Tempol prevents cardiac oxidative damage and left ventricular dysfunction in the PPAR-α KO mouse

2013 ◽  
Vol 304 (11) ◽  
pp. H1505-H1512 ◽  
Author(s):  
Aziz Guellich ◽  
Thibaud Damy ◽  
Marc Conti ◽  
Victor Claes ◽  
Jane-Lise Samuel ◽  
...  
Keyword(s):  
Glutathione Peroxidase ◽  
Glutathione Reductase ◽  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Papillary Muscle ◽  
Ex Vivo ◽  
Left Ventricular ◽  
Lv Function ◽  
Wild Type ◽  
Contractile Parameters

Peroxisome proliferator-activated receptor (PPAR)-α deletion induces a profound decrease in MnSOD activity, leading to oxidative stress and left ventricular (LV) dysfunction. We tested the hypothesis that treatment of PPAR-α knockout (KO) mice with the SOD mimetic tempol prevents the heart from pathological remodelling and preserves LV function. Twenty PPAR-α KO mice and 20 age-matched wild-type mice were randomly treated for 8 wk with vehicle or tempol in the drinking water. LV contractile parameters were determined both in vivo using echocardiography and ex vivo using papillary muscle mechanics. Translational and posttranslational modifications of myosin heavy chain protein as well as the expression and activity of major antioxidant enzymes were measured. Tempol treatment did not affect LV function in wild-type mice; however, in PPAR-α KO mice, tempol prevented the decrease in LV ejection fraction and restored the contractile parameters of papillary muscle, including maximum shortening velocity, maximum extent of shortening, and total tension. Moreover, compared with untreated PPAR-α KO mice, myosin heavy chain tyrosine nitration and anion superoxide production were markedly reduced in PPAR-α KO mice after treatment. Tempol also significantly increased glutathione peroxidase and glutathione reductase activities (∼ 50%) in PPAR-α KO mice. In conclusion, these findings demonstrate that treatment with the SOD mimetic tempol can prevent cardiac dysfunction in PPAR-α KO mice by reducing the oxidation of contractile proteins. In addition, we show that the beneficial effects of tempol in PPAR-α KO mice involve activation of the glutathione peroxidase/glutathione reductase system.

scholarly journals Role of oxidative stress in cardiac dysfunction of PPARα−/− mice

2007 ◽  
Vol 293 (1) ◽  
pp. H93-H102 ◽  
Author(s):  
Aziz Guellich ◽  
Thibaud Damy ◽  
Yves Lecarpentier ◽  
Marc Conti ◽  
Victor Claes ◽  
...  
Keyword(s):  
Superoxide Dismutase ◽  
Glutathione Peroxidase ◽  
Papillary Muscle ◽  
Ex Vivo ◽  
Left Ventricular ◽  
Protein Adducts ◽  
Contractile Dysfunction ◽  
Wild Type ◽  
Copper Zinc

This study was designed to determine the effects of PPARα lack on cardiac mechanical performance and to identify potential intracellular mechanisms linking PPARα pathway deficiency to cardiac contractile dysfunction. Echocardiography, ex vivo papillary muscle assays, and in vitro motility assays were used to assess global, intrinsic ventricular muscle performance and myosin mechanical properties, respectively, in PPARα−/− and age-matched wild-type mice. Three-nitrotyrosine formation and 4-hydroxy-2-nonenal protein-adducts, both markers of oxidative damage, were analyzed by Western blot analysis and immunolabeling. Radical scavenging capacity was analyzed by measuring protein levels and/or activities of the main antioxidant enzymes, including catalase, glutathione peroxidase, and manganese and copper-zinc superoxide dismutases. Echocardiographic left ventricular fractional shortening in PPARα−/− was 16% lower than that in wild-type. Ex vivo left ventricular papillary muscle exhibited reduced shortening velocity and isometric tension (three- and twofold, respectively). In vitro myosin-based velocity was ≈20% slower in PPARα−/−, indicating that myosin itself was involved in the contractile dysfunction. Staining of 3-nitrotyrosine was more pronounced in PPARα−/−, and myosin heavy chain was the main nitrated protein. Formation of 3-nitrotyrosine myosin heavy chain was twofold higher in PPARα−/− and 4-hydroxy-2-nonenal protein-adducts were threefold higher. The expression and activity of manganese superoxide dismutase were respectively 33% and 50% lower in PPARα−/−, with no changes in copper-zinc superoxide dismutase, catalase, or glutathione peroxidase. These findings demonstrate that PPARα pathway deficiency impairs cardiac function and also identify oxidative damage to myosin as a link between PPARα deficiency and contractile dysfunction.

