title: Heme-induced contractile dysfunction in human cardiomyocytes caused by oxidant damage to thick filament proteins.
abstract: Intracellular free heme predisposes to oxidant-mediated tissue damage. We hypothesized that free heme causes alterations in myocardial contractility via disturbed structure and/or regulation of the contractile proteins. Isometric force production and its Ca(2+)-sensitivity (pCa50) were monitored in permeabilized human ventricular cardiomyocytes. Heme exposure altered cardiomyocyte morphology and evoked robust decreases in Ca(2+)-activated maximal active force (Fo) while increasing Ca(2+)-independent passive force (F passive). Heme treatments, either alone or in combination with H2O2, did not affect pCa50. The increase in F passive started at 3 µM heme exposure and could be partially reversed by the antioxidant dithiothreitol. Protein sulfhydryl (SH) groups of thick myofilament content decreased and sulfenic acid formation increased after treatment with heme. Partial restoration in the SH group content was observed in a protein running at 140 kDa after treatment with dithiothreitol, but not in other proteins, such as filamin C, myosin heavy chain, cardiac myosin binding protein C, and α-actinin. Importantly, binding of heme to hemopexin or alpha-1-microglobulin prevented its effects on cardiomyocyte contractility, suggesting an allosteric effect. In line with this, free heme directly bound to myosin light chain 1 in human cardiomyocytes. Our observations suggest that free heme modifies cardiac contractile proteins via posttranslational protein modifications and via binding to myosin light chain 1, leading to severe contractile dysfunction. This may contribute to systolic and diastolic cardiac dysfunctions in hemolytic diseases, heart failure, and myocardial ischemia-reperfusion injury.
authors.affiliation: Division of Clinical Physiology, Institute of Cardiology, Faculty of Medicine, University of Debrecen, H-4032 Debrecen, Hungary; Department of Nephrology, Institute of Internal Medicine, Faculty of Medicine, University of Debrecen, H-4032 Debrecen, Hungary.
authors.forename: Gerardo
authors.initials: G
authors.lastname: Alvarado
authors.affiliation: Department of Nephrology, Institute of Internal Medicine, Faculty of Medicine, University of Debrecen, H-4032 Debrecen, Hungary; MTA-DE Vascular Biology, Thrombosis and Hemostasis Research Group, Hungarian Academy of Sciences, H-4032 Debrecen, Hungary.
authors.forename: Viktória
authors.initials: V
authors.lastname: Jeney
authors.affiliation: Division of Clinical Physiology, Institute of Cardiology, Faculty of Medicine, University of Debrecen, H-4032 Debrecen, Hungary.
authors.forename: Attila
authors.initials: A
authors.lastname: Tóth
authors.affiliation: Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Debrecen, H-4032 Debrecen, Hungary.
authors.forename: Éva
authors.initials: É
authors.lastname: Csősz
authors.affiliation: Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Debrecen, H-4032 Debrecen, Hungary.
authors.forename: Gergő
authors.initials: G
authors.lastname: Kalló
authors.affiliation: Division of Clinical Physiology, Institute of Cardiology, Faculty of Medicine, University of Debrecen, H-4032 Debrecen, Hungary.
authors.forename: An T
authors.initials: AT
authors.lastname: Huynh
authors.affiliation: Division of Clinical Physiology, Institute of Cardiology, Faculty of Medicine, University of Debrecen, H-4032 Debrecen, Hungary.
authors.forename: Csaba
authors.initials: C
authors.lastname: Hajnal
authors.affiliation: Division of Clinical Physiology, Institute of Cardiology, Faculty of Medicine, University of Debrecen, H-4032 Debrecen, Hungary.
authors.forename: Judit
authors.initials: J
authors.lastname: Kalász
authors.affiliation: Division of Clinical Physiology, Institute of Cardiology, Faculty of Medicine, University of Debrecen, H-4032 Debrecen, Hungary.
authors.forename: Enikő T
authors.initials: ET
authors.lastname: Pásztor
authors.affiliation: Division of Clinical Physiology, Institute of Cardiology, Faculty of Medicine, University of Debrecen, H-4032 Debrecen, Hungary.
authors.forename: István
authors.initials: I
authors.lastname: Édes
authors.affiliation: Department of Clinical Sciences, Division of Infection Medicine, Lund University, Lund, Sweden.
authors.forename: Magnus
authors.initials: M
authors.lastname: Gram
authors.affiliation: Department of Clinical Sciences, Division of Infection Medicine, Lund University, Lund, Sweden.
authors.forename: Bo
authors.initials: B
authors.lastname: Akerström
authors.affiliation: School of Biological Sciences, University of Missouri-Kansas City, MO, USA.
authors.forename: Ann
authors.initials: A
authors.lastname: Smith
authors.affiliation: Molecular Targets Program, James Graham Brown Cancer Center, University of Louisville, Louisville, KY 40059, USA.
authors.forename: John W
authors.initials: JW
authors.lastname: Eaton
authors.affiliation: MTA-DE Vascular Biology, Thrombosis and Hemostasis Research Group, Hungarian Academy of Sciences, H-4032 Debrecen, Hungary; Institute of Pediatrics, Faculty of Medicine, University of Debrecen, H-4032 Debrecen, Hungary.
authors.forename: György
authors.initials: G
authors.lastname: Balla
authors.affiliation: Division of Clinical Physiology, Institute of Cardiology, Faculty of Medicine, University of Debrecen, H-4032 Debrecen, Hungary.
authors.forename: Zoltán
authors.initials: Z
authors.lastname: Papp
authors.affiliation: Department of Nephrology, Institute of Internal Medicine, Faculty of Medicine, University of Debrecen, H-4032 Debrecen, Hungary; MTA-DE Vascular Biology, Thrombosis and Hemostasis Research Group, Hungarian Academy of Sciences, H-4032 Debrecen, Hungary. Electronic address: balla@internal.med.unideb.hu.
authors.forename: József
authors.initials: J
authors.lastname: Balla
mesh_terms: D008841:Actin Cytoskeleton; D000185:Actinin / Q000378:metabolism; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism; D002352:Carrier Proteins / Q000378:metabolism; D002478:Cells, Cultured; D064448:Filamins / Q000378:metabolism; D006352:Heart Ventricles / Q000187:drug effects / Q000378:metabolism / Q000473:pathology*; D006418:Heme / Q000494:pharmacology*; D006801:Humans; D015151:Immunoblotting; D009200:Myocardial Contraction / Q000187:drug effects*; D032383:Myocytes, Cardiac / Q000187:drug effects / Q000378:metabolism / Q000473:pathology*; D009219:Myosin-Light-Chain Kinase / Q000378:metabolism*; D016877:Oxidants / Q000494:pharmacology; D011499:Protein Processing, Post-Translational; D015800:Protozoan Proteins / Q000378:metabolism; D000099163:Myosin Binding Protein C
chemical_list: D000185:Actinin; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D002352:Carrier Proteins; D064448:Filamins; D006418:Heme; D009219:Myosin-Light-Chain Kinase; D016877:Oxidants; D015800:Protozoan Proteins; D000099163:Myosin Binding Protein C; C033142:myosin-heavy-chain kinase
keywords: Calcium sensitivity; Cardiac myosin binding protein C; Cardiomyocyte; Contractile function; H(2)O(2); Heme; Myosin heavy chain; Myosin light chain 1; Oxidation; Sulfenic acid; Titin