title: Rheb GTPase controls apoptosis by regulating interaction of FKBP38 with Bcl-2 and Bcl-XL.
abstract: FKBP38 is a member of the family of FK506-binding proteins that acts as an inhibitor of the mammalian target of rapamycin (mTOR). The inhibitory action of FKBP38 is antagonized by Rheb, an oncogenic small GTPase, which interacts with FKBP38 and prevents its association with mTOR. In addition to the role in mTOR regulation, FKBP38 is also involved in binding and recruiting Bcl-2 and Bcl-X(L), two anti-apoptotic proteins, to mitochondria. In this study, we investigated the possibility that Rheb controls apoptosis by regulating the interaction of FKBP38 with Bcl-2 and Bcl-X(L). We demonstrate in vitro that the interaction of FKBP38 with Bcl-2 is regulated by Rheb in a GTP-dependent manner. In cultured cells, the interaction is controlled by Rheb in response to changes in amino acid and growth factor conditions. Importantly, we found that the Rheb-dependent release of Bcl-X(L) from FKBP38 facilitates the association of this anti-apoptotic protein with the pro-apoptotic protein Bak. Consequently, when Rheb activity increases, cells become more resistant to apoptotic inducers. Our findings reveal a novel mechanism through which growth factors and amino acids control apoptosis.
authors.affiliation: Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15213, USA.
authors.forename: Dongzhu
authors.initials: D
authors.lastname: Ma
authors.forename: Xiaochun
authors.initials: X
authors.lastname: Bai
authors.forename: Huafei
authors.initials: H
authors.lastname: Zou
authors.forename: Yumei
authors.initials: Y
authors.lastname: Lai
authors.forename: Yu
authors.initials: Y
authors.lastname: Jiang
mesh_terms: D000596:Amino Acids / Q000737:chemistry; D017209:Apoptosis; D019204:GTP-Binding Proteins / Q000378:metabolism; D005786:Gene Expression Regulation; D015972:Gene Expression Regulation, Neoplastic; D005982:Glutathione Transferase / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D008928:Mitochondria / Q000378:metabolism; D008954:Models, Biological; D020559:Monomeric GTP-Binding Proteins / Q000378:metabolism*; D009479:Neuropeptides / Q000378:metabolism*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism*; D000076205:Ras Homolog Enriched in Brain Protein; D022021:Tacrolimus Binding Proteins / Q000378:metabolism*; D000077004:Tuberous Sclerosis Complex 1 Protein; D025521:Tumor Suppressor Proteins / Q000378:metabolism; D051020:bcl-X Protein / Q000378:metabolism*
chemical_list: D000596:Amino Acids; C471205:FKBP8 protein, human; D009479:Neuropeptides; D019253:Proto-Oncogene Proteins c-bcl-2; C490211:RHEB protein, human; D000076205:Ras Homolog Enriched in Brain Protein; D000077004:Tuberous Sclerosis Complex 1 Protein; D025521:Tumor Suppressor Proteins; D051020:bcl-X Protein; D005982:Glutathione Transferase; D019204:GTP-Binding Proteins; D020559:Monomeric GTP-Binding Proteins; D022021:Tacrolimus Binding Proteins