scholarly journals Novel Myosin Heavy Chain Kinase Involved in Disassembly of Myosin II Filaments and Efficient Cleavage in MitoticDictyostelium Cells

2002 ◽  
Vol 13 (12) ◽  
pp. 4333-4342 ◽  
Author(s):  
Akira Nagasaki ◽  
Go Itoh ◽  
Shigehiko Yumura ◽  
Taro Q.P. Uyeda
Keyword(s):  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Myosin Ii ◽  
Kinase Domain ◽  
Cleavage Furrow ◽  
Wild Type ◽  
Daughter Cells ◽  
Cleavage Process ◽  
Interphase Cells ◽  
Myosin Heavy Chain Kinase

We have cloned a full-length cDNA encoding a novel myosin II heavy chain kinase (mhckC) from Dictyostelium. Like other members of the myosin heavy chain kinase family, themhckC gene product, MHCK C, has a kinase domain in its N-terminal half and six WD repeats in the C-terminal half. GFP-MHCK C fusion protein localized to the cortex of interphase cells, to the cleavage furrow of mitotic cells, and to the posterior of migrating cells. These distributions of GFP-MHCK C always corresponded with that of myosin II filaments and were not observed in myosin II-null cells, where GFP-MHCK C was diffusely distributed in the cytoplasm. Thus, localization of MHCK C seems to be myosin II-dependent. Cells lacking the mhckC gene exhibited excessive aggregation of myosin II filaments in the cleavage furrows and in the posteriors of the daughter cells once cleavage was complete. The cleavage process of these cells took longer than that of wild-type cells. Taken together, these findings suggest MHCK C drives the disassembly of myosin II filaments for efficient cytokinesis and recycling of myosin II that occurs during cytokinesis.

scholarly journals Computational Investigation of Transmural Differences in Left Ventricular Contractility

2016 ◽  
Vol 138 (11) ◽  
Author(s):  
Hua Wang ◽  
Xiaoyan Zhang ◽  
Shauna M. Dorsey ◽  
Jeremy R. McGarvey ◽  
Kenneth S. Campbell ◽  
...  
Keyword(s):  
Myocardial Contractility ◽  
Ex Vivo ◽  
Experimental Studies ◽  
Contractile Force ◽  
Left Ventricular ◽  
Lv Function ◽  
Fe Model ◽  
Myocardial Layers ◽  
Best Fit

Myocardial contractility of the left ventricle (LV) plays an essential role in maintaining normal pump function. A recent ex vivo experimental study showed that cardiomyocyte force generation varies across the three myocardial layers of the LV wall. However, the in vivo distribution of myocardial contractile force is still unclear. The current study was designed to investigate the in vivo transmural distribution of myocardial contractility using a noninvasive computational approach. For this purpose, four cases with different transmural distributions of maximum isometric tension (Tmax) and/or reference sarcomere length (lR) were tested with animal-specific finite element (FE) models, in combination with magnetic resonance imaging (MRI), pressure catheterization, and numerical optimization. Results of the current study showed that the best fit with in vivo MRI-derived deformation was obtained when Tmax assumed different values in the subendocardium, midmyocardium, and subepicardium with transmurally varying lR. These results are consistent with recent ex vivo experimental studies, which showed that the midmyocardium produces more contractile force than the other transmural layers. The systolic strain calculated from the best-fit FE model was in good agreement with MRI data. Therefore, the proposed noninvasive approach has the capability to predict the transmural distribution of myocardial contractility. Moreover, FE models with a nonuniform distribution of myocardial contractility could provide a better representation of LV function and be used to investigate the effects of transmural changes due to heart disease.

scholarly journals Impaired left ventricular mechanical and energetic function in mice after cardiomyocyte-specific excision of Serca2

2014 ◽  
Vol 306 (7) ◽  
pp. H1018-H1024 ◽  
Author(s):  
N. T. Boardman ◽  
J. M. Aronsen ◽  
W. E. Louch ◽  
I. Sjaastad ◽  
F. Willoch ◽  
...  
Keyword(s):  
Ex Vivo ◽  
Left Ventricular ◽  
Lv Function ◽  
Mechanical Function ◽  
Transport Mechanisms ◽  
Working Capacity ◽  
Excitation Contraction Coupling ◽  
Contraction Coupling ◽  
Plasmic Reticulum ◽  
The Relationship

