Gavito, A LCabello, RSuarez, JSerrano, APavón, F JVida, MRomero, MPardo, VBautista, DArrabal, SDecara, JCuesta, A LValverde, A MRodríguez de Fonseca, FBaixeras, E2023-01-252023-01-252016-02-22http://hdl.handle.net/10668/9715Lipogenesis is intimately controlled by hormones and cytokines as well as nutritional conditions. IL-6 participates in the regulation of fatty acid metabolism in the liver. We investigated the role of IL-6 in mediating fasting/re-feeding changes in the expression of hepatic lipogenic enzymes. Gene and protein expression of lipogenic enzymes were examined in livers of wild-type (WT) and IL-6-deficient (IL-6(-/-) ) mice during fasting and re-feeding conditions. Effects of exogenous IL-6 administration on gene expression of these enzymes were evaluated in vivo. The involvement of STAT3 in mediating these IL-6 responses was investigated by using siRNA in human HepG2 cells. During feeding, the up-regulation in the hepatic expression of lipogenic genes presented similar time kinetics in WT and IL-6(-/-) mice. During fasting, expression of lipogenic genes decreased gradually over time in both strains, although the initial drop was more marked in IL-6(-/-) mice. Protein levels of hepatic lipogenic enzymes were lower in IL-6(-/-) than in WT mice at the end of the fasting period. In WT, circulating IL-6 levels paralleled gene expression of hepatic lipogenic enzymes. IL-6 administration in vivo and in vitro showed that IL-6-mediated signalling was associated with the up-regulation of hepatic lipogenic enzyme genes. Moreover, silencing STAT3 in HepG2 cells attenuated IL-6 mediated up-regulation of lipogenic gene transcription levels. IL-6 sustains levels of hepatic lipogenic enzymes during fasting through activation of STAT3. Our findings indicate that clinical use of STAT3-associated signalling cytokines, particularly against steatosis, should be undertaken with caution.enAcetyl-CoA CarboxylaseAnimalsFastingFatty Acid Synthase, Type IGene Expression Regulation, EnzymologicHep G2 CellsHumansInterleukin-6LipogenesisLiverMaleMice, Inbred C57BLMice, KnockoutRecombinant ProteinsSTAT3 Transcription FactorStearoyl-CoA Desaturaseresearch article26750868open access10.1111/bph.134231476-5381PMC5341237https://bpspubs.onlinelibrary.wiley.com/doi/pdfdirect/10.1111/bph.13423https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5341237/pdf