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Alleyne J, Dopico AM. Alcohol Use Disorders and Their Harmful Effects on the Contractility of Skeletal, Cardiac and Smooth Muscles. ADVANCES IN DRUG AND ALCOHOL RESEARCH 2021; 1:10011. [PMID: 35169771 PMCID: PMC8843239 DOI: 10.3389/adar.2021.10011] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Accepted: 09/21/2021] [Indexed: 06/14/2023]
Abstract
Alcohol misuse has deleterious effects on personal health, family, societal units, and global economies. Moreover, alcohol misuse usually leads to several diseases and conditions, including alcoholism, which is a chronic condition and a form of addiction. Alcohol misuse, whether as acute intoxication or alcoholism, adversely affects skeletal, cardiac and/or smooth muscle contraction. Ethanol (ethyl alcohol) is the main effector of alcohol-induced dysregulation of muscle contractility, regardless of alcoholic beverage type or the ethanol metabolite (with acetaldehyde being a notable exception). Ethanol, however, is a simple and "promiscuous" ligand that affects many targets to mediate a single biological effect. In this review, we firstly summarize the processes of excitation-contraction coupling and calcium homeostasis which are critical for the regulation of contractility in all muscle types. Secondly, we present the effects of acute and chronic alcohol exposure on the contractility of skeletal, cardiac, and vascular/ nonvascular smooth muscles. Distinctions are made between in vivo and in vitro experiments, intoxicating vs. sub-intoxicating ethanol levels, and human subjects vs. animal models. The differential effects of alcohol on biological sexes are also examined. Lastly, we show that alcohol-mediated disruption of muscle contractility, involves a wide variety of molecular players, including contractile proteins, their regulatory factors, membrane ion channels and pumps, and several signaling molecules. Clear identification of these molecular players constitutes a first step for a rationale design of pharmacotherapeutics to prevent, ameliorate and/or reverse the negative effects of alcohol on muscle contractility.
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Affiliation(s)
| | - Alex M. Dopico
- Department of Pharmacology, Addiction Science, and Toxicology, College of Medicine, The University of Tennessee Health Science Center, Memphis, TN, United States
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2
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Cao L, Wang Z, Zhang D, Li X, Hou C, Ren C. Phosphorylation of myosin regulatory light chain at Ser17 regulates actomyosin dissociation. Food Chem 2021; 356:129655. [PMID: 33831832 DOI: 10.1016/j.foodchem.2021.129655] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 03/07/2021] [Accepted: 03/16/2021] [Indexed: 11/19/2022]
Abstract
Phosphorylation of myosin regulatory light chain (MRLC) can regulate muscle contraction and thus affect actomyosin dissociation and meat quality. The objective of this study was to explore the mechanism by how MRLC phosphorylation regulates actomyosin dissociation and thus develop strategies for improving meat quality. Here, the phosphorylation status of MRLC was modulated by myosin light chain kinase and myosin light chain kinase inhibitor. MRLC phosphorylation at Ser17 decreased the kinetic energy and total energy of actomyosin, thus stabilized the structure, facilitating the interaction between myosin and actin; this was one possible way that MRLC phosphorylation at Ser17 negatively affects actomyosin dissociation. Moreover, MRLC phosphorylation at Ser17 was beneficial to the formation of ionic bonds, hydrogen bonds, and hydrophobic interaction between myosin and actin, and was the second possible way that MRLC phosphorylation at Ser17 negatively affects actomyosin dissociation.
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Affiliation(s)
- Lichuang Cao
- Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences, Key Laboratory of Agro-Products Processing, Ministry of Agriculture and Rural Affairs, Beijing 100193, PR China; Department of Food Science, Faculty of Science, University of Copenhagen, 1958 Frederiksberg C, Denmark.
| | - Zhenyu Wang
- Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences, Key Laboratory of Agro-Products Processing, Ministry of Agriculture and Rural Affairs, Beijing 100193, PR China.
| | - Dequan Zhang
- Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences, Key Laboratory of Agro-Products Processing, Ministry of Agriculture and Rural Affairs, Beijing 100193, PR China.
