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Herrera-Rincon C, Pai VP, Moran KM, Lemire JM, Levin M. The brain is required for normal muscle and nerve patterning during early Xenopus development. Nat Commun 2017; 8:587. [PMID: 28943634 PMCID: PMC5610959 DOI: 10.1038/s41467-017-00597-2] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Accepted: 07/10/2017] [Indexed: 01/20/2023] Open
Abstract
Possible roles of brain-derived signals in the regulation of embryogenesis are unknown. Here we use an amputation assay in Xenopus laevis to show that absence of brain alters subsequent muscle and peripheral nerve patterning during early development. The muscle phenotype can be rescued by an antagonist of muscarinic acetylcholine receptors. The observed defects occur at considerable distances from the head, suggesting that the brain provides long-range cues for other tissue systems during development. The presence of brain also protects embryos from otherwise-teratogenic agents. Overexpression of a hyperpolarization-activated cyclic nucleotide-gated ion channel rescues the muscle phenotype and the neural mispatterning that occur in brainless embryos, even when expressed far from the muscle or neural cells that mispattern. We identify a previously undescribed developmental role for the brain and reveal a non-local input into the control of early morphogenesis that is mediated by neurotransmitters and ion channel activity.Functions of the embryonic brain prior to regulating behavior are unclear. Here, the authors use an amputation assay in Xenopus laevis to demonstrate that removal of the brain early in development alters muscle and peripheral nerve patterning, which can be rescued by modulating bioelectric signals.
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Affiliation(s)
- Celia Herrera-Rincon
- Biology Department and Allen Discovery Center, Tufts University, 200 Boston Avenue, suite 4600, Medford, MA, 02155-4243, USA
| | - Vaibhav P Pai
- Biology Department and Allen Discovery Center, Tufts University, 200 Boston Avenue, suite 4600, Medford, MA, 02155-4243, USA
| | - Kristine M Moran
- Biology Department and Allen Discovery Center, Tufts University, 200 Boston Avenue, suite 4600, Medford, MA, 02155-4243, USA
| | - Joan M Lemire
- Biology Department and Allen Discovery Center, Tufts University, 200 Boston Avenue, suite 4600, Medford, MA, 02155-4243, USA
| | - Michael Levin
- Biology Department and Allen Discovery Center, Tufts University, 200 Boston Avenue, suite 4600, Medford, MA, 02155-4243, USA.
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Sabillo A, Ramirez J, Domingo CR. Making muscle: Morphogenetic movements and molecular mechanisms of myogenesis in Xenopus laevis. Semin Cell Dev Biol 2016; 51:80-91. [PMID: 26853935 DOI: 10.1016/j.semcdb.2016.02.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Accepted: 02/01/2016] [Indexed: 12/15/2022]
Abstract
Xenopus laevis offers unprecedented access to the intricacies of muscle development. The large, robust embryos make it ideal for manipulations at both the tissue and molecular level. In particular, this model system can be used to fate map early muscle progenitors, visualize cell behaviors associated with somitogenesis, and examine the role of signaling pathways that underlie induction, specification, and differentiation of muscle. Several characteristics that are unique to X. laevis include myogenic waves with distinct gene expression profiles and the late formation of dermomyotome and sclerotome. Furthermore, myogenesis in the metamorphosing frog is biphasic, facilitating regeneration studies. In this review, we describe the morphogenetic movements that shape the somites and discuss signaling and transcriptional regulation during muscle development and regeneration. With recent advances in gene editing tools, X. laevis remains a premier model organism for dissecting the complex mechanisms underlying the specification, cell behaviors, and formation of the musculature system.
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Affiliation(s)
- Armbien Sabillo
- Department of Molecular & Cell Biology, University of California, Berkeley, CA 94720, USA
| | - Julio Ramirez
- Department of Biology, San Francisco State University, CA 94132, USA
| | - Carmen R Domingo
- Department of Biology, San Francisco State University, CA 94132, USA.
