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Glycosylation of glomerular basement membrane in Type 1 (insulin-dependent) diabetic children
Insights
Diabetic children show altered glomerular basement membrane antigen mobility in urine. Non-enzymatic glycosylation of these proteins may contribute to diabetic glomerulosclerosis development.
Area of Science:
- Nephrology
- Diabetology
- Biochemistry
Background:
- Diabetic glomerulosclerosis is a major complication of Type 1 diabetes.
- Glomerular basement membrane (GBM) changes are implicated in diabetic nephropathy.
Purpose of the Study:
- To investigate GBM antigens in the urine of children with Type 1 diabetes.
- To explore the role of non-enzymatic glycosylation in GBM alterations.
Main Methods:
- Urine immunoelectrophoresis of GBM antigens in diabetic and healthy children.
- Incubation of GBM antigens and split products with glucose.
- Thiobarbituric acid assay to detect glycosylation.
Main Results:
- Altered alpha-1-mobility of urinary GBM antigens observed in 50% of diabetic children.
- Healthy children's GBM antigens showed alpha-2-mobility, shifting to alpha-1 after glucose incubation.
- Evidence of non-enzymatic glycosylation of GBM proteins after glucose incubation.
Conclusions:
- Urinary GBM antigen mobility patterns differ between diabetic and healthy children.
- Non-enzymatic glycosylation of GBM proteins is suggested in Type 1 diabetes.
- Glycosylated GBM proteins may play a role in the pathogenesis of diabetic glomerulosclerosis.
Abstract:
Immunoelectrophoresis of glomerular basement membrane antigens in the urine of 20 Type 1 (insulin-dependent) diabetic and 10 healthy children was performed. In 10 of the diabetic children, there was altered alpha-1-mobility, while the other diabetic and normal children showed alpha-2-mobility. After incubation with glucose, glomerular basement membrane antigens in the urine of healthy children showed alpha-1-mobility. Isolated human kidney glomerular basement membrane split products obtained by proteolytic degradation (papain, trypsin, chymotrypsin) were also investigated by immunoelectrophoresis. A difference was observed in the immunoelectrophoretic pattern of native and glycosylated glomerular basement membrane split products. A distinct increase of thiobarbituric acid assay positive glomerular basement membrane structures after incubation with glucose provides suggestive evidence for the occurrence of non-enzymatic glycosylation of glomerular basement membrane proteins. Glycosylated glomerular basement membrane proteins may contribute to both functional and morphological changes in diabetic glomerulosclerosis.