| | - Xin Li
- Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences, Key Laboratory of Agro-Products Processing, Ministry of Agriculture and Rural Affairs, Beijing 100193, PR China
| | - Chengli Hou
- Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences, Key Laboratory of Agro-Products Processing, Ministry of Agriculture and Rural Affairs, Beijing 100193, PR China
| | - Chi Ren
- Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences, Key Laboratory of Agro-Products Processing, Ministry of Agriculture and Rural Affairs, Beijing 100193, PR China
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3
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Cao L, Hou C, Hussain Z, Zhang D, Wang Z. Quantitative phosphoproteomics analysis of actomyosin dissociation affected by specific site phosphorylation of myofibrillar protein. Lebensm Wiss Technol 2020. [DOI: 10.1016/j.lwt.2020.109269] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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4
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Huang H, Scheffler TL, Gerrard DE, Larsen MR, Lametsch R. Quantitative Proteomics and Phosphoproteomics Analysis Revealed Different Regulatory Mechanisms of Halothane and Rendement Napole Genes in Porcine Muscle Metabolism. J Proteome Res 2018; 17:2834-2849. [PMID: 29916714 DOI: 10.1021/acs.jproteome.8b00294] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Pigs with the Halothane (HAL) or Rendement Napole (RN) gene mutations demonstrate abnormal muscle energy metabolism patterns and produce meat with poor quality, classified as pale, soft, and exudative (PSE) meat, but it is not well understood how HAL and RN mutations regulate glucose and energy metabolism in porcine muscle. To investigate the potential signaling pathways and phosphorylation events related to these mutations, muscle samples were collected from four genotypes of pigs, wild type, RN, HAL, and RN-HAL double mutations, and subjected to quantitative proteomic and phosphoproteomic analysis using the TiO2 enrichment strategy. The study led to the identification of 932 proteins from the nonmodified peptide fractions and 1885 phosphoproteins with 9619 phosphorylation sites from the enriched fractions. Among them, 128 proteins at total protein level and 323 phosphosites from 91 phosphoproteins were significantly regulated in mutant genotypes. The quantitative analysis revealed that the RN mutation mainly affected the protein expression abundance in muscle. Specifically, high expression was observed for proteins related to mitochondrial respiratory chain and energy metabolism, thereby enhancing the muscle oxidative capacity. The high content of UDP-glucose pyrophosphorylase 2 (UGP2) in RN mutant animals may contribute to high glycogen storage. However, the HAL mutation mainly contributes to the up-regulation of phosphorylation in proteins related to calcium signaling, muscle contraction, glycogen, glucose, and energy metabolism, and cellular stress. The increased phosphorylation of Ca2+/calmodulin-dependent protein kinase II (CAMK2) in HAL mutation may act as a key regulator in these processes of muscle. Our findings indicate the different regulatory mechanisms of RN and HAL mutations in relation to porcine muscle energy metabolism and meat quality.