Sarco(endo)plasmic reticulum Ca2+-ATPase (SERCA)2 transports Ca2+ from the cytosol into the sarcoplasmic reticulum of cardiomyocytes and is essential for maintaining myocardial Ca2+ handling and thus the mechanical function of the heart. SERCA2 is a major ATP consumer in excitation-contraction coupling but is regarded to contribute to energetically efficient Ca2+ handling in the cardiomyocyte. Previous studies using cardiomyocyte-specific SERCA2 knockout (KO) mice have demonstrated that decreased SERCA2 activity reduces the Ca2+ transient amplitude and induces compensatory Ca2+ transport mechanisms that may lead to more inefficient Ca2+ transport. In this study, we examined the relationship between left ventricular (LV) function and myocardial O2 consumption (MV̇o2) in ex vivo hearts from SERCA2 KO mice to directly measure how SERCA2 elimination influences mechanical and energetic features of the heart. Ex vivo hearts from SERCA2 KO hearts developed mechanical dysfunction at 4 wk and demonstrated virtually no working capacity at 7 wk. In accordance with the reported reduction in Ca2+ transient amplitude in cardiomyocytes from SERCA2 KO mice, work-independent MV̇o2 was decreased due to a reduced energy cost of excitation-contraction coupling. As these hearts also showed a marked impairment in the efficiency of chemomechanical energy transduction (contractile efficiency, i.e, work-dependent MV̇o2), hearts from SERCA2 KO mice were found to be mechanically inefficient. This ex vivo evaluation of mechanical and energetic function in hearts from SERCA2 KO mice brings together findings from previous experimental and mathematical modeling-based studies and demonstrates that reduced SERCA2 activity not only leads to mechanical dysfunction but also to energetic dysfunction.

Regulation of β myosin heavy chain, c-myc and c-fos proto-oncogenes in thyroid hormone-induced hypertrophy of the rat myocardium

1993 ◽  
Vol 84 (1) ◽  
pp. 61-67 ◽  
Author(s):  
N. K. Green ◽  
M. D. Gammage ◽  
J. A. Franklyn ◽  
A. M. Heagerty ◽  
M. C. Sheppard
Keyword(s):  
Thyroid Hormone ◽  
Right Ventricular ◽  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Molecular Mechanisms ◽  
Left Ventricular ◽  
Transcriptional Level ◽  
Messenger Rnas ◽  
Hypertrophic Response ◽  
Left And Right

1. In order to investigate the molecular mechanisms determining the hypertrophic response of the ventricular myocardium to thyroid hormone administration, changes in left and right ventricular expression of the c-myc, c-fos and H-ras proto-oncogenes in response to treatment with 3,3′,5-tri-iodothyronine were defined. 2. Adult female Wistar rats were treated with daily subcutaneous injections of 3,3′,5-tri-iodothyronine (50 μg) for 1, 3, 7 or 14 days (n = 6 in each treatment group) and the results from 3,3′,5-tri-iodothyronine-treated animals were compared with those obtained from untreated controls (n = 6). Changes in the weight of the left and right ventricles in response to 3,3′,5-tri-iodothyronine treatment were measured; changes in expression of the c-myc, c-fos and H-ras proto-oncogenes were determined in parallel by measurement of specific messenger RNAs by Northern and dot hybridization, as well as changes in expression of β myosin heavy chain messenger RNA. 3. Treatment with 3,3′,5-tri-iodothyronine resulted in increases in both left and right ventricular weights after 3 days, an effect maintained up to 14 days. Despite an increase in left ventricular weight, levels of β myosin heavy chain, c-myc, c-fos and H-ras mRNAs in the left ventricle were unchanged; in contrast, an increase in right ventricular weight was associated with increased expression of β myosin heavy chain, c-myc and c-fos messenger RNAs. 4. These specific ventricular changes in gene expression, in the face of a hypertrophic response of both ventricles to 3,3′,5-tri-iodothyronine, suggest that the cardiac growth response to thyroid hormones reflects the well-documented secondary haemodynamic influences rather than direct gene regulatory actions of 3,3′,5-tri-iodothyronine at the transcriptional level on the genes studied. Changes in right ventricular proto-oncogene and β myosin heavy chain expression may in turn reflect an increase in right ventricular pressure load.

scholarly journals A novel positive selection for identifying cold-sensitive myosin II mutants in Dictyostelium.

