Examinando por Autor "Palacios, R"

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Activation of p38 and ERK1/2 MAPK by superoxide anion participates in Angiotensin II-induced COX-2 expression in smooth muscle cells from resistance arteries
(2009-09) Hernanz, R; Beltrán, AE; Pérez-Girón, JV; Martín, A; Briones, AM; Palacios, R; Salaices, M; Alonso, MJ
Introduction: Angiotensin II (Ang II) regulates vascular smooth muscle cell (VSMC) function by activating signalling cascades that promote vasoconstriction, growth and inflammation. The mechanisms implicated in Ang II-induced pro-inflammatory actions include activation of several mitogen-activated protein kinases (MAPKs), reactive oxygen species generation and the modulation of prostaglandins production by regulating cyclooxygenase-2 (COX-2) expression. Aim: To investigate the effect of Ang II on COX-2 expression in VSMC derived from small resistance arteries and the mechanisms involved. Methods: VSMC derived from rat mesenteric resistance arteries were used. Protein expression was determined by Western Blot, mRNA levels by Q-RT-PCR and superoxide anion (O2-) production by dihydroethidine fluorescence. Results: Ang II (0.1 ¿M) time-dependently increased COX-2 protein expression (30 min - 8 h) and mRNA levels (15 min - 4 h), while COX- 1 expression remained unmodified. In addition, Ang II did not modify AT1 receptor expression. The AT1 antagonist losartan (10 ¿M), but not the AT2 antagonist PD 122319 (10 ¿M), abolished the increase in COX-2 expression induced by Ang II (2 h). COX-2 expression was also reduced by the respective NADPHox and xanthine oxidase inhibitors, apocynin (30 mM) and allopurinol (10 mM). Furthermore, Ang II (3- 30 min) increased O2- production; this effect was reduced by losartan, allopurinol and apocynin but not by PD 123319. Ang II (2-30 min) induced the phosphorylation of p38 and ERK1/2 MAPK; this effect was reduced by losartan, allopurinol and apocynin. In addition, the respective inhibitors of p38 and ERK1/2, SB 203580 (10 mM) and PD 98059 (25 mM), reduced the Ang II-induced COX-2 expression. Conclusions: The present results provide evidences that angiotensin II increases COX-2 expression in VSMC from resistance arteries, at least in part, through mechanisms that include O2- production and the subsequent activation of p38 and ERK1/2 MAPK
PPAR¿ activation improves oxidative stress and downregulates COX-2 expression in vascular cells
(2009-09) Palacios, R; Pérez-Girón, JV; Martín, A; Hernanz, R; Briones, AM; Salaices, M; Alonso, MJ
Introduction: The increased renin-angiotensin system (RAS) activity seems to contribute to the pathophysiology of hypertension by the increase in reactive oxygen species (ROS) levels and proinflammatory mediators. Endothelin-1 (ET-1) has been proposed to explain the cardiovascular damage induced by angiotensin II (AngII). Moreover, peroxisome proliferator activated receptor ¿ (PPAR¿) agonists have anti-inflammatory actions by interference with redox-sensitive transcription factors, such as NFkB or AP-1, involved in the transcription of proinflammatory genes including cyclooxygenase-2 (COX-2). Aim: To analyze if AngII contributes to the increased COX-2 levels in vascular smooth muscle cells (VSMC) from spontaneously hypertensive (SHR) rats by mechanisms dependent of ROS and ET-1 production and whether PPAR¿ activation regulates this effect. Methods: Aortic VSMC from SHR were stimulated with AngII in the absence and the presence of different drugs. mRNA levels were measured by qRT-PCR and protein expression by Western blot. Aortic segments from SHR and Wistar-Kyoto (WKY) rats untreated and treated with losartan (15 mg/Kg/day, 12 weeks) were also used. Results: COX-2 mRNA levels were greater in segments from SHR than WKY; the treatment with losartan reduced COX-2 