title: The Arabidopsis double-stranded RNA-binding protein HYL1 plays a role in microRNA-mediated gene regulation.
abstract: The Arabidopsis HYL1 gene encodes a nuclear double-stranded RNA-binding protein. A knockout mutation of the hyl1 gene is recessive and pleiotropic, causing developmental abnormalities, increasing sensitivity to abscisic acid, and reducing sensitivity to auxin and cytokinin. We report that levels of several microRNAs (miRNAs; miR159, -167, and -171) are reduced in homozygous mutant plants, and levels of two of three tested target mRNAs are elevated. Conversely, the miRNA levels are elevated in plants expressing a HYL1 cDNA from a strong promoter, and the corresponding target RNAs are reduced. These changes result from alterations in the stability of the target RNAs. However, double-stranded RNA-induced posttranscriptional gene silencing is unaffected by the hyl1 mutation. One-third to one-half of the cellular HYL1 protein is in a macromolecular complex, and a GFP-HYL1 fusion protein is found predominantly in the nucleus, although it is observed in both nucleus and cytoplasm in some cells. Within nuclei, HYL1 is associated with subnuclear bodies and ring-like structures. These observations provide evidence that the HYL1 protein is part of a nuclear macromolecular complex that is involved in miRNA-mediated gene regulation. Because hyl1 mutants show marked abnormalities in hormone responses, these results further suggest that miRNA-mediated changes in mRNA stability play a vital role in plant hormone signaling.
authors.affiliation: Biology Department and Huck Institutes of Life Sciences, Pennsylvania State University, University Park, PA 16802, USA.
authors.forename: Meng-Hsuan
authors.initials: MH
authors.lastname: Han
authors.forename: Saiprasad
authors.initials: S
authors.lastname: Goud
authors.forename: Liang
authors.initials: L
authors.lastname: Song
authors.forename: Nina
authors.initials: N
authors.lastname: Fedoroff
mesh_terms: D017360:Arabidopsis / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000502:physiology*; D001483:Base Sequence; D017931:DNA Primers; D018076:DNA, Complementary; D018506:Gene Expression Regulation, Plant / Q000502:physiology*; D020868:Gene Silencing; D035683:MicroRNAs / Q000502:physiology*; D018613:Microscopy, Confocal; D009154:Mutation; D011401:Promoter Regions, Genetic; D016601:RNA-Binding Proteins / Q000235:genetics / Q000502:physiology*; D013347:Subcellular Fractions / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D017931:DNA Primers; D018076:DNA, Complementary; C420966:HYL1 protein, Arabidopsis; C577006:MIRN159 microRNA, Arabidopsis; D035683:MicroRNAs; D016601:RNA-Binding Proteins