AJP - Cell Physiology, Vol 253, Issue 4 C567-C574, Copyright © 1987 by American Physiological Society
Platelet-derived growth factor stimulated mechanisms of glucosamine incorporation
M. A. Harrington and W. J. Pledger
Department of Pharmacology, University of North Carolina, Chapel Hill 27514.
Platelet-derived growth factor (PDGF) treatment of density-arrested
BALB/c-3T3 cells results in increased [3H]glucosamine (GlcN) incorporation
into cellular material. The enhanced GlcN incorporation is not due to a
preferential increase in proteoglycan synthesis as measured by [35S]H2SO4
incorporation. Approximately 50% of the GlcN incorporated in PDGF or
platelet-poor plasma (PPP)-treated cultures enters N-linked glycoproteins.
Addition of dolichol-phosphate (dolichol-P), a required intermediate in
N-linked glycosylation, did not alter [3H]GlcN incorporation in
PDGF-treated cells but did increase incorporation in PPP-treated cultures
to a level comparable to that observed for PDGF-treated cultures.
PDGF-treated cultures contained twofold greater quantities of [3H]GlcN
dolichol intermediates and lipid-free glycoprotein. Over a 12-h time course
3-hydroxy-3-methylglutaryl coenzyme A reductase (HMG CoA reductase)
activity was similar in cultures treated with PDGF or PPP. Results of these
studies reveal that enhanced protein glycosylation in response to PDGF
treatment is not the result of a direct effect on HMG CoA reductase.