Genetics ◽  
1995 ◽  
Vol 140 (2) ◽  
pp. 505-515 ◽  
Author(s):  
B Patterson ◽  
J A Spudich
Keyword(s):  
Positive Selection ◽  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Time Scale ◽  
Myosin Ii ◽  
Rapid Onset ◽  
Chemical Mutagenesis ◽  
Wild Type ◽  
Cold Sensitive ◽  
Selection For

Abstract We developed a positive selection for myosin heavy chain mutants in Dictyostelium. This selection is based on the fact that brief exposure to azide causes wild-type cells to release from the substrate, whereas myosin null cells remain adherent. This procedure assays myosin function on a time scale of minutes and has therefore allowed us to select rapid-onset cold-sensitive mutants after random chemical mutagenesis of Dictyostelium cells. We developed a rapid technique for determining which mutations lie in sequences of the myosin gene that encode the head (motor) domain and localized 27 of 34 mutants to this domain. We recovered the appropriate sequences from five of the mutants and demonstrated that they retain their cold-sensitive properties when expressed from extrachromosomal plasmids.

Aberrant pattern formation in myosin heavy chain mutants of Dictyostelium

Development ◽  
1994 ◽  
Vol 120 (3) ◽  
pp. 591-601 ◽  
Author(s):  
D. Traynor ◽  
M. Tasaka ◽  
T. Takeuchi ◽  
J. Williams
Keyword(s):  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Cell Types ◽  
Culture Conditions ◽  
Wild Type ◽  
Multicellular Aggregate ◽  
A Cells ◽  
Air Water Interface ◽  
Shape Changes ◽  
Roller Tube Culture

In mutant Dictyostelium strains that fail to accumulate the myosin heavy chain (MHC A), development is relatively normal up to the tight aggregate stage but is arrested prior to formation of the apical tip (DeLozanne and Spudich 1987, Knecht and Loomis, 1987). We show that in aggregates formed by such MHC A deficient (MHC A-) strains the proportions of pstA and pstB cells, the two prestalk cell types, and of prespore cells are similar to those found during normal development but their distribution is radically different. During the initial stages of normal slug formation, pstA cells move to the tip, pstB cells accumulate in the base and prespore cells occupy the remainder of the aggregate. In the aggregates initially formed by MHC A- mutants pstA cells are present in a central core, pstB cells are present in the cortex and prespore cells lie sandwiched between them. Eventually, cells within the cortex differentiate into mature stalk cells but spores are never formed. Mixing experiments, in which MHC A- cells are allowed to co-aggregate with an excess of normal cells, show that MHC A- prestalk cells enter the aggregate relatively normally but are unable to enter the slug tip or to migrate into the stalk at culmination and that MHC A- prespore cells accumulate in the lower part of the spore head during culmination. Thus MHC A- cells appear to be able to move within the multicellular aggregate but are incapable of participating in normal morphogenesis. The structures formed by MHC A- cells are very similar to those of the agglomerates that form when wild-type cells are developed in roller-tube culture, conditions that result in loss of the polarity imparted by the presence of an air-water interface. We propose formation of such a structure by MHC A- cells to be a default response, caused by their inability to undertake the shape changes and intercalatory cell movements that are necessary to form and extend the tip.

scholarly journals Ifm(2)2 is a myosin heavy chain allele that disrupts myofibrillar assembly only in the indirect flight muscle of Drosophila melanogaster.

1988 ◽  
Vol 107 (6) ◽  
pp. 2613-2621 ◽  
Author(s):  
M Chun ◽  
S Falkenthal
Keyword(s):  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Flight Muscle ◽  
Microscopic Analysis ◽  
Thick Filament ◽  
Indirect Flight Muscle ◽  
Chain Gene ◽  
Wild Type ◽  
Electron Microscopic ◽  
Sarcomere Assembly

Using a combination of molecular and genetic techniques we demonstrate that Ifm(2)2 is an allele of the single-copy sarcomeric myosin heavy chain gene. Flies homozygous for this allele accumulate wild-type levels of mRNA and protein in tubular muscle of adults, but fail to accumulate detectable amounts of myosin heavy chain mRNA or protein in the indirect flight muscle. We propose that the mutation interferes with either transcription of the gene or splicing of the primary transcript in the indirect flight muscle and not in other muscle tissues. Biochemical and electron microscopic analysis of flies homozygous for this mutation has revealed that thick filament assembly is abolished in the indirect flight muscle resulting in the instability of wild-type thick filament proteins. In contrast, thin filament and Z disc assembly are marginally affected. We discuss a working hypothesis for sarcomere assembly and define and experimental approach to test the predictions of this proposed pathway for sarcomere assembly.

scholarly journals Effects of low-level α-myosin heavy chain expression on contractile kinetics in porcine myocardium

