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Ian A Johnston - One of the best experts on this subject based on the ideXlab platform.
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paralogs of atlantic salmon myoblast determination factor genes are distinctly regulated in proliferating and differentiating Myogenic cells
American Journal of Physiology-regulatory Integrative and Comparative Physiology, 2010Co-Authors: Neil I Bower, Ian A JohnstonAbstract:The mRNA expression of Myogenic Regulatory Factors, including myoD1 (myoblast determination factor) gene paralogs, and their regulation by amino acids and insulin-like growth Factors were investiga...
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Phasing of muscle gene expression with fasting-induced recovery growth in Atlantic salmon
Frontiers in Zoology, 2009Co-Authors: Neil I Bower, Richard G Taylor, Ian A JohnstonAbstract:Background Many fish species experience long periods of fasting in nature often associated with seasonal reductions in water temperature and prey availability or spawning migrations. During periods of nutrient restriction, changes in metabolism occur to provide cellular energy via catabolic processes. Muscle is particularly affected by prolonged fasting as myofibrillar proteins act as a major energy source. To investigate the mechanisms of metabolic reorganisation with fasting and refeeding in a saltwater stage of Atlantic salmon ( Salmo salar L .) we analysed the expression of genes involved in myogenesis, growth signalling, lipid biosynthesis and myofibrillar protein degradation and synthesis pathways using qPCR. Results Hierarchical clustering of gene expression data revealed three clusters. The first cluster comprised genes involved in lipid metabolism and triacylglycerol synthesis ( ALDOB , DGAT1 and LPL ) which had peak expression 3-14d after refeeding. The second cluster comprised ADIPOQ , MLC2 , IGF-I and TALDO1 , with peak expression 14-32d after refeeding. Cluster III contained genes strongly down regulated as an initial response to feeding and included the ubiquitin ligases MuRF1 and MAFbx , Myogenic Regulatory Factors and some metabolic genes. Conclusion Early responses to refeeding in fasted salmon included the synthesis of triacylglycerols and activation of the adipogenic differentiation program. Inhibition of MuRF1 and MAFbx respectively may result in decreased degradation and concomitant increased production of myofibrillar proteins. Both of these processes preceded any increase in expression of Myogenic Regulatory Factors and IGF-I . These responses could be a necessary strategy for an animal adapted to long periods of food deprivation whereby energy reserves are replenished prior to the resumption of myogenesis.
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temperature influences the coordinated expression of Myogenic Regulatory Factors during embryonic myogenesis in atlantic salmon salmo salar l
The Journal of Experimental Biology, 2007Co-Authors: Daniel J Macqueen, David Robb, Ian A JohnstonAbstract:SUMMARY Potential molecular mechanisms regulating developmental plasticity to temperature were investigated in Atlantic salmon embryos ( Salmo salar L.). Six orthologues of the four Myogenic Regulatory Factors (MRFs: individually: smyf5, smyoD1a/1b/1c, smyoG and sMRF4), the master transcription Factors regulating vertebrate myogenesis, were characterised at the mRNA/genomic level. In situ hybridisation was performed with specific cRNA probes to determine the expression patterns of each gene during embryonic myogenesis. To place the MRF data in the context of known muscle fibre differentiation events, the expression of slow myosin light chain-1 and Pax7 were also investigated. Adaxial myoblasts expressed smyoD1a prior to and during somitogenesis followed by smyoD1c (20-somite stage, ss), and sMRF4 (25–30 ss), before spreading laterally across the myotome, followed closely by the adaxial cells. Smyf5 was detected prior to somitogenesis, but not in the adaxial cells in contrast to other teleosts studied. The expression domains of smyf5 , smyoD1b and smyoG were not confined to the s-smlc1 expression field, indicating a role in fast muscle myogenesis. From the end of segmentation, each MRF was expressed to a greater or lesser extent in zones of new muscle fibre production, the precursor cells for which probably originated from the Pax7 expressing cell layer external to the single layer of s-smlc1 + fibres. SmyoD1a and smyoG showed similar expression patterns with respect to somite stage at three different temperatures investigated (2°C, 5°C and 8°C) in spite of different rates of somite formation (one somite added each 5 h, 8 h and 15 h at 8°C, 5°C and 2°C, respectively). In contrast, the expression of smyf5 , sMRF4 and s-smlc1 was retarded with respect to somite stage at 2°C compared to 8°C, potentially resulting in heterochronies in downstream pathways influencing later muscle phenotype.
