title: Urothelial plaque formation in post-Golgi compartments.
abstract: Urothelial plaques are specialized membrane domains in urothelial superficial (umbrella) cells, composed of highly ordered uroplakin particles. We investigated membrane compartments involved in the formation of urothelial plaques in mouse umbrella cells. The Golgi apparatus did not contain uroplakins organized into plaques. In the post-Golgi region, three distinct membrane compartments containing uroplakins were characterized: i) Small rounded vesicles, located close to the Golgi apparatus, were labelled weakly with anti-uroplakin antibodies and they possessed no plaques; we termed them "uroplakin-positive transporting vesicles" (UPTVs). ii) Spherical-to-flattened vesicles, termed "immature fusiform vesicles" (iFVs), were uroplakin-positive in their central regions and contained small urothelial plaques. iii) Flattened "mature fusiform vesicles" (mFVs) contained large plaques, which were densely labelled with anti-uroplakin antibodies. Endoytotic marker horseradish peroxidase was not found in these post-Golgi compartments. We propose a detailed model of de novo urothelial plaque formation in post-Golgi compartments: UPTVs carrying individual 16-nm particles detach from the Golgi apparatus and subsequently fuse into iFV. Concentration of 16-nm particles into plaques and removal of uroplakin-negative membranes takes place in iFVs. With additional fusions and buddings, iFVs mature into mFVs, each carrying two urothelial plaques toward the apical surface of the umbrella cell.
authors: Faculty of Medicine, Institute of Cell Biology, University of Ljubljana, Ljubljana, Slovenia. samo.hudoklin@mf.uni-lj.si
authors: Samo
authors: S
authors: Hudoklin
authors: Kristijan
authors: K
authors: Jezernik
authors: Josef
authors: J
authors: Neumüller
authors: Margit
authors: M
authors: Pavelka
authors: Rok
authors: R
authors: Romih
mesh_terms: D000818:Animals; D002451:Cell Compartmentation; D006056:Golgi Apparatus / Q000378:metabolism* / Q000648:ultrastructure; D021962:Membrane Microdomains / Q000378:metabolism* / Q000648:ultrastructure; D051379:Mice; D008810:Mice, Inbred C57BL; D008954:Models, Biological; D022161:Transport Vesicles / Q000378:metabolism / Q000648:ultrastructure; D060165:Uroplakins / Q000378:metabolism* / Q000648:ultrastructure; D019459:Urothelium / Q000378:metabolism* / Q000648:ultrastructure
chemical_list: D060165:Uroplakins