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Meat Science Apr 2023The effect of pre-rigor temperature incubation on the activity and distribution in sarcoplasmic and myofibrillar fractions of calpains, and meat quality attributes was...
The effect of pre-rigor temperature incubation on the activity and distribution in sarcoplasmic and myofibrillar fractions of calpains, and meat quality attributes was investigated. Porcine longissimus thoracis muscles were incubated pre-rigor at 14, 22, 30 and 38 °C to 6 h postmortem, followed by another 2 h incubation at 14 °C. Thereafter, muscles were stored at 2 °C for 1 or 4 days. With higher pre-rigor temperature, sarcoplasmic Ca concentration, purge loss and myofibril-bound calpain-1 content increased, while shear force declined. Water-holding capacity of isolated myofibrils was lower after pre-rigor incubation at 38 °C. Desmin and troponin T degradation, and myofibril fragmentation was greater upon incubation of isolated myofibrils with added Ca in the order 800 μM Ca > 40 μM Ca > no Ca, suggesting that calpain-1 and calpain-2 were associated to myofibrils and proteolytically active with sufficient Ca. Activity of myofibril-bound calpain-1 in muscle incubated pre-rigor at 22 and 30 °C were higher than when incubated at 14 and 38 °C. These results indicate that calpains translocate from the sarcoplasm onto myofibrils with higher pre-rigor temperature to 30 °C and the proteolytic potential of myofibril-associated calpains is thereby increased.
Topics: Swine; Animals; Proteolysis; Myofibrils; Calpain; Red Meat; Pork Meat; Temperature; Muscle, Skeletal; Meat
PubMed: 36608417
DOI: 10.1016/j.meatsci.2022.109094 -
Molecules (Basel, Switzerland) Feb 2020We compare steps observed during the fibrillogenesis of myofibrils with the sequence of steps predictable by a recent analysis of the structurization and functioning of...
We compare steps observed during the fibrillogenesis of myofibrils with the sequence of steps predictable by a recent analysis of the structurization and functioning of striated muscles. The predicted assembly steps are based solely on fundamental equilibrium processes, particularly supramolecular interactions and liquid crystalline alignment of the rigid thick and thin filaments hosted within the sarcomer. Satisfactory agreement is obtained between several of the observed and the predicted fibrillogenesis steps. In several cases, however, the actual steps appear to be more complex than expected, evidencing the occurrence of transport and kinetic pathways that may assist the attainment of the equilibrium structure. The memory of the order of a precursor mesophase is imprinted during the remodeling of the surfaces at which the two sets of filaments are anchored. The relevance of the present analysis to the functioning of the myofibril is considered.
Topics: Actin Cytoskeleton; Actins; Animals; Connectin; Humans; Liquid Crystals; Models, Biological; Myofibrils; Myosins
PubMed: 32075335
DOI: 10.3390/molecules25040862 -
PloS One 2020In sarcomeres, α-actinin crosslinks thin filaments and anchors them at the Z-disc. Drosophila melanogaster Zasp52 also localizes at Z-discs and interacts with...
In sarcomeres, α-actinin crosslinks thin filaments and anchors them at the Z-disc. Drosophila melanogaster Zasp52 also localizes at Z-discs and interacts with α-actinin via its extended PDZ domain, thereby contributing to myofibril assembly and maintenance, yet the detailed mechanism of Zasp52 function is unknown. Here we show a strong genetic interaction between actin and Zasp52 during indirect flight muscle assembly, indicating that this interaction plays a critical role during myofibril assembly. Our results suggest that Zasp52 contains an actin-binding site, which includes the extended PDZ domain and the ZM region. Zasp52 binds with micromolar affinity to monomeric actin. A co-sedimentation assay indicates that Zasp52 can also bind to F-actin. Finally, we use in vivo rescue assays of myofibril assembly to show that the α-actinin-binding domain of Zasp52 is not sufficient for a full rescue of Zasp52 mutants suggesting additional contributions of Zasp52 actin-binding to myofibril assembly.
Topics: Actins; Animals; Carrier Proteins; Drosophila Proteins; Drosophila melanogaster; Myofibrils; PDZ Domains; Protein Binding
PubMed: 32614896
DOI: 10.1371/journal.pone.0232137 -
Archives of Biochemistry and Biophysics Mar 2019
Review
Topics: Animals; Muscle Contraction; Muscle, Striated; Myofibrils
PubMed: 30639328
DOI: 10.1016/j.abb.2019.01.008 -
Frontiers in Bioscience (Landmark... Jan 2012Cardiomyocytes are coordinated by linking together at their ends through the intercalated disc. The intercalated disc with its complex folded membrane, encompasses many... (Review)
Review
Cardiomyocytes are coordinated by linking together at their ends through the intercalated disc. The intercalated disc with its complex folded membrane, encompasses many structural and signalling functions and is thought to play a role in cell growth and sarcomere addition. Its relationship to the contractile myofibrils is central to myocyte function. The myofibrils continue their ordered sarcomeric structure up to the edge of the intercalated disc where there is no terminal Z-disc but, instead a transitional junction. Thin actin-containing filaments from the final half sarcomere extend beyond their normal length through the transitional junction to the folded intercalated disc membrane where tension is transmitted. The peaks of the membrane folds also occur at the transitional level. They are spectrin rich and associated with sarcoplasmic reticulum vesicles. A subset of Z-disc proteins including titin, alpha-actinin and ZASP/cypher/oracle are found in the transitional region while others such as telethonin and FATZ/calsarcin/myozenin are absent. The presence of titin enables ordered sarcomeres to be maintained independently of changes in the amplitude of the membrane folds. The transitional junction is therefore poised to act as a site for a new Z-disc/SR/T-tubule complex and sarcomere addition. The evidence for this is reviewed.