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Effects of 28 days of resistance exercise while consuming commercially available pre- and post-workout supplements, NO-Shotgun® and NO-Synthesize® on body composition, muscle strength and mass, markers of protein synthesis, and clinical safety markers in males. Nutr Metab (Lond) 2011; 8:78. [PMID: 22050827 PMCID: PMC3226541 DOI: 10.1186/1743-7075-8-78] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2011] [Accepted: 11/03/2011] [Indexed: 11/10/2022] Open
Abstract
Purpose The effects of 28 days of heavy resistance training while ingesting the pre- and post-workout supplements, NO-Shotgun® and NO-Synthesize® were determined on body composition, muscle strength and mass, markers of protein synthesis, and clinical safety markers. Methods Nineteen non-resistance-trained males participated in a resistance training program 4 times/week for 28 days while either ingesting 27 g/day of carbohydrate (CARB) or NO-Shotgun® 30 min pre-exercise and 27 g/day of carbohydrate or NO- Synthesize® 30 min post-exercise (NOSS). Data were analyzed with separate 2 × 2 ANOVA (p < 0.05). Results Total body mass was increased in both groups (p = 0.001), but not different between groups. Fat mass was unchanged with CARB, but NOSS decreased fat mass (p = 0.026). Both groups increased fat-free mass (p = 0.001); however, the increases were greater with NOSS (p = 0.023). NOSS underwent greater increases in upper-body (p = 0.023) and lower-body (p = 0.035) strength than CARB. Myofibrillar protein significantly increased in both groups (p = 0.041), with NOSS being greater than CARB (p = 0.049). All of the MHC isoforms were significantly increased in both groups; however, NOSS was greater than CARB for MHC 1 (p = 0.013) and MHC 2A (p = 0.046). All of the myogenic regulatory factors were significantly increased in both groups; however, NOSS was greater than CARB for Myo-D (p = 0.038) and MRF-4 (p = 0.001). For the whole blood and serum clinical chemistry markers, all variables remained within normal clinical ranges. Conclusions Heavy resistance training for 28 days, with NO-Shotgun® and NO-Synthesize® ingested before and after exercise, respectively, significantly improved body composition and increased muscle mass and performance without abnormally impacting any of the clinical chemistry markers.
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Wilborn CD, Taylor LW, Greenwood M, Kreider RB, Willoughby DS. Effects of different intensities of resistance exercise on regulators of myogenesis. J Strength Cond Res 2010; 23:2179-87. [PMID: 19826309 DOI: 10.1519/jsc.0b013e3181bab493] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
A single bout of high-intensity resistance exercise is capable of activating the expression of various genes in skeletal muscle involved in hypertrophy such as myosin heavy chain (MHC) isoforms, myogenic regulatory factors (MRFs), and growth factors. However, the specific role exercise intensity plays on the expression of these genes is not well defined. The purpose of this study was to investigate the effects of exercise intensity on MHC (type I, IIA, IIX), MRF (Myo-D, myogenin, MRF-4, myf5), and growth factor (insulin-like growth factor [IGF]-1, IGF-1 receptor [IGF-R1], mechano-growth factor [MGF]) mRNA expression. Thirteen male participants (21.5 +/- 2.9 years, 86.1 +/- 19.5 kg, 69.7 +/- 2.7 in.) completed bouts of resistance exercise involving 4 sets of 18-20 repetitions with 60-65% 1 repetition maximum (1RM) and 4 sets of 8-10 repetitions with 80-85% 1RM. Vastus lateralis biopsies were obtained immediately before exercise, and at 30 minutes, 2 hours, and 6 hours after each bout. The levels of mRNA expression were determined using real-time polymerase chain reaction. Data were analyzed using 2 x 4 multivariate analysis of variance (p
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Affiliation(s)
- Colin D Wilborn
- Department of Exercise Sport Science, University of Mary Hardin Baylor, Belton, Texas, USA
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Shelmadine B, Cooke M, Buford T, Hudson G, Redd L, Leutholtz B, Willoughby DS. Effects of 28 days of resistance exercise and consuming a commercially available pre-workout supplement, NO-Shotgun(R), on body composition, muscle strength and mass, markers of satellite cell activation, and clinical safety markers in males. J Int Soc Sports Nutr 2009; 6:16. [PMID: 19656392 PMCID: PMC2731073 DOI: 10.1186/1550-2783-6-16] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2009] [Accepted: 08/05/2009] [Indexed: 11/10/2022] Open
Abstract
Purpose This study determined the effects of 28 days of heavy resistance exercise combined with the nutritional supplement, NO-Shotgun®, on body composition, muscle strength and mass, markers of satellite cell activation, and clinical safety markers. Methods Eighteen non-resistance-trained males participated in a resistance training program (3 × 10-RM) 4 times/wk for 28 days while also ingesting 27 g/day of placebo (PL) or NO-Shotgun® (NO) 30 min prior to exercise. Data were analyzed with separate 2 × 2 ANOVA and t-tests (p < 0.05). Results Total body mass was increased in both groups (p = 0.001), but without any significant increases in total body water (p = 0.77). No significant changes occurred with fat mass (p = 0.62); however fat-free mass did increase with training (p = 0.001), and NO was significantly greater than PL (p = 0.001). Bench press strength for NO was significantly greater than PL (p = 0.003). Myofibrillar protein increased with training (p = 0.001), with NO being significantly greater than PL (p = 0.019). Serum IGF-1 (p = 0.046) and HGF (p = 0.06) were significantly increased with training and for NO HGF was greater than PL (p = 0.002). Muscle phosphorylated c-met was increased with training for both groups (p = 0.019). Total DNA was increased in both groups (p = 0.006), while NO was significantly greater than PL (p = 0.038). For DNA/protein, PL was decreased and NO was not changed (p = 0.014). All of the myogenic regulatory factors were increased with training; however, NO was shown to be significantly greater than PL for Myo-D (p = 0.008) and MRF-4 (p = 0.022). No significant differences were located for any of the whole blood and serum clinical chemistry markers (p > 0.05). Conclusion When combined with heavy resistance training for 28 days, NO-Shotgun® is not associated with any negative side effects, nor does it abnormally impact any of the clinical chemistry markers. Rather, NO-Shotgun® effectively increases muscle strength and mass, myofibrillar protein content, and increases the content of markers indicative of satellite cell activation.
