Hepatic ischemia/reperfusion (I/R) injury produces necrosis and apoptosis in a variety of clinical settings, including liver surgery, liver preservation for transplantation, veno-occlusive disease, hemorrhagic shock, heart failure and toxic liver disease. The mitochondrial permeability transition (MPT) is a key mechanism contributing to apoptotic and necrotic hepatocellular death after I/R injury. The overall goal of this project is to understand the molecular mechanisms promoting the MPT and MPT-dependent apoptosis and necrosis after I/R. We hypothesize that: 1) a convergence of cellular and mitochondrial changes including NAD(P)H oxidation, Ca2+ loading, reactive oxygen species (ROS) formation, glutathione depletion and alkalinization contribute to MPT-dependent apoptosis and necrosis after I/R; 2) a combination of iron release from lysosomes (first hit) and mitochondrial superoxide/hydrogen peroxide generation (second hit) acts to initiate hydroxyl radical formation and peroxidation chain reactions to promote MPT onset after I/R; 3) the same mechanisms causing I/R injury to cultured hepatocytes underlie hepatic I/R injury in vivo; and 4) the X-linked inhibitor of apoptosis protein (XIAP) decreases during ischemia and sensitizes hepatocytes to the action of death receptor ligands and MPT-dependent apoptosis after reperfusion. To evaluate these hypotheses, we will use hepatocytes from rats and genetically modified mice to 1) characterize the mechanistic roles of extra- and intramitochondrial alterations (Ca2+, ROS, NAD(P)H, pH, etc.) in MPT induction after I/R to cultured hepatocytes; 2) evaluate the contribution of chelatable iron released from lysosomes in promoting the MPT and cell death after reperfusion; 3) validate findings in cultured hepatocytes in a mouse model of hepatic I/R to show directly that hepatic I/R induces the MPT in vivo, that both apoptosis and necrosis follow the MPT in vivo, and that the major findings and conclusions from Specific Aims 1 and 2 extend to in vivo hepatic I/R; and 4) examine in vitro and in vivo l/R-induced apoptotic signaling in XIAP deficient and wildtype hepatocytes and in hepatocytes with adenoviral XIAP overexpression. The proposed work will combine a variety of experimental approaches, especially confocal and multiphoton microscopy of living hepatocytes labeled with parameter-indicating fluorophores and intravital multiphoton microscopy of livers in anesthetized mice. Our results will enhance the understanding of the molecular mechanisms underlying I/R injury to liver and lead to practical strategies to decrease injury and improve liver function after human hepatic ischemia in a variety of disease states. ? ? ?

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
5R01DK073336-02
Application #
7385085
Study Section
Hepatobiliary Pathophysiology Study Section (HBPP)
Program Officer
Doo, Edward
Project Start
2007-03-20
Project End
2011-02-28
Budget Start
2008-03-01
Budget End
2009-02-28
Support Year
2
Fiscal Year
2008
Total Cost
$293,314
Indirect Cost
Name
Medical University of South Carolina
Department
Pharmacology
Type
Schools of Pharmacy
DUNS #
183710748
City
Charleston
State
SC
Country
United States
Zip Code
29425
Ramshesh, Venkat K; Lemasters, John J (2018) Imaging of Mitochondrial pH Using SNARF-1. Methods Mol Biol 1782:351-356
Zhong, Zhi; Lemasters, John J (2018) A Unifying Hypothesis Linking Hepatic Adaptations for Ethanol Metabolism to the Proinflammatory and Profibrotic Events of Alcoholic Liver Disease. Alcohol Clin Exp Res 42:2072-2089
DeHart, David N; Lemasters, John J; Maldonado, Eduardo N (2018) Erastin-Like Anti-Warburg Agents Prevent Mitochondrial Depolarization Induced by Free Tubulin and Decrease Lactate Formation in Cancer Cells. SLAS Discov 23:23-33
DeHart, David N; Fang, Diana; Heslop, Kareem et al. (2018) Opening of voltage dependent anion channels promotes reactive oxygen species generation, mitochondrial dysfunction and cell death in cancer cells. Biochem Pharmacol 148:155-162
Teplova, Vera V; Kruglov, Alexey G; Kovalyov, Leonid I et al. (2017) Glutamate contributes to alcohol hepatotoxicity by enhancing oxidative stress in mitochondria. J Bioenerg Biomembr 49:253-264
Baburina, Yulia; Odinokova, Irina; Azarashvili, Tamara et al. (2017) 2',3'-Cyclic nucleotide 3'-phosphodiesterase as a messenger of protection of the mitochondrial function during melatonin treatment in aging. Biochim Biophys Acta Biomembr 1859:94-103
Liu, Qinlong; Rehman, Hasibur; Krishnasamy, Yasodha et al. (2017) 8-pCPT-cGMP prevents mitochondrial depolarization and improves the outcome of steatotic partial liver transplantation. Int J Physiol Pathophysiol Pharmacol 9:69-83
Lemasters, John J (2017) Evolution of Voltage-Dependent Anion Channel Function: From Molecular Sieve to Governator to Actuator of Ferroptosis. Front Oncol 7:303
Lemasters, John J; Ramshesh, Venkat K; Lovelace, Gregory L et al. (2017) Compartmentation of Mitochondrial and Oxidative Metabolism in Growing Hair Follicles: A Ring of Fire. J Invest Dermatol 137:1434-1444
Hendriks, Giel; Derr, Remco S; Misovic, Branislav et al. (2016) The Extended ToxTracker Assay Discriminates Between Induction of DNA Damage, Oxidative Stress, and Protein Misfolding. Toxicol Sci 150:190-203

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