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Summary The mammalian target of rapamycin (mTOR) is a serine-threonine kinase involved in cellular innate immunity, metabolism, and senescence. FK506-binding protein 12 (FKBP12) inhibits mTOR kinase activity via direct association. The FKBP12-mTOR association can be strengthened by the immunosuppressant rapamycin, but the underlying mechanism remains elusive. We show here that the FKBP12-mTOR association is tightly regulated by an acetylation–deacetylation cycle. FKBP12 is acetylated on the lysine cluster (K45/K48/K53) by CREB-binding protein (CBP) in mammalian cells in response to nutrient treatment. Acetyl-FKBP12 associates with CBP acetylated Rheb. Rapamycin recruits SIRT2 with a high affinity for FKBP12 association and deacetylation. SIRT2-deacetylated FKBP12 then switches its association from Rheb to mTOR. Nutrient-activated mTOR phosphorylates IRF3S386 for the antiviral response. In contrast, rapamycin strengthening FKBP12-mTOR association blocks mTOR antiviral activity by recruiting SIRT2 to deacetylate FKBP12. Hence, on/off mTOR activity in response to environmental nutrients relies on FKBP12 acetylation and deacetylation status in mammalian cells., Graphical abstract, Highlights • FKBP12-mTOR association is tightly regulated by an acetylation–deacetylation cycle • SIRT2 is responsible for FKBP12 deacetylation • Acetylation of Rheb is indispensable to mTOR activation • mTOR phosphorylates IRF3 S386 for type-I interferon gene expression, Biochemistry; Protein; Molecular biology

Background LOX-like 1 (LOXL1) is a lysyl oxidase, and emerging evidence has revealed its effect on malignant cancer progression. However, its role in colorectal cancer (CRC) and the underlying molecular mechanisms have not yet been elucidated. Methods LOXL1 expression in colorectal cancer was detected by immunohistochemistry, western blotting and real-time PCR. In vitro, colony formation, wound healing, migration and invasion assays were performed to investigate the effects of LOXL1 on cell proliferation, migration and invasion. In vivo, metastasis models and mouse xenografts were used to assess tumorigenicity and metastasis ability. Molecular biology experiments were utilized to reveal the underlying mechanisms by which LOXL1 modulates the Hippo pathway. Results LOXL1 was highly expressed in normal colon tissues compared with cancer tissues. In vitro, silencing LOXL1 in CRC cell lines dramatically enhanced migration, invasion, and colony formation, while overexpression of LOXL1 exerted the opposite effects. The results of the in vivo experiments demonstrated that the overexpression of LOXL1 in CRC cell lines drastically inhibited metastatic progression and tumour growth. Mechanistically, LOXL1 inhibited the transcriptional activity of Yes-associated protein (YAP) by interacting with MST1/2 and increasing the phosphorylation of MST1/2. Conclusions LOXL1 may function as an important tumour suppressor in regulating tumour growth, invasion and metastasis via negative regulation of YAP activity. Graphical abstract