-
Oral Diseases Nov 2018The masticatory muscles achieve a broad range of different activities such as chewing, sucking, swallowing, and speech. In order to accomplish these duties, masticatory... (Review)
Review
The masticatory muscles achieve a broad range of different activities such as chewing, sucking, swallowing, and speech. In order to accomplish these duties, masticatory muscles have a unique and heterogeneous structure and fiber composition, enabling them to produce their strength and contraction speed largely dependent on their motor units and myosin proteins that can change in response to genetic and environmental factors. Human masticatory muscles express unique myosin isoforms, including a combination of thick fibers, expressing myosin light chains (MyLC) and myosin class I and II heavy chains (MyHC) -IIA, -IIX, α-cardiac, embryonic and neonatal and thin fibers, respectively. In this review, we discuss the current knowledge regarding the importance of fiber-type diversity in masticatory muscles versus supra- and infrahyoid muscles, and versus limb and trunk muscles. We also highlight new information regarding the adaptive response and specific genetic variations of muscle fibers on the functional significance of the masticatory muscles, which influences craniofacial characteristics, malocclusions, or asymmetry. These findings may offer future possibilities for the prevention of craniofacial growth disturbances.
Topics: Humans; Integrins; Masseter Muscle; Mastication; Masticatory Muscles; Muscle Fibers, Skeletal; Myosins
PubMed: 29156093
DOI: 10.1111/odi.12806 -
Seminars in Cell & Developmental Biology Oct 2015Apicomplexan parasites, including Plasmodium and Toxoplasma, employ a unique form of substrate-dependent locomotion known as gliding motility. In these obligate,... (Review)
Review
Apicomplexan parasites, including Plasmodium and Toxoplasma, employ a unique form of substrate-dependent locomotion known as gliding motility. In these obligate, intracellular parasites, gliding motility is used for migration through the tissues and cells of the host, for active penetration of the host cell, and, at times, for proactive egress from the host. Gliding motility is powered by an actin-myosin based motor apparatus, known as the glideosome, which is situated within the elaborate cortical domain of the parasite. In this system, myosin is anchored to an internal membrane complex and drives the rearward translocation of actin-associated cell surface adhesins, thus leading to forward movement of the parasite. This review outlines our current understanding of glideosome architecture and the molecular basis of parasite motility.
Topics: Actins; Animals; Apicomplexa; Host-Parasite Interactions; Humans; Locomotion; Microscopy, Electron; Models, Biological; Myosins; Parasitic Diseases
PubMed: 26428297
DOI: 10.1016/j.semcdb.2015.09.020 -
Biochemistry. Biokhimiia Aug 2018This review summarizes current data on the structure and functions of myosin essential light chains (ELCs) and on their role in functioning of the myosin head as a... (Review)
Review
This review summarizes current data on the structure and functions of myosin essential light chains (ELCs) and on their role in functioning of the myosin head as a molecular motor. The data on structural and functional features of the N-terminal extension of myosin ELC from skeletal and cardiac muscles are analyzed; the role of this extension in the ATP-dependent interaction of myosin heads with actin in the molecular mechanism of muscle contraction is discussed. The data on possible interactions of the ELC N-terminal extension with the myosin head motor domain in the myosin ATPase cycle are presented, including the results of the authors' studies that are in favor of such interactions.
Topics: Amino Acid Sequence; Animals; Humans; Myosin Light Chains; Protein Isoforms; Structure-Activity Relationship
PubMed: 30208831
DOI: 10.1134/S0006297918080060 -
Journal of Cell Science Mar 2023Mitochondrial homeostasis requires a dynamic balance of fission and fusion. The actin cytoskeleton promotes fission, and we found that the mitochondrially localized...
