title: Sterol binding by OSBP-related protein 1L regulates late endosome motility and function.
abstract: ORP1L is an oxysterol binding homologue that regulates late endosome (LE) positioning. We show that ORP1L binds several oxysterols and cholesterol, and characterize a mutant, ORP1L Δ560-563, defective in oxysterol binding. While wild-type ORP1L clusters LE, ORP1L Δ560-563 induces LE scattering, which is reversed by disruption of the endoplasmic reticulum (ER) targeting FFAT motif, suggesting that it is due to enhanced LE-ER interactions. Endosome motility is reduced upon overexpression of ORP1L. Both wild-type ORP1L and the Δ560-563 mutant induce the recruitment of both dynactin and kinesin-2 on LE. Most of the LE decorated by overexpressed ORP1L fail to accept endocytosed dextran or EGF, and the transfected cells display defective degradation of internalized EGF. ORP1L silencing in macrophage foam cells enhances endosome motility and results in inhibition of [(3)H]cholesterol efflux to apolipoprotein A-I. These data demonstrate that LE motility and functions in both protein and lipid transport are regulated by ORP1L.
authors.affiliation: Minerva Foundation Institute for Medical Research, Biomedicum Helsinki 2U, Tukholmankatu 8, 00290 Helsinki, Finland.
authors.forename: Terhi
authors.initials: T
authors.lastname: Vihervaara
authors.forename: Riikka-Liisa
authors.initials: RL
authors.lastname: Uronen
authors.forename: Gerd
authors.initials: G
authors.lastname: Wohlfahrt
authors.forename: Ingemar
authors.initials: I
authors.lastname: Björkhem
authors.forename: Elina
authors.initials: E
authors.lastname: Ikonen
authors.forename: Vesa M
authors.initials: VM
authors.lastname: Olkkonen
mesh_terms: D000818:Animals; D016632:Apolipoprotein A-I / Q000378:metabolism; D002352:Carrier Proteins / Q000032:analysis / Q000235:genetics* / Q000378:metabolism*; D002460:Cell Line; D002784:Cholesterol / Q000378:metabolism; D004705:Endocytosis; D011992:Endosomes / Q000378:metabolism* / Q000648:ultrastructure; D005786:Gene Expression Regulation; D006367:HeLa Cells; D006801:Humans; D008247:Lysosomes / Q000378:metabolism; D008264:Macrophages / Q000378:metabolism / Q000648:ultrastructure; D051379:Mice; D008958:Models, Molecular; D020409:Molecular Motor Proteins / Q000378:metabolism; D009154:Mutation; D011485:Protein Binding; D011987:Receptors, Steroid; D013261:Sterols / Q000378:metabolism*; D000098825:Oxysterol Binding Proteins
chemical_list: D016632:Apolipoprotein A-I; D002352:Carrier Proteins; D020409:Molecular Motor Proteins; D011987:Receptors, Steroid; D013261:Sterols; D000098825:Oxysterol Binding Proteins; D002784:Cholesterol