scholarly journals Characterization of the ATP-hydrolysing activity of α-sarcoglycan

2004 ◽  
Vol 381 (1) ◽  
pp. 105-112 ◽  
Author(s):  
Dorianna SANDONÀ ◽  
Stefano GASTALDELLO ◽  
Tiziana MARTINELLO ◽  
Romeo BETTO
Keyword(s):  
Muscular Dystrophy ◽  
Molecular Mechanisms ◽  
C2c12 Cells ◽  
C2c12 Myotubes ◽  
Atp Binding ◽  
Binding Motif ◽  
Nucleotidase Activity ◽  
Reactive Blue 2 ◽  
Definitive Evidence ◽  
Dystrophin Complex

α-Sarcoglycan is a glycoprotein associated with the dystrophin complex at sarcolemma of skeletal and cardiac muscles. Gene defects in α-sarcoglycan lead to a severe muscular dystrophy whose molecular mechanisms are not yet clear. A first insight into the function of α-sarcoglycan was obtained by finding that it is an ATP-binding protein and that it probably confers ability to hydrolyse ATP to the purified dystrophin complex [Betto, Senter, Ceoldo, Tarricone, Biral and Salviati (1999) J. Biol. Chem. 274, 7907–7912]. In the present study, we present definitive evidence showing that α-sarcoglycan is an ATP-hydrolysing enzyme. The appearance of α-sarcoglycan protein expression was correlated with the increase in ecto-nucleotidase activity during differentiation of C2C12 cells. Approx. 25% of ecto-nucleotidase activity displayed by the C2C12 myotubes was inhibited by preincubating cells with an antibody specific for the ATP-binding motif of α-sarcoglycan. This demonstrates that α-sarcoglycan substantially contributes to total ecto-nucleotidase activity of C2C12 myotubes. To characterize further this activity, human embryonic kidney 293 cells were transfected with expression plasmids containing α-sarcoglycan cDNA. Transfected cells exhibited a significant increase in the ATP-hydrolysing activity that was abolished by the anti-α-sarcoglycan antibody. The enzyme had a substrate specificity for ATP and ADP, did not hydrolyse other triphosphonucleosides, and the affinity for ATP was in the low mM range. The ATPase activity strictly required the presence of both Mg2+ and Ca2+ and was completely inhibited by suramin and reactive blue-2. These results show that α-sarcoglycan is a Ca2+, Mg2+-ecto-ATPDase. The possible consequences of the absence of α-sarcoglycan activity in the pathogenesis of muscular dystrophy are discussed.

scholarly journals TNF-αand IFN-s-Dependent Muscle Decay Is Linked to NF-κB- and STAT-1α-StimulatedAtrogin1andMuRF1Genes in C2C12 Myotubes

2013 ◽  
Vol 2013 ◽  
pp. 1-18 ◽  
Author(s):  
Barbara Pijet ◽  
Maja Pijet ◽  
Anna Litwiniuk ◽  
Małgorzata Gajewska ◽  
Beata Pająk ◽  
...  
Keyword(s):  
Protein Expression ◽  
Signaling Pathways ◽  
Molecular Mechanisms ◽  
C2c12 Cells ◽  
Metabolic Inhibitors ◽  
C2c12 Myotubes ◽  
Protein Expression Level ◽  
C2c12 Myoblasts ◽  
Stat Signaling ◽  
Increased Activity

TNF-αwas shown to stimulate mitogenicity in C2C12 myoblasts. Selected cytokines TNF-α, IFNα, or IFNγreduced the expression of myosin heavy chain (MyHC IIa) when given together. Molecular mechanisms of cytokine activities were controlled by NF-κB and JAK/STAT signaling pathways, as metabolic inhibitors, curcumin and AG490, inhibited some of TNF-αand IFNα/IFNγeffects. Insulin was hardly antagonistic to TNF-α- and IFNα/IFNγ-dependent decrease in MyHC IIa protein expression. Cytokines used individually or together also repressed myogenesis of C2C12 cells. Moreover, TNF-α- and IFNα/IFNγ-dependent effects on C2C12 myotubes were associated with increased activity ofAtrogin1andMuRF1genes, which code ubiquitin ligases.MyHC IIagene activity was unaltered by cytokines. Inhibition of NF-κB or JAK/STAT with specific metabolic inhibitors decreased activity ofAtrogin1andMuRF1but notMyHC IIagene. Overall, these results suggest cooperation between cytokines in the reduction of MyHC IIa protein expression level via NF-κB/JAK/STAT signaling pathways and activation ofAtrogin1andMuRF1genes as their molecular targets. Insulin cotreatment or pretreatment does not protect against muscle decay induced by examined proinflammatory cytokines.

