Most of the human protein-encoding genes undergo alternative pre-mRNA processing, generating multiple gene products from a relatively low number of genes. Alternative splicing plays an important role in gene expression; therefore missplicing events are responsible for an increasing number of diseases.

Tra2-beta1 is one of the proteins that regulate splice site selection by recruiting splicing factors to exon sequences. It is the homologue of the Drosophila Transformer-2 protein that is a regulator of sex determination in flies. hTra2-beta1 is an SR-like splicing factor containing an RNA Recognition Motif (RRM) that is responsible for the RNA:Tra2-beta1 interaction and contains an evolutionary conserved Protein Phosphatase-1 (PP1) binding site. The RRM is located between two RS domains, the RS domains are responsible for protein-protein interactions and seem to be regulated by phosphorylation / dephosphorylation of the domains. Tra2-beta2 is involved in the regulation of many genes (Tra2, SMN, CLB and Dystrophin) as well as in genes important for neuronal and testis differentiation (APP, Tau, FGF-2R). It promotes, in a concentration–dependent manner, the inclusion of a large number of alternative exons that contain its recognition sequence. Tra2-beta1 preferentially binds to GA-rich sequences that are found more frequently in exons than in introns. Recently, based on structue and affinity measurments, the optimal recognition sequence for Tra2-beta1 binding was described, and found that 5`-NGAAN-3`is the optimal and minimal binding partner for hTra2-beta1 RRM. (Cléry, A., Benderska N., Sandrine Jayne, S., Dominguez, C., Stamm, S. Allain, F.H-T (2011), Molecular basis of Purine-rich recognition by the SR-like protein Tra2-beta1, Nat. Struct. Mol. Biol., 18, 443–450).

Spinal muscular atrophy (SMA) is caused by the loss of the survival of motoneuron 1 gene (SMN1). In humans there is an almost identical copy of SMN1, named SMN2. A crucial C to T transition in exon 7 of SMN2 gene results in a transcript where exon 7 is predominantly skipped, leading to a truncated protein and inability to compensate for the absence of the SMN1 gene. An increase in the activity of tra2-beta1 promotes exon 7 usage and could therefore be a therapeutic principle for SMA.

The main focus of my project is to understand the regulation of alternative splicing by hTra2-beta1. I am identifying genome wide hTra2-beta1 dependent exons by performing microarray analysis. I study the interaction between PP1 and Tra2-beta1 via its RRM. PP1 binding is a novel evolutionary conserved function of the RRM. Since hTra2-beta1 promotes exon 7 inclusion in a concentration-dependent manner, a better understanding of the mechanism of hTra2-beta1 regulation has potentially a high importance in SMA therapy.

Publications:

Zhang, Z., Kelemen, O., van Santen, M. A., Yelton, S. M., Wendlandt, A. E., Sviripa, V. M., Bollen, M., Beullens, M., Urlaub, H., Lührmann, R., Watt D.S., Stamm S. (2011). Synthesis and Characterization of Pseudocantharidins, Novel Compounds That Promote Inclusion of the SMN2 Exon 7. J Biol Chem. 286, 10126-10136.

Szvetnik, A., Bihari Z., Kelemen O., Kiss I. (2010). Genetic manipulation tools for Dietzia spp., J Appl Microbiol. 109, 1845-52

Bartos, P., Balázs, M., Kiss, I., Bihari, Z., Kelemen, O., Mécs, I.: Toxic effect of MTBE on growth of soil isolate Pseudomonas veronii T1/1 (2008). World J Microbiol and Biotechnol. 24, 875-878.

Kelemen, O.: Characterization of a novel n-alkane degrading strain, Dietzia sp. E1 (2007). Diploma thesis.

 

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