsis.

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