RESUMEN
Resumen Antecedentes: Las interacciones proteicas participan en una gran cantidad de mecanismos moleculares que rigen los procesos celulares. La proteína de unión a la caja TATA humana (hTBP) interacciona con Antennapedia (Antp) a través de su extremo N-terminal, específicamente a través de sus homopéptidos de glutaminas. Esta región PolyQ sirve como sitio de unión a factores de transcripción en condiciones normales, pero cuando se expande genera la ataxia espinal cerebelosa 17 (SCA17), cuyos agregados proteicos en el cerebro impiden su funcionamiento correcto. Objetivo: Determinar si la región rica en glutaminas de hTBP interviene en su interacción con homeoproteínas y el papel que tiene en la formación de agregados proteicos en SCA17. Material y métodos: Se caracterizó la interacción de hTBP con otras homeoproteínas usando BiFC y se modeló SCA17 en Drosophila melanogaster dirigiendo hTBPQ80 al cerebro de las moscas usando UAS/GAL4. Resultados: Existió interacción de hTBP con homeoproteínas a través de su región rica en glutaminas. Los agregados proteicos de hTBP con las glutaminas expandidas afectaron la capacidad locomotriz de las moscas. Conclusiones: El estudio de las interacciones de hTBP abre la posibilidad para la búsqueda de nuevas estrategias terapéuticas en patologías neurodegenerativas como SCA17.
Abstract Background: Protein interactions participate in many molecular mechanisms involved in cellular processes. The human TATA box binding protein (hTBP) interacts with Antennapedia (Antp) through its N-terminal region, specifically via its glutamine homopeptides. This PolyQ region acts as a binding site for other transcription factors under normal conditions, but when it expands, it generates spinocerebellar ataxia 17 (SCA17), whose protein aggregates in the brain prevent its correct functioning. Objective: To determine whether the hTBP glutamine-rich region is involved in its interaction with homeoproteins and the role it plays in the formation of protein aggregates in SCA17. Material and methods: We characterized hTBP interaction with other homeoproteins using BiFC, and modeled SCA17 in Drosophila melanogaster by targeting hTBPQ80 to the fly brain using UAS/GAL4. Results: There was hTBP interaction with homeoproteins through its glutamine-rich region, and hTBP protein aggregates with expanded glutamines were found to affect the locomotor capacity of flies. Conclusions: The study of hTBP interactions opens the possibility for the search for new therapeutic strategies in neurodegenerative pathologies such as SCA17.
RESUMEN
BACKGROUND: Abnormal expansion of trinucleotide repeats in genes causing spinocerebellar ataxias such as SCA2, SCA3, SCA8, or SCA17 was reported in sporadic or familial Parkinson's disease. Genetic factors play an important role especially in early-onset Parkinson's disease (EOPD). To investigate mutations of ATXN2, ATXN3, and TBP as a possible cause in Korean EOPD, we analyzed mutations in these genes. We also investgated the possibility that trinucleotide repeats numbers in these genes contribute to the development of EOPD. METHODS: Mutation analysis of ATXN2, ATXN3, and TBP was done in 153 EOPD defined as age-at-onset before 51. Distribution of CAG repeats numbers were compared between EOPD and age- and sex-matched controls. RESULTS: No patients with EOPD had CAG repeats numbers in ATXN2, ATXN3, and TBP in mutation range. There was no difference in the distribution of CAG repeats between EOPD and controls, although we found a trend that CAG repeats numbers in ATXN3 appear larger in EOPD than in controls. CONCLUSIONS: Mutations of genes causing SCA2, SCA3, or SCA17 may not be a common genetic cause in Korean EOPD.