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Biomolecules Jan 2022Contraction of striated muscle is triggered by a massive release of calcium from the sarcoplasmic reticulum (SR) into the cytoplasm. This intracellular calcium release... (Review)
Review
Contraction of striated muscle is triggered by a massive release of calcium from the sarcoplasmic reticulum (SR) into the cytoplasm. This intracellular calcium release is initiated by membrane depolarization, which is sensed by voltage-gated calcium channels Ca1.1 (in skeletal muscle) and Ca1.2 (in cardiac muscle) in the plasma membrane (PM), which in turn activate the calcium-releasing channel ryanodine receptor (RyR) embedded in the SR membrane. This cross-communication between channels in the PM and in the SR happens at specialized regions, the SR-PM junctions, where these two compartments come in close proximity. Junctophilin1 and Junctophilin2 are responsible for the formation and stabilization of SR-PM junctions in striated muscle and actively participate in the recruitment of the two essential players in intracellular calcium release, Ca and RyR. This short review focuses on the roles of junctophilins1 and 2 in the formation and organization of SR-PM junctions in skeletal and cardiac muscle and on the functional consequences of the absence or malfunction of these proteins in striated muscle in light of recently published data and recent advancements in protein structure prediction.
Topics: Calcium; Calcium Signaling; Cell Membrane; Muscle, Skeletal; Ryanodine Receptor Calcium Release Channel; Sarcoplasmic Reticulum
PubMed: 35053257
DOI: 10.3390/biom12010109 -
IUBMB Life Jun 2013Discovered about a decade ago, obscurin (~720 kDa) is a member of a family of giant proteins expressed in striated muscle that are essential for normal muscle function.... (Review)
Review
Discovered about a decade ago, obscurin (~720 kDa) is a member of a family of giant proteins expressed in striated muscle that are essential for normal muscle function. Much of what we understand about obscurin stems from its functions in cardiac and skeletal muscle. However, recent evidence has indicated that variants of obscurin ("obscurins") are expressed in diverse cell types, where they contribute to distinct cellular processes. Dysfunction or abrogation of obscurins has also been implicated in the development of several pathological conditions, including cardiac hypertrophy and cancer. Herein, we present an overview of obscurins with an emphasis on novel findings that demonstrate their heretofore-unsuspected importance in cell signaling and disease progression.
Topics: Animals; Cardiomyopathy, Hypertrophic, Familial; Humans; Muscle Development; Muscle, Skeletal; Mutation, Missense; Neoplasms; Organ Specificity; Protein Interaction Maps; Protein Serine-Threonine Kinases; Rho Guanine Nucleotide Exchange Factors
PubMed: 23512348
DOI: 10.1002/iub.1157 -
Skeletal Muscle Mar 2019Striated muscles express an array of sarcomeric myosin motors that are tuned to accomplish specific tasks. Each myosin isoform found in muscle fibers confers unique... (Review)
Review
Striated muscles express an array of sarcomeric myosin motors that are tuned to accomplish specific tasks. Each myosin isoform found in muscle fibers confers unique contractile properties to the fiber in order to meet the demands of the muscle. The sarcomeric myosin heavy chain (MYH) genes expressed in the major cardiac and skeletal muscles have been studied for decades. However, three ancient myosins, MYH7b, MYH15, and MYH16, remained uncharacterized due to their unique expression patterns in common mammalian model organisms and due to their relatively recent discovery in these genomes. This article reviews the literature surrounding these three ancient sarcomeric myosins and the specialized muscles in which they are expressed. Further study of these ancient myosins and how they contribute to the functions of the specialized muscles may provide novel insight into the history of striated muscle evolution.
Topics: Animals; Evolution, Molecular; Humans; Muscle, Skeletal; Myocytes, Cardiac; Myosin Heavy Chains; Protein Isoforms
PubMed: 30836986
DOI: 10.1186/s13395-019-0192-3 -
Developmental Dynamics : An Official... Apr 2022Lamin A/C gene (LMNA) mutations frequently cause cardiac and/or skeletal muscle diseases called striated muscle laminopathies. We created a zebrafish muscular...
BACKGROUND
Lamin A/C gene (LMNA) mutations frequently cause cardiac and/or skeletal muscle diseases called striated muscle laminopathies. We created a zebrafish muscular laminopathy model using CRISPR/Cas9 technology to target the zebrafish lmna gene.
