Hu Fei, Yan Hua-Juan, Gao Cun-Xiu, Sun Wei-Wen, Long Yue-Sheng
Key Laboratory of Neurogenetics and Channelopathies of Guangdong Province and the Ministry of Education of China, Institute of Neuroscience and the Second Affiliated Hospital of Guangzhou Medical University, Guangzhou, China.
Neuroendocrinology. 2023;113(1):80-91. doi: 10.1159/000526752. Epub 2022 Aug 26.
Fat mass and obesity-associated (FTO) gene is strongly associated with obesity which brings a major health threat. Altered expression of its encoded protein FTO in the hypothalamus has been identified to contribute to central control of appetite and body weight. However, its molecular mechanisms remain elusive.
Mouse hypothalamic POMC cell line N43/5 was treated with FTO inhibitor rhein, FTO shRNA, or extracellular signal-regulated kinase 1/2 (ERK1/2) inhibitor U0126 to inhibit FTO or ERK1/2. Rhein and U0126 were injected into lateral ventricle of the mice by intracerebroventricular cannulation. Western blotting and immunofluorescent assays were performed to monitor protein level.
This study identified that inhibition of FTO in N43/5 cells led to phosphorylation of signal transducer and activator of transcription 3 (STAT3) at S727 site and induced p-STAT3-S727 nuclear translocation. We further showed that FTO inhibition promoted phosphorylation of ERK1/2; specific inhibition of ERK1/2 signaling by U0126 could abolish the effect of FTO inhibition on STAT3-S727 phosphorylation and nuclear translocation. Furthermore, we found that inhibition of hypothalamic FTO promoted STAT3-S727 phosphorylation in the hypothalamic arcuate nucleus, and the mice showed reductions in food intake and body weight. In addition, inhibition of hypothalamic ERK1/2 could abolish the effects of FTO inhibition on STAT3-S727 phosphorylation, reductions of food intake and body weight.
Our in vitro and in vivo data suggest that the inhibition of hypothalamic FTO could activate STAT3 through ERK1/2, which is potentially associated with reductions in food intake and body weight.
脂肪量和肥胖相关（FTO）基因与肥胖密切相关，肥胖对健康构成重大威胁。已确定其编码蛋白FTO在下丘脑中的表达改变有助于对食欲和体重的中枢控制。然而，其分子机制仍不清楚。
用FTO抑制剂大黄酸、FTO短发夹RNA（shRNA）或细胞外信号调节激酶1/2（ERK1/2）抑制剂U0126处理小鼠下丘脑促黑素细胞皮质激素（POMC）细胞系N43/5，以抑制FTO或ERK1/2。通过脑室内插管将大黄酸和U0126注入小鼠侧脑室。进行蛋白质印迹和免疫荧光分析以监测蛋白质水平。
本研究发现，抑制N43/5细胞中的FTO会导致信号转导子和转录激活子3（STAT3）在S727位点磷酸化，并诱导p-STAT3-S727核转位。我们进一步表明，抑制FTO可促进ERK1/2磷酸化；U0126对ERK1/2信号的特异性抑制可消除FTO抑制对STAT3-S727磷酸化和核转位的影响。此外，我们发现抑制下丘脑FTO可促进下丘脑弓状核中STAT3-S727磷酸化，且小鼠的食物摄入量和体重降低。此外，抑制下丘脑ERK1/2可消除FTO抑制对STAT3-S727磷酸化、食物摄入量和体重降低的影响。
我们的体外和体内数据表明，抑制下丘脑FTO可通过ERK1/2激活STAT3，这可能与食物摄入量和体重降低有关。
