De novo glycosphingolipid synthesis and the proliferative response
of a proximal tubule cell line to growth in high glucose.
El-Khatib, Mahmoud, Norman S. Radin, and James A. Shayman.
Nephrology Division, Department of Internal Medicine, University of
Michigan, Box 0676, 1560 MSRB II, 1150 West Medical Center Drive, Ann
Arbor, MI 48109-0676 and V.A. Medical Center, Ann Arbor
APStracts 2:0172F, 1995.
We evaluated the role of sphingolipids as potential mediators of the
renal epithelial growth response to growth in high glucose media. The
mouse cortical tubule cell line (MCT) was studied under high glucose
(450 mg/dl) and normal glucose (100 mg/dl) conditions. In cells
plated at low density, high glucose media stimulated cell
proliferation as measured by DNA, protein and cell number and
[3H]thymidine incorporation with a corresponding increase in
glucosylceramide. The glucosylceramide synthase inhibitor, 1-phenyl
-2-decanoylamino-3-morpholino-1-propanol (PDMP), blocked the
proliferative response to high glucose in association with a decrease
in endogenous glucosylceramide and an increase in ceramide
concentrations. Addition of N-acetylsphingosine, a short chain
homologue of natural ceramides, increased the levels of endogenous
ceramides and inhibited proliferation. In contrast, the [beta]
-glucosidase inhibitor conduritol B epoxide resulted in increased cell
glucosylceramide, but did not increase proliferation. We conclude
that MCT cells proliferate when grown in the presence of high
glucose. Glucosylceramide levels increase and ceramide levels
decrease in concert with the proliferative response.
Pharmacologically increasing endogenous levels of ceramide inhibits
the proliferative response to high glucose, but increasing endogenous
levels of glucosylceramide does not stimulate proliferation.
Received 7 March 1995; accepted in final form 21 September 1995.
APS Manuscript Number F77-5.
Article publication pending Am. J. Physiol. (Renal Fluid Electrolyte
Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 6 November 95