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1.
Artigo em Inglês | MEDLINE | ID: mdl-39122107

RESUMO

The growth hormone (GH)-insulin-like growth factor-1 (IGF-1) system regulates skeletal muscle growth and function. GH has a major function of targeting the liver to regulate IGF-1 production and release, and IGF-1 mediates the primary anabolic action of GH on growth. However, skeletal muscle is a target tissue of GH as evidenced by dynamic GH receptor expression, but it is unclear if GH elicits any direct actions on extrahepatic tissues as it is difficult to distinguish the effects of IGF-1 from GH. Fish growth regulation is complex compared to mammals, as genome duplication events have resulted in multiple isoforms of GHs, GHRs, IGFs, and IGFRs expressed in most fish tissues. This study investigated the potential for GH direct actions on fish skeletal muscle using an in vitro system, where rainbow trout myogenic precursor cells (MPCs) were cultured in normal and serum-deprived media, to mimic in vivo fasting conditions. Fasting reduces IGF-1 signaling in the muscle, which is critical for disentangling the roles of GH from IGF-1. The direct effects of GH were analyzed by measuring changes in myogenic proliferation and differentiation genes, as well as genes regulating muscle growth and proteolysis. This study provides the first in-depth analysis of the direct actions of GH on serum-deprived fish muscle cells in vitro. Data suggest that GH induces the expression of markers for proliferation and muscle growth in the presence of serum, but all observed GH action was blocked in serum-deprived conditions. Additionally, serum deprivation alone reduced the expression of several proliferation and differentiation markers, while increasing growth and proteolysis markers. Results also demonstrate dynamic gene expression response in the presence of GH and a JAK inhibitor in serum-provided but not serum-deprived conditions. These data provide a better understanding of GH signaling in relation to serum in trout muscle cells in vitro.


Assuntos
Hormônio do Crescimento , Fator de Crescimento Insulin-Like I , Músculo Esquelético , Oncorhynchus mykiss , Animais , Oncorhynchus mykiss/metabolismo , Oncorhynchus mykiss/genética , Hormônio do Crescimento/metabolismo , Fator de Crescimento Insulin-Like I/metabolismo , Músculo Esquelético/metabolismo , Músculo Esquelético/efeitos dos fármacos , Transdução de Sinais , Células Cultivadas , Proteínas de Peixes/metabolismo , Proteínas de Peixes/genética , Receptores da Somatotropina/metabolismo , Receptores da Somatotropina/genética
2.
Gen Comp Endocrinol ; 237: 19-26, 2016 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-27444129

RESUMO

Cortisol, the primary corticosteroid in teleost fishes, is released in response to stressors to elicit local functions, however little is understood regarding muscle-specific responses to cortisol in these fishes. In mammals, glucocorticoids strongly regulate the muscle growth inhibitor, myostatin, via glucocorticoid response elements (GREs) leading to muscle atrophy. Bioinformatics methods suggest that this regulatory mechanism is conserved among vertebrates, however recent evidence suggests some fishes exhibit divergent regulation. Therefore, the aim of this study was to evaluate the conserved actions of cortisol on myostatin and hsp90 expression to determine if variations in cortisol interactions have emerged in salmonid species. Representative salmonids; Chinook salmon (Oncorhynchus tshawytscha), cutthroat trout (Oncorhynchus clarki), brook trout (Salvelinus fontinalis), and Atlantic salmon (Salmo salar); were injected intraperitoneally with a cortisol implant (50µg/g body weight) and muscle gene expression was quantified after 48h. Plasma glucose and cortisol levels were significantly elevated by cortisol in all species, demonstrating physiological effectiveness of the treatment. HSP90 mRNA levels were elevated by cortisol in brook trout, Chinook salmon, and Atlantic salmon, but were decreased in cutthroat trout. Myostatin mRNA levels were affected in a species, tissue (muscle type), and paralog specific manner. Cortisol treatment increased myostatin expression in brook trout (Salvelinus) and Atlantic salmon (Salmo), but not in Chinook salmon (Oncorhynchus) or cutthroat trout (Oncorhynchus). Interestingly, the VC alone increased myostatin mRNA expression in Chinook and Atlantic salmon, while the addition of cortisol blocked the response. Taken together, these results suggest that cortisol affects muscle-specific gene expression in species-specific manners, with unique Oncorhynchus-specific divergence observed, that are not predictive solely based upon mammalian stress responses.


