Movement generated by interactions between the dense material at the ends of microtubles and non-actin-containing microfilaments in Sticholonche zanclea.

Axopods of the planktonic protozoan, Sticholonche, are used as oars to propel the organism through seawater. Within each axopod is an orgainzed array of microtubules which inserts into a dense material that assumes the form of the head of a hip joint. This material, in turn, articulates on the surface of the nucleus. Microfilaments, 20-30 A in diameter, connect the dense material associated with the microtubules to the surface of the nucleus, and they move the axopod by their contractions. The active phase of the movement may take as little as about 0.04 s and the recovery phase may take between 0.2 and 0.4 s. The microfilaments are not actin, as based on: (a) their small diameter, (b) the lack of decoration with heavy meromyosin, and (c) their ability to coil, spiral or fold during contraction. By the use of Thorotrast, we were able to demonstrate that the cell surface is deeply infolded, extending all the way to the hip joint. Here, there is a specialized membrane system that resembles the diad in skeletal muscle. From cytochemical tests and the use of ionophores and chelators, there is some evidence that the motile process may be controlled by calcium. This study demonstrates that, in at least one system, microtubules can be moves by contractile microfilaments attached to the dense material at there tips.

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Effect of insulin on GLUT4 cell surface content and turnover rate in human skeletal muscle as measured by the exofacial bis-mannose photolabeling technique

Diabetes ◽

10.2337/diabetes.46.12.1965 ◽

1997 ◽

Vol 46 (12) ◽

pp. 1965-1969 ◽

Cited By ~ 5

Author(s):

S. Lund ◽

G. D. Holman ◽

J. R. Zierath ◽

J. Rincon ◽

L. A. Nolte ◽

...

Keyword(s):

Skeletal Muscle ◽

Cell Surface ◽

Human Skeletal Muscle ◽

Turnover Rate ◽

Surface Content

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Contraction-related stimuli regulate GLUT4 traffic in C2C12-GLUT4myc skeletal muscle cells

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.00773.2009 ◽

2010 ◽

Vol 298 (5) ◽

pp. E1058-E1071 ◽

Cited By ~ 37

Author(s):

Wenyan Niu ◽

Philip J. Bilan ◽

Shuhei Ishikura ◽

Jonathan D. Schertzer ◽

Ariel Contreras-Ferrat ◽

...

Keyword(s):

Skeletal Muscle ◽

Cell Surface ◽

Glucose Uptake ◽

Nicotinic Acetylcholine Receptors ◽

Cell Model ◽

Cytosolic Calcium ◽

Atpase Inhibitor ◽

Cellular Models ◽

Compound C

Muscle contraction stimulates glucose uptake acutely to increase energy supply, but suitable cellular models that faithfully reproduce this complex phenomenon are lacking. To this end, we have developed a cellular model of contracting C2C12 myotubes overexpressing GLUT4 with an exofacial myc-epitope tag (GLUT4 myc) and explored stimulation of GLUT4 traffic by physiologically relevant agents. Carbachol (an acetylcholine receptor agonist) induced a gain in cell surface GLUT4 myc that was mediated by nicotinic acetylcholine receptors. Carbachol also activated AMPK, and this response was sensitive to the contractile myosin ATPase inhibitor N-benzyl- p-toluenesulfonamide. The gain in surface GLUT4 myc elicited by carbachol or by the AMPK activator 5-amino-4-carboxamide-1 β-ribose was sensitive to chemical inhibition of AMPK activity by compound C and partially reduced by siRNA-mediated knockdown of AMPK catalytic subunits or LKB1. In addition, the carbachol-induced gain in cell surface GLUT4 myc was partially sensitive to chelation of intracellular calcium with BAPTA-AM. However, the carbachol-induced gain in cell surface GLUT4 myc was not sensitive to the CaMKK inhibitor STO-609 despite expression of both isoforms of this enzyme and a rise in cytosolic calcium by carbachol. Therefore, separate AMPK- and calcium-dependent signals contribute to mobilizing GLUT4 in response to carbachol, providing an in vitro cell model that recapitulates the two major signals whereby acute contraction regulates glucose uptake in skeletal muscle. This system will be ideal to further analyze the underlying molecular events of contraction-regulated GLUT4 traffic.

