Glycation of hepatocyte cytosolic proteins in streptozotocin-induced diabetic rats

A role for glycation in diabetic pathology appears beyond doubt and one of the present trends is to focus the poorly explored field of intracellular glycation. In this work we studied the pattern of early glycation in hepatocyte cytosolic proteins from streptozotocin-induced diabetic rats (n=14) compared to control animals (n=8). Glycated proteins were present in the cytosol of control rats and increased three-fold after one mouth of diabetes, while glycated Hb and glycated plasma proteins rose two- and three-fold, respectively. A good correlation (r=0.82, p<0.001) was found between glycated cytosolic proteins and glycated plasma proteins, suggesting the latter could provide an indirect indication of intracellular glycation. Using PBA affinity chromatography followed by SDS-PAGE we detected 7 major glycated bands in cytosols from control animals which increased dramatically in diabetic rats. Moreover, other glycated proteins, which were undetectable in control animals, became prominent, and more than 15 major hands can thus be resolved. No major differences in the patterns can be seen after 1, 5. or 12 months of diabetes, suggesting that early glycation in cytosolic proteins reaches an equilibrium in a short period of one to two weeks (further supported by the tight correlation with glycated plasma proteins). Through comparison of the patterns obtained with an antiglucytollysine antibody on Western blots with those of silver stained gels from the PBA eluates we present evidence that intracellular glucation is mediated by glucose but mainly by other sugars. (C) 1996 Academic Press.