scholarly journals Anabolic Activity of a Soy Extract and Three Major Isoflavones in C2C12 Myotubes

Planta Medica ◽  
2018 ◽  
Vol 84 (14) ◽  
pp. 1022-1029 ◽  
Author(s):  
Wenya Zheng ◽  
Marie Hemker ◽  
Mingyong Xie ◽  
Sebastian Soukup ◽  
Patrick Diel
Keyword(s):  
Molecular Mechanisms ◽  
Control Cell ◽  
Muscle Growth ◽  
In Vitro Study ◽  
C2c12 Cells ◽  
C2c12 Myotubes ◽  
Gene Expressions ◽  
Insulin Growth Factor ◽  
Anabolic Activity

AbstractIsoflavones have been reported to stimulate muscle growth. The aim of this in vitro study was to examine anabolic activity and associated molecular mechanisms of a soy extract (SoyEx), isoflavone aglycones, and a mixture simulating the composition of SoyEx in C2C12 myotubes. C2C12 cells were differentiated into myotubes. The effects of SoyEx, genistein, daidzein, glycitein, and the mixture of genistein-daidzein-glycitein (Mix) on myotube diameter and number were determined. In addition, the expression of genes and proteins associated with anabolic activity was analyzed. Treatment with SoyEx, genistein, and Mix led to a significant increase of myotube diameter and an increase of the number of myotubes per area compared to the control cell. The increase of diameter by SoyEx was antagonized by an antiestrogen, not by an antiandrogen. Furthermore, gene expressions of insulin growth factor (IGF)-1 and its receptor (IGF-1R), as well as protein expression of myosin heavy chain (MHC), were significantly increased by SoyEx, genistein, and Mix. The effects induced by genistein and Mix were comparable to SoyEx. In conclusion, SoyEx displays an anabolic activity in C2C12 myotubes by binding to ER and modulating IGF-1 and MHC expression. Our studies with isoflavone aglycones and Mix indicate that the isoflavone aglycone with the highest anabolic bioactivity in SoyEx is genistein.

scholarly journals Emerin Represses STAT3 Signaling through Nuclear Membrane-Based Spatial Control

2021 ◽  
Vol 22 (13) ◽  
pp. 6669
Author(s):  
Byongsun Lee ◽  
Seungjae Lee ◽  
Younggwang Lee ◽  
Yongjin Park ◽  
Jaekyung Shim
Keyword(s):  
Muscular Dystrophy ◽  
Nuclear Membrane ◽  
Target Genes ◽  
Janus Kinase ◽  
C2c12 Cells ◽  
Specific Gene ◽  
Lamin A ◽  
Stat3 Signaling ◽  
Exact Function ◽  
Muscle Homeostasis

Emerin is the inner nuclear membrane protein involved in maintaining the mechanical integrity of the nuclear membrane. Mutations in EMD encoding emerin cause Emery-Dreifuss muscular dystrophy (EDMD). There has been accumulating evidence that emerin regulation of specific gene expression is associated with this disease, but the exact function of emerin has still less revealing. Here, we have shown that emerin downregulates signal transducers and activators of transcription 3 (STAT3) signaling, activated exclusively by Janus-kinase (JAK). Deletion mutation experiments showed that the lamin-binding domain of emerin is essential for the inhibition of STAT3 signaling. Emerin interacted directly and co-localized with STAT3 in the nuclear membrane. Emerin knockdown induced STAT3 target genes Bcl2 and Survivin to increase cell survival signals and suppress hydrogen peroxide-induced cell death in HeLa cells. Specifically, downregulation of BAF or lamin A/C increases STAT3 signaling, suggesting that correct-localized emerin by assembling with BAF and lamin A/C acts as an intrinsic inhibitor against STAT3 signaling. In C2C12 cells, emerin knockdown induced STAT3 target gene, Pax7, and activated abnormal myoblast proliferation associated with muscle wasting in skeletal muscle homeostasis. Our results indicate that emerin downregulates STAT3 signaling by inducing retention of STAT3 and delaying STAT3 signaling in the nuclear membrane. This mechanism provides clues to the etiology of emerin-related muscular dystrophy and could be a new therapeutic target for treatment.

