Human and rat mesangial cell receptors for glucose-modified proteins: potential role in kidney tissue remodelling and diabetic nephropathy.

Abstract

SummaryAdvanced glycosylation endproducts (AGEs) are derived from the nonenzymatic addition of glucose to proteins. AGEs have been found to accumulate on tissue proteins in patients with diabetes, and their accumulation is thought to play a role in the development of diabetic complications. The finding that macrophages and endothelial cells contain AGE-specific receptors led us to examine whether mesangial cells (MCs) also possess a mechanism for recognizing and processing AGEs. Membrane extracts isolated from rat and human MCs were found to bind AGE-bovine serum albumin (BSA) in a saturable fashion, with a binding affinity of 2.0 _+ 0.4 x 106 M-1 (500 nM). The binding was specific for the AGE adduct, since AGE-modified collagen I and ribonuclease both competitively inhibited nSI-AGE-BSA binding to MC membranes, while the unmodified proteins did not compete. Binding of AGE proteins was followed by slow internalization and degradation of the ligand. Ligand blotting of MC membrane extracts demonstrated three distinct AGE-binding membrane proteins of 50, 40, and 30 kD. Growth of MCs on various AGE-modified matrix proteins resulted in alterations in MC function, as demonstrated by enhanced production of fibronectin and decreased proliferation. These results point to the potential role that the interaction of AGE-modified proteins with MCs may play in vivo in promoting diabetic kidney disease.

Advanced glycation end products and their receptors co-localise in rat organs susceptible to diabetic microvascular injury

“…Although this study has focussed on RAGE, previous studies have isolated other receptors for AGEs including 60 kDa and 90 kDa proteins from rat liver macrophages [51]. More recently one of these receptors has been shown to have homology with the protein, galectin-3 [52].…”

High glucose level inhibits capacitative Ca 2 + influx in cultured rat mesangial cells by a protein kinase C-dependent mechanism

“…Altering the glucose concentration of the growth media of cultured cells modifies their functional behaviour [23][24][25]. This concept has been developed in different cell systems derived fom target organs for the complications of diabetes [26,27].…”

Toxic action of advanced glycation end products on cultured retinal capillary pericytes and endothelial cells: relevance to diabetic retinopathy

“…Proteins were transferred to Hybond-ECL (Amersham, Aylesbury, UK) and the presence of 60 kDa AGE-binding receptor detected by immunoblotting using a polyclonal antibody specific to the NH 2 -terminal peptide of the p60 component of the AGE-receptor as reported [12,13]. Membrane was blocked with 5 % BSA in 20 mmol/l Tris-HCL pH 7.5, 0.05 mol/l NaCl, and 0.05 % Tween 20 (Tris buffered saline TBST).…”

“…AGE-modified proteins bind specifically to AGE-receptors on the surface of endothelial cells, resulting in receptor-mediated endocytosis, changes in cellular proliferation, endothelial cell permeability, coagulant functions [10] and altered expression of endothelialderived relaxing activity [11]. Receptors that specifically recognize AGE adducts on proteins have also been identified on macrophages, mesangial cells and other cell types [12,13].…”