CHANGES IN STEADY-STATE LEVELS OF MESSENGER-RNAS CODING FOR TYPE-IV COLLAGEN, LAMININ AND FIBRONECTIN FOLLOWING CAPILLARY BASEMENT-MEMBRANE THICKENING IN HUMAN ADULT ONSET DIABETES

The development of capillary basement membrane thickening has been linked to microvascular changes known to occur in tissues of patients with type II diabetes. Previous evidence has suggested that capillary basement membrane thickening is due to increased basement membrane synthesis. In this study, skin samples from 8 diabetic patients with confirmed capillary basement membrane thickening and 7 non-diabetic controls were used to assess steady state levels of mRNAs coding for several basement components including proα1(IV) collagen, laminin and fibronectin. Total RNA was extracted from abdominal skin samples and levels of mRNAs coding for the basement membrane components laminin, fibronectin and proα1(IV) collagen, a fibrillar collagenous protein, proα1(I) collagen and an intracellular polypeptide, -γactin, were determined by dot blot hybridization analysis. While there were no changes of steady state levels of proα1(I) collagen mRNA and laminin mRNA, a significant reduction was noted in the quantitative recovery of mRNA levels for proα1(IV) collagen, γactin and fibronectin in total RNA isolated from the skin of diabetic patients. This reduction in levels of mRNAs coding for basement membrane components contrasts with pathological confirmation of an accumulation of endothelial capillary basement membrane in skin from diabetic patients and suggests that basement membrane thickening arises more as a consequence of reduced basement membrane degradation than elevated synthesis of basement membrane components. © 1990 Informa UK Ltd All rights reserved: reproduction in whole or part not permitted.