title: Identification of a mitochondrial target of thiazolidinedione insulin sensitizers (mTOT)--relationship to newly identified mitochondrial pyruvate carrier proteins.
abstract: Thiazolidinedione (TZD) insulin sensitizers have the potential to effectively treat a number of human diseases, however the currently available agents have dose-limiting side effects that are mediated via activation of the transcription factor PPARγ. We have recently shown PPARγ-independent actions of TZD insulin sensitizers, but the molecular target of these molecules remained to be identified. Here we use a photo-catalyzable drug analog probe and mass spectrometry-based proteomics to identify a previously uncharacterized mitochondrial complex that specifically recognizes TZDs. These studies identify two well-conserved proteins previously known as brain protein 44 (BRP44) and BRP44 Like (BRP44L), which recently have been renamed Mpc2 and Mpc1 to signify their function as a mitochondrial pyruvate carrier complex. Knockdown of Mpc1 or Mpc2 in Drosophila melanogaster or pre-incubation with UK5099, an inhibitor of pyruvate transport, blocks the crosslinking of mitochondrial membranes by the TZD probe. Knockdown of these proteins in Drosophila also led to increased hemolymph glucose and blocked drug action. In isolated brown adipose tissue (BAT) cells, MSDC-0602, a PPARγ-sparing TZD, altered the incorporation of (13)C-labeled carbon from glucose into acetyl CoA. These results identify Mpc1 and Mpc2 as components of the mitochondrial target of TZDs (mTOT) and suggest that understanding the modulation of this complex, which appears to regulate pyruvate entry into the mitochondria, may provide a viable target for insulin sensitizing pharmacology.
authors.affiliation: Metabolic Solutions Development Company, Kalamazoo, Michigan, United States of America. jcolca@msdRx.com
authors.forename: Jerry R
authors.initials: JR
authors.lastname: Colca
authors.forename: William G
authors.initials: WG
authors.lastname: McDonald
authors.forename: Gregory S
authors.initials: GS
authors.lastname: Cavey
authors.forename: Serena L
authors.initials: SL
authors.lastname: Cole
authors.forename: Danielle D
authors.initials: DD
authors.lastname: Holewa
authors.forename: Angela S
authors.initials: AS
authors.lastname: Brightwell-Conrad
authors.forename: Cindy L
authors.initials: CL
authors.lastname: Wolfe
authors.forename: Jean S
authors.initials: JS
authors.lastname: Wheeler
authors.forename: Kristin R
authors.initials: KR
authors.lastname: Coulter
authors.forename: Peter M
authors.initials: PM
authors.lastname: Kilkuskie
authors.forename: Elena
authors.initials: E
authors.lastname: Gracheva
authors.forename: Yulia
authors.initials: Y
authors.lastname: Korshunova
authors.forename: Michelle
authors.initials: M
authors.lastname: Trusgnich
authors.forename: Robert
authors.initials: R
authors.lastname: Karr
authors.forename: Sandra E
authors.initials: SE
authors.lastname: Wiley
authors.forename: Ajit S
authors.initials: AS
authors.lastname: Divakaruni
authors.forename: Anne N
authors.initials: AN
authors.lastname: Murphy
authors.forename: Patrick A
authors.initials: PA
authors.lastname: Vigueira
authors.forename: Brian N
authors.initials: BN
authors.lastname: Finck
authors.forename: Rolf F
authors.initials: RF
authors.lastname: Kletzien
mesh_terms: D002001:Adipose Tissue, Brown / Q000166:cytology / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D004331:Drosophila melanogaster; D055785:Gene Knockdown Techniques; D057809:HEK293 Cells; D006801:Humans; D007004:Hypoglycemic Agents / Q000494:pharmacology*; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D026901:Membrane Transport Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008928:Mitochondria / Q000187:drug effects*; D033681:Mitochondrial Membrane Transport Proteins; D008969:Molecular Sequence Data; D027501:Monocarboxylic Acid Transporters; D017386:Sequence Homology, Amino Acid; D045162:Thiazolidinediones / Q000494:pharmacology*
chemical_list: D007004:Hypoglycemic Agents; D007328:Insulin; C573718:MPC1 protein, human; D026901:Membrane Transport Proteins; D033681:Mitochondrial Membrane Transport Proteins; D027501:Monocarboxylic Acid Transporters; D045162:Thiazolidinediones