ABSTRACT
Hyponastic Leaves 1 (HYL1) [also known as Double-stranded RNA-Binding protein 1 (DRB1)] is a double-stranded RNA-binding protein involved in microRNA (miRNA) processing in plants. It is a core component of the Microprocessor complex and enhances the efficiency and precision of miRNA processing by the Dicer-Like 1 protein. In this work, we report a novel function of the HYL1 protein in the transcription of miRNA (MIR) genes. HYL1 colocalizes with RNA polymerase II and affects its distribution along MIR genes. Moreover, proteomic experiments revealed that the HYL1 protein interacts with many transcription factors. Finally, we show that the action of HYL1 is not limited to MIR genes and impacts the expression of many other genes, a majority of which are involved in plastid organization. These discoveries indicate HYL1 as an additional player in gene regulation at the transcriptional level, independent of its role in miRNA biogenesis.
Subject(s)
Arabidopsis Proteins , Arabidopsis , MicroRNAs , Arabidopsis Proteins/genetics , Arabidopsis Proteins/metabolism , Arabidopsis/genetics , Arabidopsis/metabolism , RNA Polymerase II/genetics , RNA Polymerase II/metabolism , Proteomics , RNA-Binding Proteins/genetics , RNA-Binding Proteins/metabolism , MicroRNAs/genetics , MicroRNAs/metabolism , Plant Leaves/genetics , Plant Leaves/metabolism , Gene Expression Regulation, PlantABSTRACT
The SERRATE (SE) protein is involved in the processing of RNA polymerase II (RNAPII) transcripts. It is associated with different complexes engaged in different aspects of plant RNA metabolism, including assemblies involved in transcription, splicing, polyadenylation, miRNA biogenesis, and RNA degradation. SE stability and interactome properties can be influenced by phosphorylation. SE exhibits an intriguing liquid-liquid phase separation property that may be important in the assembly of different RNA-processing bodies. Therefore, we propose that SE seems to participate in the coordination of different RNA-processing steps and can direct the fate of transcripts, targeting them for processing or degradation when they cannot be properly processed or are synthesized in excess.
Subject(s)
Arabidopsis Proteins , Arabidopsis , MicroRNAs , Arabidopsis Proteins/metabolism , Arabidopsis/genetics , Arabidopsis/metabolism , Calcium-Binding Proteins/genetics , Calcium-Binding Proteins/metabolism , RNA Processing, Post-Transcriptional/genetics , Serrate-Jagged Proteins/genetics , Serrate-Jagged Proteins/metabolism , RNA/metabolism , MicroRNAs/genetics , RNA, Plant/genetics , RNA, Plant/metabolism , Gene Expression Regulation, PlantABSTRACT
MicroRNAs are small RNAs, 20-22 nt long, the main role of which is to downregulate gene expression at the level of mRNAs. MiRNAs are fundamental regulators of plant growth and development in response to internal signals as well as in response to abiotic and biotic factors. Therefore, the deficiency or excess of individual miRNAs is detrimental to particular aspects of a plant's life. In consequence, the miRNA levels must be appropriately adjusted. To obtain proper expression of each miRNA, their biogenesis is controlled at multiple regulatory layers. Here, we addressed processes discovered to influence miRNA steady-state levels, such as MIR transcription, co-transcriptional pri-miRNA processing (including splicing, polyadenylation, microprocessor assembly and activity) and miRNA-encoded peptides synthesis. MiRNA stability, RISC formation and miRNA export out of the nucleus and out of the plant cell also define the levels of miRNAs in various plant tissues. Moreover, we show the evolutionary conservation of miRNA biogenesis core proteins across the plant kingdom.
