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Skeletal muscle-specific troponin

Fei Chen, Yong Peng, Mao Chen
Cardiac involvement in idiopathic inflammatory myopathies (IIMs) attracts more attention than it ever did because of its morbidity and impact on worse prognosis, although the accurate information needs further epidemiological studies. Early identification and intervention for the diseased heart may help improve the clinical outcomes of IIMs with cardiac involvement. Cardiac troponin assays, allowing for sensitive detection of minor myocardium injury, may provide a new way for early detection for heart involvement in IIMs...
March 30, 2018: International Heart Journal
Jamie R Johnston, P Bryant Chase, Jose Renato Pinto
Troponin is a heterotrimeric Ca2+ -binding protein that has a well-established role in regulating striated muscle contraction. However, mounting evidence points to novel cellular functions of troponin, with profound implications in cancer, cardiomyopathy pathogenesis and skeletal muscle aging. Here, we highlight the non-canonical roles and aberrant expression patterns of troponin beyond the sarcomeric milieu. Utilizing bioinformatics tools and online databases, we also provide pathway, subcellular localization, and protein-protein/DNA interaction analyses that support a role for troponin in multiple subcellular compartments...
January 2, 2018: Oncotarget
Richard A Goldstein
Skeletal muscle (SKM) injury or myopathy results in structural or functional defects in SKMs that can be caused by variety of factors such as (1) genetic, (2) drug-induced, (3) disease progression (cachexia), or (4) aging (sarcopenia). Creatine kinase (CK) and aspartate transaminase (AST) activity assays have been routinely used as SKM injury biomarkers, but they lack sensitivity and tissue specificity. In collaboration with the Predictive Safety Testing Consortium, we evaluated the diagnostic performance of a muscle injury biomarker panel (MIP) compared to CK and AST and their correlation with the histology scores across 34 different rat studies...
October 2017: Toxicologic Pathology
Iain M Dykes, Kelly Lammerts van Bueren, Peter J Scambler
Physiological changes during embryonic development are associated with changes in the isoform expression of both myocyte sarcomeric proteins and of erythrocyte haemoglobins. Cell type-specific isoform expression of these genes also occurs. Although these changes appear to be coordinated, it is unclear how changes in these disparate cell types may be linked. The transcription factor Hic2 is required for normal cardiac development and the mutant is embryonic lethal. Hic2 embryos exhibit precocious expression of the definitive-lineage haemoglobin Hbb-bt in circulating primitive erythrocytes and of foetal isoforms of cardiomyocyte genes (creatine kinase, Ckm, and eukaryotic elongation factor Eef1a2) as well as ectopic cardiac expression of fast-twitch skeletal muscle troponin isoforms...
January 2018: Journal of Molecular and Cellular Cardiology
Liming Wei, Zachery R Gregorich, Ziqing Lin, Wenxuan Cai, Yutong Jin, Susan H McKiernan, Sean McIlwain, Judd M Aiken, Richard L Moss, Gary M Diffee, Ying Ge
Sarcopenia, the age-related loss of skeletal muscle mass and strength, is a significant cause of morbidity in the elderly and is a major burden on health care systems. Unfortunately, the underlying molecular mechanisms in sarcopenia remain poorly understood. Herein, we utilized top-down proteomics to elucidate sarcopenia-related changes in the fast- and slow-twitch skeletal muscles of aging rats with a focus on the sarcomeric proteome, which includes both myofilament and Z-disc proteins-the proteins that constitute the contractile apparatuses...
January 2018: Molecular & Cellular Proteomics: MCP
Kyung Chan Park, David C Gaze, Paul O Collinson, Michael S Marber
Elucidation of the physiologically distinct subunits of troponin in 1973 greatly facilitated our understanding of cardiac contraction. Although troponins are expressed in both skeletal and cardiac muscle, there are isoforms of troponin I/T expressed selectively in the heart. By exploiting cardiac-restricted epitopes within these proteins, one of the most successful diagnostic tests to date has been developed: cardiac troponin (cTn) assays. For the past decade, cTn has been regarded as the gold-standard marker for acute myocardial necrosis: the pathological hallmark of acute myocardial infarction (AMI)...
December 1, 2017: Cardiovascular Research
Ajay D Verma, Veena K Parnaik
Lamins are key determinants of nuclear organization and function in the metazoan nucleus. Mutations in human lamin A cause a spectrum of genetic diseases that affect cardiac muscle and skeletal muscle as well as other tissues. A few laminopathies have been modeled using the mouse. As zebrafish is a well established model for the study of cardiac development and disease, we have investigated the effects of heart-specific lamin A mutations in transgenic zebrafish. We have developed transgenic lines of zebrafish expressing conserved lamin A mutations that cause cardiac dysfunction in humans...