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Affiliation(s)
- Honggang Huang
- Department of Biochemistry and Molecular Biology , University of Southern Denmark , DK-5230 Odense M , Denmark.,Department of Food Science, Faculty of Science , University of Copenhagen , DK-1958 Frederiksberg , Denmark.,The Danish Diabetes Academy , 5000 Odense , Denmark.,Arla Foods Ingredients Group P/S , Soenderupvej 26 , 6920 Videbaek , Denmark
| | - Tracy L Scheffler
- Department of Animal Sciences , University of Florida , Gainesville , Florida 32608 , United States
| | - David E Gerrard
- Department of Animal and Poultry Sciences , Virginia Tech , Blacksburg , Virginia 24061 , United States
| | - Martin R Larsen
- Department of Biochemistry and Molecular Biology , University of Southern Denmark , DK-5230 Odense M , Denmark
| | - René Lametsch
- Department of Food Science, Faculty of Science , University of Copenhagen , DK-1958 Frederiksberg , Denmark
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5
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Wang Y, Burghardt TP. In vitro actin motility velocity varies linearly with the number of myosin impellers. Arch Biochem Biophys 2017; 618:1-8. [PMID: 28131772 DOI: 10.1016/j.abb.2017.01.012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Revised: 01/23/2017] [Accepted: 01/24/2017] [Indexed: 11/26/2022]
Abstract
Cardiac myosin is the motor powering the heart. It moves actin with 3 step-size varieties generated by torque from the myosin heavy chain lever-arm rotation under the influence of myosin essential light chain whose N-terminal extension binds actin. Proposed mechanisms adapting myosin mechanochemical characteristics on the fly sometimes involve modulation of step-size selection probability via motor strain sensitivity. Strain following the power stroke, hypothetically imposed by the finite actin detachment rate 1/ton, is shown to have no effect on unloaded velocity when multiple myosins are simultaneously strongly actin bound in an in vitro motility assay. Actin filaments slide ∼2 native step-sizes while more than 1 myosin strongly binds actin probably ruling out an actin detachment limited model for imposing strain. It suggests that single myosin estimates for ton are too large, not applicable to the ensemble situation, or both. Parallel motility data quantitation involving instantaneous particle velocities (frame velocity) and actin filament track averaged velocities (track velocity) give an estimate of the random walk step-size, δ. Comparing δ for slow and fast motility components suggests the higher speed component has cardiac myosin upshifting to longer steps. Variable step-size characteristics imply cardiac myosin maintains a velocity dynamic range not involving strain.
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Affiliation(s)
- Y Wang
- Department of Biochemistry and Molecular Biology, Mayo Clinic Rochester, Rochester, MN 55905, United States
| | - T P Burghardt
- Department of Biochemistry and Molecular Biology, Mayo Clinic Rochester, Rochester, MN 55905, United States; Department of Physiology and Biomedical Engineering, Mayo Clinic Rochester, Rochester, MN 55905, United States.
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Burghardt TP, Sun X, Wang Y, Ajtai K. In vitro and in vivo single myosin step-sizes in striated muscle. J Muscle Res Cell Motil 2015; 36:463-77. [PMID: 26728749 PMCID: PMC4764389 DOI: 10.1007/s10974-015-9440-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Accepted: 12/11/2015] [Indexed: 10/22/2022]
Abstract
Myosin in muscle transduces ATP free energy into the mechanical work of moving actin. It has a motor domain transducer containing ATP and actin binding sites, and, mechanical elements coupling motor impulse to the myosin filament backbone providing transduction/mechanical-coupling. The mechanical coupler is a lever-arm stabilized by bound essential and regulatory light chains. The lever-arm rotates cyclically to impel bound filamentous actin. Linear actin displacement due to lever-arm rotation is the myosin step-size. A high-throughput quantum dot labeled actin in vitro motility assay (Qdot assay) measures motor step-size in the context of an ensemble of actomyosin interactions. The ensemble context imposes a constant velocity constraint for myosins interacting with one actin filament. In a cardiac myosin producing multiple step-sizes, a "second characterization" is step-frequency that adjusts longer step-size to lower frequency maintaining a linear actin velocity identical to that from a shorter step-size and higher frequency actomyosin cycle. The step-frequency characteristic involves and integrates myosin enzyme kinetics, mechanical strain, and other ensemble affected characteristics. The high-throughput Qdot assay suits a new paradigm calling for wide surveillance of the vast number of disease or aging relevant myosin isoforms that contrasts with the alternative model calling for exhaustive research on a tiny subset myosin forms. The zebrafish embryo assay (Z assay) performs single myosin step-size and step-frequency assaying in vivo combining single myosin mechanical and whole muscle physiological characterizations in one model organism. The Qdot and Z assays cover "bottom-up" and "top-down" assaying of myosin characteristics.
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Affiliation(s)
- Thomas P Burghardt
- Department of Biochemistry and Molecular Biology, Mayo Clinic Rochester, Rochester, MN, 55905, USA.
