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Cardiac Myosin - Crossref

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Last Updated: 16 August 2022

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The HCM-linked W792R mutation in cardiac myosin-binding protein C reduces C6 FnIII domain stability

We introduced the pathogenic W792R mutation in mouse cardiomyocytes lacking endogenous cMyBP-C missense mutations on contractile function in mouse cardiomyocytes lacking endogenous cMyBP-C, as well as the functional implications using three-dimensional engineered cardiac tissue constructs to gain insight into the effects of disease-causing cMyBP-C missense mutations on contractile function. We hypothesized that the W792R mutation leads to complete conservation of tryptophan at this location in fibronectin type II domains, destabilizing the mutant protein. With W792R cDNA, Adenoviral transduction of wild-type and W792R cDNA yielded equivalent mRNA transcript abundance, but not equivalent protein levels, as compared with WT controls. W792R mECTs that expressed W792R showed abnormal contractile kinetics in comparison with WT mECTs that were nearly identical to cMyBP-C-deficient mECTs. This research reveals that missing significant mutations in cMyBP-C can cause disease-related to domain stability, as a result of haploinsufficiency.

Source link: https://doi.org/10.1152/ajpheart.00686.2017


Mavacamten, a First-in-Class Cardiac Myosin Inhibitor for Obstructive Hypertrophic Cardiomyopathy

The aim of this study: To determine mavacamtenu2019s involvement in hypertrophic cardiomyopathy therapy. While improving Kansas City Cardiomyopathy Questionnaire-Clinical Summary Scores in patients with obstructive hypertrophic cardiomyopathy, Mavacamten reduces left ventricular outflow obstruction and New York Heart Association functional class. There were changes in N-terminal probrain natriuretic peptide and high-sensitivity cardiac troponin biochemical markers in those with unobstructive hypertrophic cardiomyopathy. Mavacamten is a substrate for CYP2C19 and CYP3A4 enzyme enzymes, as well as a CYP3A4 and CYP3A4; it is also a CYP enzyme inducer. Patients with obstructive hypertrophic cardiomyopathy and an ejection percentage of u22655 percent have a new option if they persist symptomatic despite maximally supportive u03b2-blocker or non-dihydropyridine calcium channel blocker therapy. Conclusions: Mavacamten is a new drug for patients with refractory hypertrophic cardiomyopathy and an ejection percentage of u22655 percent, but its costs make therapy not cost-effective.

Source link: https://doi.org/10.1177/10600280221117812


Smooth muscle myosin light chain kinase expression in cardiac and skeletal muscle

The only true MLCK detected in cardiac tissue, purified cardiac myocytes, and in a cardiac myocyte cell line was identical to the 130-kDa smooth muscle MLCK. Subsequently, during myoblast differentiation, expression of the 220-kDa MLCK has decreased and expression of this form is replaced by a 130-kDa smMLCK and a skeletal muscle-specific isoform, skMLCK in adult skeletal muscle. Likewise, the 130-kDa smMLCK is present in all adult tissues, including skeletal and cardiac muscle, showing that although the 130-kDa smMLCK is present at its highest rate in smooth muscle tissue, it is not a smooth muscle-specific protein.

Source link: https://doi.org/10.1152/ajpcell.2000.279.5.c1656


α-Cardiac-like myosin heavy chain as an intermediate between MHCIIa and MHCIβ in transforming rabbit muscle

To elucidate the sequence of myosin heavy chain shifts in fast-to-slow transforming rabbit muscle, step-biosynthesis was used, with direct reverse transcriptase chain reactions applied to detecting mRNAs specific to five MHC isoforms in single fibers from control and low-frequency-stimulated tibialis anterior muscles. The RT-PCR assay for MHCIIa mRNA was based on the discovery of a cDNA sequence in the 3rd U2032-region, from which specific primers were derived. The allocation of MHCIIa and MHCI U03b1 between MHCIIa and MHCI appears to be in accordance with graded sequence identity of the three mRNA isoforms' 3u2032-regions.

Source link: https://doi.org/10.1152/ajpcell.1998.274.3.c595


Hormonal and neurogenic control of Na-K-ATPase and myosin isoforms in neonatal rat cardiac myocytes

The MHC isoform switch was triggered by thyroid hormones, but to various extents, all Na-K-ATPase isoforms were present in various forms. Without introducing the other isoforms, Dexamethasone failed to induce the MHC switch and reduced the Na-K-ATPase alpha 1 isoform expression. With both hormones present, the adult phenotype for MHC and Na-K-ATPase was seen, but with low Na-K-ATPase alpha 2 was seen. By analysis of mRNA levels, the paucity of alpha 2 protein was not predicted. Expression of Na-K-ATPase alpha 2 was highly enhanced when cardiomyocytes were cocultured with sympathetic neurons from superior cervical ganglia, but there were no changes in the MHC isoforms.

