title: Cytosolic FoxO1 is essential for the induction of autophagy and tumour suppressor activity.
abstract: Autophagy is characterized by the sequestration of bulk cytoplasm, including damaged proteins and organelles, and delivery of the cargo to lysosomes for degradation. Although the autophagic pathway is also linked to tumour suppression activity, the mechanism is not yet clear. Here we report that cytosolic FoxO1, a forkhead O family protein, is a mediator of autophagy. Endogenous FoxO1 was required for autophagy in human cancer cell lines in response to oxidative stress or serum starvation, but this process was independent of the transcriptional activity of FoxO1. In response to stress, FoxO1 was acetylated by dissociation from sirtuin-2 (SIRT2), a NAD(+)-dependent histone deacetylase, and the acetylated FoxO1 bound to Atg7, an E1-like protein, to influence the autophagic process leading to cell death. This FoxO1-modulated cell death is associated with tumour suppressor activity in human colon tumours and a xenograft mouse model. Our finding links the anti-neoplastic activity of FoxO1 and the process of autophagy.
authors.affiliation: Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education), Department of Biochemistry and Molecular Biology, Peking University Health Science Center, Beijing 100191, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Zhao
authors.forename: Jing
authors.initials: J
authors.lastname: Yang
authors.forename: Wenjuan
authors.initials: W
authors.lastname: Liao
authors.forename: Xiangyu
authors.initials: X
authors.lastname: Liu
authors.forename: Hui
authors.initials: H
authors.lastname: Zhang
authors.forename: Shan
authors.initials: S
authors.lastname: Wang
authors.forename: Donglai
authors.initials: D
authors.lastname: Wang
authors.forename: Jingnan
authors.initials: J
authors.lastname: Feng
authors.forename: Li
authors.initials: L
authors.lastname: Yu
authors.forename: Wei-Guo
authors.initials: WG
authors.lastname: Zhu
mesh_terms: D000107:Acetylation; D000199:Actins / Q000235:genetics / Q000378:metabolism; D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism; D000818:Animals; D001343:Autophagy / Q000187:drug effects*; D000071193:Autophagy-Related Protein 7; D015153:Blotting, Western; D045744:Cell Line, Tumor; D003600:Cytosol / Q000187:drug effects / Q000378:metabolism*; D000071161:Forkhead Box Protein O1; D051858:Forkhead Transcription Factors / Q000235:genetics / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D051379:Mice; D008819:Mice, Nude; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding; D034622:RNA Interference; D000071456:Sequestosome-1 Protein; D056565:Sirtuin 2 / Q000235:genetics / Q000378:metabolism; D044764:Ubiquitin-Activating Enzymes / Q000235:genetics / Q000378:metabolism
chemical_list: D000199:Actins; D048868:Adaptor Proteins, Signal Transducing; C085126:FOXO1 protein, human; D000071161:Forkhead Box Protein O1; D051858:Forkhead Transcription Factors; C477012:MAP1LC3A protein, human; D008869:Microtubule-Associated Proteins; C099718:SQSTM1 protein, human; D000071456:Sequestosome-1 Protein; D006861:Hydrogen Peroxide; C474199:SIRT2 protein, human; D056565:Sirtuin 2; C509349:ATG7 protein, human; D000071193:Autophagy-Related Protein 7; D044764:Ubiquitin-Activating Enzymes