levels in SHR. In VSMC from SHR, AngII (0.1 ¿M, 2 h) induced COX-2, ET-1 and NOX-1 mRNA levels; this effect was reduced by losartan (10 ¿M). AngII-induced COX-2 protein expression was also reduced by the NADPHox inhibitor apocynin (30 mM). The antagonist of the ETA receptor BQ 123 (1 ¿M), but not of the ETB receptor BQ 788 (1 ¿M), also reduced COX-2 and NOX-1 mRNA levels after AngII. The proteasome inhibitor lactacystin (20 ¿M) did not modify the ET-1 mRNA levels but inhibited those of NOX-1 and COX-2. AngII also increased c-jun expression; this expression was reduced by losartan but not by BQ 123. Moreover, the PPAR¿ activator pioglitazone (10 ¿M) decreased AngII-induced COX-2 and NOX-1 mRNA levels in VSMC from SHR. Conclusions: 1) The RAS activation contributes to the increased vascular COX-2 expression in hypertension. 2) AngII-induced COX-2 expression in VSMC is related with NOX-1 induction and NFkB and AP-1 activation. 3) AngII-induced ET-1 production and ETA activation contributes, at least partially, to the increased NOX-1 and COX-2 expression. 4) PPAR¿ activation inhibits AngII-induced COX-2 expression by reducing NOX-1 levels; we suggest that transrepression mechanisms on NFkB and/or AP-1 can play an important role in this inhibitory effect of PPAR¿ activation.
El tratamiento con pioglitazona modifica la participación de derivados de la Ciclooxigenasa-2 y de especies reactivas de oxígeno en la respuesta a fenilefrina de arterias de resistencia de ratas hipertensas
(2009-07) Hernanz, R; Martín, A; Pérez-Girón, JV; Avendaño, MS; Roque, FR; Palacios, R; Salaices, M; Alonso, MJ
Los receptores activadores de la proliferación peroxisomal-¿ (PPAR¿) son factores de transcripción expresados en la pared vascular con actividad cardioprotectora. Además, las glitazonas, agonistas PPAR¿, tienen acciones antiinflamatorias asociadas a la interferencia con factores de transcripción redox-sensibles como NF-kappaB, implicados en la transcripción de diversos genes, incluyendo la isoforma inducible de la ciclooxigenasa (COX-2) Objetivo: Analizar el efecto del tratamiento de ratas espontáneamente hipertensas (SHR)con pioglitazona sobre la respuesta a fenilefrina de arterias de resistencia, así como el efecto del mismo sobre el papel de prostanoides y especies reactivas de oxígeno (ROS) en dicha respuesta. Métodos: Se han utilizado arterias mesentéricas de resistencia de ratas SHR de 6 meses tratadas o no con el agonista PPARgamma pioglitazona (2,5 mg/Kg/día, 28 días). La reactividad vascular se ha estudiado en un miógrafo isométrico y la expresión proteica por western blot. Resultados: El tratamiento con pioglitazona no modificó la PAS ni la contracción inducida por fenilefrina. Indometacina (10 microM), el inhibidor selectivo de COX-2 NS 398 (1 microM), el antagonista del receptor TP SQ 29,548 (1 microM) y el antagonista del receptor EP1 SC 19220 (10 µM) redujeron la respuesta a fenilefrina sólo en segmentos de ratas tratadas, mientras que el inhibidor de la TXA2 sintasa furegrelato (1 microM) no modificó la respuesta en ningún grupo. La expresión de COX-2 fue mayor en arterias mesentéricas de ratas tratadas. Además, pioglitazona abolió el efecto inhibitorio de apocinina (0.3 mM) y alopurinol (0.3 mM), inhibidores respectivos de la NADPH oxidasa y la xantina oxidasa, sobre la respuesta a fenilefrina y redujo la expresión vascular de Cu/Zn- y Mn-SOD. Conclusiones: El tratamiento crónico de ratas hipertensas con pioglitazona incrementa la expresión vascular de COX-2 y la participación de prostanoides vasoconstrictores en la respuesta a fenilefrina. A pesar de que el tratamiento reduce la expresión de las isoformas citosólica y mitocondrial de SOD, la reducción en la participación de ROS en la respuesta a fenilefrina puede explicar que la respuesta a este vasoconstrictor sea similar.