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) grow n for six to eight passages in media containing either 5.6 or 25 mM gl ucose. 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 contra st, [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 isoto pes between media and cell layer fractions was not different in the tw o conditions. Addition of 19.4 mM mannitol to 5.6 mM glucose containin g media had no effect on isotope incorporation. The HPLC-DEAE and Seph arose CL-GB elution profiles of media S-35-proteoglycans synthesized u nder each condition were similar. A Sepharose CL4B K-av 0.08 heparan s ulfate proteoglycan accounted for 20% of the total S-35-incorporation. Perlecan domain III mRNA was identified by Northern analysis and doma in I by the polymerase chain reaction (PCR) in total BMEC RNA. A mixtu re of chondroitin/dermatan sulfate proteoglycans accounted for 67% of S-35-incorporation. They eluted from Sepharose CL-6B at K-av 0 and 0.2 2. Two [H-3]leucine labeled core proteins of 135 and 50 kD were identi fied in each of these S-35-proteoglycan peaks. Biglycan but not decori n mRNAs were detected by Northern analysis and by PCR. These data demo nstrate that prolonged exposure to high glucose concentrations in vitr o stimulate the accumulation of [S-35]sulfate into microvascular endot helial cell proteoglycans without significant alterations in their ove rall hydrodynamic or charge related properties. Modulation of proteogl ycan synthesis by glucose may participate in the pathogenesis of the s mall vessel complications of diabetes. (C) 1995 Wiley-Liss, Inc.