Diana Baralle

Research Focus

Diana Baralle is a Consultant in Clinical Genetics at the Princes Anne Hospital, Southampton and Honorary Senior Lecturer in Clincial and Molecular Genetics at the University of Southampton. Her particular interest is the role of splicing mutations in disease, phenotype penetrance and clinical diagnosis. Her group bridges clinical diagnostics and splicing mechanisms, exploiting human pathology to investigate new modulatory elements of splicing, previously unreported RNA-protein interactions and develop new systems to assess the effect on splicing of sequence variants found during molecular diagnostic testing.

We have studied several mutations through the NF 1 gene that affected splicing through non-canonical mechanisms. In a specfic 5’ splice variant whose effect was uncertain we found a series of trans acting factors interfering with 5’ splice site recognition, making the 5’ss weaker than would appear by simple inspection of the sequence and in silico analysis. This was a clear example of why similar nucleotide substitutions can either be neutral or disruptive depending on genomic context and specific protein binding signatures. A second example of 5’ss definition altered by a different type of interaction (U1 independent pathway) is currently under study (NF1 exon 31).

We have also analysed exonic mutations for their effect on splicing finding interesting subtle variations of exon definition even with synonymous changes. The impact of this type of variation on disease is harder to evaluate but it may provide an explanation for variable phenotypic penetrance of the same mutation in different individuals.

We have also highlighted the importance of analysing deep intronic mutations for disease causing effects as in the case of NF1 intron 30 and undertook detailed mechanistic studies of pseudoexon creation focusing on the internal exonic elements that determine whether a newly created splice site will define a pseudo exon inclusion event or not. In this particular example we have found that PTB binding plays a significant role in marking the sequences as exons and the presence of binding sites prevents pseudoexoon inclusion after a natural mutation creates a new splice site while disruption of the binding site favors it.

Publications

1. Bianchi F, Raponi M, Piva F, Viel A, Bearzi I, Galizia E, Bracci R, Belvederesi L, Loretelli C, Brugiati C, Corradini F, Baralle D, Cellerino R. (2010) An intronic mutation in MLH1 associated with familial colon and breast cancer. Fam Cancer. 2010 Aug 18.
2. Buratti E, Baralle D. (2010) Novel roles of U1 snRNP in alternative splicing regulation. RNA Biol. 2010 Jul 23;7(4).
3. Blyth M, Raponi M, Treacy R, Raymond FL, Yates JR, Baralle D. (2010) Expanding the tuberous sclerosis phenotype: mild disease caused by a TSC1 splicing mutation. J Neurol Neurosurg Psychiatry. 2010 Mar;81(3):350-2.
4. Tosi M, Stamm S, Baralle D. (2010). RNA splicing meets genetic testing: detection and interpretation of splicing defects in genetic diseases. Eur J Hum Genet. 2010 Feb 24.
5. Baralle D. (2010) Novel aspects of alternative splicing. FEBS J. 2010 Jan 15.
6. Raponi M, Baralle D. (2010). Alternative splicing: good and bad effects of translationally silent substitutions. FEBS J. 2010 Jan 15.
7. Baralle D, Lucassen A, Buratti E.(2009). Missed threads. The impact of pre-mRNA splicing defects on clinical practice. EMBO Rep. 2009 Aug;10(8):810-6.
8. Edwards E, Yearwood C, Sillibourne, Baralle D, Eccles D. (2009). Identification of a de novo BRCA1 mutation in a woman with early onset bilateral breast cancer. Fam Cancer. 2009;8(4):479-82.
9. Raponi, M., Buratti, E., Dassie, E., Upadhyaya, M., Baralle, D. (2009). Low U1 snRNP dependence at the NF1 exon 29 donor splice site. FEBS Journal 276(7), 2060-73.
10. Raponi, M., Buratti, E., Llorian, M., Stuani, C., Smith, C.W., Baralle, D. (2008). Polypyrimidine tract binding protein regulates alternative splicing of an aberrant pseudoexon in NF1. FEBS Journal 275 (24), 6101-6108. (doi: 10.1111 /j.1742-4658.2008.06734.x)

Key lab techniques: Minigene assays, RNAi, eukaryotic cell culture, sequencing, snp analysis.

Lab contact: Dr Michela Raponi, at the Human Genetics Division address.