Seong Wook Yang
Section for Plant Biochemistry
Thorvaldsensvej 40, 1871 Frederiksberg C
Research: MicroRNAs (miRNAs) are a class of regulatory small RNAs that control various biological roles in degradation and translation of target messenger RNAs in plants, animals and single cell eukaryotes. Since the important roles of miRNAs in many aspects of cellular events, extensive researches have been performed to unveil the precise mechanism of miRNA biogenesis and miRNA functions and evolutionary diversities.
The first project aims to define novel mechanism of COP1 E3 ligase in miRNA biogenesis. Constitutive Photomorphogenic 1 (COP1) is a RING-finger E3 ligase that plays a central role in photomorphogenesis by destabilizing many light-regulated transcription factors and photoreceptors. Here, we show an unrevealed function of COP1 E3 ligase that controls one of the most important gene regulatory layers in eukaryotes, miRNA biogenesis. In cop1 mutants, the level of miRNAs was dramatically reduced, due to the diminution of HYPONASTIC LEAVES 1 (HYL1), a crucial RNA binding protein for precise miRNA processing. HYL1 was destabilized by an unidentified protease, tentatively called protease X, which specifically cleaved off the N-terminal region of HYL1 to neutralize its function. Our results further showed that the cytoplasmic partitioning of COP1 under light is essential to protect HYL1 against the protease X. Taken together, we suggest a novel regulatory network amongst HYL1, protease X, COP1, and light signaling that is indispensable for miRNA biogenesis in Arabidopsis thaliana.
Our second project involves small plant RNA biology in which we aim to uncover the upstream regulation of miRNA (microRNA) biogenesis and participating components in plants. For instance, an integration of post-transcriptional modification and/or epigenic regulation into miRNA biogenesis is of high interest. We are currently investigating STABILIZED1 (STA1), a regulator of pre-mRNA stability and splicing, and whether it is crucial for the biogenesis of miRNAs. To answer this interesting question in plant miRNAs biology, we are applying various approaches (molecular, biochemical, genetic, bioinformatical) as well as silver nanocluster technology, in the STA1 study. For these projects, extensive domestic and international collaborations are on-going.