- Department of Physiology and Biomedical Engineering, Mayo Clinic Rochester, Rochester, MN, 55905, USA.
| | - Xiaojing Sun
- Department of Biochemistry and Molecular Biology, Mayo Clinic Rochester, Rochester, MN, 55905, USA
| | - Yihua Wang
- Department of Biochemistry and Molecular Biology, Mayo Clinic Rochester, Rochester, MN, 55905, USA
| | - Katalin Ajtai
- Department of Biochemistry and Molecular Biology, Mayo Clinic Rochester, Rochester, MN, 55905, USA
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New Isoform of Cardiac Myosin Light Chain Kinase and the Role of Cardiac Myosin Phosphorylation in α1-Adrenoceptor Mediated Inotropic Response. PLoS One 2015; 10:e0141130. [PMID: 26512720 PMCID: PMC4626101 DOI: 10.1371/journal.pone.0141130] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Accepted: 10/04/2015] [Indexed: 12/15/2022] Open
Abstract
Background & Aims Cardiac myosin light chain kinase (cMLCK) plays an obligatory role in maintaining the phosphorylation levels of regulatory myosin light chain (MLC2), which is thought to be crucial for regulation of cardiac function. To test this hypothesis, the role played by ventricular MLC2 (MLC2v) phosphorylation was investigated in the phenylephrine-induced increase in twitch tension using the naturally-occurring mouse strain, C57BL/6N, in which cMLCK is down regulated. Methods and Results By Western blot and nanoLC-MS/MS analysis, cMLCKs with molecular mass of 61-kDa (cMLCK-2) and/or 86-kDa were identified in mice heart. Among various mouse strains, C57BL/6N expressed cMLCK-2 alone and the closest relative strain C57BL/6J expressed both cMLCKs. The levels of MLC2v phosphorylation was significantly lower in C57BL/6N than in C57BL/6J. The papillary muscle twitch tension induced by electrical field stimulation was smaller in C57BL/6N than C57BL/6J. Phenylephrine had no effect on MLC2v phosphorylation in either strains but increased the twitch tension more potently in C57BL/6J than in C57BL/6N. Calyculin A increased papillary muscle MLC2v phosphorylation to a similar extent in both strains but increased the phenylephrine-induced inotropic response only in C57BL/6N. There was a significant positive correlation between the phenylephrine-induced inotropic response and the levels of MLC2v phosphorylation within ranges of 15–30%. Conclusions We identified a new isoform of cMLCK with a molecular mass of 61kDa(cMLCK-2) in mouse heart. In the C57BL/6N strain, only cMLCK-2 was expressed and the basal MLC2v phosphorylation levels and the phenylephrine-induced inotropic response were both smaller. We suggest that a lower phenylephrine-induced inotropic response may be caused by the lower basal MLC2v phosphorylation levels in this strain.
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Zhang YS, Liu B, Luo XJ, Li TB, Zhang JJ, Peng JJ, Zhang XJ, Ma QL, Hu CP, Li YJ, Peng J, Li Q. Nuclear cardiac myosin light chain 2 modulates NADPH oxidase 2 expression in myocardium: a novel function beyond muscle contraction. Basic Res Cardiol 2015; 110:38. [PMID: 25982880 DOI: 10.1007/s00395-015-0494-5] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/26/2015] [Revised: 05/02/2015] [Accepted: 05/08/2015] [Indexed: 12/21/2022]
Abstract
Recent studies demonstrated that NADPH oxidase 2 (NOX2) expression in myocardium after ischemia-reperfusion (IR) is significantly upregulated. However, the underlying mechanisms remain unknown. This study aims to determine if nuclear cardiac myosin light chain 2 (MYL2), a well-known regulatory subunit of myosin, functions as a transcription factor to promote NOX2 expression following myocardial IR in a phosphorylation-dependent manner. We examined the phosphorylation status of nuclear MYL2 (p-MYL2) in a rat model of myocardial IR (left main coronary artery subjected to 1 h ligation and 3 h reperfusion) injury, which showed IR injury and upregulated NOX2 expression as expected, accompanied by elevated H₂O₂ and nuclear p-MYL2 levels; these effects were attenuated by inhibition of myosin light chain kinase (MLCK). Next, we explored the functional relationship of nuclear p-MYL2 with NOX2 expression in H9c2 cell model of hypoxia-reoxygenation (HR) injury. In agreement with our in vivo findings, HR treatment increased apoptosis, NOX2 expression, nuclear p-MYL2 and H₂O₂ levels, and the increases were ameliorated by inhibition of MLCK or knockdown of MYL2. Finally, molecular biology techniques including co-immunoprecipitation (Co-IP), chromatin immunoprecipitation (ChIP), DNA pull-down and luciferase reporter gene assay were utilized to decipher the molecular mechanisms. We found that nuclear p-MYL2 binds to the consensus sequence AGCTCC in NOX2 gene promoter, interacts with RNA polymerase II and transcription factor IIB to form a transcription preinitiation complex, and thus activates NOX2 gene transcription. Our results demonstrate that nuclear MYL2 plays an important role in IR injury by transcriptionally upregulating NOX2 expression to enhance oxidative stress in a phosphorylation-dependent manner.
