L-carnosine inhibits high-glucose-mediated matrix accumulation in human mesangial cells by interfering with TGF-β production and signalling.

Background: Transforming growth factor beta is recognized as a major cytokine in extracellular matrix (ECM) pathobiology as occurs in diabetic nephropathy. While experimental studies have advanced a protective role of carnosine for diabetic complications, a link between carnosine, TGF-β and matrix accumulation remains to be elucidated. In the present study, we tested the hypothesis that L-carnosine inhibits TGF-β production and signalling, thereby reducing hyperglycaemia-associated ECM accumulation.

N-glycosylation of carnosinase influences protein secretion and enzyme activity: implications for hyperglycemia.

Objective: The (CTG)(n) polymorphism in the serum carnosinase (CN-1) gene affects CN-1 secretion. Since CN-1 is heavily glycosylated and glycosylation might influence protein secretion as well, we tested the role of N-glycosylation for CN-1 secretion and enzyme activity. We also tested whether CN-1 secretion is changed under hyperglycemic conditions.

A CTG polymorphism in the CNDP1 gene determines the secretion of serum carnosinase in Cos-7 transfected cells.

Recently, we demonstrated that a polymorphism in exon 2 of the serum carnosinase (CNDP1) gene is associated with susceptibility to developing diabetic nephropathy. Based on the number of CTG repeats in the signal peptide, five different alleles coding for 4, 5, 6, 7, or 8 leucines (4L-8L) are known. Diabetic patients without nephropathy are homozygous for the 5L allele more frequently than those with nephropathy.

Carnosine as a protective factor in diabetic nephropathy: association with a leucine repeat of the carnosinase gene CNDP1.

The risk of diabetic nephropathy is partially genetically determined. Diabetic nephropathy is linked to a gene locus on chromosome 18q22.3-q23.