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J. Biol. Chem., Vol. 277, Issue 4, 2682-2686, January 25, 2002

This Article Full Text Full Text (PDF) All Versions of this Article: 277/4/2682    most recent M107227200v1 Submit a Letter to Editor Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Montell, E. Articles by Gómez-Foix, A. M. Search for Related Content PubMed PubMed Citation Articles by Montell, E. Articles by Gómez-Foix, A. M. Social Bookmarking                      What's this?

Effects of Modulation of Glycerol Kinase Expression on Lipid and Carbohydrate Metabolism in Human Muscle Cells^*

Eulàlia Montell, Carlos Lerín^§, Christopher B. Newgard^¶, and Anna M. Gómez-Foix

From the  Departament de Bioquímica i Biologia Molecular, Universitat de Barcelona, Martí i Franquès, 1, 08028 Barcelona, Spain and the ^¶ Departments of Biochemistry and Internal Medicine and the Touchstone Center for Diabetes Research, University of Texas Southwestern Medical Center, Dallas, Texas 75235

Glycerol is taken up by human muscle in vivo and incorporated into lipids, but little is known about regulation of glycerol metabolism in this tissue. In this study, we have analyzed the role of glycerol kinase (GlK) in the regulation of glycerol metabolism in primary cultured human muscle cells. Isolated human muscle cells exhibited lower GlK activity than fresh muscle explants, but the activity in cultured cells was increased by exposure to insulin. [U-¹⁴C]Glycerol was incorporated into cellular phospholipids and triacylglycerides (TAGs), but little or no increase in TAG content or lactate release was observed in response to changes in the medium glycerol concentration. Adenovirus-mediated delivery of the Escherichia coli GlK gene (AdCMV-GlK) into muscle cells caused a 30-fold increase in GlK activity, which was associated with a marked rise in the labeling of phospholipid or TAG from [U-¹⁴C]glycerol compared with controls. Moreover, GlK overexpression caused [U-¹⁴C]glycerol to be incorporated into glycogen, which was dependent on the activation of glycogen synthase. Co-incubation of AdCMV-GlK-treated muscle cells with glycerol and oleate resulted in a large accumulation of TAG and an increase in lactate production. We conclude that GlK is the limiting step in muscle cell glycerol metabolism. Glycerol 3-phosphate is readily used for TAG synthesis but can also be diverted to form glycolytic intermediates that are in turn converted to glycogen or lactate. Given the high levels of glycerol in muscle interstitial fluid, these finding suggest that changes in GlK activity in muscle can exert important influences on fuel deposition in this tissue.

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