Acetylation Of FKBP12 Regulates MTORC1 Signaling Pathway

MTOR(the mammalian target of rapamyein)is a member of the PIKK(the phosphatidylinositol kinase-related kinase)superfamily and plays a role as Ser/Thr kinase,which is highly conserved in evolution and regulates various anabolic metabolism and immune activities in cells.FKBP12(the fk506-binding protein 12)is a 12KD small molecule protein that binds to the immunosuppressive inhibitor rapamycin and negatively regulates the mTOR signaling pathway.The mechanism by which fkbp 12-rapamycin regulates mTOR has not been fully elucidated.Through mass spectrometry analysis,we found that in the presence of amino acids/serum,the lysine cluster(K48/K53)on FKBP12 could be acetylated by CBP,and the interaction between FKBP 12 and mTOR in the acetylated state was weakened.Immunoprecipitation showed that acetylated FKBP 12 had stronger binding force with Rheb(Ras homologue enriched in brain),which relieved the inhibition of mTOR and promoted its kinase activity.Rheb,as GTPase combined with GTP,can activate mTOR activity.Mass spectrometry analysis shows that the lysine K8 site of rheb can also be acetylated by CBP.After acetylation,Rheb interacts with FKBP 12 to enhance the activity of mTORC1.Studies have shown that mTOR plays an important regulatory role in innate immunity in mammalian cells,but the specific mechanism remains unclear.Through maldi-tof-s,we found that mTOR phosphorylates the serine 386 site of IRF3,promoting antiviral activity.In addition,we constructed stable cell lines of FKBP 12 mutants in MEF cells,and the simulated acetylated stable cell lines had stronger antiviral ability under the condition of virus infection.These results suggest that in the presence of amino acids/serum,acetylated FKBP 12 has a reduced inhibitory effect on mTOR.MTOR plays an antiviral role by phosphorylating serine at IRF3 386,while acetylated FKBP 12 enhances the antiviral function of cells by promoting mTOR activity.This study revealed the important regulatory effect of FKBP 12 acetylation on mTORC1 signaling pathway for the first time,and verified the specific regulatory mechanism of FKBP12 acetylation from the cellular and molecular level.In addition,we proved that IRF3 is a new target of mTOR through various technical means,revealing a new anti-virus mechanism of mTOR.