Assuntos
Regulação da Expressão Gênica/efeitos dos fármacos , Proteínas de Choque Térmico HSP90/genética , Hidrocortisona/farmacologia , Músculos/metabolismo , Miostatina/genética , Salmão/genética , Animais , Glicemia/metabolismo , Feminino , Proteínas de Choque Térmico HSP90/metabolismo , Hidrocortisona/administração & dosagem , Hidrocortisona/sangue , Masculino , Músculos/efeitos dos fármacos , Miostatina/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Salmão/sangue , Especificidade da Espécie
3.
Cell Tissue Res ; 359(3): 715-27, 2015 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-25487404

RESUMO

The extraordinary muscle growth potential of teleost fish, particular those of the Salmoninae clade, elicits questions about the regulation of the relatively highly conserved transcription factors of the myogenic program. The pseudotetraploid nature of the salmonid genome adds another layer of regulatory complexity that must be reconciled with epigenetic data to improve our understanding of the achievement of lifelong muscle growth in these fish. We identify three paralogous pax7 genes (pax7a1, pax7a2 and pax7b) in the rainbow trout genome. During in vitro myogenesis, pax7a1 transcripts remain stable, whereas pax7a2 and pax7b mRNAs increase in abundance, similarly to myogenin mRNAs but in contrast to the expression pattern of the mammalian ortholog. We also profile the distribution of repressive H3K27me3 and H3K9me3 and permissive H3K4me3 marks during in vitro myogenesis across these loci and find that pax7a2 expression is associated with decreased H3K27 trimethylation, whereas pax7b expression is correlated with decreased H3K9me3 and H3K27me3. These data link the unique differential expression of pax7 paralogs with epigenetic histone modifications in a vertebrate species displaying growth divergent from that of mammals and highlight an important divergence in the regulatory mechanisms of pax7 expression among vertebrates. The system described here provides a more comprehensive picture of the combinatorial control mechanisms orchestrating skeletal muscle growth in a salmonid, leading to a better understanding of myogenesis in this species and across Vertebrata more generally.


Assuntos
Epigênese Genética , Evolução Molecular , Oncorhynchus mykiss/genética , Fator de Transcrição PAX7/genética , Homologia de Sequência do Ácido Nucleico , Animais , Diferenciação Celular , Proliferação de Células , Imunoprecipitação da Cromatina , Proteínas de Peixes/genética , Proteínas de Peixes/metabolismo , Perfilação da Expressão Gênica , Regulação da Expressão Gênica no Desenvolvimento , Loci Gênicos , Histonas/metabolismo , Metilação , Desenvolvimento Muscular/genética , Fator de Transcrição PAX7/metabolismo , Filogenia , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Células Satélites de Músculo Esquelético/citologia , Células Satélites de Músculo Esquelético/metabolismo , Sintenia/genética
4.
Artigo em Inglês | MEDLINE | ID: mdl-24875565