RESULTS
Heterozygous and homozygous lmna mutants present skeletal muscle damage at 1 day post-fertilization (dpf), and mobility impairment at 4 to 7 dpf. Cardiac structure and function analyses between 1 and 7 dpf show mild and transient defects in the lmna mutants compared to wild type (WT). Quantitative RT-PCR analysis of genes implicated in striated muscle laminopathies show a decrease in jun and nfκb2 expression in 7 dpf homozygous lmna mutants compared to WT. Homozygous lmna mutants have a 1.26-fold protein increase in activated Erk 1/2, kinases associated with striated muscle laminopathies, compared to WT at 7 dpf. Activated Protein Kinase C alpha (Pkc α), a kinase that interacts with lamin A/C and Erk 1/2, is also upregulated in 7 dpf homozygous lmna mutants compared to WT.
CONCLUSIONS
This study presents an animal model of skeletal muscle laminopathy where heterozygous and homozygous lmna mutants exhibit prominent skeletal muscle abnormalities during the first week of development. Furthermore, this is the first animal model that potentially implicates Pkc α in muscular laminopathies.
Topics: Animals; CRISPR-Cas Systems; Disease Models, Animal; Lamin Type A; Laminopathies; Muscle, Skeletal; Mutation; Zebrafish
PubMed: 34599606
DOI: 10.1002/dvdy.427 -
Exercise and Sport Sciences Reviews Jul 2019Regular exercise enhances mitochondrial function by promoting healthy mitochondrial remodeling, but the underlying mechanisms are not thoroughly understood. An emerging... (Review)
Review
Regular exercise enhances mitochondrial function by promoting healthy mitochondrial remodeling, but the underlying mechanisms are not thoroughly understood. An emerging hypothesis suggests that, in addition to anabolic events such as mitochondria biogenesis, the selective degradation of dysfunctional mitochondria (i.e., mitophagy) also is a key component of exercise-mediated adaptations in striated muscle, which eventually leads to better mitochondrial functions.
Topics: AMP-Activated Protein Kinase Kinases; Adaptation, Physiological; Exercise; Humans; Mitochondria, Heart; Mitochondria, Muscle; Mitophagy; Muscle, Skeletal; Physical Conditioning, Human; Protein Kinases
PubMed: 30985475
DOI: 10.1249/JES.0000000000000192 -
Circulation Feb 2019
Topics: Glucose; Homeostasis; Humans; Insulin; Insulin Resistance; Muscle, Skeletal; Muscle, Striated
PubMed: 30742526
DOI: 10.1161/CIRCULATIONAHA.118.038387 -
Annual Review of Nursing Research 2013The health of skeletal muscle is promoted by optimal nutrition and activity/exercise through the activation of molecular signaling pathways. Reactive oxygen species... (Review)
Review
The health of skeletal muscle is promoted by optimal nutrition and activity/exercise through the activation of molecular signaling pathways. Reactive oxygen species (ROS) or reactive nitrogen species (RNS) have been shown to modulate numerous biochemical processes including glucose uptake, gene expression, calcium signaling, and contractility. In pathological conditions, ROS/RNS signaling excess or dysfunction contributes to contractile dysfunction and myopathy in skeletal muscle. Here we provide a brief review of ROS/RNS chemistry and discuss concepts of ROS/RNS signaling and its role in physiological and pathophysiological processes within striated muscle.
