RESUMEN
Uncoupling protein 2 (UCP2) is a member of the uncoupling protein family. It is expressed in the inner mitochondrial membrane and plays a role in the control of free radical production, oxidative damage, insulin secretion, and fatty-acid peroxide exportation. Although UCP2 expression occurs in several tissues, some of its most remarkable functions are exerted in organs of difficult experimental access, such as the central nervous system, particularly the hypothalamus and the pancreatic islets. In addition, due to its low levels of expression in the mitochondrial membrane, studying UCP2 expression and function depends on specific- and well-established methods. This chapter describes methods for directly assessing UCP2 expression and function in different tissues. Purified mitochondria preparations are used for enhancing the capacity of detection of UCP2 protein or for evaluating the role of UCP2 in mitochondria respiration. Exposure of experimental animals to cold environment leads to increased UCP2 expression, while reduction of its expression can be achieved directly by targeting its mRNA with antisense oligonucleotides, or indirectly by targeting PGC-1alpha expression with antisense oligonucleotides.
Asunto(s)
Regulación de la Expresión Génica , Canales Iónicos/genética , Canales Iónicos/metabolismo , Proteínas Mitocondriales/genética , Proteínas Mitocondriales/metabolismo , Animales , Elementos sin Sentido (Genética) , Frío , Hipotálamo/metabolismo , Immunoblotting , Canales Iónicos/aislamiento & purificación , Islotes Pancreáticos/metabolismo , Masculino , Ratones , Mitocondrias/genética , Mitocondrias/metabolismo , Proteínas Mitocondriales/aislamiento & purificación , Oxígeno/metabolismo , Coactivador 1-alfa del Receptor Activado por Proliferadores de Peroxisomas gamma , Reacción en Cadena de la Polimerasa , Proteínas de Unión al ARN/genética , Ratas , Ratas Wistar , Factores de Transcripción/genética , Proteína Desacopladora 2RESUMEN
Uncoupling protein 2 (UCP2) is highly expressed in the hypothalamus; however, little is known about the functions it exerts in this part of the brain. Here, we hypothesized that UCP2 protects hypothalamic cells from oxidative and pro-apoptotic damage generated by inflammatory stimuli. Intracerebroventricular injection of tumor necrosis factor alpha (TNF-alpha)-induced an increase of UCP2 expression in the hypothalamus, which was accompanied by increased expression of markers of oxidative stress and pro-apoptotic proteins. The inhibition of UCP2 expression by an antisense oligonucleotide enhanced the damaging effects of TNF-alpha. Conversely, increasing the hypothalamic expression of UCP2 by cold exposure reversed most of the effects of the cytokine. Thus, UCP2 acts as a protective factor against cellular damage induced by an inflammatory stimulus in the hypothalamus.