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Description
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Most eucaryotic genes are transcribed as precursor RNAs (pre-mRNAs) and are processed into mature RNAs through processes such as splicing, 5’ capping and 3’ polyadenylation. RNA splicing is the process through which introns are removed and neighboring exons are joined. This process is carried out by the spliceosome, a large RNA-protein complex that is assembled in a temporally and spatially defined fashion. In addition to canonical, constitutive splicing, where the primary transcript is obtained, alternative splicing mechanisms can give rise to multiple transcript isoforms from a single pre-mRNA. Different kinds of alternative splicing exist, defined based on differences with the primary transcript. These include intron retention (IR), by far the most common type of alternative splicing in plants, and exclusion of one or more exons (exon skipping, ES or mutually exclusive exon, MXE) in the processed transcript. In addition, different splicing acceptor sites (A3’SS) or donor sites (A5’SS), which define intron boundaries, can be processed to obtain different mRNAs. Abiotic stresses, including heat and drought, are ever more clearly emerging as factors that induce differential alternative splicing (DAS, Punzo et al., 2020 Biochem Soc Transactions 48, 2117-2126). Interestingly, stress-induced DAS genes only partially overlap with Differentially Expressed Genes (DEGs), indicating that different loci respond to stress in specific fashions. The connection between stress and ABA-mediated responses, and splicing is clearly illustrated by the phenotype of mutants in splicing factors or associated proteins. The group of Prof. Lee isolated and characterized Arabidopsis nuclear STABILIZED1 (STA1), a putative pre-mRNA splicing factor similar to the human U5 snRNP-associated 102-kDaprotein (PRPF6). STA1 is ubiquitously expressed, and encodes a nuclear localized protein (Lee et al.,2006 Plant Cell 18, 1736-1749; Dou etal.,2013 Nucleic Acids Res 41: 8489-8502). STA1 was demonstrated to be involved in pre-mRNA splicing and, surprisingly, in RNA stability, microRNA processing, and RNA-directed DNA methylation (Lee et al.,2006; Ben Chaabane et al., 2013 Nucleic Acids Res 41: 1984-1997; Dou et al., 2013). Proponents of this project defined the splicing factor DRT111 (Xin et al., 2017 Proc Natl Acad Sci USA 114, 7018-7027; Punzo et al., 2020 Plant Phys 183, 793-807), associated to U2 SnRNP, as a key mediator of stress and ABA-dependent responses. In seeds, DRT111 controls ABA seed germination sensitivity through splicing of specific transcripts such as ABA INSENSITIVE 3 (ABI3). The project has several goals: -Defining the molecular basis of the stomatal phenotype in drt111 mutants. -Exploring the role of DRT111 and STA1 in responses to combined heat and drought stress. -Identifying additional splicing factors involved in abiotic stress responses. -Establishing a collaboration between the IBBR group and the group of Prof. Byeong-Ha Lee. |