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Affiliation(s)
- Brian Shelmadine
- Department of Health, Human Performance, and Recreation, Baylor University, Box 97313, Waco, TX 76798, USA.
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Kim JA, Laney C, Curry J, Unguez GA. Expression of myogenic regulatory factors in the muscle-derived electric organ of Sternopygus macrurus. ACTA ACUST UNITED AC 2008; 211:2172-84. [PMID: 18552307 DOI: 10.1242/jeb.016592] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
In most groups of electric fish, the current-producing cells of electric organs (EOs) derive from striated muscle fibers but retain some phenotypic characteristics of their precursor muscle cells. Given the role of the MyoD family of myogenic regulatory factors (MRFs) in the transcriptional activation of the muscle program in vertebrates, we examined their expression in the electrocytes of the gymnotiform Sternopygus macrurus. We estimated the number of MRF genes in the S. macrurus genome and our Southern blot analyses revealed a single MyoD, myogenin, myf5 and MRF4 gene. Quantitative RT-PCR showed that muscle and EO transcribe all MRF genes. With the exception of MyoD, the endogenous levels of myogenin, myf5 and MRF4 transcripts in electrocytes were greater than those detected in muscle fibers. These data indicate that MRF expression levels are not sufficient to predict the level to which the muscle program is manifested. Qualitative expression analysis of MRF co-regulators MEF2C, Id1 and Id2 also revealed these genes not to be unique to either muscle or EO, and detected similar expression patterns in the two tissues. Therefore, the partial muscle program of the EO is not associated with a partial expression of MRFs or with apparent distinct levels of some MRF co-factors. In addition, electrical inactivation by spinal cord transection (ST) resulted in the up-regulation of some muscle proteins in electrocytes without an accompanying increase in MRF transcript levels or notable changes in the co-factors MEF2C, Id1 and Id2. These findings suggest that the neural regulation of the skeletal muscle program via MRFs in S. macrurus might differ from that of their mammalian counterparts. Together, these data further our understanding of the molecular processes involved in the plasticity of the vertebrate skeletal muscle program that brings about the muscle-like phenotype of the non-contractile electrogenic cells in S. macrurus.
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Affiliation(s)
- Jung A Kim
- Department of Biology, New Mexico State University, Las Cruces, NM 88003, USA
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Chanoine C, Della Gaspera B, Charbonnier F. Myogenic regulatory factors: Redundant or specific functions? Lessons fromXenopus. Dev Dyn 2004; 231:662-70. [PMID: 15499556 DOI: 10.1002/dvdy.20174] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
The discovery, in the late 1980s, of the MyoD gene family of muscle transcription factors has proved to be a milestone in understanding the molecular events controlling the specification and differentiation of the muscle lineage. From gene knock-out mice experiments progressively emerged the idea that each myogenic regulatory factor (MRF) has evolved a specialized as well as a redundant role in muscle differentiation. To date, MyoD serves as a paradigm for the MRF mode of function. The features of gene regulation by MyoD support a model in which subprograms of gene expression are achieved by the combination of promoter-specific regulation of MyoD binding and MyoD-mediated binding of various ancillary proteins. This binding likely includes site-specific chromatin reorganization by means of direct or indirect interaction with remodeling enzymes. In this cascade of molecular events leading to the proper and reproducible activation of muscle gene expression, the role and mode of function of other MRFs still remains largely unclear. Recent in vivo findings using the Xenopus embryo model strongly support the concept that a single MRF can specifically control a subset of muscle genes and, thus, can be substituted by other MRFs albeit with dramatically lower efficiency. The topic of this review is to summarize the molecular data accounting for a redundant and/or specific involvement of each member of the MyoD family in myogenesis in the light of recent studies on the Xenopus model.
