Expression of Neurofilament Proteins in Proliferating C2C12 Mouse Skeletal Muscle Cells

Abe, Masami; Saitoh, Osamu; Nakata, Hajime; Yoda, Akinori; Matsuda, Ryoichi

doi:10.1006/excr.1996.0342

Cited by 10 publications

(9 citation statements)

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“…Tn-T was up-regulated whereas desmin remained at similar level. These results are consistent with the Northern blot analysis results presented in our previous report (2).…”

Section: Resultssupporting

confidence: 94%

“…On day 5, mononucleated myoblasts which resided in the space between myotubes were still NF140K-positive whereas all of the myotubes were NF140K-negative. This result is consistent with our previous findings that hyper-producers of NF140K among recloned C2C12 muscle cells (C2C12-11) exhibited a delay in myogenesis (2). Changes in the The filamentous structure stained with anti-NF140K antibody is also stained with antidesmin antibody suggesting colocalization of NF 1 40K and desmin (indicated by arrows).…”

Section: Resultssupporting

confidence: 92%

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Unfused C2C12 Mouse Skeletal Muscle Cells Express Neurofilament 140K Protein.

Matsuda

Abe

1997

Cell Struct. Funct.

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ABSTRACT. Expression of neurofilament 140K protein in C2C12 mouse skeletal muscle cells was studied. Immunofluorescence and immunoblot analyses revealed that NF140Kwas expressed at the proliferative stage and was colocalized with the muscle-specific intermediate protein desmin. As muscle cell differentiation proceeded, the numberof NF140K-positive cells decreased whereas the numberof cells expressing muscle-specific marker proteins such as sarcomeric myosin heavy chain and troponin-T increased. Down-regulation of NF140Kand upregulation of a myogenic regulatory gene, the myogenin gene, started simultaneously. In differentiated muscle cell cultures, un fused cells residing between myotubes remained NF140K-positive. NF140Kand desmin doublepositive cells were also found in a primary culture of adult mouseskeletal muscle cells. The results suggest that NF140Kmay be a unique marker for uncommitted myoblasts.Intermediate filaments (IFs) were discovered in differentiating muscle cells (6, 7

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“…Tn-T was up-regulated whereas desmin remained at similar level. These results are consistent with the Northern blot analysis results presented in our previous report (2).…”

Section: Resultssupporting

confidence: 94%

Section: Resultssupporting

confidence: 92%

Unfused C2C12 Mouse Skeletal Muscle Cells Express Neurofilament 140K Protein.

Matsuda

Abe

1997

Cell Struct. Funct.

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“…Differentiation involves expression of musclespecific genes, as shown by the appearance of certain mRNAs and proteins, such as α-actin, myosin, troponin-T and creatine kinase. Expression of other genes is suppressed in differentiating myoblasts, as indicated by the diminished levels of some mRNAs and proteins, such as junB, β-and γ-actin, fibronectin and the neurofilament protein NF-140K [26][27][28]30]. Still other proteins seem to be unchanged during myoblast differentiation, such as α-and β-tubulin.…”

Section: Discussionmentioning

confidence: 99%

“…Little is known, however, about the regulation responsible for the diminution of proteins in differentiating myoblasts ; such protein diminution might be due to repressed transcription, altered mRNA processing, and\or inhibition of translation, and\or decreased stability. For proteins such as junB and possibly NF-140K, β-actin and γ-actin, down-regulated transcription or diminished mRNA stability may be the primary event involved, since their mRNA levels appear to decrease soon after shifting the myoblasts to DM [27,28,30]. No information is available on the step(s) at which calpastatin gene expression is regulated and the reasons for its diminution in the differentiating myoblasts studied here have not been elucidated.…”

Section: Discussionmentioning

confidence: 99%

Regulation of calpain and calpastatin in differentiating myoblasts: mRNA levels, protein synthesis and stability

Barnoy

Supino-Rosin

Kosower

2000

Biochemical Journal

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Tel Aviv 69978, IsraelCalpain (Ca# + -dependent intracellular protease)-induced proteolysis has been considered to play a role in myoblast fusion to myotubes. We found previously that calpastatin (the endogenous inhibitor of calpain) diminishes transiently during myoblast differentiation. To gain information about the regulation of calpain and calpastatin in differentiating myoblasts, we evaluated the stability and synthesis of calpain and calpastatin, and measured their mRNA levels in L8 myoblasts. We show here that µ-calpain and m-calpain are stable, long-lived proteins in both dividing and differentiating L8 myoblasts. Calpain is synthesized in differentiating myoblasts, and calpain mRNA levels do not change during differentiation. In contrast, calpastatin (though also a long-lived protein in myoblasts), is less stable in differentiating myoblasts than in the dividing cells, and its synthesis is inhibited upon initiation of differentiation. Inhibition of cal-