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Temperature and the expression of Myogenic Regulatory Factors (MRFs) and myosin heavy chain isoforms during embryogenesis in the common carp Cyprinus carpio L.
Journal of Experimental Biology, 2004Co-Authors: Nicholas J. Cole, Shugo Watabe, Thomas E. Hall, Christopher I. Martin, Mark A. Chapman, Atsushi Kobiyama, Yoshiaki Nihei, Ian A JohnstonAbstract:SUMMARY Embryos of the common carp, Cyprinus carpio L., were reared from fertilization of the eggs to inflation of the swim bladder in the larval stage at 18 and 25°C. cRNA probes were used to detect transcripts of the Myogenic Regulatory Factors MyoD, Myf-5 and myogenin, and five myosin heavy chain (MyHC) isoforms during development. The genes encoding Myf-5 and MyoD were switched on first in the unsegmented mesoderm, followed by myogenin as the somites developed. Myf-5 and MyoD transcripts were initially limited to the adaxial cells, but Myf-5 expression spread laterally into the presomitic mesoderm before somite formation. Two distinct bands of staining could be seen corresponding to the cellular fields of the forming somites, but as each furrow delineated, Myf-5 mRNA levels declined. Upon somite formation, MyoD expression spread laterally to encompass the full somite width. Expression of the myogenin gene was also switched on during somite formation, and expression of both transcripts persisted until the somites became chevron-shaped. Expression of MyoD was then downregulated shortly before myogenin. The expression patterns of the carp Myogenic Regulatory factor (MRF) genes most-closely resembled that seen in the zebrafish rather than the rainbow trout (where expression of MyoD remains restricted to the adaxial domain of the somite for a prolonged period) or the herring (where expression of MyoD persists longer than that of myogenin). Expression of two embryonic forms of MyHC began simultaneously at the 25-30 somite stage and continued until approximately two weeks post-hatch. However, the three adult isoforms of fast muscle MyHC were not detected in any stage examined, emphasizing a developmental gap that must be filled by other, as yet uncharacterised, MyHC isoform(s). No differences in the timing of expression of any mRNA transcripts were seen between temperature groups. A phylogenetic analysis of the MRFs was conducted using all available full-length amino acid sequences. A neighbour-joining tree indicated that all four members evolved from a common ancestral gene, which first duplicated into two lineages, each of which underwent a further duplication to produce Myf-5 and MyoD, and myogenin and MRF4. Parologous copies of MyoD from trout and Xenopus clustered closely together within clades, indicating recent duplications. By contrast, MyoD paralogues from gilthead seabream were more divergent, indicating a more-ancient duplication.
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Temperature and the expression of Myogenic Regulatory Factors (MRFs) and myosin heavy chain isoforms during embryogenesis in the common carp Cyprinus carpio L.