Mitochondrial homeostasis requires a dynamic balance of fission and fusion. The actin cytoskeleton promotes fission, and we found that the mitochondrially localized myosin, myosin 19 (Myo19), is integral to this process. Myo19 knockdown induced mitochondrial elongation, whereas Myo19 overexpression induced fragmentation. This mitochondrial fragmentation was blocked by a Myo19 mutation predicted to inhibit ATPase activity and strong actin binding but not by mutations predicted to affect the working stroke of the motor that preserve ATPase activity. Super-resolution imaging indicated a dispersed localization of Myo19 on mitochondria, which we found to be dependent on metaxins. These observations suggest that Myo19 acts as a dynamic actin-binding tether that facilitates mitochondrial fragmentation. Myo19-driven fragmentation was blocked by depletion of either the CAAX splice variant of the endoplasmic reticulum (ER)-anchored formin INF2 or the mitochondrially localized F-actin nucleator Spire1C (a splice variant of Spire1), which together polymerize actin at sites of mitochondria-ER contact for fission. These observations imply that Myo19 promotes fission by stabilizing mitochondria-ER contacts; we used a split-luciferase system to demonstrate a reduction in these contacts following Myo19 depletion. Our data support a model in which Myo19 tethers mitochondria to ER-associated actin to promote mitochondrial fission.
Topics: Actins; Mitochondrial Dynamics; Myosins; Mitochondria; Endoplasmic Reticulum
PubMed: 36744380
DOI: 10.1242/jcs.260612 -
Skeletal Muscle Aug 2023The occurrence of hyperplasia, through myofibre splitting, remains a widely debated phenomenon. Structural alterations and fibre typing of skeletal muscle fibres, as...
BACKGROUND
The occurrence of hyperplasia, through myofibre splitting, remains a widely debated phenomenon. Structural alterations and fibre typing of skeletal muscle fibres, as seen during regeneration and in certain muscle diseases, can be challenging to interpret. Neuromuscular electrical stimulation can induce myofibre necrosis followed by changes in spatial and temporal cellular processes. Thirty days following electrical stimulation, remnants of regeneration can be seen in the myofibre and its basement membrane as the presence of small myofibres and encroachment of sarcolemma and basement membrane (suggestive of myofibre branching/splitting). The purpose of this study was to investigate myofibre branching and fibre type in a systematic manner in human skeletal muscle undergoing adult regenerative myogenesis.
METHODS
Electrical stimulation was used to induce myofibre necrosis to the vastus lateralis muscle of one leg in 5 young healthy males. Muscle tissue samples were collected from the stimulated leg 30 days later and from the control leg for comparison. Biopsies were sectioned and stained for dystrophin and laminin to label the sarcolemma and basement membrane, respectively, as well as ATPase, and antibodies against types I and II myosin, and embryonic and neonatal myosin. Myofibre branches were followed through 22 serial Sects. (264 μm). Single fibres and tissue blocks were examined by confocal and electron microscopy, respectively.
RESULTS
Regular branching of small myofibre segments was observed (median length 144 μm), most of which were observed to fuse further along the parent fibre. Central nuclei were frequently observed at the point of branching/fusion. The branch commonly presented with a more immature profile (nestin + , neonatal myosin + , disorganised myofilaments) than the parent myofibre, together suggesting fusion of the branch, rather than splitting. Of the 210 regenerating muscle fibres evaluated, 99.5% were type II fibres, indicating preferential damage to type II fibres with our protocol. Furthermore, these fibres demonstrated 7 different stages of "fibre-type" profiles.
CONCLUSIONS
By studying the regenerating tissue 30 days later with a range of microscopy techniques, we find that so-called myofibre branching or splitting is more likely to be fusion of myotubes and is therefore explained by incomplete regeneration after a necrosis-inducing event.