RESUMO

Glucocorticoids (GCs) strongly regulate myostatin expression in mammals via glucocorticoid response elements (GREs), and bioinformatics methods suggest that this regulatory mechanism is conserved among many vertebrates. However, the multiple myostatin genes found in some fishes may be an exception. In silico promoter analyses of the three putative rainbow trout (Oncorhynchus mykiss) myostatin promoters have failed to identify putative GREs, suggesting a divergence in myostatin function. Therefore, we hypothesized that myostatin mRNA expression is not regulated by glucocorticoids in rainbow trout. In this study, both juvenile rainbow trout and primary trout myoblasts were treated with cortisol to examine the effects on myostatin mRNA expression. Results suggest that exogenous cortisol does not regulate myostatin-1a and -1b expression in vivo, as myostatin mRNA levels were not significantly affected by cortisol treatment in either red or white muscle tissue. In red muscle, myostatin-2a levels were significantly elevated in the cortisol treatment group relative to the control, but not the vehicle control, at both 12 h and 24 h post-injection. As such, it is unclear if cortisol was acting alone or in combination with the vehicle. Cortisol increased myostatin-1b expression in a dose-dependent manner in vitro. Further work is needed to determine if this response is the direct result of cortisol acting on the myostatin-1b promoter or through an alternative mechanism. These results suggest that regulation of myostatin by cortisol may not be as highly conserved as previously thought and support previous work that describes potential functional divergence of the multiple myostatin genes in fishes.


Assuntos
Hidrocortisona/farmacologia , Miostatina/biossíntese , Regiões Promotoras Genéticas , Transcrição Gênica/efeitos dos fármacos , Animais , Simulação por Computador , Regulação da Expressão Gênica/efeitos dos fármacos , Miostatina/efeitos dos fármacos , Oncorhynchus mykiss/crescimento & desenvolvimento , RNA Mensageiro/biossíntese
5.
Fish Physiol Biochem ; 40(3): 875-86, 2014 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-24264425

RESUMO

Muscle growth is an energetically demanding process that is reliant on intramuscular fatty acid depots in most fishes. The complex mechanisms regulating this growth and lipid metabolism are of great interest for human health and aquaculture applications. It is well established that the skeletal muscle chalone, myostatin, plays a role in lipid metabolism and adipogenesis in mammals; however, this function has not been fully assessed in fishes. We therefore examined the interaction between dietary lipid levels and myostatin expression in rainbow trout (Oncorhynchus mykiss). Five weeks of high-fat diet (HFD; 25 % lipid) intake increased white muscle lipid content and decreased circulating glucose levels and hepatosomatic index when compared to low-fat diet (LFD; 10 % lipid) intake. In addition, HFD intake reduced myostatin-1a and myostatin-1b expression in white muscle and myostatin-1b expression in brain tissue. Characterization of the myostatin-1a, myostatin-1b, and myostatin-2a promoters revealed putative binding sites for a subset of transcription factors associated with lipid metabolism. Taken together, these data suggest that HFD may regulate myostatin expression through cis-regulatory elements sensitive to increased lipid intake. Further, these findings provide a framework for future investigations of mechanisms describing the relationships between myostatin and lipid metabolism in fish.


Assuntos
Dieta Hiperlipídica , Proteínas de Peixes/metabolismo , Metabolismo dos Lipídeos , Miostatina/metabolismo , Oncorhynchus mykiss/metabolismo , Animais , Proteínas de Peixes/genética , Músculo Esquelético/metabolismo , Miostatina/genética , Oncorhynchus mykiss/genética , Regiões Promotoras Genéticas , Isoformas de Proteínas/metabolismo
6.
Geroscience ; 46(1): 171-181, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-37889438

RESUMO

Comparative studies of aging are a promising approach to identifying general properties of and processes leading to aging. While to date, many comparative studies of aging in animals have focused on relatively narrow species groups, methodological innovations now allow for studies that include evolutionary distant species. However, comparative studies of aging across a wide range of species that have distinct life histories introduce additional challenges in experimental design. Here, we discuss these challenges, highlight the most pressing problems that need to be solved, and provide suggestions based on current approaches to successfully carry out comparative aging studies across the animal kingdom.