The Journal of experimental biology, 2004Co-Authors: Nicholas J. Cole, Shugo Watabe, Thomas E. Hall, Christopher I. Martin, Mark A. Chapman, Atsushi Kobiyama, Yoshiaki Nihei, Ian A JohnstonAbstract:Embryos of the common carp, Cyprinus carpio L., were reared from fertilization of the eggs to inflation of the swim bladder in the larval stage at 18 and 25 degrees C. cRNA probes were used to detect transcripts of the Myogenic Regulatory Factors MyoD, Myf-5 and myogenin, and five myosin heavy chain (MyHC) isoforms during development. The genes encoding Myf-5 and MyoD were switched on first in the unsegmented mesoderm, followed by myogenin as the somites developed. Myf-5 and MyoD transcripts were initially limited to the adaxial cells, but Myf-5 expression spread laterally into the presomitic mesoderm before somite formation. Two distinct bands of staining could be seen corresponding to the cellular fields of the forming somites, but as each furrow delineated, Myf-5 mRNA levels declined. Upon somite formation, MyoD expression spread laterally to encompass the full somite width. Expression of the myogenin gene was also switched on during somite formation, and expression of both transcripts persisted until the somites became chevron-shaped. Expression of MyoD was then downregulated shortly before myogenin. The expression patterns of the carp Myogenic Regulatory factor (MRF) genes most-closely resembled that seen in the zebrafish rather than the rainbow trout (where expression of MyoD remains restricted to the adaxial domain of the somite for a prolonged period) or the herring (where expression of MyoD persists longer than that of myogenin). Expression of two embryonic forms of MyHC began simultaneously at the 25-30 somite stage and continued until approximately two weeks post-hatch. However, the three adult isoforms of fast muscle MyHC were not detected in any stage examined, emphasizing a developmental gap that must be filled by other, as yet uncharacterised, MyHC isoform(s). No differences in the timing of expression of any mRNA transcripts were seen between temperature groups. A phylogenetic analysis of the MRFs was conducted using all available full-length amino acid sequences. A neighbour-joining tree indicated that all four members evolved from a common ancestral gene, which first duplicated into two lineages, each of which underwent a further duplication to produce Myf-5 and MyoD, and myogenin and MRF4. Parologous copies of MyoD from trout and Xenopus clustered closely together within clades, indicating recent duplications. By contrast, MyoD paralogues from gilthead seabream were more divergent, indicating a more-ancient duplication.
Simon M Hughes - One of the best experts on this subject based on the ideXlab platform.
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Differential requirements for Myogenic Regulatory Factors distinguish medial and lateral somitic, cranial and fin muscle fibre populations.
Development (Cambridge England), 2009Co-Authors: Yaniv Hinits, Daniel P S Osborn, Simon M HughesAbstract:Myogenic Regulatory Factors of the Myod family (MRFs) are transcription Factors essential for mammalian skeletal myogenesis. However, the roles of each gene in myogenesis remain unclear, owing partly to genetic linkage at the Myf5/Mrf4 locus and to rapid morphogenetic movements in the amniote somite. In mice, Myf5 is essential for the earliest epaxial myogenesis, whereas Myod is required for timely differentiation of hypaxially derived muscle. A second major subdivision of the somite is between primaxial muscle of the somite proper and abaxial somite-derived migratory muscle precursors. Here, we use a combination of mutant and morphant analysis to ablate the function of each of the four conserved MRF genes in zebrafish, an organism that has retained a more ancestral bodyplan. We show that a fundamental distinction in somite myogenesis is into medial versus lateral compartments, which correspond to neither epaxial/hypaxial nor primaxial/abaxial subdivisions. In the medial compartment, Myf5 and/or Myod drive adaxial slow fibre and medial fast fibre differentiation. Myod-driven Myogenin activity alone is sufficient for lateral fast somitic and pectoral fin fibre formation from the lateral compartment, as well as for cranial myogenesis. Myogenin activity is a significant contributor to fast fibre differentiation. Mrf4 does not contribute to early myogenesis in zebrafish. We suggest that the differential use of duplicated MRF paralogues in this novel two-component Myogenic system facilitated the diversification of vertebrates.