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Affiliation(s)
- Yi-Shuai Zhang
- Department of Pharmacology, School of Pharmaceutical Sciences, Central South University, Changsha, 410078, China
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Hatta K, Guo J, Ludke A, Dhingra S, Singh K, Huang ML, Weisel RD, Li RK. Expression of CNPY2 in mouse tissues: quantification and localization. PLoS One 2014; 9:e111370. [PMID: 25393402 PMCID: PMC4230931 DOI: 10.1371/journal.pone.0111370] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2014] [Accepted: 09/30/2014] [Indexed: 12/18/2022] Open
Abstract
Canopy FGF signaling regulator 2 (CNPY2) is a FGF21-modulated protein containing a saposin B-type domain. In vitro studies have shown CNPY2 is able to enhance neurite outgrowth in neurons and stabilize the expression of low density lipoprotein receptor in macrophages and hepatocytes. However, no in vivo data are available on the normal expression of CNPY2 and information is lacking on which cell types express this protein in tissues. To address this, the present study examined CNPY2 expression at the mRNA and protein levels. Quantitative PCR and ELISA examination of mouse tissues showed that CNPY2 varies between organs, with the highest expression in the heart, lung and liver. Immunohistochemistry detected CNPY2 in a variety of cell types including skeletal, cardiac and smooth muscle myocytes, endothelial cells and epithelial cells. CNPY2 was also detectable in mouse blood and human and mouse uteri. These data demonstrate CNPY2 is widely distributed in tissues and suggest the protein has biological functions that have yet to be identified. Using these new observations we discuss possible functions of the protein.
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Affiliation(s)
- Kota Hatta
- Division of Cardiovascular Surgery, Toronto General Research Institute, University Health Network, Toronto, Ontario, Canada
- Institute of Medical Sciences, University of Toronto, Toronto, Ontario, Canada
| | - Jian Guo
- Division of Cardiovascular Surgery, Toronto General Research Institute, University Health Network, Toronto, Ontario, Canada
| | - Ana Ludke
- Division of Cardiovascular Surgery, Toronto General Research Institute, University Health Network, Toronto, Ontario, Canada
| | - Sanjiv Dhingra
- Division of Cardiovascular Surgery, Toronto General Research Institute, University Health Network, Toronto, Ontario, Canada
| | - Kaustabh Singh
- Division of Cardiovascular Surgery, Toronto General Research Institute, University Health Network, Toronto, Ontario, Canada
| | - Ming-Li Huang
- Department of Gynecology and Obstetrics, First Affiliated Hospital of Harbin Medical University, Harbin, China
| | - Richard D. Weisel
- Division of Cardiovascular Surgery, Toronto General Research Institute, University Health Network, Toronto, Ontario, Canada
- Institute of Medical Sciences, University of Toronto, Toronto, Ontario, Canada
| | - Ren-Ke Li
- Division of Cardiovascular Surgery, Toronto General Research Institute, University Health Network, Toronto, Ontario, Canada
- Institute of Medical Sciences, University of Toronto, Toronto, Ontario, Canada
- * E-mail:
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Wang Y, Ajtai K, Burghardt TP. Analytical comparison of natural and pharmaceutical ventricular myosin activators. Biochemistry 2014; 53:5298-306. [PMID: 25068717 PMCID: PMC4139156 DOI: 10.1021/bi500730t] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
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Ventricular myosin (βMys) is
the motor protein in cardiac
muscle generating force using ATP hydrolysis free energy to translate
actin. In the cardiac muscle sarcomere, myosin and actin filaments
interact cyclically and undergo rapid relative translation facilitated
