Abstract 200: Beta-Myosin Heavy Chain Induction after Pressure Overload Is in a Minor Sub-population of Myocytes and Requires the Alpha-1A-Adrenergic Receptor

Circulation ◽  
2007 ◽  
Vol 116 (suppl_16) ◽  
Author(s):  
Javier E Lopez ◽  
Bat-Erdene Myagmar ◽  
Philip Swigart ◽  
Marty Bigos ◽  
Manoj Rodrigo ◽  
...  
Keyword(s):  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Adrenergic Receptor ◽  
Pressure Overload ◽  
Transverse Aortic Constriction ◽  
Wild Type ◽  
Rt Pcr ◽  
Aortic Constriction ◽  
Double Knockout ◽  
A Minor

Background: Induction of the fetal hypertrophic gene beta-myosin heavy chain (MHC) is a signature feature of pressure overload, and is thought to occur in most hypertrophied myocytes. Beta-MHC mRNA is not induced after transverse aortic constriction (TAC) in a double knockout (KO) model of the alpha-1A and alpha-1B-adrenergic receptor (AR) subtypes, but it is unknown whether the A or B or both are required. Hypothesis: We tested the hypothesis that native beta-MHC protein induction is in a sub-population of myocytes and requires only a single alpha-1 subtype. Methods: TAC was done in wild type (WT) and alpha-1 KO male mice ages 12–14 weeks. Beta-MHC protein was measured in isolated adult myocytes by a novel flow cytometry approach, with antibodies validated for beta-MHC and total sarcomeric MHC. Results: In WT mice, the fraction of myocytes expressing beta-MHC was 3% in shams (SE =1, n =4 hearts), and increased to 26% of myocytes at 1–3 weeks after TAC (SE =4, n =8, p< 0.01 vs. sham). Myocytes expressing beta-MHC were predominantly large cells (see Figure ). In alpha-1A KO mice (AKO), beta-MHC was induced in only 6% of myocytes (SE =2, n =3, p<0.05 vs. WT TAC, p =NS vs. sham), or in only 15% as many myocytes as in WT hearts. Western blotting and quantitative RT-PCR confirmed reduced beta-MHC induction in alpha-1A KO myocytes. Conclusion: Beta-MHC induction after pressure overload is in only a minor sub-population of cardiac myocytes, contrary to common models of fetal hypertrophic gene induction. Furthermore, beta-MHC induction requires a single alpha-1-AR subtype, the alpha-1A, which cannot be compensated by other hypertrophic receptors.

scholarly journals β-Myosin Heavy Chain Is Induced by Pressure Overload in a Minor Subpopulation of Smaller Mouse Cardiac Myocytes

2011 ◽  
Vol 109 (6) ◽  
pp. 629-638 ◽  
Author(s):  
Javier E. López ◽  
Bat-Erdene Myagmar ◽  
Philip M. Swigart ◽  
Megan D. Montgomery ◽  
Stephen Haynam ◽  
...  
Keyword(s):  
Myosin Heavy Chain ◽  
Cardiac Myocytes ◽  
Heavy Chain ◽  
Pressure Overload ◽  
A Minor

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 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.

scholarly journals Aerobic Exercise Attenuates Pressure Overload-Induced Cardiac Dysfunction through Promoting Skeletal Muscle Microcirculation and Increasing Muscle Mass

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Ling-Yan Yuan ◽  
Pei-Zhao Du ◽  
Min-Min Wei ◽  
Qi Zhang ◽  
Le Lu ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Cardiac Function ◽  
Aerobic Exercise ◽  
Muscle Mass ◽  
Cardiac Dysfunction ◽  
Pressure Overload ◽  
Transverse Aortic Constriction ◽  
Aortic Constriction ◽  
Protein Levels ◽  
Skeletal Muscle Microcirculation

Background. Aerobic exercise has been proven to have a positive effect on cardiac function after hypertension; however, the mechanism is not entirely clarified. Skeletal muscle mass and microcirculation are closely associated with blood pressure and cardiac function. Objective. This study was designed to investigate the effects of aerobic exercise on the skeletal muscle capillary and muscle mass, to explore the possible mechanisms involved in exercise-induced mitigation of cardiac dysfunction in pressure overload mice. Methods. In this study, 60 BALB/C mice aged 8 weeks were randomly divided into 3 groups: control (CON), TAC, and TAC plus exercise (TAE) group and utilized transverse aortic constriction (TAC) to establish hypertensive model; meanwhile, treadmill training is used for aerobic exercise. After 5 days of recovery, mice in the TAE group were subjected to 10-week aerobic exercise. Carotid pressure and cardiac function were examined before mice were executed by Millar catheter and ultrasound, respectively. Muscle mass of gastrocnemius was weighed; cross-sectional area and the number of capillaries of gastrocnemius were detected by HE and immunohistochemistry, respectively. The mRNA and protein levels of VEGF in skeletal muscle were determined by RT-PCR and western blot, respectively. Results. We found that ① 10-week aerobic exercise counteracted hypertension and attenuated cardiac dysfunction in TAC-induced hypertensive mice; ② TAC decreased muscle mass of gastrocnemius and resulted in muscle atrophy, while 10-week aerobic exercise could reserve transverse aortic constriction-induced the decline of muscle mass and muscle atrophy; and ③ TAC reduced the number of capillaries and the protein level of VEGF in gastrocnemius, whereas 10-week aerobic exercise augmented the number of capillaries, the mRNA and protein levels of VEGF in mice were subjected to TAC surgery. Conclusions. This study indicates that 10-week aerobic exercise might fulfill its blood pressure-lowering effect via improving skeletal muscle microcirculation and increasing muscle mass.

