Author/Editor		Rituper, Boštjan; Guček, Alenka; Lisjak, Marjeta; Górska, Urszula; Šakanović, Aleksandra; Trkov, Saša; Lasič, Eva; Božić, Mićo; Jorgačevski, Jernej; Kreft, Marko; Verkhratsky, Alexei; Anderluh, Gregor; Stenovec, Matjaž; Božič, Bojan; Zorec, Robert
Title		Vesicle cholesterol controls exocytotic fusion pore
Type		članek
Vol. and No.		, št. Vol. 101
Publication year		2022
Volume		str. 1-17
ISSN		1532-1991 - Cell calcium
Language		eng
Abstract		In some lysosomal storage diseases (LSD) cholesterol accumulates in vesicles. Whether increased vesicle cholesterol affects vesicle fusion with the plasmalemma, where the fusion pore, a channel between the vesicle lumen and the extracellular space, is formed, is unknown. Super-resolution microscopy revealed that after stimulation of exocytosis, pituitary lactotroph vesicles discharge cholesterol which transfers to the plasmalemma. Cholesterol depletion in lactotrophs and astrocytes, both exhibiting Ca2+-dependent exocytosis regulated by distinct Ca2+sources, evokes vesicle secretion. Although this treatment enhanced cytosolic levels of Ca2+ in lactotrophs but decreased it in astrocytes, this indicates that cholesterol may well directly define the fusion pore. In an attempt to explain this mechanism, a new model of cholesterol-dependent fusion pore regulation is proposed. High-resolution membrane capacitance measurements, used to monitor fusion pore conductance, a parameter related to fusion pore diameter, confirm that at resting conditions reducing cholesterol increases, while enrichment with cholesterol decreases the conductance of the fusion pore. In resting fibroblasts, lacking the Npc1 protein, a cellular model of LSD in which cholesterol accumulates in vesicles, the fusion pore conductance is smaller than in controls, showing that vesicle cholesterol controls fusion pore and is relevant for pathophysiology of LSD.
Keywords		cholesterol exocytosis fusion pore conductance holesterol eksocitoza prevodnost fuzijskih por