Volume 52 (5): 567-580, 2004 Copyright ©The Histochemical Society, Inc. Sorting of Furin in Polarized Epithelial and Endothelial Cells : Expression Beyond the Golgi Apparatus
Département de Pathologie et Biologie Cellulaire (GM,MB) et Département de Biochimie (GB), Université de Montréal, Montréal, Québec, Canada Correspondence to: Dr. Moïse Bendayan, Pathologie et Biologie Cellulaire, Université de Montréal, CP 6128 Succ Centre Ville, Montréal, Québec H3C 3J7, Canada. E-mail: moise.bendayan{at}umontreal.ca The conversion of proteins into their mature forms underlies the functionality of many fundamental cellular pathways. One posttranslational modification leading to maturation of precursor proteins consists of the cleavage of their prodomain at pairs of basic amino acids by enzymes of the subtilisin-like mammalian proprotein convertase family. One of these enzymes, furin, acts in the constitutive secretory pathway of almost every cell type. However, in spite of furin's major roles in many pathophysiological processes, the exact subcellular sites of processing and activation of its substrates remain elusive. In this study, furin antigenic sites were tracked in subcellular compartments of various tissues and corresponding cell lines by high-resolution immunogold electron microscopy, Western blotting, cell transfection, and in vivo gene delivery of the furin cDNA. In addition to the Golgi apparatus, furin was assigned to endosomes and plasma membranes of polarized intestinal and renal epithelial cells and endothelial cells of the continuous, fenestrated, and discontinuous capillaries. Roles of furin in endothelial permeability, basement membrane turnover, and shedding of transmembrane proteins are supported by our data. (J Histochem Cytochem 52:567579, 2004)
Key Words: furin cell surface endosomes electron microscopy
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