Topics: Male; Adult; Infant, Newborn; Humans; Muscle Fibers, Skeletal; Muscle, Skeletal; Regeneration; Myosins; Necrosis
PubMed: 37573332
DOI: 10.1186/s13395-023-00322-2 -
Advances in Experimental Medicine and... 2020Unconventional myosins are a large superfamily of actin-based molecular motors that use ATP as fuel to generate mechanical motions/forces. The distinct tails in... (Review)
Review
Unconventional myosins are a large superfamily of actin-based molecular motors that use ATP as fuel to generate mechanical motions/forces. The distinct tails in different unconventional myosin subfamilies can recognize various cargoes including proteins and lipids. Thus, they can play diverse roles in many biological processes such as cellular trafficking, mechanical supports, force sensing, etc. This chapter focuses on some recent advances on the structural studies of how unconventional myosins specifically bind to cargoes with their cargo-binding domains.
Topics: Actins; Biological Transport; Myosins; Protein Binding
PubMed: 32451854
DOI: 10.1007/978-3-030-38062-5_3 -
International Journal of Molecular... Jan 2020The objective of this article was to document the energy-transducing and regulatory interactions in supramolecular complexes such as motor, pump, and clock ATPases. The... (Review)
Review
The objective of this article was to document the energy-transducing and regulatory interactions in supramolecular complexes such as motor, pump, and clock ATPases. The dynamics and structural features were characterized by motion and distance measurements using spin-labeling electron paramagnetic resonance (EPR) spectroscopy. In particular, we focused on myosin ATPase with actin-troponin-tropomyosin, neural kinesin ATPase with microtubule, P-type ion-motive ATPase, and cyanobacterial clock ATPase. Finally, we have described the relationships or common principles among the molecular mechanisms of various energy-transducing systems and how the large-scale thermal structural transition of flexible elements from one state to the other precedes the subsequent irreversible chemical reactions.
Topics: Actins; Electron Spin Resonance Spectroscopy; Energy Transfer; Kinesins; Microtubules; Muscle, Skeletal; Myosins; P-type ATPases; Spin Labels; Tropomyosin; Troponin
PubMed: 31968570
DOI: 10.3390/ijms21020672 -
Current Opinion in Structural Biology Aug 2022Myosins are a superfamily of ATP-driven actin-dependent molecular motors that are responsible for diverse functions from muscle contraction to cell division. The... (Review)
Review
Myosins are a superfamily of ATP-driven actin-dependent molecular motors that are responsible for diverse functions from muscle contraction to cell division. The resolution revolution in cryo-EM has enabled characterisation of the interaction of myosin with its actin track in several states of the myosin motor cycle, for multiple myosin classes, allowing increased insight into the force generation mechanism. A major advancement in our understanding of myosin-2 regulation has come through solving structures of its shutdown state, dysregulation of which is implicated in multiple diseases. This review will discuss what has been accomplished so far with cryoEM, what is still yet to do, but within reach, and how better understanding of myosin structure-function relationships may lead to future therapeutic interventions.
Topics: Actins; Cryoelectron Microscopy; Mechanical Phenomena; Myosins
PubMed: 35636003
DOI: 10.1016/j.sbi.2022.102391 -
Traffic (Copenhagen, Denmark) Aug 2016
Topics: Animals; Humans; Myosins
PubMed: 27094097
DOI: 10.1111/tra.12405 -
Current Opinion in Microbiology Dec 2017Myosin motors are one of the largest protein families in eukaryotes that exhibit divergent cellular functions. Their roles in protozoans, a diverse group of anciently... (Review)
Review
Myosin motors are one of the largest protein families in eukaryotes that exhibit divergent cellular functions. Their roles in protozoans, a diverse group of anciently diverged, single celled organisms with many prominent members known to be parasitic and to cause diseases in human and livestock, are largely unknown. In the recent years many different approaches, among them whole genome sequencing, phylogenetic analyses and functional studies have increased our understanding on the distribution, protein architecture and function of unconventional myosin motors in protozoan parasites. In Apicomplexa, myosins turn out to be highly specialized and to exhibit unique functions tailored to accommodate the lifestyle of these parasites.
Topics: Animals; Apicomplexa; Humans; Myosins; Protozoan Infections; Protozoan Proteins
PubMed: 29161623
DOI: 10.1016/j.mib.2017.11.003