Assuntos
Envelhecimento , Longevidade , Animais , Modelos Animais , Evolução Biológica
7.
Gen Comp Endocrinol ; 194: 45-54, 2013 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-24018114

RESUMO

In the last decade, myostatin (MSTN), a member of the TGFß superfamily, has emerged as a strong inhibitor of muscle growth in mammals. In fish many studies reveal a strong conservation of mstn gene organization, sequence, and protein structures. Because of ancient genome duplication, teleostei may have retained two copies of mstn genes and even up to four copies in salmonids due to additional genome duplication event. In sharp contrast to mammals, the different fish mstn orthologs are widely expressed with a tissue-specific expression pattern. Quantification of mstn mRNA in fish under different physiological conditions, demonstrates that endogenous expression of mstn paralogs is rarely related to fish muscle growth rate. In addition, attempts to inhibit MSTN activity did not consistently enhance muscle growth as in mammals. In vitro, MSTN stimulates myotube atrophy and inhibits proliferation but not differentiation of myogenic cells as in mammals. In conclusion, given the strong mstn expression non-muscle tissues of fish, we propose a new hypothesis stating that fish MSTN functions as a general inhibitors of cell proliferation and cell growth to control tissue mass but is not specialized into a strong muscle regulator.


Assuntos
Peixes/metabolismo , Miostatina/metabolismo , Vertebrados/metabolismo , Animais , Peixes/crescimento & desenvolvimento , Miostatina/genética , Vertebrados/crescimento & desenvolvimento
8.
Artigo em Inglês | MEDLINE | ID: mdl-23047051

RESUMO

Although the zebrafish (Danio rerio) has been widely utilized as a model organism for several decades, there is little information available on physiological variation underlying genetic variation among the most commonly used inbred strains. This study evaluated growth performance using physiological and molecular markers of growth in response to fasting in six commonly used zebrafish strains [AB, TU, TL, SJA, WIK, and petstore (PET) zebrafish]. Fasting resulted in a standard decrease in whole blood glucose levels, a typical vertebrate glucose metabolism pattern, in AB, PET, TL, and TU zebrafish strains. Alternatively, fasting did not affect glucose levels in SJA and WIK zebrafish strains. Similarly, fasting had no effect on myostatin mRNA levels in AB, PET, TU, and WIK zebrafish strains, but decreased myostatin-1 and -2 mRNA levels in SJA zebrafish. Consistent with previous work, fasting increased myostatin-2 mRNA levels in TL zebrafish. These data demonstrate that variation is present in growth performance between commonly used inbred strains of zebrafish. These data can help future research endeavors by highlighting the attributes of each strain with regard to growth performance so that the most fitting strain may be utilized.


Assuntos
Privação de Alimentos , Regulação da Expressão Gênica no Desenvolvimento , Miostatina/metabolismo , Proteínas de Peixe-Zebra/metabolismo , Peixe-Zebra/crescimento & desenvolvimento , Animais , Animais Endogâmicos/genética , Animais Endogâmicos/crescimento & desenvolvimento , Animais Endogâmicos/metabolismo , Biomarcadores/metabolismo , Glicemia , Peso Corporal , Feminino , Variação Genética , Glucose/análise , Glucose/metabolismo , Masculino , Músculos/citologia , Músculos/metabolismo , Miostatina/genética , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Especificidade da Espécie , Baço/citologia , Baço/metabolismo , Fatores de Tempo , Peixe-Zebra/genética , Peixe-Zebra/metabolismo , Proteínas de Peixe-Zebra/genética
9.
Front Physiol ; 13: 1031264, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36523555

RESUMO

Skeletal muscle regulation is responsible for voluntary muscular movement in vertebrates. The genes of two essential proteins, teneurins and latrophilins (LPHN), evolving in ancestors of multicellular animals form a ligand-receptor pair, and are now shown to be required for skeletal muscle function. Teneurins possess a bioactive peptide, termed the teneurin C-terminal associated peptide (TCAP) that interacts with the LPHNs to regulate skeletal muscle contractility strength and fatigue by an insulin-independent glucose importation mechanism in rats. CRISPR-based knockouts and siRNA-associated knockdowns of LPHN-1 and-3 in the C2C12 mouse skeletal cell line shows that TCAP stimulates an LPHN-dependent cytosolic Ca2+ signal transduction cascade to increase energy metabolism and enhance skeletal muscle function via increases in type-1 oxidative fiber formation and reduce the fatigue response. Thus, the teneurin/TCAP-LPHN system is presented as a novel mechanism that regulates the energy requirements and performance of skeletal muscle.

