Fig. 3.

Schematic intracellular lipid flows regulated by sterol transfer proteins and their inhibitors (indicated in red): A) cholesterol efflux from LE/Lys: the cationic amphiphilic drug U18666A binds to NPC1 and inhibits the LDL-derived cholesterol exit from lysosomes thereby inducing NPC phenotype [76,77]. BMP (green conical cylinder) favors the acid hydrolysis of LDL-derived cholesterol ester [22] and stimulates the rate of cholesterol transfer by NPC2 [52,51]. B) Cholesterol transfer at MCS between ER and Golgi/LE. OSBP exchanges cholesterol with PI4P between ER and trans Golgi (TGN) membranes [78,79]. Itraconazole (ITZ) and OSW-1 interact with OSBP and ORP4 disrupting OSBP lipid-shuttling function [80]. TTP-8307 inhibits directly the OSBP-dependent activities [81]. ORP1L, ORP5 and ORP 6, localized to LE membrane, mediate cholesterol transfer from LE to ER [[82], [83], [84]] and could be implicated in virus replication [54].