Martinez, J.A. (José Alfredo)Algarabel, M. (Miriam)Miguel-Vázquez, C. (Carlos) deMilagro-Yoldi, F.I. (Fermín Ignacio)Palacios-Ortega, S. (Sara)Varela-Guruceaga, M. (Maider)2015-09-212015-09-212015Palacios-Ortega S, Varela-Guruceaga M, Algarabel M, Milagro FI, Martínez JA, de Miguel C. Effect of TNF-Alpha on caveolin-1 expression and insulin signaling during adipocyte differentiation and in mature adipocytes. Cell Physiol Biochem. 2015 Jul 6;36(4):1499-15161015-8987https://hdl.handle.net/10171/39073Background/Aims: Tumor necrosis factor-α (TNF-α)-mediated chronic low-grade inflammation of adipose tissue is associated with obesity and insulin resistance. Caveolin-1 (Cav-1) is the central component of adipocyte caveolae and has an essential role in the regulation of insulin signaling. The effects of TNF-α on Cav-1 expression and insulin signaling during adipocyte differentiation and in mature adipocytes were studied. Methods: 3T3-L1 cells were differentiated (21 days) in the presence TNF-α (10 ng/mL) and mature adipocytes were also treated with TNF-α for 48 hours. Cav-1 and insulin receptor (IR) gene methylation were determined as well as Cav-1, IR, PKB/AKT-2 and Glut-4 expression and activation by real time RT-PCR and western blot. Baseline and insulin-induced glucose uptake was measured by the 2-[C14]-deoxyglucose uptake assay. Results: TNF-α slowed down the differentiation program, hindering the expression of some insulin signaling intermediates without fully eliminating insulin-mediated glucose uptake. In mature adipocytes, TNF-α did not compromise lipidstorage capacity, but downregulated the expression of the insulin signaling intermediates, totally blocking insulin-mediated glucose uptake. Insulin sensitivity correlated with the level of activated phospho-Cav-1 in both situations, strongly suggesting the direct contribution of Cav-1 to the maintenance of this physiological response. Conclusion: Cav-1 activation by phosphorylation seems to be essential for the maintenance of an active and insulin-sensitive glucose uptake.enginfo:eu-repo/semantics/openAccessAdipogenesisInflammationInsulin receptorInsulin-stimulated glucose uptakeDNA methylation3T3-L1info:eu-repo/semantics/articlehttp://dx.doi.org/10.1159/000430314