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Reversible Thiol Oxidation Increases Mitochondrial Electron Transport Complex Enzyme Activity but Not Respiration in Cardiomyocytes from Patients with End-Stage Heart Failure.

ABSTRACT: Cardiomyocyte dysfunction in patients with end-stage heart failure with reduced ejection fraction (HFrEF) stems from mitochondrial dysfunction, which contributes to an energetic crisis. Mitochondrial dysfunction reportedly relates to increased markers of oxidative stress, but the impact of reversible thiol oxidation on myocardial mitochondrial function in patients with HFrEF has not been investigated. In the present study, we assessed mitochondrial function in ventricular biopsies from patients with end-stage HFrEF in the presence and absence of the thiol-reducing agent dithiothreitol (DTT). Isolated mitochondria exposed to DTT had increased enzyme activity of complexes I (p = 0.009) and III (p = 0.018) of the electron transport system, while complexes II (p = 0.630) and IV (p = 0.926) showed no changes. However, increased enzyme activity did not carry over to measurements of mitochondrial respiration in permeabilized bundles. Oxidative phosphorylation conductance (p = 0.439), maximal respiration (p = 0.312), and ADP sensitivity (p = 0.514) were unchanged by 5 mM DTT treatment. These results indicate that mitochondrial function can be modulated through reversible thiol oxidation, but other components of mitochondrial energy transfer are rate limiting in end-stage HFrEF. Optimal therapies to normalize cardiac mitochondrial respiration in patients with end-stage HFrEF may benefit from interventions to reverse thiol oxidation, which limits complex I and III activities.

SUBMITTER: Kumar RA

PROVIDER: S-EPMC9330889 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:This proteomic study This proteomic study focuses on the role of reversible thiol oxidation after hexyl aminolevulinate mediated PDT (HAL-PDT). The human epidermoid carcinoma cell line A431 was used as model system and red light as light source, a clinical relevant in vitro model. The light dose dependent cell cytotoxicity was measured by resazurin assay. The most clinical relevant dose, LD100, was used for the proteomic part of the study and cells where harvested 30 min after treatment. The reversibly oxidized thiol proteins were selected by biotinylation and identified by mass spectrometry. This proteomic technique revealed over 1100 thiol proteins which were reversibly oxidized after HAL-PDT. Identified proteins were analysed by bioinformatics (IPA and GO) and a list of reliable identified proteins (282 proteins) where further analysed. Both the cellular location and function was determined for these proteins. In addition, 18 of the proteins where identified as redox regulated, 36 to be a part of the apoptotic pathway and 9 to be both redox regulated and a part of apoptotic pathway. From these results we suggest redox regulated proteins as a trigger mechanism for PDT induced apoptosis.focuses on the role of reversible thiol oxidation after hexyl aminolevulinate mediated PDT (HAL-PDT). The human epidermoid carcinoma cell line A431 was used as model system and red light as light source, a clinical relevant in vitro model. The light dose dependent cell cytotoxicity was measured by resazurin assay. The most clinical relevant dose, LD100, was used for the proteomic part of the study and cells where harvested 30 min after treatment. The reversibly oxidized thiol proteins were selected by biotinylation and identified by mass spectrometry. This proteomic technique revealed over 1100 thiol proteins which were reversibly oxidized after HAL-PDT. Identified proteins were analysed by bioinformatics (IPA and GO) and a list of reliable identified proteins (282 proteins) where further analysed. Both the cellular location and function was determined for these proteins. In addition, 18 of the proteins where identified as redox regulated, 36 to be a part of the apoptotic pathway and 9 to be both redox regulated and a part of apoptotic pathway. From these results we suggest redox regulated proteins as a trigger mechanism for PDT induced apoptosis.

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Reversible Thiol Oxidation Increases Mitochondrial Electron Transport Complex Enzyme Activity but Not Respiration in Cardiomyocytes from Patients with End-Stage Heart Failure.

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