Topics: Animals; Cell Membrane; Mice; Microscopy, Electron; Myocardium; Myofibrils
PubMed: 22201789
DOI: 10.2741/3972 -
Cell Structure and Function Feb 1997Desmin, the muscle-specific member of the intermediate filament (IF) family, is one of the earliest known myogenic markers in both skeletal muscle and heart. Its... (Review)
Review
Desmin, the muscle-specific member of the intermediate filament (IF) family, is one of the earliest known myogenic markers in both skeletal muscle and heart. Its expression precedes that of all known muscle proteins including the members of the MyoD family of myogenic helix-loop-helix (mHLH) regulators with the exception of myf5. In mature striated muscle, desmin IFs surround the Z-discs, interlink them together and integrate the contractile apparatus with the sarcolemma and the nucleus. In vitro studies using both antisense RNA and homologous recombination techniques in embryonic stem (ES) cells demonstrated that desmin plays a crucial role during myogenesis, as inhibition of desmin expression blocked myoblast fusion and myotube formation. Both in C2C12 cells and differentiating embryoid bodies, the absence of desmin interferes with the normal myogenic program, as manifested by the inhibition of the mHLH transcription regulators. To investigate the function of desmin in all muscle types in vivo, we generated desmin null mice through homologous recombination. Surprisingly, a considerable number of these mice are viable and fertile, potentially due to compensation by vimentin, nestin or synemin. However, desmin null mice demonstrate a multisystem disorder involving cardiac, skeletal and smooth muscle, beginning early in their postnatal life. Histological and electron microscopic analysis in both heart and skeletal muscle tissues reveals severe disruption of muscle architecture and degeneration. Structural abnormalities include loss of lateral alignment of myofibrils, perturbation of myofibril anchorage to the sarcolemma, abnormal mitochondrial number and organization, and loss of nuclear shape and positioning. Loose cell adhesion and increased intercellular space are prominent defects. The consequences of these abnormalities are most severe in the heart, which exhibits progressive degeneration and necrosis of the myocardium accompanied by extensive calcification. Abnormalities of smooth muscle included hypoplasia and degeneration. There is a direct correlation between severity of damage and muscle usage, possibly due to increased susceptibility to normal mechanical damage and/or to repair deficiency in the absence of desmin. In conclusion, the studies so far have demonstrated that though desmin is absolutely necessary for muscle differentiation in vitro, muscle development can take place in vivo in the absence of this intermediate filament protein. However, desmin seems to play an essential role in the maintenance of myofibril, myofiber and whole muscle tissue structural and functional integrity.
Topics: Animals; Cells, Cultured; Desmin; Down-Regulation; Heart; Intermediate Filament Proteins; Mice; Muscles; Myofibrils; Nerve Tissue Proteins; Nestin; Vimentin
PubMed: 9113396
DOI: 10.1247/csf.22.103 -
Journal of Biomechanics 1991Animal muscles generate forces and induce movements at desirable rates. These roles are interactive and must be considered together. Performance of the organism and... (Review)
Review
Animal muscles generate forces and induce movements at desirable rates. These roles are interactive and must be considered together. Performance of the organism and survival of the species also involve potential optimization of control and of energy consumption. Further, individual variability arising partly via ontogeny and partly from phylogenetic history often has pronounced and sometime conflicting effects on structures and their uses. Hence, animal bodies are generally adequate for their tasks rather than being elegantly matched to them. For muscle, matching to role is reflected at all levels of muscular organization, from the nature of the sarcoplasm and contractile filaments to architectural arrangements of the parts and whole of organs. Vertebrate muscles are often analyzed by mapping their placement and then "explaining" this on the basis of currently observed roles. A recent alternative asks the obverse; given a mass of tissue that may be developed and maintained at a particular cost, what predictions do physical principles permit about its placement. Three architectural patterns that deserve discussion are the classical arrangement of fibers in pinnate patterns, the more recent assumption of sarcomere equivalence, and the issue of compartmentation. All have potential functional implications. 1. The assumption of equivalence of the sarcomeres of motor units allows predictions of the fiber length between sites of origin and insertion. In musculoskeletal systems that induce rotation, the observed (but not the pinnation-associated) insertion angle will differ with the radial lines on which the fibers insert. In a dynamic contraction inducing rotation, a shift of moment arm has no effect for muscles of equal mass. 2. Classical pinnate muscles contain many relatively short fibers positioned in parallel but at an angle to the whole muscle, reducing the per fiber force contribution. However, the total physiological cross-section and total muscle force are thus increased relative to arrangements with fibers parallel to the whole muscle. Equivalent muscles may be placed in various volumetric configurations matching other demands of the organism. The loss of fiber force due to (pinnate, not equivalent) angulation is compensated for by the reduced shortening of fibers in multipinnate arrays. 3. Compartmentation, i.e., the subdivision of muscles into independently controlled, spatially discrete volumes, is likely ubiquitous. Differential activation of the columns of radial arrays may facilitate change of vector and with this of function. Compartmentation is apt to be particularly important in strap muscles with short fiber architecture; their motor units generally occupy columnar, rather than transversely stacked, subdivisions; this may affect recovery from fiber atrophy and degeneration.(ABSTRACT TRUNCATED AT 400 WORDS)
Topics: Animals; Biomechanical Phenomena; Muscle Contraction; Muscles; Myofibrils; Sarcomeres
PubMed: 1791182
DOI: 10.1016/0021-9290(91)90377-y -
The Journal of Cell Biology Oct 2018Myofibril breakdown is a fundamental cause of muscle wasting and inevitable sequel of aging and disease. We demonstrated that myofibril loss requires depolymerization of...