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Caveolin-3 Associates with Developing T-tubules during Muscle Differentiation

The Journal of Cell Biology ◽

10.1083/jcb.136.1.137 ◽

1997 ◽

Vol 136 (1) ◽

pp. 137-154 ◽

Cited By ~ 238

Author(s):

Robert G. Parton ◽

Michael Way ◽

Natasha Zorzi ◽

Espen Stang

Keyword(s):

Skeletal Muscle ◽

Plasma Membrane ◽

Muscle Cells ◽

Membrane System ◽

C2c12 Cells ◽

Double Labeling ◽

Specific Antibodies ◽

T Tubules ◽

Α1 Subunit

Caveolae, flask-shaped invaginations of the plasma membrane, are particularly abundant in muscle cells. We have recently cloned a muscle-specific caveolin, termed caveolin-3, which is expressed in differentiated muscle cells. Specific antibodies to caveolin-3 were generated and used to characterize the distribution of caveolin-3 in adult and differentiating muscle. In fully differentiated skeletal muscle, caveolin-3 was shown to be associated exclusively with sarcolemmal caveolae. Localization of caveolin-3 during differentiation of primary cultured muscle cells and development of mouse skeletal muscle in vivo suggested that caveolin-3 is transiently associated with an internal membrane system. These elements were identified as developing transverse-(T)-tubules by double-labeling with antibodies to the α1 subunit of the dihydropyridine receptor in C2C12 cells. Ultrastructural analysis of the caveolin-3– labeled elements showed an association of caveolin-3 with elaborate networks of interconnected caveolae, which penetrated the depths of the muscle fibers. These elements, which formed regular reticular structures, were shown to be surface-connected by labeling with cholera toxin conjugates. The results suggest that caveolin-3 transiently associates with T-tubules during development and may be involved in the early development of the T-tubule system in muscle.

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Complete sequence and in vitro expression of a tissue-specific phosphatidylinositol-linked N-CAM isoform from skeletal muscle

Development ◽

10.1242/dev.104.1.165 ◽

1988 ◽

Vol 104 (1) ◽

pp. 165-173 ◽

Cited By ~ 1

Author(s):

C.H. Barton ◽

G. Dickson ◽

H.J. Gower ◽

L.H. Rowett ◽

W. Putt ◽

...

Keyword(s):

Skeletal Muscle ◽

Amino Acids ◽

Cell Surface ◽

Protein Sequence ◽

Single Copy ◽

In Vitro Transcription ◽

Full Length ◽

Covalent Attachment ◽

Size Difference

Neural cell adhesion molecules (N-CAMs) are a family of cell surface sialoglycoproteins encoded by a single copy gene. A full-length cDNA clone that encodes a nontransmembrane phosphatidylinositol (PI) linked N-CAM of Mr 125 × 10(3) has been isolated from a human skeletal muscle cDNA library. The deduced protein sequence encodes a polypeptide of 761 amino acids and is highly homologous to the N-CAM isoform in brain of Mr 120 × 10(3). The size difference between the 125 × 10(3). The size difference between the 125 × 10(3) Mr skeletal muscle form and the 120 × 10(3) Mr N-CAM form from brain is accounted for by the insertion of a block of 37 amino acids called MSD1, in the extracellular domain of the muscle form. Transient expression of the human cDNA in COS cells results in cell surface N-CAM expression via a putative covalent attachment to PI-containing phospholipid. Linked in vitro transcription and translation experiments followed by immunoprecipitation with anti-N-CAM antibodies demonstrate that the full-length clone of 761 amino acid coding potential produces a core polypeptide of Mr 110 × 10(3) which is processed by microsomal membranes to yield a 122 × 10(3) Mr species. Taken together, these results demonstrate that the cloned cDNA sequence encodes a lipid-linked, PI-specific phospholipase C releasable surface isoform of N-CAM with core glycopeptide molecular weight corresponding to the authentic muscle 125 × 10(3) Mr N-CAM isoform. This is the first direct correlation of cDNA and deduced protein sequence with a known PI-linked N-CAM isoform from skeletal muscle.

