title: Reactive oxygen species deglycosilate glomerular alpha-dystroglycan.
abstract: In the kidney, dystroglycan (DG) has been shown to cover the basolateral and apical membranes of the podocyte. alpha-DG is heavily glycosilated, which is important for its binding to laminin and agrin in the glomerular basement membrane. Furthermore, alpha-DG is negatively charged, which maintains the filtration slit open. Reactive oxygen species (ROS) are known to degrade and depolymerize carbohydrates, and to play a role in several glomerular diseases. Therefore, we evaluated the effect of ROS on the glycosilation of glomerular alpha-DG. By using specific antibodies directed against the core protein or glyco-epitopes of alpha-DG, this was studied in a solid-phase assay, in situ on kidney sections, and in vivo in adriamycin nephropathy. A ligand overlay assay was used to study binding of alpha-DG to its ligands. Exposure to ROS leads to a loss of carbohydrate epitopes on alpha-DG both in vitro and on kidney sections. In the in vitro assays, a decreased binding of deglycosilated alpha-DG to laminin and agrin was found. In adriamycin nephropathy, where radicals play a role, we observed a loss of alpha-DG carbohydrate epitopes. We conclude that deglycosilation of glomerular alpha-DG by ROS leads to disruption of the agrin-DG complex, which in vivo may lead to the detachment of podocytes. Furthermore, loss of negative charge in the filtration slit may lead to foot process effacement of podocytes.
authors: Division of Nephrology, Nijmegen Centre for Molecular Life Sciences, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands.
authors: N P J
authors: NP
authors: Vogtländer
authors: W P M
authors: WP
authors: Tamboer
authors: M A H
authors: MA
authors: Bakker
authors: K P
authors: KP
authors: Campbell
authors: J
authors: J
authors: van der Vlag
authors: J H M
authors: JH
authors: Berden