西亚试剂：Transcriptional regulation of autophagy by an FXR–CREB axis

Sunmi Seok, Ting Fu, Sung-E Choi, Yang Li, Rong Zhu, Subodh Kumar, Xiaoxiao Sun,Gyesoon Yoon, Yup Kang, Wenxuan Zhong, Jian Ma, Byron Kemper & Jongsook Kim Kemper

Lysosomal degradation of cytoplasmic components by autophagy is essential for cellular survival and homeostasis under nutrient-deprived conditions1, 2, 3, 4. Acute regulation of autophagy by nutrient-sensing kinases is well defined3, 5, 6, 7, but longer-term transcriptional regulation is relatively unknown. Here we show that the fed-state sensing nuclear receptor farnesoid X receptor (FXR)8, 9 and the fasting transcriptional activator cAMP response element-binding protein (CREB)10, 11 coordinately regulate the hepatic autophagy gene network. Pharmacological activation of FXR repressed many autophagy genes and inhibited autophagy even in fasted mice, and feeding-mediated inhibition of macroautophagy was attenuated in FXR-knockout mice. From mouse liver chromatin immunoprecipitation and high-throughput sequencing data12, 13, 14, 15, FXR and CREB binding peaks were detected at 178 and 112 genes, respectively, out of 230 autophagy-related genes, and 78 genes showed shared binding, mostly in their promoter regions. CREB promoted autophagic degradation of lipids, or lipophagy16, under nutrient-deprived conditions, and FXR inhibited this response. Mechanistically, CREB upregulated autophagy genes, including Atg7, Ulk1 and Tfeb, by recruiting the coactivator CRTC2. After feeding or pharmacological activation, FXR trans-repressed these genes by disrupting the functional CREB–CRTC2 complex. This study identifies the new FXR–CREB axis as a key physiological switch regulating autophagy, resulting in sustained nutrient regulation of autophagy during feeding/fasting cycles.

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