July 2017: Cell Biology International
Lorenza Brocca, Jamie S McPhee, Emanuela Longa, Monica Canepari, Olivier Seynnes, Giuseppe De Vito, Maria Antonietta Pellegrino, Marco Narici, Roberto Bottinelli
KEY POINTS: Loss of muscle mass and strength in the growing population of elderly people is a major health concern for modern societies. This condition, termed sarcopenia, is a major cause of falls and of the subsequent increase in morbidity and mortality. Despite numerous studies on the impact of ageing on individual muscle fibres, the contribution of single muscle fibre adaptations to ageing-induced atrophy and functional impairment is still unsettled. The level of physical function and disuse is often associated with ageing...
July 15, 2017: Journal of Physiology
Zherong Xu, Xin Feng, Juan Dong, Zhong-Min Wang, Jingyun Lee, Cristina Furdui, Daniel Clark Files, Kristen M Beavers, Stephen Kritchevsky, Carolanne Milligan, Jian-Ping Jin, Osvaldo Delbono, Tan Zhang
BACKGROUND: Ageing skeletal muscle undergoes chronic denervation, and the neuromuscular junction (NMJ), the key structure that connects motor neuron nerves with muscle cells, shows increased defects with ageing. Previous studies in various species have shown that with ageing, type II fast-twitch skeletal muscle fibres show more atrophy and NMJ deterioration than type I slow-twitch fibres. However, how this process is regulated is largely unknown. A better understanding of the mechanisms regulating skeletal muscle fibre-type specific denervation at the NMJ could be critical to identifying novel treatments for sarcopenia...
October 2017: Journal of Cachexia, Sarcopenia and Muscle
Sergey Y Bershitsky, Natalia A Koubassova, Michael A Ferenczi, Galina V Kopylova, Theyencheri Narayanan, Andrey K Tsaturyan
Muscle contraction is powered by actin-myosin interaction controlled by Ca(2+) via the regulatory proteins troponin (Tn) and tropomyosin (Tpm), which are associated with actin filaments. Tpm forms coiled-coil dimers, which assemble into a helical strand that runs along the whole ∼1 μm length of a thin filament. In the absence of Ca(2+), Tn that is tightly bound to Tpm binds actin and holds the Tpm strand in the blocked, or B, state, where Tpm shields actin from the binding of myosin heads. Ca(2+) binding to Tn releases the Tpm from actin so that it moves azimuthally around the filament axis to a closed, or C, state, where actin is partially available for weak binding of myosin heads...
April 11, 2017: Biophysical Journal
Brian Leei Lin, Taejeong Song, Sakthivel Sadayappan
Striated cardiac and skeletal muscles play very different roles in the body, but they are similar at the molecular level. In particular, contraction, regardless of the type of muscle, is a precise and complex process involving the integral protein myofilaments and their associated regulatory components. The smallest functional unit of muscle contraction is the sarcomere. Within the sarcomere can be found a sophisticated ensemble of proteins associated with the thick filaments (myosin, myosin binding protein-C, titin, and obscurin) and thin myofilaments (actin, troponin, tropomyosin, nebulin, and nebulette)...
March 16, 2017: Comprehensive Physiology
Katerina Vlasakova, Pamela Lane, Laura Michna, Nagaraja Muniappa, Frank D Sistare, Warren E Glaab
The skeletal muscle (SKM) injury biomarkers, skeletal troponin I (sTnI), myosin light chain 3 (Myl3), and creatine kinase muscle isoform (Ckm) have been shown recently to be more sensitive and specific for monitoring drug-induced SKM injury than the conventional biomarkers, aspartate transaminase (AST) and creatine kinase (CK) enzymatic assays in rat toxicology studies. To evaluate the utility of these SKM biomarkers across species, they were assessed in 2 dog models: a drug-induced injury study in Beagle dogs and a 160 km endurance exercise run completed by Alaskan sled dogs...
April 1, 2017: Toxicological Sciences: An Official Journal of the Society of Toxicology
Han-Zhong Feng, J-P Jin
Carbonic anhydrase III (CAIII) is a metabolic enzyme and a regulator for intracellular pH. CAIII has been reported with high level expression in slow twitch skeletal muscles. Here we demonstrate that CAIII is expressed in multiple slow and fast twitch muscles of adult mouse independent of the expression of myosin isoforms. Expressing similar fast type of myofilament proteins, CAIII-positive tibial anterior (TA) muscle exhibits higher tolerance to fatigue than that of CAIII-negative fast twitch extensor digitorum longus (EDL) muscle in in situ contractility studies...
2016: Frontiers in Physiology
Fangze Cai, Monica X Li, Sandra E Pineda-Sanabria, Shorena Gelozia, Steffen Lindert, Frederick West, Brian D Sykes, Peter M Hwang
In cardiac and skeletal muscle, the troponin complex turns muscle contraction on and off in a calcium-dependent manner. Many small molecules are known to bind to the troponin complex to modulate its calcium binding affinity, and this may be useful in a broad range of conditions in which striated muscle function is compromised, such as congestive heart failure. As a tool for developing drugs specific for the cardiac isoform of troponin, we have designed a chimeric construct (cChimera) consisting of the regulatory N-terminal domain of cardiac troponin C (cNTnC) fused to the switch region of cardiac troponin I (cTnI), mimicking the key binding event that turns on muscle contraction...
