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Upstream stimulating factor 1 suppresses autophagy and hepatic lipid droplet catabolism by activating mTOR
Author(s) -
Guo Jun,
Fang Weiwei,
Chen Xiehui,
Lin Yajun,
Hu Gang,
Wei Jie,
Zhang Xiaoyi,
Yang Chunxiao,
Li Jian
Publication year - 2018
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1002/1873-3468.13203
Subject(s) - autophagy , pi3k/akt/mtor pathway , downregulation and upregulation , transcription factor , lipid metabolism , microbiology and biotechnology , chemistry , catabolism , lipid droplet , sterol regulatory element binding protein , biochemistry , biology , metabolism , gene , signal transduction , apoptosis
Previous studies indicate that the transcription factor upstream stimulating factor 1 (USF1) is involved in the regulation of lipid and glucose metabolism. However, the role of USF1 in lipid‐induced autophagy remains unknown. Interestingly, we found that USF1 overexpression suppresses autophagy‐related gene expression in HepG2 cells. Further assays confirmed that USF1 could transcriptionally activate mTOR expression, thereby suppressing rapamycin‐induced autophagy in HepG2 cells. Moreover, pharmacological activation of autophagy with rapamycin decreases the numbers and sizes of lipid droplets (LDs) in HepG2 cells exposed to an oleate/palmitate mixture. Of note, USF1 upregulation decreases colocalization of LDs and autophagosomes. In conclusion, our data provide evidence that USF1 contributes to abnormal lipid accumulation in the liver by suppressing autophagy via regulation of mTOR transcription.