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signals and Myogenic Regulatory Factors restrict pax3 and pax7 expression to dermomyotome like tissue in zebrafish
Developmental Biology, 2007Co-Authors: Christina L Hammond, Yaniv Hinits, Daniel P S Osborn, James E N Minchin, Gianluca Tettamanti, Simon M HughesAbstract:Pax3/7 paired homeodomain transcription Factors are important markers of muscle stem cells. Pax3 is required upstream of myod for lateral dermomyotomal cells in the amniote somite to form particular muscle cells. Later Pax3/7-dependent cells generate satellite cells and most body muscle. Here we analyse early myogenesis from, and regulation of, a population of Pax3-expressing dermomyotome-like cells in the zebrafish. Zebrafish pax3 is widely expressed in the lateral somite and, along with pax7, becomes restricted anteriorly and then to the external cells on the lateral somite surface. Midline-derived Hedgehog signals appear to act directly on lateral somite cells to repress Pax3/7. Both Hedgehog and Fgf8, signals that induce muscle formation within the somite, suppress Pax3/7 and promote expression of Myogenic Regulatory Factors (MRFs) myf5 and myod in specific muscle precursor cell populations. Loss of MRF function leads to loss of myogenesis by specific populations of muscle fibres, with parallel up-regulation of Pax3/7. Myod is required for lateral fast muscle differentiation from pax3-expressing cells. In contrast, either Myf5 or Myod is sufficient to promote slow muscle formation from adaxial cells. Thus, Myogenic signals act to drive somite cells to a Myogenic fate through up-regulation of distinct combinations of MRFs. Our data show that the relationship between Pax3/7 genes and myogenesis is evolutionarily ancient, but that changes in the MRF targets for particular signals contribute to Myogenic differences between species.
Daniel Adesse - One of the best experts on this subject based on the ideXlab platform.
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Toxoplasma gondii Impairs Myogenesis in vitro, With Changes in Myogenic Regulatory Factors, Altered Host Cell Proliferation and Secretory Profile
Frontiers in Cellular and Infection Microbiology, 2019Co-Authors: Paloma De Carvalho Vieira, Gillian Butler-browne, Mariana Caldas Waghabi, Daniela Gois Beghini, Danilo Predes, Jose Garcia Abreu, Vincent Mouly, Helene Santos Barbosa, Daniel AdesseAbstract:Toxoplasma gondii is the causative agent of toxoplasmosis, a parasitic disease with a wide global prevalence. The parasite forms cysts in skeletal muscle cells and neurons, although no evident association with inflammatory infiltrates has been typically found. We studied the impact of T. gondii infection on the Myogenic program of mouse skeletal muscle cells (SkMC). The C2C12 murine myoblast cell line was infected with T. gondii tachyzoites (ME49 strain) for 24 h followed by Myogenic differentiation induction. T. gondii infection caused a general decrease in myotube differentiation, fusion and maturation, along with decreased expression of myosin heavy chain. The expression of Myogenic Regulatory Factors Myf5, MyoD, Mrf4 and myogenin was modulated by the infection. Infected cultures presented increased proliferation rates, as assessed by Ki67 immunostaining, whereas neither host cell lysis nor apoptosis were significantly augmented in infected dishes. Cytokine Bead Array indicated that IL-6 and MCP-1 were highly increased in the medium from infected cultures, whereas TGF-β1 was consistently decreased. Inhibition of the IL-6 receptor or supplementation with recombinant TGF-β failed to reverse the deleterious effects caused by the infection. However, conditioned medium from infected cultures inhibited myogenesis in C2C12 cells. Activation of the Wnt/β-catenin pathway was impaired in T. gondii-infected cultures. Our data indicate that T. gondii leads SkMCs to a pro-inflammatory phenotype, leaving cells unresponsive to β-catenin activation, and inhibition of the Myogenic differentiation program. Such deregulation may suggest muscle atrophy and molecular mechanisms similar to those involved in myositis observed in human patients.
Charles P. Emerson - One of the best experts on this subject based on the ideXlab platform.
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Myogenic Regulatory Factors and the specification of muscle progenitors in vertebrate embryos.
Annual review of cell and developmental biology, 2002Co-Authors: Mary Elizabeth Pownall, Marcus K. Gustafsson, Charles P. EmersonAbstract:▪ Abstract Embryological and genetic studies of mouse, bird, zebrafish, and frog embryos are providing new insights into the Regulatory functions of the Myogenic Regulatory Factors, MyoD, Myf5, Myogenin, and MRF4, and the transcriptional and signaling mechanisms that control their expression during the specification and differentiation of muscle progenitors. Myf5 and MyoD genes have genetically redundant, but developmentally distinct Regulatory functions in the specification and the differentiation of somite and head muscle progenitor lineages. Myogenin and MRF4 have later functions in muscle differentiation, and Pax and Hox genes coordinate the migration and specification of somite progenitors at sites of hypaxial and limb muscle formation in the embryo body. Transcription enhancers that control Myf5 and MyoD activation in muscle progenitors and maintain their expression during muscle differentiation have been identified by transgenic analysis. In epaxial, hypaxial, limb, and head muscle progenitors, Myf...