10.
Aging Cell ; 21(2): e13542, 2022 02.
Artigo em Inglês | MEDLINE | ID: mdl-35072344

RESUMO

Sex differences in aging occur in many animal species, and they include sex differences in lifespan, in the onset and progression of age-associated decline, and in physiological and molecular markers of aging. Sex differences in aging vary greatly across the animal kingdom. For example, there are species with longer-lived females, species where males live longer, and species lacking sex differences in lifespan. The underlying causes of sex differences in aging remain mostly unknown. Currently, we do not understand the molecular drivers of sex differences in aging, or whether they are related to the accepted hallmarks or pillars of aging or linked to other well-characterized processes. In particular, understanding the role of sex-determination mechanisms and sex differences in aging is relatively understudied. Here, we take a comparative, interdisciplinary approach to explore various hypotheses about how sex differences in aging arise. We discuss genomic, morphological, and environmental differences between the sexes and how these relate to sex differences in aging. Finally, we present some suggestions for future research in this area and provide recommendations for promising experimental designs.


Assuntos
Envelhecimento , Longevidade , Envelhecimento/genética , Animais , Feminino , Longevidade/genética , Masculino , Caracteres Sexuais
11.
Artigo em Inglês | MEDLINE | ID: mdl-19654052

RESUMO

Zebrafish (Danio rerio) have become an important model organism for developmental biology and human health studies. We recently demonstrated differential growth patterns between the zebrafish and a close relative the giant danio (Danio aequipinnatus), where the giant danio appears to exhibit indeterminate growth similar to most fish species important for commercial production, while zebrafish exhibit determinate growth more similar to mammalian growth. This study focused on evaluating muscle growth regulation differences in adult zebrafish and giant danio utilizing growth hormone treatment as a mode of growth manipulation. Growth hormone treatment resulted in increased overall growth in giant danio, but failed to increase growth in the zebrafish. Growth hormone treatment increased muscle IGF-I and GHrI gene expression in both species, but to a larger degree in the giant danio. In contrast, zebrafish exhibited a larger increase in IrA and IGF-IrB gene expression in muscle in response to GH treatment. In addition muscle myostatin levels were differentially regulated between the two species, with a down-regulation observed in rapidly growing, GH-treated giant danio and an up-regulation in zebrafish not actively growing in response to GH. This is the first report of differential expression of growth-regulating genes in closely related fish species exhibiting opposing growth paradigms. These results further support the role that the zebrafish and giant danio can play important model organisms for determinate and indeterminate growth.


Assuntos
Regulação da Expressão Gênica/fisiologia , Hormônio do Crescimento/fisiologia , Peixe-Zebra/crescimento & desenvolvimento , Peixe-Zebra/genética , Animais , Sequência de Bases , Primers do DNA , Miostatina/genética , Reação em Cadeia da Polimerase , Especificidade da Espécie
12.
Front Neurosci ; 13: 177, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30890915

RESUMO

Teneurins have well established roles in function and maintenance of the central nervous systems of vertebrates. In addition, teneurin c-terminal associated peptide (TCAP), a bioactive peptide found on the c-terminal portion of teneurins, has been shown to regulate glucose metabolism. Although, the majority of research conducted on the actions of teneurins and TCAPs has strictly focused on neurological systems in rodents, TCAP was first identified in rainbow trout after screening trout hypothalamic cDNA. This suggests a conserved functional role of TCAP across vertebrates, however, the current depth of literature on teneurins and TCAPs in fish is limited. In addition, the overall function of TCAP in regulating metabolism is unclear. This review will highlight work that has been conducted specifically in fish species in relation to the teneurin system and metabolism in order to identify areas of research that are needed for future work.