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Affiliation(s)
- Christophe Chanoine
- UMR 7060 CNRS, Equipe Biologie du Développement et de la Différenciation Neuromusculaire, Centre Universitaire des Saints-Pères, Université René Descartes, Paris, France.
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Weber AM, Buchsbaum GM, Chen B, Clark AL, Damaser MS, Daneshgari F, Davis G, DeLancey J, Kenton K, Weidner AC, Word RA. Basic science and translational research in female pelvic floor disorders: proceedings of an NIH-sponsored meeting. Neurourol Urodyn 2004; 23:288-301. [PMID: 15227643 DOI: 10.1002/nau.20048] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
AIMS To report the findings of a multidisciplinary group of scientists focusing on issues in basic science and translational research related to female pelvic floor disorders, and to produce recommendations for a research agenda for investigators studying female pelvic floor disorders. METHODS A National Institutes of Health (NIH)-sponsored meeting was held on November 14-15, 2002, bringing together scientists in diverse fields including obstetrics, gynecology, urogynecology, urology, gastroenterology, biomechanical engineering, neuroscience, endocrinology, and molecular biology. Recent and ongoing studies were presented and discussed, key gaps in knowledge were identified, and recommendations were made for research that would have the highest impact in making advances in the field of female pelvic floor disorders. RESULTS The meeting included presentations and discussion on the use of animal models to better understand physiology and pathophysiology; neuromuscular injury (such as at childbirth) as a possible pathogenetic factor and mechanisms for recovery of function after injury; the use of biomechanical concepts and imaging to better understand the relationship between structure and function; and molecular and biochemical mechanisms that may underlie the development of female pelvic floor disorders. CONCLUSIONS While the findings of current research will help elucidate the pathophysiologic pathways leading to the development of female pelvic floor disorders, much more research is needed for full understanding that will result in better care for patients through specific rather than empiric therapy, and lead to the potential for prevention on primary and secondary levels.
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Affiliation(s)
- Anne M Weber
- Contraception and Reproductive Health Branch, Center for Population Research, National Institute of Child Health and Human Development, Pittsburgh, Pennsylvania 15238, USA.
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Armand AS, Launay T, Gaspera BD, Charbonnier F, Gallien CL, Chanoine C. Effects of eccentric treadmill running on mouse soleus: degeneration/regeneration studied with Myf-5 and MyoD probes. ACTA PHYSIOLOGICA SCANDINAVICA 2003; 179:75-84. [PMID: 12940941 DOI: 10.1046/j.1365-201x.2003.01187.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
AIM The aim of this report is to show that eccentric exercise under well-controlled conditions is an alternative model, to chemical and mechanical analyses, and analyse the process of degeneration/regeneration in mouse soleus. METHODS For this, mice were submitted to a single bout of eccentric exercise on a treadmill down a 14 degrees decline for 150 min and the soleus muscle was analysed at different times following exercise by histology and in situ hybridization in comparison with cardiotoxin-injured muscles. RESULTS We analyse the regenerative process by detection of the accumulation of transcripts coding for the two myogenic regulatory factors, Myf-5 and MyoD, which are good markers of the activated satellite cells. From 24 h post-exercise (P-E), clusters of mononucleated Myf-5/MyoD-positive cells were detected. Their number increased up to 96 h P-E when young MyoD-positive myotubes with central nuclei began to appear. From 96 to 168 h P-E the number of myotubes increased, about 10-fold, the new myotubes representing 58% of the muscle cells (168 h P-E). CONCLUSION These results show that this protocol of eccentric exercise is able to induce a drastic degeneration/regeneration process in the soleus muscle. This offers the opportunity to perform biochemical and molecular analyses of a process of regeneration without muscle environment defects. The advantages of this model are discussed in the context of fundamental and therapeutical perspectives.
