HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: 291/4/E817    most recent 00194.2006v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (5) Citing Articles via Google Scholar Google Scholar Articles by Nedachi, T. Articles by Kanzaki, M. Search for Related Content PubMed PubMed Citation Articles by Nedachi, T. Articles by Kanzaki, M.

Regulation of glucose transporters by insulin and extracellular glucose in C₂C₁₂ myotubes

TUBERO/Tohoku University Biomedical Engineering Research Organization, Tohoku University, Sendai, Japan

Submitted 25 April 2006 ; accepted in final form 24 May 2006

It is well established that insulin stimulation of glucose uptake in skeletal muscle cells is mediated through translocation of GLUT4 from intracellular storage sites to the cell surface. However, the established skeletal muscle cell lines, with the exception of L6 myocytes, reportedly show minimal insulin-dependent glucose uptake and GLUT4 translocation. Using C₂C₁₂ myocytes expressing exofacial-Myc-GLUT4-enhanced cyan fluorescent protein, we herein show that differentiated C₂C₁₂ myotubes are equipped with basic GLUT4 translocation machinery that can be activated by insulin stimulation (3-fold increase as assessed by anti-Myc antibody uptake and immunostaining assay). However, this insulin stimulation of GLUT4 translocation was difficult to demonstrate with a conventional 2-deoxyglucose uptake assay because of markedly elevated basal glucose uptake via other glucose transporter(s). Intriguingly, the basal glucose transport activity in C₂C₁₂ myotubes appeared to be acutely suppressed within 5 min by preincubation with a pathophysiologically high level of extracellular glucose (25 mM). In contrast, this activity was augmented by acute glucose deprivation via an unidentified mechanism that is independent of GLUT4 translocation but is dependent on phosphatidylinositol 3-kinase activity. Taken together, these findings indicate that regulation of the facilitative glucose transport system in differentiated C₂C₁₂ myotubes can be achieved through surprisingly acute glucose-dependent modulation of the activity of glucose transporter(s), which apparently contributes to obscuring the insulin augmentation of glucose uptake elicited by GLUT4 translocation. We herein also describe several methods of monitoring insulin-dependent glucose uptake in C₂C₁₂ myotubes and propose this cell line to be a useful model for analyzing GLUT4 translocation in skeletal muscle.

This article has been cited by other articles:

				T. Nedachi, H. Hatakeyama, T. Kono, M. Sato, and M. Kanzaki Characterization of contraction-inducible CXC chemokines and their roles in C2C12 myocytes Am J Physiol Endocrinol Metab, October 1, 2009; 297(4): E866 - E878. [Abstract] [Full Text] [PDF]

				T. Nedachi, H. Fujita, and M. Kanzaki Contractile C2C12 myotube model for studying exercise-inducible responses in skeletal muscle Am J Physiol Endocrinol Metab, November 1, 2008; 295(5): E1191 - E1204. [Abstract] [Full Text] [PDF]

				T. Nedachi, A. Kadotani, M. Ariga, H. Katagiri, and M. Kanzaki Ambient glucose levels qualify the potency of insulin myogenic actions by regulating SIRT1 and FoxO3a in C2C12 myocytes Am J Physiol Endocrinol Metab, April 1, 2008; 294(4): E668 - E678. [Abstract] [Full Text] [PDF]