scholarly journals Amelioration of Muscular Dystrophy by Transgenic Expression of Niemann-Pick C1

2009 ◽  
Vol 20 (1) ◽  
pp. 146-152 ◽  
Author(s):  
Michelle S. Steen ◽  
Marvin E. Adams ◽  
Yan Tesch ◽  
Stanley C. Froehner
Keyword(s):  
Skeletal Muscle ◽  
Muscular Dystrophy ◽  
Molecular Mechanisms ◽  
Mdx Mouse ◽  
Lysosomal Storage ◽  
Transgenic Expression ◽  
New Therapeutic Approaches ◽  
Human Disorders ◽  
Niemann Pick ◽  
Dystrophin Protein

Duchenne muscular dystrophy (DMD) and other types of muscular dystrophies are caused by the loss or alteration of different members of the dystrophin protein complex. Understanding the molecular mechanisms by which dystrophin-associated protein abnormalities contribute to the onset of muscular dystrophy may identify new therapeutic approaches to these human disorders. By examining gene expression alterations in mouse skeletal muscle lacking α-dystrobrevin (Dtna−/−), we identified a highly significant reduction of the cholesterol trafficking protein, Niemann-Pick C1 (NPC1). Mutations in NPC1 cause a progressive neurodegenerative, lysosomal storage disorder. Transgenic expression of NPC1 in skeletal muscle ameliorates muscular dystrophy in the Dtna−/− mouse (which has a relatively mild dystrophic phenotype) and in the mdx mouse, a model for DMD. These results identify a new compensatory gene for muscular dystrophy and reveal a potential new therapeutic target for DMD.

Receptor and Molecular Mechanism of AGGF1 Signaling in Endothelial Cell Functions and Angiogenesis

2021 ◽  
Author(s):  
Jingjing Wang ◽  
Huixin Peng ◽  
Ayse Anil Timur ◽  
Vinay Pasupuleti ◽  
Yufeng Yao ◽  
...  
Keyword(s):  
Amino Acids ◽  
Endothelial Cell ◽  
Neutralizing Antibodies ◽  
Molecular Mechanisms ◽  
Capillary Tube ◽  
Therapeutic Angiogenesis ◽  
Angiogenic Factor ◽  
Single Amino Acid ◽  
Binding Motif ◽  
Cell Functions

Objective: Angiogenic factor AGGF1 (angiogenic factor and G-patch and FHA [Forkhead-associated] domain 1) promotes angiogenesis as potently as VEGFA (vascular endothelial growth factor A) and regulates endothelial cell (EC) proliferation, migration, specification of multipotent hemangioblasts and venous ECs, hematopoiesis, and vascular development and causes vascular disease Klippel-Trenaunay syndrome when mutated. However, the receptor for AGGF1 and the underlying molecular mechanisms remain to be defined. Approach and Results: Using functional blocking studies with neutralizing antibodies, we identified α5β1 as the receptor for AGGF1 on ECs. AGGF1 interacts with α5β1 and activates FAK (focal adhesion kinase), Src, and AKT. Functional analysis of 12 serial N-terminal deletions and 13 C-terminal deletions by every 50 amino acids mapped the angiogenic domain of AGGF1 to a domain between amino acids 604-613 (FQRDDAPAS). The angiogenic domain is required for EC adhesion and migration, capillary tube formation, and AKT activation. The deletion of the angiogenic domain eliminated the effects of AGGF1 on therapeutic angiogenesis and increased blood flow in a mouse model for peripheral artery disease. A 40-mer or 15-mer peptide containing the angiogenic domain blocks AGGF1 function, however, a 15-mer peptide containing a single amino acid mutation from −RDD- to −RGD- (a classical RGD integrin-binding motif) failed to block AGGF1 function. Conclusions: We have identified integrin α5β1 as an EC receptor for AGGF1 and a novel AGGF1-mediated signaling pathway of α5β1-FAK-Src-AKT for angiogenesis. Our results identify an FQRDDAPAS angiogenic domain of AGGF1 crucial for its interaction with α5β1 and signaling.

scholarly journals Interaction of CREB and PGC-1α Induces Fibronectin Type III Domain-Containing Protein 5 Expression in C2C12 Myotubes

