報告題目：Multiple roles of RBPs: 
mRNA targeting to the ER and beyond  

報告人：田莉  博士

時間：2019年9月19日16:00

地點：北校區六號樓報告廳

報告人簡介：The transport and targeting of glutelin and prolamine mRNAs to distinct subdomains of the cortical endoplasmic reticulum is a model for mRNA localization in plants. This process requires a number of RNA-binding proteins (RBPs) that recognize and bind to mRNA cis-localization (zipcode) elements to form messenger ribonucleoprotein complexes (mRNPs), which then transport the RNAs to their destination sites at the cortical endoplasmic reticulum. Here, we present evidences that two rice (Oryza sativa) RNA- binding proteins, RBP-P and RBP-L, specifically bind to glutelin and prolamine zipcode RNA sequences and are required for proper mRNA localization in rice endosperm cells. Mutations within RBP-P and knockdown of RBP-L caused partial mislocalization of both glutelin and prolamine RNAs. Given that RBP-P and RBP-L directly interact with each other to form protein complexes that exist in both the nucleus and cytoplasm, they may serve as a scaffold to bind glutelin and prolamine RNAs for selective transport. Transcriptome analyses revealed the distinct roles of RBP-P and RBP-L in controlling gene expression of glutelin and prolamine family genes and other genes involved in several essential biological processes as reflected by the broad phenotypic variation ranging from dwarfism, chlorophyll deficiency, late flowering, low spikelet fertility and smaller seeds displayed by the RBP-P mutant lines and/or RBP-L knockdown line. Further studies on the mutual interaction among RBP-L and RBP-P with another RBP, RBP208, revealed that these proteins formed multiple complexes in nucleus and cytoplasm, supporting the diverse roles of the three RBPs in RNA metabolism, including RNA processing in nucleus, RNA translation, localization and decay in cytoplasm, and regulation during abiotic stress. Taken together, our studies demonstrate that RBP-P and RBP-L are essential RBPs that drive prolamine and glutelin mRNA localization in rice endosperm cells and exhibit broad regulatory roles in plant growth and development.