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Food deprivation during active phase induces skeletal muscle atrophy via IGF-1 reduction in mice

Archives of Biochemistry and Biophysics ◽

10.1016/j.abb.2019.108160 ◽

2019 ◽

Vol 677 ◽

pp. 108160 ◽

Cited By ~ 3

Author(s):

Tomoki Abe ◽

Rei Kazama ◽

Hiroki Okauchi ◽

Katsutaka Oishi

Keyword(s):

Skeletal Muscle ◽

Food Deprivation ◽

Muscle Atrophy ◽

Active Phase ◽

Skeletal Muscle Atrophy

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Inhibition by Palmitoyl CoA of EDTA- and Mg2+-ATPase of Heavy Meromyosin from Rabbit Skeletal Muscle

The Journal of Biochemistry ◽

10.1093/oxfordjournals.jbchem.a133530 ◽

1981 ◽

Vol 90 (3) ◽

pp. 757-763 ◽

Cited By ~ 5

Author(s):

Akiko FUJIWARA ◽

Hisao FUJISAKI ◽

Hiroshi ASAI ◽

Ikuo YASUMASU

Keyword(s):

Skeletal Muscle ◽

Rabbit Skeletal Muscle ◽

Heavy Meromyosin

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Polarity and Development of The Cell Surface in Skeletal Muscle

Cell Polarity - Advances in Molecular and Cell Biology ◽

10.1016/s1569-2558(08)60022-3 ◽

1998 ◽

pp. 157-199

Author(s):

Annelise O. Jorgensen

Keyword(s):

Skeletal Muscle ◽

Cell Surface

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Insulin-sensitive regulation of glucose transport and GLUT4 translocation in skeletal muscle of GLUT1 transgenic mice

Biochemical Journal ◽

10.1042/bj3370051 ◽

1998 ◽

Vol 337 (1) ◽

pp. 51-57 ◽

Cited By ~ 2

Author(s):

Garret J. ETGEN ◽

William J. ZAVADOSKI ◽

Geoffrey D. HOLMAN ◽

E. Michael GIBBS

Keyword(s):

Skeletal Muscle ◽

Cell Surface ◽

Transgenic Mice ◽

Glucose Transport ◽

Hind Limb ◽

Glucose Transporter ◽

Glut4 Translocation ◽

Transport Activity ◽

Fast Twitch Muscle ◽

Fast Twitch

Skeletal muscle glucose transport was examined in transgenic mice overexpressing the glucose transporter GLUT1 using both the isolated incubated-muscle preparation and the hind-limb perfusion technique. In the absence of insulin, 2-deoxy-d-glucose uptake was increased ∼ 3–8-fold in isolated fast-twitch muscles of GLUT1 transgenic mice compared with non-transgenic siblings. Similarly, basal glucose transport activity was increased ∼ 4–14-fold in perfused fast-twitch muscles of transgenic mice. In non-transgenic mice insulin accelerated glucose transport activity ∼ 2–3-fold in isolated muscles and to a much greater extent (∼ 7–20-fold) in perfused hind-limb preparations. The observed effect of insulin on glucose transport in transgenic muscle was similarly dependent upon the technique used for measurement, as insulin had no effect on isolated fast-twitch muscle from transgenic mice, but significantly enhanced glucose transport in perfused fast-twitch muscle from transgenic mice to ∼ 50–75% of the magnitude of the increase observed in non-transgenic mice. Cell-surface glucose transporter content was assessed via 2-N-4-(l-azi-2,2,2-trifluoroethyl)benzoyl-1,3-bis-(d -mannos-4-yloxy)-2-propylamine photolabelling methodology in both isolated and perfused extensor digitorum longus (EDL). Cell-surface GLUT1 was enhanced by as much as 70-fold in both isolated and perfused EDL of transgenic mice. Insulin did not alter cell-surface GLUT1 in either transgenic or non-transgenic mice. Basal levels of cell-surface GLUT4, measured in either isolated or perfused EDL, were similar in transgenic and non-transgenic mice. Interestingly, insulin enhanced cell-surface GLUT4 ∼ 2-fold in isolated EDL and ∼ 6-fold in perfused EDL of both transgenic and non-transgenic mice. In summary, these results reveal differences between isolated muscle and perfused hind-limb techniques, with the latter method showing a more robust responsiveness to insulin. Furthermore, the results demonstrate that muscle overexpressing GLUT1 has normal insulin-induced GLUT4 translocation and the ability to augment glucose-transport activity above the elevated basal rates.

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