2018 ◽  
Vol 50 (4) ◽  
pp. 1574-1584 ◽  
Author(s):  
Xiu-ying Yang ◽  
Margaret C.L. Tse ◽  
Xiang Hu ◽  
Wei-hua Jia ◽  
Guan-hua Du ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Molecular Mechanisms ◽  
Metabolic Effects ◽  
Hek293 Cells ◽  
Metabolic Phenotype ◽  
C2c12 Myotubes ◽  
Type Iii ◽  
Fibronectin Type Iii ◽  
Fibronectin Type Iii Domain ◽  
Fibronectin Type

Background/Aims: Fibronectin type III domain-containing protein 5 (FNDC5), also known as irisin, is a myokine secreted from muscle in response to exercise. However, the molecular mechanisms that regulate FNDC5 expression and the functional significance of irisn in skeletal muscle remain unknown. In this study, we explored the potential pathways that induce FNDC5 expression and delineated the metabolic effects of irisin on skeletal muscle. Methods: C2C12 myotubes were treated with drugs at various concentrations and durations. The expression and activation of genes were measured by real-time polymerase chain reaction (qRT-PCR) and Western blotting. Oxidative phosphorylation was quantified by measuring the oxygen consumption rate (OCR). Results: We found that the exercise-mimicking treatment (cAMP, forskolin and isoproterenol) increased Fndc5 expression in C2C12 myotubes. CREB over-expressed C2C12 myotubes displayed higher Fndc5 expression. CREB over-expression also promoted peroxisome proliferator-activated receptor gamma coactivator 1α (PGC-1α) expression. PGC-1α-induced Fndc5 expression was blocked when the dominant negative form of CREB (S133A) was present. PGC-1α mutation (S570A) also decreased Fndc5 expression. Immunoprecipitation showed that overexpressed PGC-1α complexed with CREB in HEK293 cells. C2C12 myotubes treated with forskolin also increased endogenous CREB and PGC-1α binding. Functionally, irisin treatment increased mitochondrial respiration, enhanced ATP production, promoted fatty acid oxidation but decreased glycolysis in myotubes. Conclusion: Our observation indicates that cAMP-mediated PGC-1α/CREB interaction triggers Fndc5 expression, which acts as an autocrine/paracrine to shape the metabolic phenotype of myotubes.

scholarly journals Dust from hog confinement facilities impairs Ca2+ mobilization from sarco(endo)plasmic reticulum by inhibiting ryanodine receptors

2013 ◽  
Vol 114 (5) ◽  
pp. 665-674
Author(s):  
Chengju Tian ◽  
Caronda J. Moore ◽  
Puttappa Dodmane ◽  
Chun Hong Shao ◽  
Debra J. Romberger ◽  
...  
Keyword(s):  
Binding Sites ◽  
Molecular Mechanisms ◽  
Ryanodine Receptors ◽  
Cell Types ◽  
C2c12 Cells ◽  
Common Element ◽  
Plasmic Reticulum ◽  
Skeletal Muscle Weakness ◽  
Intracellular Ca ◽  
Phosphate Buffered Saline

Individuals working in commercial hog confinement facilities have elevated incidences of headaches, depression, nausea, skeletal muscle weakness, fatigue, gastrointestinal disorders, and cardiovascular diseases, and the molecular mechanisms for these nonrespiratory ailments remain incompletely undefined. A common element underlying these diverse pathophysiologies is perturbation of intracellular Ca2+ homeostasis. This study assessed whether the dust generated inside hog confinement facilities contains compounds that alter Ca2+ mobilization via ryanodine receptors (RyRs), key intracellular channels responsible for mobilizing Ca2+ from internal stores to elicit an array of physiologic functions. Hog barn dust (HBD) was extracted with phosphate-buffered saline, sterile-filtered (0.22 μm), and size-separated using Sephadex G-100 resin. Fractions (F) 1 through 9 (Mw >10,000 Da) had no measurable effects on RyR isoforms. However, F10 through F17, which contained compounds of Mw ≤2,000 Da, modulated the [3H]ryanodine binding to RyR1, RyR2, and RyR3 in a biphasic (Gaussian) manner. The Ki values for F13, the most potent fraction, were 3.8 ± 0.2 μg/ml for RyR1, 0.2 ± 0.01 μg/ml and 19.1 ± 2.8 μg/ml for RyR2 (two binding sites), and 44.9 ± 2.8 μg/ml and 501.6 ± 9.2 μg/ml for RyR3 (two binding sites). In lipid bilayer assays, F13 dose-dependently decreased the open probabilities of RyR1, RyR2, and RyR3. Pretreating differentiated mouse skeletal myotubes (C2C12 cells) with F13 blunted the amplitudes of ryanodine- and K+-induced Ca2+ transients. Because RyRs are present in many cell types, impairment in Ca2+ mobilization from internal stores via these channels is a possible mechanism by which HBD may trigger these seemingly unrelated pathophysiologies.

