Endogenous carbohydrate-binding proteins of rabbit and human bladder

Objectives. To identify the endogenous lectins of the human bladder with th e long-term goal of developing improved strategies for the treatment of int erstitial cystitis and other bladder disorders. Methods. Rabbit and human bladder sections were examined histochemically us ing biotinylated neoglycoconjugates. Affinity chromatography of extracts of rabbit bladder was performed on immobilized lactose to purify the galactos e-binding protein. Results. Biotinylated beta-D-galactose neoglycoconjugate showed the stronge st specific staining of the rabbit and human bladder sections. The beta-D-N -acetylglucosamine neoglycoconjugate also showed significant staining; the alpha-L-fucose, alpha-D-mannose, alpha-D-N-acetylneuraminic acid, and alpha -D-N-acetylgalactosamine neoglycoconjugates showed either very weak or no r eaction. The strong Ca2+-independent binding of beta-D-galactose neoglycoco njugates suggested the presence of galectins in rabbit and human bladder, A ffinity chromatography of rabbit bladder extract on lactose gel yielded a g alectin of about 30 kDa, consistent with the molecular biological data conf irming the expression of galectin-3 in bladder. Conclusions. Beta-D-galactose binds strongly and specifically to rabbit and human bladder tissue sections. This information would be useful for the pu rpose of modifying drugs used for the treatment of bladder disorders with l igands of galactose-binding lectins to improve their retention in the bladd er. (C) 1999, Elsevier Science Inc. All rights reserved.