Topics: Humans; Muscle, Skeletal; Reactive Nitrogen Species; Reactive Oxygen Species; Signal Transduction
PubMed: 24894146
DOI: 10.1891/0739-6686.31.367 -
Journal of Applied Physiology... May 2013During acute exacerbations of chronic obstructive pulmonary disease (COPD), limb and respiratory muscle dysfunction develops rapidly and functional recovery is partial... (Review)
Review
During acute exacerbations of chronic obstructive pulmonary disease (COPD), limb and respiratory muscle dysfunction develops rapidly and functional recovery is partial and slow. The mechanisms leading to this muscle dysfunction are not yet fully established. However, recent evidence has shown that several pathways involved in muscle catabolism, apoptosis, and oxidative stress are activated in the vastus lateralis muscle of patients during acute exacerbations of COPD, while those implicated in mitochondrial function are downregulated. These pathways may be targeted in different ways by factors related to exacerbations. These factors include enhanced systemic inflammation, oxidative stress, impaired energy balance, hypoxia, hypercapnia and acidosis, corticosteroid treatment, and physical inactivity. Data on the respiratory muscles are limited, but these muscles are undoubtedly overloaded during exacerbations. While they are also subjected to the same systemic elements as the limb muscles (except for inactivity), they also face a specific mechanical disadvantage caused by changes in lung volume during exacerbation. The latter will affect the ability to generate force by the foreshortening of the muscle (especially for the diaphragm), but also by altering rib orientation and motion (especially for the parasternal intercostals and the external intercostals). Because acute exacerbations of COPD are associated with an increase in both prevalence and severity of generalized muscle dysfunction, and both remain present even during recovery, early interventions to minimize muscle dysfunction during exacerbation are warranted. Although rehabilitation may be promising, other therapeutic strategies such as counterbalancing the adverse effects of exacerbations on skeletal muscle pathways may also be used.
Topics: Acute Disease; Adrenal Cortex Hormones; Animals; Extremities; Humans; Inflammation Mediators; Muscle Strength; Muscle Weakness; Muscle, Skeletal; Oxidative Stress; Pulmonary Disease, Chronic Obstructive; Pulmonary Gas Exchange; Respiratory Muscles
PubMed: 23372146
DOI: 10.1152/japplphysiol.00847.2012 -
Journal of Biomedicine & Biotechnology 2011Efficient striated muscle contraction requires precise assembly and regulation of diverse actin filament systems, most notably the sarcomeric thin filaments of the... (Review)
Review
Efficient striated muscle contraction requires precise assembly and regulation of diverse actin filament systems, most notably the sarcomeric thin filaments of the contractile apparatus. By capping the pointed ends of actin filaments, tropomodulins (Tmods) regulate actin filament assembly, lengths, and stability. Here, we explore the current understanding of the expression patterns, localizations, and functions of Tmods in both cardiac and skeletal muscle. We first describe the mechanisms by which Tmods regulate myofibril assembly and thin filament lengths, as well as the roles of closely related Tmod family variants, the leiomodins (Lmods), in these processes. We also discuss emerging functions for Tmods in the sarcoplasmic reticulum. This paper provides abundant evidence that Tmods are key structural regulators of striated muscle cytoarchitecture and physiology.
Topics: Actin Cytoskeleton; Animals; Humans; Microfilament Proteins; Muscle Development; Muscle Proteins; Muscle, Skeletal; Muscle, Striated; Myocardium; Protein Structure, Tertiary; Sarcomeres; Tropomodulin
PubMed: 22013379
DOI: 10.1155/2011/103069 -
Journal of Cell Science Aug 2020Striated muscle is a highly specialized collection of tissues with contractile properties that vary according to functional needs. Although muscle fiber types are...
Striated muscle is a highly specialized collection of tissues with contractile properties that vary according to functional needs. Although muscle fiber types are established postnatally, lifelong plasticity facilitates stimulus-dependent adaptation. Functional adaptation requires molecular adaptation, which is partially provided by miRNA-mediated post-transcriptional regulation. miR-206 is a muscle-specific miRNA enriched in slow muscles. We investigated whether miR-206 drives the slow muscle phenotype or is merely an outcome. We found that miR-206 expression increases in both physiological (including female sex and endurance exercise) and pathological conditions (muscular dystrophy and adrenergic agonism) that promote a slow phenotype. Consistent with that observation, the slow soleus muscle of male miR-206-knockout mice displays a faster phenotype than wild-type mice. Moreover, left ventricles of male miR-206 knockout mice have a faster myosin profile, accompanied by dilation and systolic dysfunction. Thus, miR-206 appears to be necessary to enforce a slow skeletal and cardiac muscle phenotype and to play a key role in muscle sexual dimorphisms.
Topics: Animals; Female; Male; Mice; MicroRNAs; Muscle Contraction; Muscle Fibers, Skeletal; Muscle, Skeletal; Phenotype
PubMed: 32620696
DOI: 10.1242/jcs.243162