Dual-specificity phosphatase 4 is upregulated during skeletal muscle atrophy and modulates extracellular signal-regulated kinase activity

Skeletal muscle atrophy results from disparate physiological conditions, including denervation, corticosteroid treatment, and aging. The purpose of this study was to describe and characterize the function of dual-specificity phosphatase 4 (Dusp4) in skeletal muscle after it was found to be induced in response to neurogenic atrophy. Quantitative PCR and Western blot analysis revealed that Dusp4 is expressed during myoblast proliferation but rapidly disappears as muscle cells differentiate. The Dusp4 regulatory region was cloned and found to contain a conserved E-box element that negatively regulates Dusp4 reporter gene activity in response to myogenic regulatory factor expression. In addition, the proximal 3′-untranslated region of Dusp4 acts in an inhibitory manner to repress reporter gene activity as muscle cells progress through the differentiation process. To determine potential function, Dusp4 was fused with green fluorescent protein, expressed in C2C12 cells, and found to localize to the nucleus of proliferating myoblasts. Furthermore, Dusp4 overexpression delayed C2C12 muscle cell differentiation and resulted in repression of a MAP kinase signaling pathway reporter gene. Ectopic expression of a Dusp4 dominant negative mutant blocked muscle cell differentiation and attenuated MAP kinase signaling by preferentially targeting the ERK1/2 branch, but not the p38 branch, of the MAP kinase signaling cascade in skeletal muscle cells. The findings presented in this study provide the first description of Dusp4 in skeletal muscle and suggest that Dusp4 may play an important role in the regulation of muscle cell differentiation by regulating MAP kinase signaling.

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Inhibition of protein phosphatase methylesterase 1 dysregulates MAP kinase signaling and attenuates muscle cell differentiation

Gene ◽

10.1016/j.gene.2020.144515 ◽

2020 ◽

Vol 739 ◽

pp. 144515 ◽

Cited By ~ 1

Author(s):

Sydney A. Labuzan ◽

Sarah A. Lynch ◽

Lisa M. Cooper ◽

David S. Waddell

Keyword(s):

Cell Differentiation ◽

Map Kinase ◽

Muscle Cell ◽

Protein Phosphatase ◽

Kinase Signaling ◽

Muscle Cell Differentiation ◽

Map Kinase Signaling

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IL-1β stimulates IL-6 production in cultured skeletal muscle cells through activation of MAP kinase signaling pathway and NF-κB

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.00490.2002 ◽

2003 ◽

Vol 284 (5) ◽

pp. R1249-R1254 ◽

Cited By ~ 70

Author(s):

Guangjo Luo ◽

Dan D. Hershko ◽

Bruce W. Robb ◽

Curtis J. Wray ◽

Per-Olof Hasselgren

Keyword(s):

Skeletal Muscle ◽

Dna Binding ◽

Map Kinase ◽

Muscle Cells ◽

Binding Activity ◽

C2c12 Cells ◽

Luciferase Reporter ◽

Kinase Signaling ◽

Dna Binding Activity ◽

Map Kinase Signaling

Recent studies suggest that the skeletal muscle may be a significant site of IL-6 production in various conditions, including exercise, inflammation, hypoperfusion, denervation, and local muscle injury. The mediators and molecular mechanisms regulating muscle IL-6 production are poorly understood. We tested the hypothesis that IL-6 production in muscle cells is regulated by IL-1β and that mitogen-activated protein (MAP) kinase signaling and NF-κB activation are involved in IL-1β-induced IL-6 production. Cultured C2C12 cells, a mouse skeletal muscle cell line, were treated with different concentrations (0.1–2 ng/ml) of IL-1β in the absence or presence of the p38 MAP kinase inhibitor SB-208350 or the p42/44 inhibitor PD-98059. Protein and gene expression of IL-6 were determined by ELISA and real-time PCR, respectively. NF-κB DNA binding activity was determined by electrophoretic mobility shift assay and by transfecting myocytes with a luciferase reporter plasmid containing a promoter construct with multiple repeats of NF-κB binding site. Treatment of myotubes with IL-1β resulted in a dose- and time-dependent increase of IL-6 production accompanied by an ∼25-fold increase in IL-6 mRNA levels. IL-1β stimulated NF-κB DNA binding activity and gene activation. SB-208350 and PD-98059 inhibited the increase in IL-6 production induced by IL-1β. The present results support the concept that skeletal muscle is an important site of IL-6 production. In addition, the results suggest the IL-1β regulates muscle IL-6 production at least in part by activating the MAP kinase pathway and NF-κB.