by the low duty cycle motor. It contrasts with high duty cycle processive
myosins for which persistent actin association is the priority. The
only pharmaceutical βMys activator, omecamtive mecarbil (OM),
upregulates cardiac contractility in vivo and is
undergoing testing for heart failure therapy. In vitro βMys step-size, motility velocity, and actin-activated myosin
ATPase were measured to determine duty cycle in the absence and presence
of OM. A new parameter, the relative step-frequency, was introduced
and measured to characterize βMys motility due to the involvement
of its three unitary step-sizes. Step-size and relative step-frequency
were measured using the Qdot assay. OM decreases motility velocity
10-fold without affecting step-size, indicating a large increase in
duty cycle converting βMys to a near processive myosin. The
OM conversion dramatically increases force and modestly increases
power over the native βMys. Contrasting motility modification
due to OM with that from the natural myosin activator, specific βMys
phosphorylation, provides insight into their respective activation
mechanisms and indicates the boilerplate screening characteristics
desired for pharmaceutical βMys activators. New analytics introduced
here for the fast and efficient Qdot motility assay create a promising
method for high-throughput screening of motor proteins and their modulators.
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Affiliation(s)
- Yihua Wang
- Department of Biochemistry and Molecular Biology and ‡Department of Physiology and Biomedical Engineering, Mayo Clinic Rochester , Rochester, Minnesota 55905, United States
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Wang Y, Ajtai K, Burghardt TP. Ventricular myosin modifies in vitro step-size when phosphorylated. J Mol Cell Cardiol 2014; 72:231-7. [PMID: 24726887 PMCID: PMC4037356 DOI: 10.1016/j.yjmcc.2014.03.022] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/29/2014] [Revised: 03/11/2014] [Accepted: 03/31/2014] [Indexed: 10/25/2022]
Abstract
Cardiac and skeletal muscle myosins have the central role in contraction transducing ATP free energy into the mechanical work of moving actin. Myosin has a motor domain containing ATP and actin binding sites and a lever-arm that undergoes rotation impelling bound actin. The lever-arm converts torque generated in the motor into the linear displacement known as step-size. The myosin lever-arm is stabilized by bound essential and regulatory light chains (ELC and RLC). RLC phosphorylation at S15 is linked to modified lever-arm mechanical characteristics contributing to myosin filament based contraction regulation and to the response of the muscle to disease. Myosin step-size was measured using a novel quantum dot (Qdot) assay that previously confirmed a 5nm step-size for fast skeletal myosin and multiple unitary steps, most frequently 5 and 8nm, and a rare 3nm displacement for β cardiac myosin (βMys). S15 phosphorylation in βMys is now shown to change step-size distribution by advancing the 8nm step frequency. After phosphorylation, the 8nm step is the dominant myosin step-size resulting in significant gain in the average step-size. An increase in myosin step-size will increase the amount of work produced per ATPase cycle. The results indicate that RLC phosphorylation modulates work production per ATPase cycle suggesting the mechanism for contraction regulation by the myosin filament.
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Affiliation(s)
- Yihua Wang
- Department of Biochemistry and Molecular Biology, United States
| | - Katalin Ajtai
- Department of Biochemistry and Molecular Biology, United States
| | - Thomas P Burghardt
- Department of Biochemistry and Molecular Biology, United States; Department of Physiology and Biomedical Engineering, United States.