13.
Artigo em Inglês | MEDLINE | ID: mdl-29780356

RESUMO

Methionine restriction (MR) has been studied extensively over the last 25 years for its role in altering metabolic hallmarks of disease. Animals subjected to MR, display changes in metabolic flexibility demonstrated by increases in energy expenditure, glucose tolerance, and lifespan. These changes have been well characterized in a number of model systems and significant progress has been made in understanding how hepatic fibroblast growth factor 21 links MR to several components of its metabolic phenotype. Despite these advances, a complete understanding of mechanisms engaged by dietary MR remains elusive. In this review, we offer a brief history of MR and its known mechanisms associated with stress, metabolism, and lifespan extension. We consider the role of epigenetics in the response of animals to MR and propose a novel epigenetic pathway involving the regulation of microRNAs during MR.

14.
Artigo em Inglês | MEDLINE | ID: mdl-29162498

RESUMO

Energy expenditure and metabolism, is a well-studied field as it is linked to many diseases as dysregulation of metabolism is associated with cancer, neurodegeneration, and aging. Classical methods of studying metabolism in vivo are well established, but most are tedious and expensive, thus, finding methods of accurately measuring metabolism in living organisms that is quick and non-invasive is of strong interest. In this work, we validate the use of resazurin; a compound that is conformationally changed into fluorescent resorufin upon metabolic reduction by NADH2, as a metabolic assay for adult zebrafish. This assay is based on the principle that increases in resorufin fluorescence intensity (FI) conveys relative changes in metabolic output of the organisms. We demonstrate the effectiveness of resazurin in measuring metabolic changes in zebrafish larvae and adults in relation to number of pooled fish, as well as temperature alteration. Moreover, we provide details on the appropriate and optimized diluents and concentrations of resazurin. Further, by using a novel sample collection technique, we can increase the temporal possibilities that were previously limited, as well as show that samples can be stored and measured at a later time point with no decrease in accuracy. Thus, the validation of this assay in adult zebrafish may increase the versatility and complexity of the types of experiments that can be performed and have many practical applications in the field.


Assuntos
Bioensaio/métodos , Metabolismo Energético , Oxazinas/metabolismo , Xantenos/metabolismo , Peixe-Zebra/metabolismo , Fatores Etários , Animais , Temperatura Baixa , Corantes Fluorescentes/metabolismo , Larva/metabolismo , NAD/metabolismo , Dinâmica Populacional , Reprodutibilidade dos Testes , Espectrometria de Fluorescência , Fatores de Tempo , Peixe-Zebra/embriologia
15.
Biol Open ; 6(11): 1720-1725, 2017 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-29025701

RESUMO

The zebrafish (Danio rerio) remains the teleost fish of choice for biological investigations due to the vast array of molecular tools and resources available. To better understand the epigenetic regulation of autophagy, we utilized a primary myotube culture system generated from isolated myogenic precursor cells (MPCs) from zebrafish grown under starvation conditions using a media devoid of serum and amino acids. Here, we report starvation-induced regulation of several autophagy-related genes (atg) expression and profile the distribution of H3K27me3, H3K9me3, and H3K4me3 marks along lc3b, atg4b and p62/sqstm1 loci. These data support epigenetic regulation of autophagy in response to starvation that suggests a level of regulation that can be sustained for chronic conditions via chromatin modification.

16.
Comp Biochem Physiol B Biochem Mol Biol ; 141(2): 218-30, 2005 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-15886039

RESUMO

In the current study, the first non-mammalian growth/differentiation factor (GDF) 11-like homolog was cloned from zebrafish. At the nucleotide level, zebrafish GDF11 is most similar to human GDF11 (79%), while the peptide is most similar to mouse GDF11 (78%). Phylogenetic analysis showed that the zebrafish GDF11 clusters with mammalian GDF11s. This study also cloned a second MSTN form in zebrafish most similar to Salmonid MSTN2 forms. Based on real time PCR, GDF11 is expressed in multiple adult tissues, with levels highest in whole heads and gonads, and expression is less ubiquitous when compared to MSTN expression. During embryonic development, real time PCR demonstrated increasing GDF11 mRNA levels 10 h post-fertilization (hpf), while MSTN mRNA levels remain low until 48 hpf. This is the first report of a transforming growth factor (TGF)-beta superfamily member in a non-mammalian species that is more closely related to GDF11 than MSTN, and also a second form of MSTN in zebrafish; suggesting that a more complex TGF-beta superfamily array exists in primitive vertebrates than previously thought.