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Dual-specificity phosphatase 29 is induced during neurogenic skeletal muscle atrophy and attenuates glucocorticoid receptor activity in muscle cell culture

AJP Cell Physiology ◽

10.1152/ajpcell.00200.2020 ◽

2020 ◽

Vol 319 (2) ◽

pp. C441-C454

Author(s):

Lisa M. Cooper ◽

Rita C. West ◽

Caleb S. Hayes ◽

David S. Waddell

Keyword(s):

Skeletal Muscle ◽

Glucocorticoid Receptor ◽

Reporter Gene ◽

Muscle Cell ◽

Muscle Atrophy ◽

Muscle Cells ◽

Proximal Promoter ◽

Skeletal Muscle Atrophy ◽

Dual Specificity Phosphatase ◽

Dual Specificity

Skeletal muscle atrophy is caused by a decrease in muscle size and strength and results from a range of physiological conditions, including denervation, immobilization, corticosteroid exposure and aging. Newly named dual-specificity phosphatase 29 ( Dusp29) has been identified as a novel neurogenic atrophy-induced gene in skeletal muscle. Quantitative PCR analysis revealed that Dusp29 expression is significantly higher in differentiated myotubes compared with proliferating myoblasts. To determine how Dusp29 is transcriptionally regulated in skeletal muscle, fragments of the promoter region of Dusp29 were cloned, fused to a reporter gene, and found to be highly inducible in response to ectopic expression of the myogenic regulatory factors (MRF), MyoD and myogenin. Furthermore, site-directed mutagenesis of conserved E-box elements within the proximal promoter of Dusp29 rendered a Dusp29 reporter gene unresponsive to MRF overexpression. Dusp29, an atypical Dusp also known as Dupd1/Dusp27, was found to attenuate the ERK1/2 branch of the MAP kinase signaling pathway in muscle cells and inhibit muscle cell differentiation when ectopically expressed in proliferating myoblasts. Interestingly, Dusp29 was also found to destabilize AMPK protein while simultaneously enriching the phosphorylated pool of AMPK in muscle cells. Additionally, Dusp29 overexpression resulted in a significant increase in the glucocorticoid receptor (GR) protein and elevation in GR phosphorylation. Finally, Dusp29 was found to significantly impair the ability of the glucocorticoid receptor to function as a transcriptional activator in muscle cells treated with dexamethasone. Identifying and characterizing the function of Dusp29 in muscle provides novel insights into the molecular and cellular mechanisms for skeletal muscle atrophy.

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Zinc finger protein 593 is upregulated during skeletal muscle atrophy and modulates muscle cell differentiation

Experimental Cell Research ◽

10.1016/j.yexcr.2019.111563 ◽

2019 ◽

Vol 383 (2) ◽

pp. 111563 ◽

Cited By ~ 5

Author(s):

Sarah A. Lynch ◽

Marc A. McLeod ◽

Hannah C. Orsech ◽

Alexander M. Cirelli ◽

David S. Waddell

Keyword(s):

Skeletal Muscle ◽

Cell Differentiation ◽

Zinc Finger ◽

Muscle Cell ◽

Muscle Atrophy ◽

Zinc Finger Protein ◽

Skeletal Muscle Atrophy ◽

Muscle Cell Differentiation ◽

Finger Protein

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Expression of rainbow trout glucose transporters GLUT1 and GLUT4 during in vitro muscle cell differentiation and regulation by insulin and IGF-I

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.90673.2008 ◽

2009 ◽

Vol 296 (3) ◽

pp. R794-R800 ◽

Cited By ~ 40

Author(s):

