title: Cyclophilin D over-expression increases mitochondrial complex III activity and accelerates supercomplex formation.
abstract: Cyclophilin D (CyPD), a mitochondrial matrix protein, has been widely studied for its role in mitochondrial-mediated cell death. Unexpectedly, we previously discovered that overexpression of CyPD in a stable cell line, increased mitochondrial membrane potentials and enhanced cell survival under conditions of oxidative stress. Here, we investigated the underlying mechanisms responsible for these findings. Spectrophotometric measurements in isolated mitochondria revealed that overexpression of CyPD in HEK293 cells increased respiratory chain activity, but only for Complex III (CIII). Acute treatment of mitochondria with the immumosupressant cyclosporine A did not affect CIII activity. Expression levels of the CIII subunits cytochrome b and Rieske-FeS were elevated in HEK293 cells overexpressing CyPD. However, CIII activity was still significantly higher compared to control mitochondria, even when normalized by protein expression. Blue native gel electrophoresis and Western blot assays revealed a molecular interaction of CyPD with CIII and increased levels of supercomplexes in mitochondrial protein extracts. Radiolabeled protein synthesis in mitochondria showed that CIII assembly and formation of supercomplexes containing CIII were significantly faster when CyPD was overexpressed. Taken together, these data indicate that CyPD regulates mitochondrial metabolism, and likely cell survival, by promoting more efficient electrons flow through the respiratory chain via increased supercomplex formation.
authors.affiliation: Department of Cell Systems and Anatomy, University of Texas Health Science Center at San Antonio, San Antonio, TX, 78229, USA.
authors.forename: Julie C
authors.initials: JC
authors.lastname: Etzler
authors.affiliation: Instituto de Investigación Médica M y M Ferreyra, INIMEC-CONICET, Universidad Nacional de Córdoba, 5016, Argentina.
authors.forename: Mariana
authors.initials: M
authors.lastname: Bollo
authors.affiliation: Department of Cell Systems and Anatomy, University of Texas Health Science Center at San Antonio, San Antonio, TX, 78229, USA.
authors.forename: Deborah
authors.initials: D
authors.lastname: Holstein
authors.affiliation: Department of Cell Systems and Anatomy, University of Texas Health Science Center at San Antonio, San Antonio, TX, 78229, USA.
authors.forename: Janice Jianhong
authors.initials: JJ
authors.lastname: Deng
authors.affiliation: Department of Biochemistry and Biophysics, Oregon State University, Corvallis, OR 73104, USA.
authors.forename: Viviana
authors.initials: V
authors.lastname: Perez
authors.affiliation: Department of Cell Systems and Anatomy, University of Texas Health Science Center at San Antonio, San Antonio, TX, 78229, USA.
authors.forename: Da-Ting
authors.initials: DT
authors.lastname: Lin
authors.affiliation: Department of Geriatrics, University of Oklahoma Health Science Center, Oklahoma City, OK, 73104, USA.
authors.forename: Arlan
authors.initials: A
authors.lastname: Richardson
authors.affiliation: Department of Cell Systems and Anatomy, University of Texas Health Science Center at San Antonio, San Antonio, TX, 78229, USA.
authors.forename: Yidong
authors.initials: Y
authors.lastname: Bai
authors.affiliation: Department of Cell Systems and Anatomy, University of Texas Health Science Center at San Antonio, San Antonio, TX, 78229, USA. Electronic address: lechleiter@uthscsa.edu.
authors.forename: James D
authors.initials: JD
authors.lastname: Lechleiter
mesh_terms: D021983:Cyclophilins / Q000378:metabolism*; D016572:Cyclosporine / Q000737:chemistry; D004579:Electron Transport; D005786:Gene Expression Regulation; D057809:HEK293 Cells; D006801:Humans; D053078:Membrane Potential, Mitochondrial; D008928:Mitochondria / Q000378:metabolism*; D051336:Mitochondrial Membranes / Q000378:metabolism; D018384:Oxidative Stress; D010100:Oxygen / Q000737:chemistry; D011485:Protein Binding; D011487:Protein Conformation; D013053:Spectrophotometry; D000097322:Peptidyl-Prolyl Isomerase D
chemical_list: D021983:Cyclophilins; D016572:Cyclosporine; D010100:Oxygen; C114456:PPID protein, human; D000097322:Peptidyl-Prolyl Isomerase D
keywords: Chaperone; Metabolic regulation; Mitochondrial permeability transition (MPT); Mitochondrial respiratory chain complex; Prolyl isomerase