Myofibril breakdown is a fundamental cause of muscle wasting and inevitable sequel of aging and disease. We demonstrated that myofibril loss requires depolymerization of the desmin cytoskeleton, which is activated by phosphorylation. Here, we developed a mass spectrometry-based kinase-trap assay and identified glycogen synthase kinase 3-β (GSK3-β) as responsible for desmin phosphorylation. GSK3-β inhibition in mice prevented desmin phosphorylation and depolymerization and blocked atrophy upon fasting or denervation. Desmin was phosphorylated by GSK3-β 3 d after denervation, but depolymerized only 4 d later when cytosolic Ca levels rose. Mass spectrometry analysis identified GSK3-β and the Ca-specific protease, calpain-1, bound to desmin and catalyzing its disassembly. Consistently, calpain-1 down-regulation prevented loss of phosphorylated desmin and blocked atrophy. Thus, phosphorylation of desmin filaments by GSK3-β is a key molecular event required for calpain-1-mediated depolymerization, and the subsequent myofibril destruction. Consequently, GSK3-β represents a novel drug target to prevent myofibril breakdown and atrophy.
Topics: Animals; Calcium; Calpain; Desmin; Down-Regulation; Gene Expression Regulation, Developmental; Glycogen Synthase Kinase 3 beta; Male; Mice; Muscular Atrophy; Myofibrils; Phosphorylation
PubMed: 30061109
DOI: 10.1083/jcb.201802018 -
Journal of Biomedicine & Biotechnology 2010We review some of the problems in determining how myofibrils may be assembled and just as importantly how this contractile structure may be renewed by sarcomeric... (Review)
Review
We review some of the problems in determining how myofibrils may be assembled and just as importantly how this contractile structure may be renewed by sarcomeric proteins moving between the sarcomere and the cytoplasm. We also address in this personal review the recent evidence that indicates that the assembly and dynamics of myofibrils are conserved whether the cells are analyzed in situ or in tissue culture conditions. We suggest that myofibrillogenesis is a fundamentally conserved process, comparable to protein synthesis, mitosis, or cytokinesis, whether examined in situ or in vitro.
Topics: Animals; Fluorescence Recovery After Photobleaching; Humans; Models, Biological; Muscle Development; Myofibrils
PubMed: 20625425
DOI: 10.1155/2010/858606 -
Cytoskeleton (Hoboken, N.J.) Nov 2010In striated muscle, the actin cytoskeleton is differentiated into myofibrils. Actin and myosin filaments are organized in sarcomeres and specialized for producing... (Review)
Review
In striated muscle, the actin cytoskeleton is differentiated into myofibrils. Actin and myosin filaments are organized in sarcomeres and specialized for producing contractile forces. Regular arrangement of actin filaments with uniform length and polarity is critical for the contractile function. However, the mechanisms of assembly and maintenance of sarcomeric actin filaments in striated muscle are not completely understood. Live imaging of actin in striated muscle has revealed that actin subunits within sarcomeric actin filaments are dynamically exchanged without altering overall sarcomeric structures. A number of regulators for actin dynamics have been identified, and malfunction of these regulators often result in disorganization of myofibril structures or muscle diseases. Therefore, proper regulation of actin dynamics in striated muscle is critical for assembly and maintenance of functional myofibrils. Recent studies have suggested that both enhancers of actin dynamics and stabilizers of actin filaments are important for sarcomeric actin organization. Further investigation of the regulatory mechanism of actin dynamics in striated muscle should be a key to understanding how myofibrils develop and operate.
Topics: Actin Cytoskeleton; Animals; Cytoskeleton; Humans; Microfilament Proteins; Muscle Proteins; Muscle, Striated; Myofibrils; Myosins; Sarcomeres
PubMed: 20737540
DOI: 10.1002/cm.20476