Glycogen serves as a carbohydrate source for glut1 glycosylation
during glucose deprivation of 3t3-l1 adipocytes.
McMahon, Robert J., and Susan C. Frost.
Department of Biochemistry and Molecular Biology, University of
Florida, Gainesville, FL 32610, Phone: (904) 392-3207, FAX: (904)
392-2953
APStracts 2:0231E, 1995.
In 3T3-L1 adipocytes, the glycosylation of the GLUT1 transporter is
altered beyond 12 h of glucose deprivation. To determine whether
glycogen degradation provides substrate for normal protein
glycosylation during this delay, we measured the glycogen content of
3T3-L1 adipocytes. From an initial value of 0.537 +/- 0.097 [mu]mol
glucose/106 cells, glycogen was depleted in a time-dependent manner
in response to glucose deprivation, exhibiting a half-time of 6 h.
Surprisingly, fructose did not prevent glycogen depletion. However,
in such glycogen-depleted adipocytes, the alteration of GLUT1
glycosylation in response to glucose deprivation was more rapid than
in normal adipocytes. CHO cells, which synthesize abbreviated
dolichol-linked oligosaccharides within minutes of glucose
deprivation (15), contained only 1% of the level of glycogen found in
3T3-L1 adipocytes. Glycosylation of GLUT1 was altered in CHO cells
within 3 h of glucose deprivation. These data demonstrate that during
glucose stress, glycogen may serve as a buffer for oligosaccharide
biosynthesis, and provide a potential explanation for varying
sensitivities of different cell types to glucose deprivation.
Received 2 August 1995; accepted in final form 9 November 1995.
APS Manuscript Number E359-5.
Article publication pending Am. J. Physiol. (Endocrinol. Metab.).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 8 December 95