SplicEcomplex · Deciphering the structure and dynamics of the early spliceosome assembly
Horizon 2020 — Marie Skłodowska-Curie Actions
- Duration
- 2018-04-01 → 2020-05-30
- EU contribution
- €171,461
- Participants
- 1
- Scheme
- MSCA-IF-EF-ST
Lines connect the coordinator with its partners.
Results in brief
Deciphering the structure and dynamics of the early spliceosome assembly
The central dogma in molecular biology, postulated by Francis Crick in 1958, describes the sequential and unidirectional flux of information from DNA to proteins. Presumed at the beginning as being a mere messenger, the intermediate RNA was shown later to be a key factor in protein synthesis variability and regulation. Currently, our knowledge of mRNA metabolism is more expanded; precursor (pre-) mRNA undergoes numerous distinct co/post-transcriptional modifications in eukaryotes, in which the mRNA, once it has been correctly processed, has to travel from the nucleus to the cytoplasm. Among the modifications that occur in the eukaryotic nucleus, pre-mRNA splicing appears as one of the most intriguing and complex aspect of RNA processing. The pre-mRNA is edited for removal of noncoding sequences (introns) and ligation of the coding sequences (exons), giving rise to an RNA sequence that encodes the corresponding protein sequence. In addition, many pre-mRNAs can be spliced in different ways, generating a great variability of processed mRNAs (alternative splicing); a prevalent process in eukaryotes that expands their complexity by increasing the number of proteins that can be encoded in a single gene. Disruption of normal splicing patterns is linked to several human diseases, ranging from metabolic syndromes, muscular dystrophies, neurodegenerative disorders, cardiovascular diseases and tumor development. Thus, a better understanding of the molecular mechanisms that perform and regulate splicing process is key to find new ways to prevent these diseases and develop better diagnostics and more effective therapeutic approaches (EU Horizon 2020 Strategy in Health). Splicing of pre-mRNA is performed by a large ribonucleoprotein (RNP) complex, the spliceosome, and consists on a precise and coordinated process in which many different components undergo a very dynamic assembly / remodelling / dissociation cycle in which the pre-mRNA recruits the different snRNPs at conserved intron sequences, at different times and in a precise sequence in order to correctly perform the two catalytic steps of splicing. A critical early aspect that directs splicing is the correct spatial disposition of the 5’ and 3’ splice sites in the intron sequence prior to splicing, which is defined as an early step in the cycle with the assembly of spliceosome components in 5' (U1snRNP) and in 3' (SF1-U2AF heterodimer) and their physical connection through bridge proteins (complex E). Despite of previous structural studies on isolated E complex components and all the exciting and novel cryo-EM structures of several spliceosome catalytic steps that have been obtained in the past few years, there is still lack of information on the whole E complex structural arrangement. Understanding molecular details of E complex and its assembly is essential to reveal mechanisms underlying the regulation of alternative splicing, where in most cases regulatory RBPs, modulate spliceosome assembly at these early steps. Thus, the main goal of this proposal is to obtain high-resolution information on the structure and dynamics of the cross-intron arrangement spliceosome in the E complex stage.
Data: CORDIS, © European Union
Project objective
Pre-mRNA splicing is the major step of RNA edition in eukaryotes. It consists on a catalytic process that removes non-coding sequences (introns) and ligates the coding ones (exons), creating the RNA sequence that codifies the final protein. This process is highly regulated and gives rise to a great variability of proteins, expanding the versatility encoded in the human genome. In the early stage of splicing, RNA 5’ and 3’ splice sites must be brought within proximity to correctly assemble the active spliceosome (cross-intron arrangement) and perform the excision and ligation reactions. Many elements participate in the assembly of the early spliceosomal complex (E complex) through different protein-protein, protein-RNA and RNA-RNA interactions, leading to the formation of a very dynamic association. Several factors regulate the correct assembly, defining the RNA sequences that should be excised and controlling the production of alternative spliced transcripts. The full comprehension of the E complex formation will allow a deeper understanding of the splicing mechanism at molecular level which is essential in human health as aberrant processes are the basis of many diseases. Currently, the structures of cross-intron arrangement factors in the early spliceosome are not known and there is a lack of structural data of the complete E complex. In this project, I propose a novel, integrative and multidisciplinary study of the structure and regulation of the early spliceosomal assembly. I will analyse the different cross-intron interactions, elucidate the high-resolution structure of the whole association and study the effects of protein post-translational modifications in the structure and complex assembly. This will lead to the discovery of new structural insights for the first step of the spliceosome formation having an impact on our understanding of the fundamental mechanism of splicing regulation and forming the basis for future innovative therapeutic approaches.
Original text from CORDIS.
Participants
- HELMHOLTZ ZENTRUM MUENCHEN DEUTSCHES FORSCHUNGSZENTRUM FUER GESUNDHEIT UND UMWELT GMBH · NeuherbergCoordinatorGermany
Links
Data: CORDIS, © European Union