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 Molecular Alterations in the Stomach of Tff1-Deficient Mice: Early Steps in Antral Carcinogenesis

2020 ◽  
Vol 21 (2) ◽  
pp. 644 ◽  
Author(s):  
Eva B. Znalesniak ◽  
Franz Salm ◽  
Werner Hoffmann
Keyword(s):  
Cysteine Residue ◽  
Molecular Forms ◽  
Amino Acid Residues ◽  
Wild Type ◽  
Rt Pcr ◽  
Molecular Alterations ◽  
Protein Levels ◽  
Increased Sensitivity ◽  
A Minor ◽  
Deficient Mice

TFF1 is a peptide of the gastric mucosa co-secreted with the mucin MUC5AC. It plays a key role in gastric mucosal protection and repair. Tff1-deficient (Tff1KO) mice obligatorily develop antropyloric adenoma and about 30% progress to carcinomas. Thus, these mice represent a model for gastric tumorigenesis. Here, we compared the expression of selected genes in Tff1KO mice and the corresponding wild-type animals (RT-PCR analyses). Furthermore, we systematically investigated the different molecular forms of Tff1 and its heterodimer partner gastrokine-2 (Gkn2) in the stomach (Western blot analyses). As a hallmark, a large portion of murine Tff1 occurs in a monomeric form. This is unexpected because of its odd number of seven cysteine residues. Probably the three conserved acid amino acid residues (EEE) flanking the 7th cysteine residue allow monomeric secretion. As a consequence, the free thiol of monomeric Tff1 could have a protective scavenger function, e.g., for reactive oxygen/nitrogen species. Furthermore, a minor subset of Tff1 forms a disulfide-linked heterodimer with IgG Fc binding protein (Fcgbp). Of special note, in Tff1KO animals a homodimeric form of Gkn2 was observed. In addition, Tff1KO animals showed strongly reduced Tff2 transcript and protein levels, which might explain their increased sensitivity to Helicobacter pylori infection.

scholarly journals Apocynum Tablet Protects against Cardiac Hypertrophy via Inhibiting AKT and ERK1/2 Phosphorylation after Pressure Overload

2014 ◽  
Vol 2014 ◽  
pp. 1-9
Author(s):  
Jianyong Qi ◽  
Qin Liu ◽  
Kaizheng Gong ◽  
Juan Yu ◽  
Lei Wang ◽  
...  
Keyword(s):  
Chinese Medicine ◽  
Cardiac Hypertrophy ◽  
Protein Expression ◽  
Molecular Mechanisms ◽  
Cardiac Fibrosis ◽  
Pressure Overload ◽  
Study Groups ◽  
Transverse Aortic Constriction ◽  
Aortic Constriction ◽  
Cardioprotective Effects

Background. Cardiac hypertrophy occurs in many cardiovascular diseases. Apocynum tablet (AT), a traditional Chinese medicine, has been widely used in China to treat patients with hypertension. However, the underlying molecular mechanisms of AT on the hypertension-induced cardiac hypertrophy remain elusive. The current study evaluated the effect and mechanisms of AT on cardiac hypertrophy.Methods. We created a mouse model of cardiac hypertrophy by inducing pressure overload with surgery of transverse aortic constriction (TAC) and then explored the effect of AT on the development of cardiac hypertrophy using 46 mice in 4 study groups (combinations of AT and TAC). In addition, we evaluated the signaling pathway of phosphorylation of ERK1/2, AKT, and protein expression of GATA4 in the cardioprotective effects of AT using Western blot.Results. AT inhibited the phosphorylation of Thr202/Tyr204 sites of ERK1/2, Ser473 site of AKT, and protein expression of GATA4 and significantly inhibited cardiac hypertrophy and cardiac fibrosis at 2 weeks after TAC surgery (P<0.05).Conclusions. We experimentally demonstrated that AT inhibits cardiac hypertrophy via suppressing phosphorylation of ERK1/2 and AKT.

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 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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