Role for protein kinase C in the mediation of increased fibronectin accumulation by mesangial cells grown in high-glucose medium

• Published in: Diabetes (New York, N.Y.) Vol. 42; no. 1; pp. 118 - 126
• Main Authors: Studer, R. K., Craven, P. A., DeRubertis, F. R.
• Format: Journal Article
• Language: English
• Published: American Diabetes Association 01-01-1993
• ISSN: 0012-1797; 1939-327X; 0012-1797
• DOI: 10.2337/diabetes.42.1.118

Role for protein kinase C in the mediation of increased fibronectin accumulation by mesangial cells grown in high-glucose
medium.
R K Studer ,
P A Craven and
F R DeRubertis
Department of Medicine, VA Medical Center, Pittsburgh, PA 15240.
Abstract
The fibronectin content of RMC cultures grown for 8-14 days in medium containing 30 mM (540 mg/dl) D-glucose was increased
30-60% relative to that of control cells cultured in 10 mM (180 mg/dl) glucose. Addition of equiosmolar concentrations (20
mM, 360 mg/dl) of L-glucose, 3-O-methylglucose, or mannitol to 10 mM glucose media did not alter fibronectin accumulation
compared with values observed in 10 mM glucose alone. The basal phosphorylation of the 80,000-M(r) MARKS protein, which is
a substrate for PKC, and the phosphorylation induced by acute (15-min) exposure of cells to 15% FCS or to 0.1 microM (50 ng/ml)
PDBu were all increased in cells grown in 30 mM compared with 10 mM glucose. By contrast, phosphorylation of the 80,000-M(r)
protein in response to a maximal concentration of PDBu (1 microM, 500 ng/ml) was not different in cells grown in 30 mM compared
with 10 mM glucose. The acute increases in phosphorylation of the 80,000-M(r) protein were blocked by the PKC inhibitor calphostin
C. Chronic (7-day) exposure of mesangial cells grown in 10 mM glucose to 0.1 microM of the PKC agonist PDBu also resulted
in a sustained 40% increase in 80,000-M(r) phosphorylation and a 20-30% increase in fibronectin accumulation. As assessed
by [35S]methionine incorporation, mesangial cell fibronectin synthesis was increased by exposure to PDBu, a finding consistent
with earlier observations with 30 mM glucose.