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Toepfer C, Caorsi V, Kampourakis T, Sikkel MB, West TG, Leung MC, Al-Saud SA, MacLeod KT, Lyon AR, Marston SB, Sellers JR, Ferenczi MA. Myosin regulatory light chain (RLC) phosphorylation change as a modulator of cardiac muscle contraction in disease. J Biol Chem 2013; 288:13446-54. [PMID: 23530050 PMCID: PMC3650382 DOI: 10.1074/jbc.m113.455444] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2013] [Revised: 03/21/2013] [Indexed: 01/26/2023] Open
Abstract
Understanding how cardiac myosin regulatory light chain (RLC) phosphorylation alters cardiac muscle mechanics is important because it is often altered in cardiac disease. The effect this protein phosphorylation has on muscle mechanics during a physiological range of shortening velocities, during which the heart generates power and performs work, has not been addressed. We have expressed and phosphorylated recombinant Rattus norvegicus left ventricular RLC. In vitro we have phosphorylated these recombinant species with cardiac myosin light chain kinase and zipper-interacting protein kinase. We compare rat permeabilized cardiac trabeculae, which have undergone exchange with differently phosphorylated RLC species. We were able to enrich trabecular RLC phosphorylation by 40% compared with controls and, in a separate series, lower RLC phosphorylation to 60% of control values. Compared with the trabeculae with a low level of RLC phosphorylation, RLC phosphorylation enrichment increased isometric force by more than 3-fold and peak power output by more than 7-fold and approximately doubled both maximum shortening speed and the shortening velocity that generated peak power. We augmented these measurements by observing increased RLC phosphorylation of human and rat HF samples from endocardial left ventricular homogenate. These results demonstrate the importance of increased RLC phosphorylation in the up-regulation of myocardial performance and suggest that reduced RLC phosphorylation is a key aspect of impaired contractile function in the diseased myocardium.
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Affiliation(s)
- Christopher Toepfer
- From the Molecular Medicine Section, National Heart and Lung Institute, Imperial College London, London SW7 2AZ, United Kingdom
- the Laboratory of Molecular Physiology, NHLBI, National Institutes of Health, Bethesda, Maryland 20892, and
| | - Valentina Caorsi
- From the Molecular Medicine Section, National Heart and Lung Institute, Imperial College London, London SW7 2AZ, United Kingdom
| | - Thomas Kampourakis
- the Randall Division of Cell and Molecular Biophysics, Guy's Campus, King's College London, London SE1 1UL, United Kingdom
| | - Markus B. Sikkel
- the National Heart and Lung Institute, 4th Floor, Imperial Center for Translational and Experimental Medicine, Hammersmith Campus, Du Cane Road, London W12 0NN, United Kingdom
| | - Timothy G. West
- the Structure and Motion Laboratory, Royal Veterinary College London, North Mymms AL9 7TA, United Kingdom
| | - Man-Ching Leung
- the National Heart and Lung Institute, 4th Floor, Imperial Center for Translational and Experimental Medicine, Hammersmith Campus, Du Cane Road, London W12 0NN, United Kingdom
| | - Sara A. Al-Saud
- From the Molecular Medicine Section, National Heart and Lung Institute, Imperial College London, London SW7 2AZ, United Kingdom
| | - Kenneth T. MacLeod
- the National Heart and Lung Institute, 4th Floor, Imperial Center for Translational and Experimental Medicine, Hammersmith Campus, Du Cane Road, London W12 0NN, United Kingdom
| | - Alexander R. Lyon
- the National Heart and Lung Institute, 4th Floor, Imperial Center for Translational and Experimental Medicine, Hammersmith Campus, Du Cane Road, London W12 0NN, United Kingdom
- the Cardiovascular Biomedical Research Unit, Royal Brompton Hospital, London SW3 6MP, United Kingdom
| | - Steven B. Marston
- the National Heart and Lung Institute, 4th Floor, Imperial Center for Translational and Experimental Medicine, Hammersmith Campus, Du Cane Road, London W12 0NN, United Kingdom
| | - James R. Sellers
- the Laboratory of Molecular Physiology, NHLBI, National Institutes of Health, Bethesda, Maryland 20892, and
| | - Michael A. Ferenczi
- From the Molecular Medicine Section, National Heart and Lung Institute, Imperial College London, London SW7 2AZ, United Kingdom
- the Lee Kong Chian School of Medicine, Nanyang Technological University, 637553 Singapore
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13