Source link: https://doi.org/10.1152/ajpcell.1997.273.2.c489


Phosphorylation of myosin in permeabilized mammalian cardiac and skeletal muscle cells

In rabbit psoas and ventricular muscle, the effect of myosin phosphorylation on tension release at less than 50% maximum activation by Ca2+ was investigated. Myosin light chain kinase and calmodulin were included, and the fibers were incubated at pCa 5. 4, resulting in an increase in light chain phosphorylation from 5-10 to 60-75%. Phosphorylation of P-light chain fibers in both permeabilized cardiac and skeletal muscle fibers heightened tension. P-light chain phosphorylation in cardiac and skeletal muscle muscles at subordinate levels of Ca2+ activation, according to these findings. These results show that P-light chain phosphorylation mediates actin-myosin interactions in cardiac and skeletal muscles at sub-optimal levels of Ca2+ activation.

Source link: https://doi.org/10.1152/ajpcell.1986.250.4.c657


An α-cardiac myosin heavy chain gene mutation impairs contraction and relaxation function of cardiac myocytes

Compared to WT myocytes, myocytes had fewer type I cells and more type III cells than those on type III cells. In mutant cells, depressed in mutant cells, but more in type II and III cells than in type I cells. In type II and III cells, the relaxation was also depressed more than in type I cells. We found that the amplitude of the Ca 2+ signal during contraction was unchanged in u03b1-MHC-403+ myocytes, but that the time required for decay was significantly delayed by 30% from its maximum was prolonged dramatically. These results reveal that the altered cardiac dysfunction of u03b1-MHC 403/+ myocytes is directly related to impaired myocyte function rather than secondary changes in global cardiac function and/or loading conditions.

Source link: https://doi.org/10.1152/ajpheart.1999.276.5.h1780


Cardiac myosin heavy chains lacking the light chain binding domain cause hypertrophic cardiomyopathy in mice

More than 40 people need significant mutations in the cardiac myosin heavy chain gene, as well as several mutations in the two myosin light chains, leading to a prevalently inherited heart disease called familial hypertrophic cardiomyopathy. We tested the possibility that such a mutant MHC would occur as a dominant mutation in cardiac muscle, despite the removal of the light chain binding domain in MHC's lever arm. After flash photolysis of diazo 2, skinned myocytes and multicellular preparations from transgenic hearts demonstrated reduced Ca 2+ sensitivity and reduced relaxation rates.

Source link: https://doi.org/10.1152/ajpheart.1999.276.6.h2148


Electrophoretic separation and quantitation of cardiac myosin heavy chain isoforms in eight mammalian species

In eight mammalian species, a technique for sample preparation and gel electrophoresis has been demonstrated that consistently results in the separation of the u03b1- and u03b2-isoforms of cardiac myosin heavy chain. MHC-u03b1 and MHC-u03b2 are separated by the separating gel in myocardial samples from various species of mice by the glycerol content. Sample load has been shown on MHC-u03b1 and MHC-u03b2 band resolutions. MHC detected on the gel for cardiac samples by a much greater degree than on skeletal muscle samples, according to the study's results, including a homogenization step during sample preparation increases the amount of MHC detected on the gel for cardiac samples to a much greater extent than on skeletal muscle samples. Although the procedure used in this study is useful for analyzing cardiac samples, it should be noted that the same technique is not appropriate for distinguishing MHC isoforms expressed in skeletal muscle.

Source link: https://doi.org/10.1152/ajpheart.1998.274.3.h1048


Effect of chronic energy deprivation on cardiac thyroid hormone receptor and myosin isoform expression

Chronic energy deprivation in the rat has an effect on cardiac MHC protein expression and hemodynamic parameters, according to a pattern typical of hypothyroidism; however, normal T3 levels are not depressed, unlike hypothyroidism. Both at the mRNA and protein levels, the aim of this research was to see if the altered MHC isoform expression in CED is associated with altered TR expression. Although there were no changes in TR mRNA levels in CED relative to 18S rRNA, the number of nuclear TRs dropped 3. 5-fold in the CED group, from a maximum binding capacity of 840 +/- 130 fmol/mg DNA in NC to 241 +/- 118 fmol/mg DNA in CED, with no change in the receptor's affinity.

Source link: https://doi.org/10.1152/ajpendo.1994.266.2.e254

* Please keep in mind that all text is summarized by machine, we do not bear any responsibility, and you should always check original source before taking any actions

* Please keep in mind that all text is summarized by machine, we do not bear any responsibility, and you should always check original source before taking any actions