Assuntos
Proteínas Morfogenéticas Ósseas/genética , Fator de Crescimento Transformador beta/genética , Proteínas de Peixe-Zebra/genética , Animais , Sequência de Bases , Proteínas Morfogenéticas Ósseas/isolamento & purificação , Componentes do Gene , Fatores de Diferenciação de Crescimento , Dados de Sequência Molecular , Miostatina , Filogenia , RNA Mensageiro/análise , Alinhamento de Sequência , Distribuição Tecidual , Fator de Crescimento Transformador beta/isolamento & purificação , Proteínas de Peixe-Zebra/isolamento & purificação
17.
J Vis Exp ; (86)2014 Apr 30.
Artigo em Inglês | MEDLINE | ID: mdl-24835774

RESUMO

Due to the inherent difficulty and time involved with studying the myogenic program in vivo, primary culture systems derived from the resident adult stem cells of skeletal muscle, the myogenic precursor cells (MPCs), have proven indispensible to our understanding of mammalian skeletal muscle development and growth. Particularly among the basal taxa of Vertebrata, however, data are limited describing the molecular mechanisms controlling the self-renewal, proliferation, and differentiation of MPCs. Of particular interest are potential mechanisms that underlie the ability of basal vertebrates to undergo considerable postlarval skeletal myofiber hyperplasia (i.e. teleost fish) and full regeneration following appendage loss (i.e. urodele amphibians). Additionally, the use of cultured myoblasts could aid in the understanding of regeneration and the recapitulation of the myogenic program and the differences between them. To this end, we describe in detail a robust and efficient protocol (and variations therein) for isolating and maintaining MPCs and their progeny, myoblasts and immature myotubes, in cell culture as a platform for understanding the evolution of the myogenic program, beginning with the more basal vertebrates. Capitalizing on the model organism status of the zebrafish (Danio rerio), we report on the application of this protocol to small fishes of the cyprinid clade Danioninae. In tandem, this protocol can be utilized to realize a broader comparative approach by isolating MPCs from the Mexican axolotl (Ambystoma mexicanum) and even laboratory rodents. This protocol is now widely used in studying myogenesis in several fish species, including rainbow trout, salmon, and sea bream(1-4).


Assuntos
Técnicas de Cultura de Células/métodos , Mioblastos/citologia , Células-Tronco Adultas/citologia , Animais , Linhagem da Célula , Cyprinidae , Desenvolvimento Muscular , Músculo Esquelético/citologia
18.
Front Genet ; 4: 159, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23967015

RESUMO

Sarcopenia and dynapenia pose significant problems for the aged, especially as life expectancy rises in developed countries. Current therapies are marginally efficacious at best, and barriers to breakthroughs in treatment may result from currently employed model organisms. Here, we argue that the use of indeterminate-growing teleost fish in skeletal muscle aging research may lead to therapeutic advancements not possible with current mammalian models. Evidence from a comparative approach utilizing the subfamily Danioninae suggests that the indeterminate growth paradigm of many teleosts arises from adult muscle stem cells with greater proliferative capacity, even in spite of smaller progenitor populations. We hypothesize that paired-box transcription factors, Pax3/7, are involved with this enhanced self-renewal and that prolonged expression of these factors may allow some fish species to escape, or at least forestall, sarcopenia/dynapenia. Future research efforts should focus on the experimental validation of these genes as key factors in indeterminate growth, both in the context of muscle stem cell proliferation and in prevention of skeletal muscle senescence.