scholarly journals MARCKS domain phosphorylation regulates the differential interaction of Diacylglycerol Kinase ζ with Rac1, RhoA and Syntrophin

2020 ◽  
Author(s):  
Ryan Ard ◽  
Jean-Christian Maillet ◽  
Elias Daher ◽  
Michael Phan ◽  
Radoslav Zinoviev ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Molecular Mechanisms ◽  
Rho Gtpase ◽  
Pdz Domain ◽  
Diacylglycerol Kinase ◽  
Binding Motif ◽  
Membrane Blebbing ◽  
Rhoa Activity ◽  
C Terminus ◽  
Mechanistic Basis

AbstractCells can switch between Rac1, lamellipodia-based and RhoA, blebbing-based migration modes but the molecular mechanisms regulating this choice are not fully understood. Diacylglycerol kinase ζ (DGKζ), which phosphorylates diacylglycerol to yield phosphatidic acid, forms independent complexes with Rac1 and RhoA, selectively dissociating each from RhoGDI. DGKζ catalytic activity is required for Rac1 dissociation but is dispensable for RhoA dissociation. Instead, DGKζ functions as a scaffold that stimulates RhoA release by enhancing RhoGDI phosphorylation by protein kinase Cα (PKCα). Here, PKCα-mediated phosphorylation of the DGKζ MARCKS domain increased DGKζ association with RhoA and decreased its interaction with Rac1. The same modification increased binding of the DGKζ C-terminus to the α1-syntrophin PDZ domain. Expression of a phosphomimetic DGKζ mutant stimulated membrane blebbing in mouse embryonic fibroblasts and C2C12 myoblasts, which was augmented by inhibition of endogenous Rac1. DGKζ expression in differentiated C2 myotubes, which have low endogenous Rac1 levels, also induced substantial membrane blebbing via the Rho-ROCK pathway. These events were independent of DGKζ catalytic activity, but dependent upon a functional C-terminal PDZ-binding motif. Rescue of RhoA activity in DGKζ-null cells required the PDZ-binding motif, suggesting syntrophin interaction is necessary for optimal RhoA activation. Collectively, our results define a switch-like mechanism involving DGKζ phosphorylation by PKCα that favours RhoA-driven blebbing over Rac1-driven lamellipodia formation and macropinocytosis. These findings provide a mechanistic basis for the effect of PKCα signaling on Rho GTPase activity and suggest PKCα activity plays a role in the interconversion between Rac1 and RhoA signaling that underlies different migration modes.

scholarly journals Structural basis for the coiled-coil architecture of human CtIP

2021 ◽  
Author(s):  
C. R. Morton ◽  
N. J. Rzechorzek ◽  
J. D. Maman ◽  
M. Kuramochi ◽  
H. Sekiguchi ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Three Dimensional ◽  
Coiled Coil ◽  
Strand Break ◽  
Structural Basis ◽  
Binding Motif ◽  
Chromosomal Dna ◽  
Dsb Repair ◽  
Critical Function ◽  
X Ray

AbstractThe DNA repair factor CtIP has a critical function in Double-Strand Break (DSB) repair by Homologous Recombination, promoting the assembly of the repair apparatus at DNA ends and participating in DNA-end resection. However, the molecular mechanisms of CtIP function in DSB repair remain unclear. Here we present an atomic model for the three-dimensional architecture of human CtIP, derived from a multi-disciplinary approach that includes X-ray crystallography, Small-angle X-ray Scattering (SAXS) and Diffracted X-ray Tracking (DXT). Our data show that CtIP adopts an extended dimer-of-dimers structure, in agreement with a role in bridging distant sites on chromosomal DNA during recombinational repair. The zinc-binding motif in CtIP’s N-terminus alters dynamically the coiled coil structure, with functional implications for the long-range interactions of CtIP with DNA. Our results provide a structural basis for the three-dimensional arrangement of chains in the CtIP tetramer, a key aspect of CtIP function in DNA DSB repair.

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