2011 ◽  
Vol 300 (3) ◽  
pp. H869-H878 ◽  
Author(s):  
Matthew R. Locher ◽  
Maria V. Razumova ◽  
Julian E. Stelzer ◽  
Holly S. Norman ◽  
Richard L. Moss
Keyword(s):  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Rate Constants ◽  
Isometric Force ◽  
Systolic Function ◽  
Specific Effect ◽  
Ventricular Myocardium ◽  
Left Ventricular ◽  
Right Atrial ◽  
Low Level

Myosin heavy chain (MHC) isoforms are principal determinants of work capacity in mammalian ventricular myocardium. The ventricles of large mammals including humans normally express ∼10% α-MHC on a predominantly β-MHC background, while in failing human ventricles α-MHC is virtually eliminated, suggesting that low-level α-MHC expression in normal myocardium can accelerate the kinetics of contraction and augment systolic function. To test this hypothesis in a model similar to human myocardium we determined composite rate constants of cross-bridge attachment ( fapp) and detachment ( gapp) in porcine myocardium expressing either 100% α-MHC or 100% β-MHC in order to predict the MHC isoform-specific effect on twitch kinetics. Right atrial (∼100% α-MHC) and left ventricular (∼100% β-MHC) tissue was used to measure myosin ATPase activity, isometric force, and the rate constant of force redevelopment ( ktr) in solutions of varying Ca2+ concentration. The rate of ATP utilization and ktr were approximately ninefold higher in atrial compared with ventricular myocardium, while tension cost was approximately eightfold greater in atrial myocardium. From these values, we calculated fapp to be ∼10-fold higher in α- compared with β-MHC, while gapp was 8-fold higher in α-MHC. Mathematical modeling of an isometric twitch using these rate constants predicts that the expression of 10% α-MHC increases the maximal rate of rise of force (dF/d tmax) by 92% compared with 0% α-MHC. These results suggest that low-level expression of α-MHC significantly accelerates myocardial twitch kinetics, thereby enhancing systolic function in large mammalian myocardium.

scholarly journals Point Mutations in Human β Cardiac Myosin Heavy Chain Have Differential Effects on Sarcomeric Structure and Assembly: An ATP Binding Site Change Disrupts Both Thick and Thin Filaments, Whereas Hypertrophic Cardiomyopathy Mutations Display Normal Assembly

1997 ◽  
Vol 137 (1) ◽  
pp. 131-140 ◽  
Author(s):  
K. David Becker ◽  
Kim R. Gottshall ◽  
Reed Hickey ◽  
Jean-Claude Perriard ◽  
Kenneth R. Chien
Keyword(s):  
Hypertrophic Cardiomyopathy ◽  
Subcellular Localization ◽  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Point Mutations ◽  
Neonatal Rat ◽  
Atp Binding ◽  
Cardiac Myosin ◽  
Wild Type ◽  
Thick Filaments

Hypertrophic cardiomyopathy is a human heart disease characterized by increased ventricular mass, focal areas of fibrosis, myocyte, and myofibrillar disorganization. This genetically dominant disease can be caused by mutations in any one of several contractile proteins, including β cardiac myosin heavy chain (βMHC). To determine whether point mutations in human βMHC have direct effects on interfering with filament assembly and sarcomeric structure, full-length wild-type and mutant human βMHC cDNAs were cloned and expressed in primary cultures of neonatal rat ventricular cardiomyocytes (NRC) under conditions that promote myofibrillogenesis. A lysine to arginine change at amino acid 184 in the consensus ATP binding sequence of human βMHC resulted in abnormal subcellular localization and disrupted both thick and thin filament structure in transfected NRC. Diffuse βMHC K184R protein appeared to colocalize with actin throughout the myocyte, suggesting a tight interaction of these two proteins. Human βMHC with S472V mutation assembled normally into thick filaments and did not affect sarcomeric structure. Two mutant myosins previously described as causing human hypertrophic cardiomyopathy, R249Q and R403Q, were competent to assemble into thick filaments producing myofibrils with well defined I bands, A bands, and H zones. Coexpression and detection of wild-type βMHC and either R249Q or R403Q proteins in the same myocyte showed these proteins are equally able to assemble into the sarcomere and provided no discernible differences in subcellular localization. Thus, human βMHC R249Q and R403Q mutant proteins were readily incorporated into NRC sarcomeres and did not disrupt myofilament formation. This study indicates that the phenotype of myofibrillar disarray seen in HCM patients which harbor either of these two mutations may not be directly due to the failure of the mutant myosin heavy chain protein to assemble and form normal sarcomeres, but may rather be a secondary effect possibly resulting from the chronic stress of decreased βMHC function.

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