Fig 2: IL-6 regulates STAT3 signaling and FTO expression in HuH7 cells. HuH7 cells were depleted for 16 hours of serum and treated with IL-6 (10 ng/ml) during different times. A) Representative Western blots and quantitative analysis of Y705 phosphorylation of STAT3 in HuH-7 cells treated with IL-6 (10 ng/ml), showing that IL-6 stimulates tyrosine phosphorylation of STA3 in a time-dependant manner in HuH7 cells expressing LepRb. B) Representative Western blots and quantitative analysis of FTO expression in HuH7 cells treated with IL-6, showing that IL-6 stimulates FTO protein levels in HuH7 cells expressing LepRb. Data are means ± SEM (n = 4/group).*p < 0.05 compared to untreated cells.

Fig 3: Model of FTO regulation of leptin action and glucose homeostasis through the LepRb-STAT3 signaling pathway. A) The binding of leptin to its receptor triggers the activation of JAK2 and the phosphorylation of STAT3 on a tyrosine residue (Y705). This modification causes the STAT3 protein to relocate to the nucleus, where as a dimer, it regulates gene expression (upregulation of both SOCS3 and LepR and reduction of G6P). Our data further suggest that FTO could be a STAT3-upregulated gene in hepatocytes. B) FTO overexpression reduces Y705 STAT3 phosphorylation, reducing its nuclear translocation and leading to a downregulation of both SOCS3 and LepRb and an upregulation of G6P mRNA levels. Just to opposite, FTO overexpression induces S727 phosphorylation of STAT3, favorizing its mitochondrial localization, where it induces mitochondrial density and function. All these effects are associated in vivo with hyperleptinemia, hyperglycemia, hyperleptinemia and glucose intolerance. Altogether, these data indicate that FTO controls leptin action and glucose metabolism in liver.

Fig 4: Regulation of JAK2/STAT3 and AMPK/mTOR signaling pathway by reoxygenation in hypoxia-induced brain injury mice. (A) The phosphorylation of JAK2 and STAT3 as well as the expression of its downstream molecule BNIP3 were analyzed by western blotting. (B) Autophagy-associated signaling was also observed by western blotting with antibodies against AMPK and mTOR. Intensities of protein bands were standardized to those of β-actin and expressed as relative band intensities. Data represent three independent experiments. Error bars reflect±s.e.m. *P<0.05, **P<0.01.

Fig 5: Radiation-induced IL6 secretion mediates activation of Notch signaling(A) Schematic model illustrating conditioned medium treated MCF7 breast cancer cells. MCF7 cells were irradiated 2 Gy × 3 as mentioned earlier. Then cell's medium was further harvested and treated to another MCF7 cells. (B) Migration and invasion assay in transwells after irradiated cultured medium those are compared with directly irradiated MCF7 cells. (C) Western blot and (D) immunocytochemistry for EMT markers after fractionated irradiation of MCF7 that are treated with irradiated cultured medium. (E) qRT PCR analysis for mRNA levels of cytokines family in MCF7 cells after fractionated irradiation. (F) Western blot for NICD2, Jagged1 and DLL4 after fractionated irradiation of MCF7 that are transfected with siRNA targeting IL-6 and IL-8. (G) qRT-PCR for Notch2, Jagged-1 and DLL4 mRNA levels after irradiation of MCF7 cells that are transfected with siRNA targeting IL-6 and IL-8. (H) Western blot for activation of STAT3 after fractionated irradiation of MCF7 that are transfected with siRNA targeting IL-6 and IL-8. β-actin was used as a loading control. Error bars represent mean ± S.D. of triplicate samples. *p < 0.05 and **p < 0.01.