Fig. 1. Expression of endogenous furin in normal rat glomerulus. (A) Cryosection labeled with the rabbit anti-furin-N-terminus and FITC-labeled secondary antibodies. The fluorescence revealing furin antigenic sites is found in perinuclear regions (asterisks) of glomerular cells and along basement membranes (arrows). Bar, 10 µm. (B-D) Immunogold electron microscopy. (B) Golgi area within the cell body of a podocyte. Gold particles are present over the Golgi cisternae (G) and the rough endoplasmic reticulum (RER). The nucleus (N) and mitochondria (M) display very few gold particles. (C) Glomerular wall. The plasma membranes of the endothelium (End) and podocytes (P) are decorated by gold particles. Slit diaphragms (arrowheads) of podocytes are preferentially labeled. (D) Over the endothelial cell, labeling for furin is particularly focalized around the fenestrations (arrows). (E) Control conditions. The anti-furin antibody was preadsorbed with an excess of its antigen. The glomerular wall is exempt of gold particles. (B-E) Bars, 200 nm. Abbreviations: Cap, capillary lumen; GBM, glomerular basement membrane; US, urinary space. (F) Glomeruli homogenates were resolved by 10% SDS-PAGE and proteins were electrotransferred onto nitrocellulose membranes. The rabbit anti-furin-N-terminus and anti-proMT1-MMP antibodies were used for immunoblotting and were revealed by chemiluminescence. Single bands were obtained for furin (98 kDa) and proMT1-MMP (63 kDa).