Angiotensin II Signaling in Human Preadipose Cells: Participation of ERK1,2-Dependent Modulation of AktReportar como inadecuado




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The renin-angiotensin system expressed in adipose tissue has been implicated in the modulation of adipocyte formation, glucose metabolism, triglyceride accumulation, lipolysis, and the onset of the adverse metabolic consequences of obesity. As we investigated angiotensin II signal transduction mechanisms in human preadipose cells, an interplay of extracellular-signal-regulated kinases 1 and 2 ERK1,2 and Akt-PKB became evident. Angiotensin II caused attenuation of phosphorylated Akt p-Akt, at serine 473; the p-Akt-Akt ratio decreased to 0.5±0.2-fold the control value without angiotensin II p<0.001. Here we report that the reduction of phosphorylated Akt associates with ERK1,2 activities. In the absence of angiotensin II, inhibition of ERK1,2 activation with U0126 or PD98059 resulted in a 2.1±0.5 p<0.001 and 1.4±0.2-fold p<0.05 increase in the p-Akt-Akt ratio, respectively. In addition, partial knockdown of ERK1 protein expression by the short hairpin RNA technique also raised phosphorylated Akt in these cells the p-Akt-Akt ratio was 1.5±0.1-fold the corresponding control; p<0.05. Furthermore, inhibition of ERK1,2 activation with U0126 prevented the reduction of p-Akt-Akt by angiotensin II. An analogous effect was found on the phosphorylation status of Akt downstream effectors, the forkhead box Fox proteins O1 and O4. Altogether, these results indicate that angiotensin II signaling in human preadipose cells involves an ERK1,2-dependent attenuation of Akt activity, whose impact on the biological functions under its regulation is not fully understood.



Autor: Natalia Dünner, Carolina Quezada, F. Andrés Berndt, José Cánovas, Cecilia V. Rojas

Fuente: http://plos.srce.hr/



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