Mònica Díaz ◽

Yoryia Vraskou ◽

Joaquim Gutiérrez ◽

Josep V. Planas

Keyword(s):

Skeletal Muscle ◽

Cell Differentiation ◽

Glucose Uptake ◽

Muscle Cell ◽

Muscle Cells ◽

Muscle Cell Differentiation ◽

Igf I ◽

Glut1 Expression ◽

Trout Muscle

Insulin is an important factor for the maintenance of glucose homeostasis, enhancing glucose uptake in its target tissues in a process that has been conserved between fish and mammals. In fish skeletal muscle cells, like in mammals, insulin promotes GLUT4 translocation to the plasma membrane and, consequently, glucose uptake, but its role regulating the expression of glucose transporters in vitro has not been demonstrated to date. Thus, we investigated the expression of GLUT4 and GLUT1 throughout skeletal muscle cell differentiation and their regulation by insulin and IGF-I using a primary culture of trout muscle cells. GLUT4 expression gradually increased during the muscle cell differentiation process, whereas GLUT1 expression remained fairly constant. Insulin and IGF-I similarly increased the mRNA levels of GLUT4 in myoblasts and myotubes. On the other hand, IGF-I appeared to be more potent than insulin in stimulating GLUT1 expression, particularly at the myoblast stage. Therefore, this work provides the first demonstration in nonmammalian vertebrates that insulin and IGF-I may act directly on trout muscle cells to regulate the expression of GLUT4 and GLUT1.

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Posttranscriptional control of embryonic rat skeletal muscle protein synthesis. Control at the level of translation by endogenous RNA.

The Journal of Cell Biology ◽

10.1083/jcb.107.3.1085 ◽

1988 ◽

Vol 107 (3) ◽

pp. 1085-1098 ◽

Cited By ~ 7

Author(s):

C R Vanderburg ◽

M A Nathanson

Keyword(s):

Skeletal Muscle ◽

Cell Differentiation ◽

Muscle Cell ◽

Translational Control ◽

Muscle Protein ◽

Muscle Protein Synthesis ◽

Skeletal Muscle Protein ◽

Rat Skeletal Muscle ◽

Total Rna ◽

Muscle Cell Differentiation

The onset of muscle cell differentiation is associated with increased transcription of muscle-specific mRNA. Studies from this laboratory using 19-d embryonic rat skeletal muscle, suggest that additional, posttranscriptional controls regulate maturation of muscle tissue via a quantitative effect upon translation, and that the regulatory component may reside within the poly A- RNA pool (Nathanson, M.A., E.W. Bush, and C. Vanderburg. 1986. J. Biol. Chem. 261:1477-1486). To further characterize muscle cell translational control, embryonic and adult total RNA were separated into oligo(dT)cellulose-bound (poly A+) and -unbound (poly A-) pools. Unbound material was subjected to agarose gel electrophoresis to resolve constituents of varying molecular size and mechanically cut into five fractions. Material of each fraction was electroeluted and recovered by precipitation. Equivalent loads of total RNA from 19-20-d embryonic rat skeletal muscle exhibited a 40% translational inhibition in comparison to its adult counterpart. Inhibition was not due to decreased message abundance because embryonic, as well as adult muscle, contained equivalent proportions of poly A+ mRNA. An inhibition assay, based upon the translatability of adult RNA and its inhibition by embryonic poly A- RNA, confirmed that inhibition was associated with a 160-2,000-nt poly A- fraction. Studies on the chemical composition of this fraction confirmed its RNA composition, the absence of ribonucleoprotein, and that its activity was absent from similarly fractionated adult RNA. Rescue of inhibition could be accomplished by addition of extra lysate or mRNA; however, smaller proportions of lysate were required, suggesting a strong interaction of inhibitor and components of the translational apparatus. Additional studies demonstrated that the inhibitor acted at the level of initiation, in a dose-dependent fashion. The present studies confirm the existence of translational control in skeletal muscle and suggest that it operates at the embryonic to adult transition. A model of muscle cell differentiation, based upon transcriptional control at the myoblast level, followed by translational regulation at the level of the postmitotic myoblast and/or myotube, is proposed.

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