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Wang Y, Ajtai K, Burghardt TP. The Qdot-labeled actin super-resolution motility assay measures low-duty cycle muscle myosin step size. Biochemistry 2013; 52:1611-21. [PMID: 23383646 DOI: 10.1021/bi301702p] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Myosin powers contraction in heart and skeletal muscle and is a leading target for mutations implicated in inheritable muscle diseases. During contraction, myosin transduces ATP free energy into the work of muscle shortening against resisting force. Muscle shortening involves relative sliding of myosin and actin filaments. Skeletal actin filaments were fluorescently labeled with a streptavidin conjugate quantum dot (Qdot) binding biotin-phalloidin on actin. Single Qdots were imaged in time with total internal reflection fluorescence microscopy and then spatially localized to 1-3 nm using a super-resolution algorithm as they translated with actin over a surface coated with skeletal heavy meromyosin (sHMM) or full-length β-cardiac myosin (MYH7). The average Qdot-actin velocity matches measurements with rhodamine-phalloidin-labeled actin. The sHMM Qdot-actin velocity histogram contains low-velocity events corresponding to actin translation in quantized steps of ~5 nm. The MYH7 velocity histogram has quantized steps at 3 and 8 nm in addition to 5 nm and larger compliance compared to that of sHMM depending on the MYH7 surface concentration. Low-duty cycle skeletal and cardiac myosin present challenges for a single-molecule assay because actomyosin dissociates quickly and the freely moving element diffuses away. The in vitro motility assay has modestly more actomyosin interactions, and methylcellulose inhibited diffusion to sustain the complex while preserving a subset of encounters that do not overlap in time on a single actin filament. A single myosin step is isolated in time and space and then characterized using super-resolution. The approach provides a quick, quantitative, and inexpensive step size measurement for low-duty cycle muscle myosin.
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Affiliation(s)
- Yihua Wang
- Department of Biochemistry and Molecular Biology, Mayo Clinic Rochester, Rochester, Minnesota 55905, USA
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Burghardt TP, Sikkink LA. Regulatory light chain mutants linked to heart disease modify the cardiac myosin lever arm. Biochemistry 2013; 52:1249-59. [PMID: 23343568 DOI: 10.1021/bi301500d] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Myosin is the chemomechanical energy transducer in striated heart muscle. The myosin cross-bridge applies impulsive force to actin while consuming ATP chemical energy to propel myosin thick filaments relative to actin thin filaments in the fiber. Transduction begins with ATP hydrolysis in the cross-bridge driving rotary movement of a lever arm converting torque into linear displacement. Myosin regulatory light chain (RLC) binds to the lever arm and modifies its ability to translate actin. Gene sequencing implicated several RLC mutations in heart disease, and three of them are investigated here using photoactivatable GFP-tagged RLC (RLC-PAGFP) exchanged into permeabilized papillary muscle fibers. A single-lever arm probe orientation is detected in the crowded environment of the muscle fiber by using RLC-PAGFP with dipole orientation deduced from the three-spatial dimension fluorescence emission pattern of the single molecule. Symmetry and selection rules locate dipoles in their half-sarcomere, identify those at the minimal free energy, and specify active dipole contraction intermediates. Experiments were performed in a microfluidic chamber designed for isometric contraction, total internal reflection fluorescence detection, and two-photon excitation second harmonic generation to evaluate sarcomere length. The RLC-PAGFP reports apparently discretized lever arm orientation intermediates in active isometric fibers that on average produce the stall force. Disease-linked mutants introduced into RLC move intermediate occupancy further down the free energy gradient, implying lever arms rotate more to reach stall force because mutant RLC increases lever arm shear strain. A lower free energy intermediate occupancy involves a lower energy conversion efficiency in the fiber relating a specific myosin function modification to the disease-implicated mutant.
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Affiliation(s)
- Thomas P Burghardt
- Department of Biochemistry and Molecular Biology, Mayo Clinic Rochester, Rochester, MN 55905, USA.
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