December 2016: Journal of Molecular and Cellular Cardiology
Jie Liu, Ruiqi Fu, Ranran Liu, Guiping Zhao, Maiqing Zheng, Huanxian Cui, Qinghe Li, Jiao Song, Jie Wang, Jie Wen
Muscle development and growth influences the efficiency of poultry meat production, and is closely related to deposition of intramuscular fat (IMF), which is crucial in meat quality. To clarify the molecular mechanisms underlying muscle development and IMF deposition in chickens, protein expression profiles were examined in the breast muscle of Beijing-You chickens at ages 1, 56, 98 and 140 days, using isobaric tags for relative and absolute quantification (iTRAQ). Two hundred and four of 494 proteins were expressed differentially...
2016: PloS One
Edward P Debold, Robert H Fitts, Christopher W Sundberg, Thomas M Nosek
The repeated intense stimulation of skeletal muscle rapidly decreases its force- and motion-generating capacity. This type of fatigue can be temporally correlated with the accumulation of metabolic by-products, including phosphate (Pi) and protons (H). Experiments on skinned single muscle fibers demonstrate that elevated concentrations of these ions can reduce maximal isometric force, unloaded shortening velocity, and peak power, providing strong evidence for a causative role in the fatigue process. This seems to be due, in part, to their direct effect on muscle's molecular motor, myosin, because in assays using isolated proteins, these ions directly inhibit myosin's ability to move actin...
November 2016: Medicine and Science in Sports and Exercise
Charles M Stevens, Kaveh Rayani, Christine E Genge, Gurpreet Singh, Bo Liang, Janine M Roller, Cindy Li, Alison Yueh Li, D Peter Tieleman, Filip van Petegem, Glen F Tibbits
Zebrafish, as a model for teleost fish, have two paralogous troponin C (TnC) genes that are expressed in the heart differentially in response to temperature acclimation. Upon Ca(2+) binding, TnC changes conformation and exposes a hydrophobic patch that interacts with troponin I and initiates cardiac muscle contraction. Teleost-specific TnC paralogs have not yet been functionally characterized. In this study we have modeled the structures of the paralogs using molecular dynamics simulations at 18°C and 28°C and calculated the different Ca(2+)-binding properties between the teleost cardiac (cTnC or TnC1a) and slow-skeletal (ssTnC or TnC1b) paralogs through potential-of-mean-force calculations...
July 12, 2016: Biophysical Journal
C R Lamboley, V L Wyckelsma, B D Perry, M J McKenna, G D Lamb
Inactivity negatively impacts on skeletal muscle function mainly through muscle atrophy. However, recent evidence suggests that the quality of individual muscle fibers is also altered. This study examined the effects of 23 days of unilateral lower limb suspension (ULLS) on specific force and sarcoplasmic reticulum (SR) Ca(2+) content in individual skinned muscle fibers. Muscle biopsies of the vastus lateralis were taken from six young healthy adults prior to and following ULLS. After disuse, the endogenous SR Ca(2+) content was ∼8% lower in type I fibers and maximal SR Ca(2+) capacity was lower in both type I and type II fibers (-11 and -5%, respectively)...
August 1, 2016: Journal of Applied Physiology
Takashi Kondo, Daisuke Kobayashi, Maki Mochizuki, Kouichi Asanuma, Satoshi Takahashi
Background Recently developed reagents for the highly sensitive measurement of cardiac troponin I are useful for early diagnosis of acute coronary syndrome. However, differences in measured values between these new reagents and previously used reagents have not been well studied. In this study, we aimed to compare the values between ARCHITECT High-Sensitive Troponin I ST (newly developed reagents), ARCHITECT Troponin I ST and STACIA CLEIA cardiac troponin I (two previously developed reagent kits). Methods Gel filtration high-performance liquid chromatography was used to analyse the causes of differences in measured values...
January 2017: Annals of Clinical Biochemistry
Sarah Morar Schneider, Amanda Erickson Coleman, Lee-Jae Guo, Sandra Tou, Bruce W Keene, Joe N Kornegay
Golden retriever muscular dystrophy (GRMD) is a model for the genetically homologous human disease, Duchenne muscular dystrophy (DMD). Unlike the mildly affected mdx mouse, GRMD recapitulates the severe DMD phenotype. In addition to skeletal muscle involvement, DMD boys develop cardiomyopathy. While the cardiomyopathy of DMD is typically slowly progressive, rare early episodes of acute cardiac decompensation, compatible with myocardial infarction, have been described. We report here a 7-month-old GRMD dog with an apparent analogous episode of myocardial infarction...
June 2016: Neuromuscular Disorders: NMD
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