title: Myocardial infarction in mice alters sarcomeric function via post-translational protein modification.
abstract: Myocardial physiology in the aftermath of myocardial infarction (MI) before remodeling is an under-explored area of investigation. Here, we describe the effects of MI on the cardiac sarcomere with focus on the possible contributions of reactive oxygen species. We surgically induced MI in 6-7-month-old female CD1 mice by ligation of the left anterior descending coronary artery. Data were collected 3-4 days after MI or sham (SH) surgery. MI hearts demonstrated ventricular dilatation and systolic dysfunction upon echo cardiographic analysis. Sub-maximum Ca-activated tension in detergent-extracted fiber bundles from papillary muscles increased significantly in the preparations from MI hearts. Ca(2+) sensitivity increased after MI, whereas cooperativity of activation decreased. To assess myosin enzymatic integrity we measured splitting of Ca-ATP in myofibrillar preparations, which demonstrated a decline in Ca-ATPase activity of myofilament myosin. Biochemical analysis demonstrated post-translational modification of sarcomeric proteins. Phosphorylation of cardiac troponin I and myosin light chain 2 was reduced after MI in papillary samples, as measured using a phospho-specific stain. Tropomyosin was oxidized after MI, forming disulfide products detectable by diagonal non-reducing-reducing SDS-PAGE. Our analysis of myocardial protein oxidation post-MI also demonstrated increased S-glutathionylation. We functionally linked protein oxidation with sarcomere function by treating skinned fibers with the sulfhydryl reducing agent dithiothreitol, which reduced Ca(2+) sensitivity in MI, but not SH, samples. Our data indicate important structural and functional alterations to the cardiac sarcomere after MI, and the contribution of protein oxidation to this process.
authors.affiliation: Department of Physiology and Biophysics, (M/C 901), College of Medicine, University of Illinois at Chicago, 835 S. Wolcott Ave., Chicago, IL 60612-7342, USA.
authors.forename: Benjamin S
authors.initials: BS
authors.lastname: Avner
authors.forename: Krystyna M
authors.initials: KM
authors.lastname: Shioura
authors.forename: Sarah B
authors.initials: SB
authors.lastname: Scruggs
authors.forename: Milana
authors.initials: M
authors.lastname: Grachoff
authors.forename: David L
authors.initials: DL
authors.lastname: Geenen
authors.forename: Donald L
authors.initials: DL
authors.lastname: Helseth
authors.forename: Mariam
authors.initials: M
authors.lastname: Farjah
authors.forename: Paul H
authors.initials: PH
authors.lastname: Goldspink
authors.forename: R John
authors.initials: RJ
authors.lastname: Solaro
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002118:Calcium / Q000378:metabolism; D000252:Calcium-Transporting ATPases / Q000378:metabolism; D024722:Cardiac Myosins / Q000378:metabolism; D004195:Disease Models, Animal; D004229:Dithiothreitol / Q000494:pharmacology; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D005978:Glutathione / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D009124:Muscle Proteins / Q000378:metabolism*; D009200:Myocardial Contraction; D009203:Myocardial Infarction / Q000000981:diagnostic imaging / Q000378:metabolism* / Q000503:physiopathology; D018994:Myosin Light Chains / Q000378:metabolism; D010084:Oxidation-Reduction; D010210:Papillary Muscles / Q000187:drug effects / Q000378:metabolism* / Q000503:physiopathology; D010766:Phosphorylation; D011499:Protein Processing, Post-Translational; D017382:Reactive Oxygen Species / Q000378:metabolism; D019163:Reducing Agents / Q000494:pharmacology; D012518:Sarcomeres / Q000187:drug effects / Q000378:metabolism*; D013318:Stroke Volume; D014335:Tropomyosin / Q000378:metabolism; D019210:Troponin I / Q000378:metabolism; D014463:Ultrasonography; D016277:Ventricular Function, Left
chemical_list: D009124:Muscle Proteins; D018994:Myosin Light Chains; D017382:Reactive Oxygen Species; D019163:Reducing Agents; D014335:Tropomyosin; D019210:Troponin I; C107184:myosin light chain 2; D024722:Cardiac Myosins; D000252:Calcium-Transporting ATPases; D005978:Glutathione; D002118:Calcium; D004229:Dithiothreitol