Transcriptional regulation of autophagy by an FXR–CREB axis

S Seok, T Fu, SE Choi, Y Li, R Zhu, S Kumar, X Sun… - Nature, 2014 - nature.com
S Seok, T Fu, SE Choi, Y Li, R Zhu, S Kumar, X Sun, G Yoon, Y Kang, W Zhong, J Ma
Nature, 2014nature.com
Lysosomal degradation of cytoplasmic components by autophagy is essential for cellular
survival and homeostasis under nutrient-deprived conditions,,,. Acute regulation of
autophagy by nutrient-sensing kinases is well defined,,,, but longer-term transcriptional
regulation is relatively unknown. Here we show that the fed-state sensing nuclear receptor
farnesoid X receptor (FXR), and the fasting transcriptional activator cAMP response element-
binding protein (CREB), coordinately regulate the hepatic autophagy gene network …
Abstract
Lysosomal degradation of cytoplasmic components by autophagy is essential for cellular survival and homeostasis under nutrient-deprived conditions,,,. Acute regulation of autophagy by nutrient-sensing kinases is well defined,,,, but longer-term transcriptional regulation is relatively unknown. Here we show that the fed-state sensing nuclear receptor farnesoid X receptor (FXR), and the fasting transcriptional activator cAMP response element-binding protein (CREB), 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 data,,,, 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 lipophagy, 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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