Author/Editor		Erdani-Kreft, Mateja; Di Giandomenico, Daniele; Beznoussenko, Galina V; Resnik, Nataša; Mironov, Alexander A; Jezernik, Kristijan
Title		Golgi apparatus fragmentation as a mechanism responsible for uniform delivery of uroplakins to the apical plasma membrane of uroepithelial cells
Type		članek
Source		Biol Cell
Vol. and No.		Letnik 102, št. 11
Publication year		2010
Volume		str. 593-607
Language		eng
Abstract		Background information. The GA (Golgi apparatus) has an essential role in membrane trafficking, determining the assembly and delivery of UPs (uroplakins) to the APM (apical plasma membrane) of superficial UCs (uroepithelial cells) of urinary bladder. UPs are synchronously and uniformly delivered from the GA to the APM by DFVs (discoidalor fusiform-shaped vesicles); however, themechanism of UP delivery is not known.We have used the culture model of UCs with the capacity to undergo terminal differentiation to study the process of uniform delivery of DFVs to the APM and to elucidate the mechanisms involved. Results. By three-dimensional localization using confocal microscopy of immunofluorescence-labelled GA-related markers [GM130 (cis-Golgi matrix protein of 130 kDa), GS15 (Golgi Snare 15 kDa), GS28 and giantin], uroepithelial differentiation-related markers (UPs), MTs (microtubules; á-tubulin) and intermediate filaments [CK7 (cytokeratin 7) and CK20], we found that in non-differentiated, UP-negative UCs the GA is mostly organized as a single ribbonlike structure close to the nucleus, whereas in differentiated, UP-positive UCs the GA is fragmented and spread almost through the entire cell. The FRAP (fluorescence recovery after photobleaching) experiments on the UCs transfected with GalT (trans-Golgi/TGN enzyme beta1,4-galactosyltransferase) fused to fluorescent protein showed that Golgi-resident enzyme cycles freely within ribbon-like GA but not within fragmented GA. By CLEM (correlative light-electron microscopy), we examined the GA fragments in cells expressing UPs. We found that GA fragments are fully functional and similar to the GA fragments that are formed after nocodazole treatment. (Abstract truncated at 2000 characters)
Descriptors		BLADDER UROTHELIUM GOLGI APPARATUS CELL MEMBRANE CYTOSKELETON CELL DIFFERENTIATION MICROSCOPY, CONFOCAL MICROSCOPY, ELECTRON NOCODAZOLE GALACTOSYLTRANSFERASES INTERMEDIATE FILAMENTS CELLS, CULTURED SWINE