PROTEOGLYCAN SYNTHESIS BY BOVINE MYOCARDIAL ENDOTHELIAL-CELLS IS INCREASED BY LONG-TERM EXPOSURE TO HIGH-CONCENTRATIONS OF GLUCOSE

The role of the metabolic milieu in control of proteoglycan synthesis was investigated using bovine myocardial endothelial cells (BMEC) grown for six to eight passages in media containing either 5.6 or 25 mM glucose. Macromolecular Na[S-35]sulfate incorporation into proteoglycans was increased by exposure to 25 mM when compared with 5.6 mM glucose (7.05 +/- 0.40 [SD] vs. 3.5 +/- 0.50 x 10(-4) dpm/mu g DNA). In contrast, [H-3]leucine incorporation was unaffected by glucose (11.27 +/- 0.85 vs. 9.88 +/- 1.23 x 10(-5) dpm/mu g DNA). The distribution of isotopes between media and cell layer fractions was not different in the two conditions. Addition of 19.4 mM mannitol to 5.6 mM glucose containing media had no effect on isotope incorporation. The HPLC-DEAE and Sepharose CL-GB elution profiles of media S-35-proteoglycans synthesized under each condition were similar. A Sepharose CL4B K-av 0.08 heparan sulfate proteoglycan accounted for 20% of the total S-35-incorporation. Perlecan domain III mRNA was identified by Northern analysis and domain I by the polymerase chain reaction (PCR) in total BMEC RNA. A mixture of chondroitin/dermatan sulfate proteoglycans accounted for 67% of S-35-incorporation. They eluted from Sepharose CL-6B at K-av 0 and 0.22. Two [H-3]leucine labeled core proteins of 135 and 50 kD were identified in each of these S-35-proteoglycan peaks. Biglycan but not decorin mRNAs were detected by Northern analysis and by PCR. These data demonstrate that prolonged exposure to high glucose concentrations in vitro stimulate the accumulation of [S-35]sulfate into microvascular endothelial cell proteoglycans without significant alterations in their overall hydrodynamic or charge related properties. Modulation of proteoglycan synthesis by glucose may participate in the pathogenesis of the small vessel complications of diabetes. (C) 1995 Wiley-Liss, Inc.