title: Alteration in mitochondrial thiol enhances calcium ion dependent membrane permeability transition and dysfunction in vitro: a cross-talk between mtThiol, Ca(2+), and ROS.
abstract: Mitochondrial permeability transition (MPT) and dysfunctions play a pivotal role in many patho-physiological and toxicological conditions. The interplay of mitochondrial thiol (mtThiol), MPT, Ca(2+) homeostasis, and resulting dysfunctions still remains controversial despite studies by several research groups. Present study was undertaken to ascertain the correlation between Ca(2+) homeostasis, mtThiol alteration and reactive oxygen species (ROS) in causing MPT leading to mitochondrial dysfunction. mtThiol depletion significantly enhanced Ca(2+) dependent MPT (swelling) and depolarization of mitochondria resulting in release of pro-apoptotic proteins like Cyt c, AIF, and EndoG. mtThiol alteration and Ca(2+) overload caused reduced mitochondrial electron flow, oxidation of pyridine nucleotides (NAD(P)H) and significantly enhanced ROS generation (DHE and DCFH-DA fluorescence). Studies with MPT inhibitor (Cyclosporin A), Ca(2+) uniport blocker (ruthenium red) and Ca(2+) chelator (BAPTA) indicated that mitochondrial dysfunction was more pronounced under dual stress of altered mtThiol and Ca(2+) overload in comparison with single stress of excessive Ca(2+). Transmission electron microscopy confirmed the changes in mitochondrial integrity under stress. Our findings suggest that the Ca(2+) overload itself is not solely responsible for structural and functional impairment of mitochondria. A multi-factorial cross-talk between mtThiol, Ca(2+) and ROS is responsible for mitochondrial dysfunction. Furthermore, minor depletion of mtThiol was found to be an important factor along with Ca(2+) overload in triggering MPT in isolated mitochondria, tilting the balance towards disturbed functionality.
authors: Herbal Research Section, Indian Institute of Toxicology Research, Formerly-Industrial Toxicology Research Centre, Mahatma Gandhi Marg, Lucknow 226001, Uttar Pradesh, India.
authors: Brijesh Kumar
authors: BK
authors: Singh
authors: Madhulika
authors: M
authors: Tripathi
authors: Pramod Kumar
authors: PK
authors: Pandey
authors: Poonam
authors: P
authors: Kakkar
mesh_terms: D000818:Animals; D051017:Apoptosis Regulatory Proteins / Q000187:drug effects / Q000378:metabolism; D002118:Calcium / Q000378:metabolism* / Q000494:pharmacology; D002463:Cell Membrane Permeability / Q000187:drug effects; D016572:Cyclosporine / Q000494:pharmacology; D004533:Egtazic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D008297:Male; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D008930:Mitochondria, Liver / Q000187:drug effects* / Q000378:metabolism* / Q000473:pathology; D033681:Mitochondrial Membrane Transport Proteins / Q000187:drug effects; D000083162:Mitochondrial Permeability Transition Pore; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D051381:Rats; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species / Q000378:metabolism*; D013438:Sulfhydryl Compounds / Q000032:analysis / Q000378:metabolism*
chemical_list: D051017:Apoptosis Regulatory Proteins; D033681:Mitochondrial Membrane Transport Proteins; D000083162:Mitochondrial Permeability Transition Pore; D017382:Reactive Oxygen Species; D013438:Sulfhydryl Compounds; D004533:Egtazic Acid; D016572:Cyclosporine; C025603:1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid; D002118:Calcium