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Myogenic Regulatory Factors and the specification of muscle progenitors in vertebrate embryos.
Annual review of cell and developmental biology, 2002Co-Authors: Mary Elizabeth Pownall, Marcus K. Gustafsson, Charles P. EmersonAbstract:Embryological and genetic studies of mouse, bird, zebrafish, and frog embryos are providing new insights into the Regulatory functions of the Myogenic Regulatory Factors, MyoD, Myf5, Myogenin, and MRF4, and the transcriptional and signaling mechanisms that control their expression during the specification and differentiation of muscle progenitors. Myf5 and MyoD genes have genetically redundant, but developmentally distinct Regulatory functions in the specification and the differentiation of somite and head muscle progenitor lineages. Myogenin and MRF4 have later functions in muscle differentiation, and Pax and Hox genes coordinate the migration and specification of somite progenitors at sites of hypaxial and limb muscle formation in the embryo body. Transcription enhancers that control Myf5 and MyoD activation in muscle progenitors and maintain their expression during muscle differentiation have been identified by transgenic analysis. In epaxial, hypaxial, limb, and head muscle progenitors, Myf5 is controlled by lineage-specific transcription enhancers, providing evidence that multiple mechanisms control progenitor specification at different sites of myogenesis in the embryo. Developmental signaling ligands and their signal transduction effectors function both interactively and independently to control Myf5 and MyoD activation in muscle progenitor lineages, likely through direct regulation of their transcription enhancers. Future investigations of the signaling and transcriptional mechanisms that control Myf5 and MyoD in the muscle progenitor lineages of different vertebrate embryos can be expected to provide a detailed understanding of the developmental and evolutionary mechanisms for anatomical muscles formation in vertebrates. This knowledge will be a foundation for development of stem cell therapies to repair diseased and damaged muscles.
S Tapscott - One of the best experts on this subject based on the ideXlab platform.
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Functional conservation of nematode and vertebrate Myogenic Regulatory Factors.
Journal of cell science. Supplement, 1992Co-Authors: M Krause, A Fire, S White-harrison, H Weintraub, S TapscottAbstract:The Caenorhabditis elegans protein, CeMyoD, is related to the vertebrate Myogenic Regulatory Factors MyoD, myogenin, MRF-4 and Myf-5. Like its vertebrate counterparts, CeMyoD accumulates in the nucleus of striated muscle cells prior to the onset of terminal differentiation. CeMyoD also shares functional similarities with the vertebrate Myogenic Regulatory Factors. Viral LTR driven expression of CeMyoD in mouse 10T1/2 cells can convert this cell line into myoblasts as well as efficiently trans-activate mouse muscle-specific promoters. Furthermore, mouse MyoD expression can activate a CeMyoD-beta-galactosidase reporter construct in a 10T1/2 co-transfection assay.
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Functional conservation of nematode and vertebrate Myogenic Regulatory Factors.
Journal of Cell Science, 1992Co-Authors: M Krause, A Fire, S White-harrison, H Weintraub, S TapscottAbstract:Summary The Caenorhabditis elegans protein, CeMyoD, is related to the vertebrate Myogenic Regulatory Factors MyoD, myogenin, MRF-4 and Myf-5. Like its vertebrate counterparts, CeMyoD accumulates in the nucleus of striated muscle cells prior to the onset of terminal differentiation. CeMyoD also shares functional similarities with the vertebrate Myogenic Regulatory Factors. Viral LTR driven expression of CeMyoD in mouse 10T1/2 cells can convert this cell line into myoblasts as well as efficiently trans-activate mouse muscle-specific promoters. Furthermore, mouse MyoD expression can activate a CeMyoD-β-galactosidase reporter construct in a 10T1/2 co-transfection assay.
