Not all mitochondrial carrier proteins support permeability transition pore formation: no involvement of uncoupling protein 1.

TitleNot all mitochondrial carrier proteins support permeability transition pore formation: no involvement of uncoupling protein 1.
Publication TypeJournal Article
Year of Publication2009
AuthorsCrichton, PG, Parker, N, Vidal-Puig, AJ, Brand, MD
JournalBiosci Rep
Volume30
Issue3
Pagination187-92
Date Published2009 Dec 15
ISSN1573-4935
KeywordsAdipose Tissue, Brown, Animals, Blotting, Western, Calcium, Cyclophilins, Cyclosporine, Dose-Response Relationship, Drug, Erythritol, Female, Ion Channels, Male, Mice, Mice, Knockout, Mitochondria, Mitochondrial ADP, ATP Translocases, Mitochondrial Membrane Transport Proteins, Mitochondrial Proteins, Mitochondrial Swelling, Polymerase Chain Reaction, Time Factors, Uncoupling Protein 1, Voltage-Dependent Anion Channels
Abstract

The mPTP (mitochondrial permeability transition pore) is a non-specific channel that is formed in the mitochondrial inner membrane in response to several stimuli, including elevated levels of matrix calcium. The pore is proposed to be composed of the ANT (adenine nucleotide translocase), voltage-dependent anion channel and cyclophilin D. Knockout studies, however, have demonstrated that ANT is not essential for permeability transition, which has led to the proposal that other members of the mitochondrial carrier protein family may be able to play a similar function to ANT in pore formation. To investigate this possibility, we have studied the permeability transition properties of BAT (brown adipose tissue) mitochondria in which levels of the mitochondrial carrier protein, UCP1 (uncoupling protein 1), can exceed those of ANT. Using an improved spectroscopic assay, we have quantified mPTP formation in de-energized mitochondria from wild-type and Ucp1KO (Ucp1-knockout) mice and assessed the dependence of pore formation on UCP1. When correctly normalized for differences in mitochondrial morphology, we find that calcium-induced mPTP activity is the same in both types of mitochondria, with similar sensitivity to GDP (approximately 50% inhibited), although the portion sensitive to cyclosporin A is higher in mitochondria lacking UCP1 (approximately 80% inhibited, compared with approximately 60% in mitochondria containing UCP1). We conclude that UCP1 is not a component of the cyclosporin A-sensitive mPTP in BAT and that playing a role in mPTP formation is not a general characteristic of the mitochondrial carrier protein family but is, more likely, restricted to specific members including ANT.

DOI10.1042/BSR20090063
Alternate JournalBiosci. Rep.
Citation Key10.1042/BSR20090063
PubMed ID19622065
PubMed Central IDPMC2805926
Grant ListMC_U105663137 / / Medical Research Council / United Kingdom
066750/B/01/Z / / Wellcome Trust / United Kingdom
G0400192 / / Medical Research Council / United Kingdom
G0600717 / / Medical Research Council / United Kingdom
065326/Z/01/Z / / Wellcome Trust / United Kingdom