19.
In Vitro Cell Dev Biol Anim ; 49(5): 371-85, 2013 May.
Artigo em Inglês | MEDLINE | ID: mdl-23613306

RESUMO

The zebrafish (Danio rerio) has been used extensively as a model system for developmental studies but, unlike most teleost fish, it grows in a determinate-like manner. A close relative, the giant danio (Devario cf. aequipinnatus), grows indeterminately, displaying both hyperplasia and hypertrophy of skeletal myofibers as an adult. To better understand adult muscle hyperplasia, a postlarval/postnatal process that closely resembles secondary myogenesis during development, we characterized the expression of Pax3/7, c-Met, syndecan-4, Myf5, MyoD1, myogenin, and myostatin during in vitro myogenesis, a technique that allows for the complete progression of myogenic precursor cells to myotubes. Pax7 appears to be expressed only in newly activated MPCs while Pax3 is expressed through most of the myogenic program, as are c-Met and syndecan-4. MyoD1 appears important in all stages of myogenesis, while Myf5 is likely expressed at low to background levels, and myogenin expression is enriched in myotubes. Myostatin, like MyoD1, appears to be ubiquitous at all stages. This is the first comprehensive report of key myogenic factor expression patterns in an indeterminate teleost, one that strongly suggests that Pax3 and/or Myf5 may be involved in the regulation of this paradigm. Further, it validates this species as a model organism for studying adult myogenesis in vitro, especially mechanisms underlying nascent myofiber recruitment.


Assuntos
Cyprinidae/fisiologia , Regulação da Expressão Gênica no Desenvolvimento/fisiologia , Modelos Animais , Desenvolvimento Muscular/fisiologia , Músculo Esquelético/crescimento & desenvolvimento , Fatores de Transcrição Box Pareados/metabolismo , Análise de Variância , Animais , Cyprinidae/metabolismo , Imuno-Histoquímica , Proteína MyoD/metabolismo , Fator Regulador Miogênico 5/metabolismo , Miogenina , Miostatina , Proteínas Proto-Oncogênicas c-met/metabolismo , Sindecana-4/metabolismo
20.
J Nutr Biochem ; 24(8): 1462-8, 2013 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-23465590

RESUMO

Gelatinases play a role in adipose and muscle hypertrophy and could be involved in tissue remodeling in response to high-fat diet (HFD) intake. This study tested potential roles of gelatinases (matrix metalloproteinses-2 and -9 [MMP-2 and -9]) in relationship to an antigrowth factor [myostatin (MSTN)] known to be dysregulated in relation to HFD-induced obesity (HFDIO) propensity. In vitro and ex vivo analyses demonstrated that MMP-9 increased mature MSTN levels, indicating a potential role of gelatinases in MSTN activation in vivo. HFD intake resulted in increased body weight and circulating blood glucose values in C57BL/6J and MMP-9 null mice, with no changes observed in SWR/J mice. HFD intake attenuated MMP-9 and MMP-2 mRNA levels in SWR/J mice while elevating MMP-2 levels in skeletal muscle in C57BL/6J mice. In MMP-9 null mice, the effects of HFD intake were muted. Consistent with changes in mRNA levels, HFD intake increased MMP-9 activity in muscle tissue of C57BL/6J mice, demonstrating a strong relationship between HFDIO susceptibility and local MMP regulation. Overall, resistance to HFDIO appears to correspond to low MMP-9 and MSTN levels, suggesting a role of MMP-9 in MSTN activation in local tissue responses to HFD intake.


Assuntos
Dieta Hiperlipídica , Metaloproteinase 2 da Matriz/metabolismo , Metaloproteinase 9 da Matriz/metabolismo , Músculo Esquelético/patologia , Miostatina/metabolismo , Obesidade/metabolismo , Animais , Glicemia/metabolismo , Peso Corporal , Gorduras na Dieta/administração & dosagem , Hipertrofia/fisiopatologia , Masculino , Metaloproteinase 2 da Matriz/genética , Metaloproteinase 9 da Matriz/genética , Camundongos , Camundongos Endogâmicos C57BL , Miostatina/genética , RNA Mensageiro/genética , RNA Mensageiro/metabolismo
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