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Affiliation(s)
- A-S Armand
- Biologie du Développement et de la Différenciation Neuromusculaire, LNRS UMR 7060 CNRS, Université René Descartes, Paris Cedex, France
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Becker C, Della Gaspera B, Guyot M, Donsez E, Armand AS, Charbonnier F, Launay T, Chanoine C. Expression of MRF4 protein in adult and in regenerating muscles in Xenopus. Dev Dyn 2003; 227:445-9. [PMID: 12815631 DOI: 10.1002/dvdy.10318] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
In Xenopus, previous studies showed that the transcripts of the myogenic regulatory factor (MRF) MRF4 accumulate during skeletal muscle differentiation, but nothing is known about the accumulation of XMRF4 protein during myogenesis. In this report, an affinity-purified polyclonal antibody against Xenopus MRF4 was developed and used to describe the pattern of expression of this myogenic factor in the adult and in regenerating muscles. From young forming myotubes, XMRF4 protein persistently accumulated in nuclei during the regeneration process and was strongly expressed in nuclei of adult muscles. No selective accumulation of XMRF4 protein was detectable at neuromuscular junctions, but XMRF4 immunoreactivity was observed in sole plate nuclei as well as in extrasynaptic myofiber nuclei. We also report that XMRF4 protein accumulated before the establishment of neuromuscular connections, showing that innervation is not necessary for the appearance of XMRF4 protein during muscle regeneration.
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Affiliation(s)
- Christel Becker
- Biologie du Développement et de la Différenciation Musculaire, LNRS UMR 7060 CNRS, Université René Descartes, Paris, France
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Pownall ME, Gustafsson MK, Emerson CP. Myogenic regulatory factors and the specification of muscle progenitors in vertebrate embryos. Annu Rev Cell Dev Biol 2003; 18:747-83. [PMID: 12142270 DOI: 10.1146/annurev.cellbio.18.012502.105758] [Citation(s) in RCA: 415] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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, 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.
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Ataian Y, Owens J, Hinterberger T. MRF4 gene expression in Xenopus embryos and aneural myofibers. Dev Dyn 2003; 226:551-4. [PMID: 12619139 DOI: 10.1002/dvdy.10233] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Vertebrate embryos express the transcription factor MRF4 during skeletal muscle differentiation. Previous studies of MRF4 expression in embryonic Xenopus laevis and its response to muscle denervation in adults have led to the suggestion that its transcription may be activated in myotomes and in multinucleate myofibers through an interaction with the motor nerves. We tested this hypothesis by assaying for MRF4 gene transcripts in early neurula stage embryos, beginning before the appearance of neurons. MRF4 transcripts were detectable by reverse transcriptase-polymerase chain reaction (RT-PCR) from at least stage 13-14, well before the differentiation of either nerves or myocytes. We also tested the nerve-dependence of MRF4 gene expression in multinucleate myofibers by comparing transcript levels between interhyoideus muscles in normal larvae and muscles whose motor innervation had been prevented through surgical removal of the brain before cranial motor axon outgrowth. RT-PCR demonstrated similar MRF4 transcript levels in the aneural muscles and controls. These results fail to support the hypothesis that MRF4 gene expression is triggered or is significantly up-regulated in myogenic cells by signals from motor axons.
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Affiliation(s)
- Yeganeh Ataian
- Department of Biological Sciences University of Alaska Anchorage, Anchorage, Alaska 99508, USA
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Rescan PY. Regulation and functions of myogenic regulatory factors in lower vertebrates. Comp Biochem Physiol B Biochem Mol Biol 2001; 130:1-12. [PMID: 11470439 DOI: 10.1016/s1096-4959(01)00412-2] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The transcription factors of the MyoD family have essential functions in myogenic lineage determination and muscle differentiation. These myogenic regulatory factors (MRFs) activate muscle-specific transcription through binding to a DNA consensus sequence known as the E-box present in the promoter of numerous muscle genes. Four members, MyoD, myogenin, myf5 and MRF4/herculin/myf6, have been identified in higher vertebrates and have been shown to exhibit distinct but overlapping functions. Homologues of these four MRFs have also been isolated in a variety of lower vertebrates, including amphibians and fish. Differences have been observed, however, in both the expression patterns of MRFs during muscle development and the function of individual MRFs between lower and higher vertebrates. These differences reflect the variety of body muscle formation patterns among vertebrates. Furthermore, as a result of an additional polyploidy that occurred during the evolution of some amphibians and fish, MyoD, myogenin, myf5 and MRF4 may exist in lower vertebrates in two distinct copies that have evolved separately, acquiring specific roles and resulting in increased complexity of the myogenic regulatory network. Evidence is now accumulating that many of the co-factors (E12, Id, MEF2 and CRP proteins) that regulate MRF activity in mammals are also present in lower vertebrates. The inductive signals controlling the initial expression of MRFs within the developing somite of lower vertebrate proteins are currently being elucidated.
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Affiliation(s)
- P Y Rescan
- Scribe-INRA, Campus de Beaulieu, 35042, Rennes, France.
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