ABSTRACT
Objetivo: la obesidad ha aumentado en todo el mundo, no obstante existen pocas opciones terapéuticas novedosas y la inclinación a actividades cruentas para la terapia de obesidad y diabetes mellitus 2 no dejan de ser un riesgo. Con el fin de valorar el efecto de compuestos sobre la actividad de la célula grasa, estudiamos en forma preclínica la actividad de ácido valproico, tricostatin a (inhibidor de histonas deacetilasas) y EID1 (inhibidor de EP300), el cual reduce la actividad de PPARg en un modelo de células preadipocíticas 3T3-l1. Métodos: se realizó transfecciones transitorias con lipofectamina a las células 3T3-l1 y 293. las células unipotentes 3T3-L1 fueron sometidas a diferenciación con el coctel específico para diferenciación y se les adicionaron los compuestos a concentraciones fisiológicas para las células. Se valoró la expresión de UCP1 mediante Western blot y los experimentos se realizaron por triplicado. Resultados: se observó que el efecto de tricostatin a fue mayor que el del ácido valproico en actividad lipolítica, no obstante ambos compuestos ejercen una efecto aditivo sobre la actividad de EID1 en la diferenciación de la célula adiposa. EID1 es capaz de estimular la actividad de proteína UCP1, cuya expresión es propia del adipocito marrón. Conclusiones: EID1 es una proteína que puede ser referente para inducir una célula adiposa calorigénica más activa, reduciendo la acumulación de lípidos en célula grasa. el efecto de ácido valproico y tricostatin a pueden servir de parámetro para la búsqueda de nuevos planes terapéuticos dirigidos a la obesidad. (Acta Med Colomb 2012; 37: 125-130).
Objective: obesity has increased worldwide, but there are currently few novel therapeutic options and the tendency to invasive procedures for the therapy of obesity and diabetes mellitus 2 are still an important risk. in order to assess the effect of compounds on the fat cell activity, we studied preclinically the activity of valproic acid, tricostatin a (histone deacetylase inhibitor) and EID1 (EP300 inhibitor) which reduces the activity of PPARg, in a model of preadipocyte 3T3-l1 cells. Methods: transient transfections were performed with lipofectamine in 3T3-l1 and 293 cells. Unipotent 3T3-L1 cells underwent differentiation with the specific cocktail and the compounds were added to cells in physiological concentrations. We assessed the UCP1 expression through western blot, and the experiments were performed in triplicate. Results: we observed that the effect of tricostatin a was higher than that of the valproic acid in regard to lipolytic activity; however, both compounds exert an additive effect on EID1 activity in adipose cell differentiation. EID1 is able to stimulate the activity of protein UCP1, whose expression is characteristic of brown adipocyte. Conclusions: EID1 is a reference protein to induce in the adipose cell higher caloric activity, reducing the accumulation of lipids in the adipocyte. The effect of valproic acid and tricostatin a can serve as a parameter for the search of new targeted therapeutic plans for obesity. (Acta Med Colomb2012; 37: 125-130).
ABSTRACT
Transcriptional activation (TA) mediated by the effect of thyroid hormones on target genes requires co-activator proteins such as the early region 1A (E1A) associated 300 kDa binding protein (p300) and the cAMP response element binding protein (CREB) binding protein (CBP), known as the p300/CBP complex, which acetylate histones 3 and 4 to allow transcriptional machinery access to the target gene promoter. Little is known on the role of p300 in thyroid hormone receptor (TR) mediated TA but the E1A-like inhibitor of differentiation 1 (EID1), an inhibitor of p300 histone acetyltransferase (HAT), is a functional homolog of E1A and may inhibit myogenic differentiation factor D (MyoD) transcriptional activity and reduces muscle cell differentiation. We evaluated the influence of EID1 on TR-mediated transcriptional activity using transfection and mammalian two-hybrid studies to show that EID1 may partially reduces TA activity of the TR receptor, probably due to p300 blockage since EID1 mutants cannot reduce TR-mediated TA. The EID1 does not affect the function of p160 co-activator proteins (160 kDa proteins of steroid receptor co-activators) and is functionally independent of co-repressor proteins or TR binding. Summarizing, EID1 reduces TR-mediated transcriptional activity by blocking p300 and may play an important role in thyroid receptor activity in muscle and other tissues.