Myocardial infarction in mice alters sarcomeric function via post-translational protein modification. Mol Cell Biochem 2012 Apr;363(1-2):203-15
Date
12/14/2011Pubmed ID
22160857Pubmed Central ID
PMC3659404DOI
10.1007/s11010-011-1172-zScopus ID
2-s2.0-84857905207 (requires institutional sign-in at Scopus site) 65 CitationsAbstract
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.
Author List
Avner BS, Shioura KM, Scruggs SB, Grachoff M, Geenen DL, Helseth DL Jr, Farjah M, Goldspink PH, Solaro RJMESH terms used to index this publication - Major topics in bold
Amino Acid SequenceAnimals
Calcium
Calcium-Transporting ATPases
Cardiac Myosins
Disease Models, Animal
Dithiothreitol
Electrophoresis, Polyacrylamide Gel
Female
Glutathione
Mice
Molecular Sequence Data
Muscle Proteins
Myocardial Contraction
Myocardial Infarction
Myosin Light Chains
Oxidation-Reduction
Papillary Muscles
Phosphorylation
Protein Processing, Post-Translational
Reactive Oxygen Species
Reducing Agents
Sarcomeres
Stroke Volume
Tropomyosin
Troponin I
Ultrasonography
Ventricular Function, Left
