Advanced glycation endproduct-specific receptors in rat and mouse osteoblast-like cells: regulation with stages of differentiation

Advanced glycation endproducts have been implicated in the development of d iabetic complications. In addition, these products could also mediate certa in bone alterations such as diabetic osteopenia. Several receptors specific for advanced glycation endproduct-modified proteins have been characterize d in different cell types, contributing to the recognition and degradation of senescent proteins. In the present report, we investigated the possible presence of advanced glycation endproduct-binding proteins on osteoblast-li ke cells. Both UMR106 and MC3T3E1 cell lines express specific advanced glyc ation endproduct-binding sites, with an affinity constant between 0.4 and 1 .7 . 10(6) M-1, depending on the stage of osteoblastic differentiation; and with a receptor capacity of 1.5-2.0 . 10(7) sites/cell. Osteoblast-like ce lls were also found to participate both in the uptake and degradation of ad vanced glycation endproduct-modified bovine serum albumin at 37 degrees C. Radiolabelled ligand blotting studies confirmed the presence of several mem brane binding proteins, with apparent molecular masses of 50, 45-40, 30, 25 and 18 kDa; the major bands corresponded to 30 and 25 kDa proteins. This s tudy provides evidence of the presence of advanced glycation endproduct-spe cific binding sites, and for their regulation with the stage of differentia tion, in two osteoblast-like cells in culture.