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“…Northern Blot-Northern blot analysis was performed as described previously (26). Digoxigenin-labeled cRNAs, which had been synthesized using RGS7 and RGS8 cDNAs, were utilized as a probe.…”

Section: Methodsmentioning

confidence: 99%

RGS7 and RGS8 Differentially Accelerate G Protein-mediated Modulation of K+ Currents

Saitoh¹,

Kubo²,

Odagiri³

et al. 1999

Journal of Biological Chemistry

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The recently discovered family of RGS (regulators of G protein signaling) proteins acts as GTPase activating proteins which bind to ␣ subunits of heterotrimeric G proteins. We previously showed that a brain-specific RGS, RGS8 speeds up the activation and deactivation kinetics of the G protein-coupled inward rectifier K ؉ channel (GIRK) upon receptor stimulation (Saitoh, O., Kubo, Y., Miyatani, Y., Asano, T., and Nakata, H. (1997) Nature 390, 525-529). Here we report the isolation of a full-length rat cDNA of another brain-specific RGS, RGS7. In situ hybridization study revealed that RGS7 mRNA is predominantly expressed in Golgi cells within granule cell layer of cerebellar cortex. We observed that RGS7 recombinant protein binds preferentially to G␣ o , G␣ i3 , and G␣ z . When co-expressed with GIRK1/2 in Xenopus oocytes, RGS7 and RGS8 differentially accelerate G protein-mediated modulation of GIRK. RGS7 clearly accelerated activation of GIRK current similarly with RGS8 but the acceleration effect of deactivation was significantly weaker than that of RGS8. These acceleration properties of RGS proteins may play important roles in the rapid regulation of neuronal excitability and the cellular responses to short-lived stimulations.Numerous extracellular signals such as hormones, neurotransmitters, and odors stimulate seven transmembrane-spanning receptors that activate heterotrimeric G proteins. These G proteins function as signal transducing molecules by regulating cellular effectors including enzymes and ion channels (1, 2). The regulatory mechanisms that control G protein signaling have not been fully studied. Recently, a new family of regulators of G protein signaling (RGS) 1 was identified in organisms ranging from yeast to mammals (3, 4). Genetic screenings for negative regulators for pheromone response pathway in yeast identified a protein, Sst2 (5). By genetic and biochemical analyses, Sst2 was revealed to interact directly with G protein ␣ subunit (6). In the last few years, full or partial sequences of 22 RGS proteins have been identified in mammals. All of them share a conserved RGS domain of ϳ120 amino acids (7-15). It has been shown that several RGS proteins (RGS1, RGS3, RGS4, GAIP) attenuate G protein signaling in cultures (9,16,17). Biochemical studies have demonstrated that some RGS members (RGS1, RGS4, RGS10, GAIP, RGSr/RGS16, RET-RGS1) function as GTPase-activating proteins (GAPs) for the Gi family of ␣ subunit, including G␣ o , G␣ i , and transducin (10, 14, 18 -20). Hence, these characterized RGS proteins are proposed to down-regulate G protein signaling in vivo by enhancing the rate of G␣ GTP hydrolysis. However, whether other RGS proteins regulate G protein signalings in a similar manner remains to be established.Because there are many G protein signaling pathways which regulate important functions such as neural transmission in the brain, it is possible that certain RGS proteins might determine a mode of G protein signaling that control neural functions. We searched RGS proteins specifically ...

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Expression of Neurofilament Proteins in Proliferating C2C12 Mouse Skeletal Muscle Cells

Cited by 10 publications

References 0 publications

Unfused C2C12 Mouse Skeletal Muscle Cells Express Neurofilament 140K Protein.

Unfused C2C12 Mouse Skeletal Muscle Cells Express Neurofilament 140K Protein.

Regulation of calpain and calpastatin in differentiating myoblasts: mRNA levels, protein synthesis and stability

RGS7 and RGS8 Differentially Accelerate G Protein-mediated Modulation of K+ Currents

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