Determinants estructurals i implicacions funcionals de l'interactoma proteix de hcnt1
- Autores: Albert Viel Oliva
- Directores de la Tesis: Marçal Pastor Anglada (dir. tes.), Sandra Pérez Torras (codir. tes.)
- Lectura: En la Universitat de Barcelona ( España ) en 2017
- Idioma: español
- Tribunal Calificador de la Tesis: Dolors Colomer Pujol (presid.), Francisco Ciruela Alférez (secret.), Sonia Fernández Veledo (voc.)
- Materias:
- Enlaces
- Tesis en acceso abierto en: TDX
- Resumen
Nucleosides are essential molecules for a living cell as they are precursors of key biomolecules. They can be synthesized inside the cell or taken up from the extracellular milieu by membrane proteins. These proteins are the nucleoside transporters. A part from internalizing nucleosides and their derivatives that are used as drugs for different therapies, these transporters mediate accessory functions acting as transceptors. This brief background reveals the biomedical relevance of the study of these proteins.
Among all nucleoside transporters, this project has focused on the protein hCNT1 (human Concentrative Nucleoside Transporter) encoded in the gene SLC28A1. There is increasing evidence that this protein promotes cellular changes when its expression is restored in a translocation independent manner. Furthermore, in oncogenic processes its expression is lost in specific tissues. These evidences prompted us to plan a study of hCNT1 where it could be demonstrated the biological function of this transporter and its physiological relevance.
One evidence that strengths the biological importance of the SLC28A1 gene was the discovery of a new mutation apparently related to a severe pathology. The molecular study of this mutated protein showed a decrease in the nucleoside uptake compared with the wild type protein. This decrease in the activity was caused by a reduction in the expression that it seems to be related to differences in protein turnover.
In order to demonstrate the mechanisms of the transceptor functions described for hCNT1 we decided to unveil the protein interactome of the transporter. Previous studies in our research group using a bacterial two-hybrid, discovered prosaposin as a putative hCNT1 partner. We discovered a functional connection between both proteins but the biochemical validation was impossible due to the lack of specific antibodies. Using an alternative and more updated technique, the Membrane Yeast Two-Hybrid, we could find three new interacting proteins. One of the proteins was RNF41, and the interaction was confirmed by other methods. Moreover, we could spot some sort of regulation between them, the function of this interaction seems to be regulating the ubiquitination state of hCNT1 and this modification appears to modulate the uptake activity of the transporter.
