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.

Apolipoprotein E Promotes β-Amyloid Trafficking and Degradation by Modulating Microglial Cholesterol Levels

“…It is notable that this property is related to the cholesterol efflux function of apoE as using the 4F mimetic peptide elicited the same results. Although the underlying reason why GDI extraction of Rab7 is modulated by cholesterol is unknown, results from previous studies suggested that this regulation perhaps involves oxysterol-binding protein-related protein 1L through the Rab7 effector Rab7-interacting lysosomal protein (35,86,87). Whether this activity subsequently regulates the extraction of Rab7 by GDI requires further investigation.…”

Small regulators, major consequences – Ca2+ and cholesterol at the endosome–ER interface

“…Glued from RILP, thereby facilitating plus-end-directed transport of late endosomes by kinesin motors (Rocha et al, 2009;Vihervaara et al, 2011). The ER thus coordinates the direction of late endosomal movement, but why is the timing of this process regulated by cholesterol?…”

Late endosomal transport and tethering are coupled processes controlled by RILP and the cholesterol sensor ORP1L

“…Silencing of RILP or ectopic expression of its dominant negative N-terminally truncated mutant (RILPD199) have been shown to impair endosomal maturation as well as phagosome fusion to lysosomes thereby facilitating intracellular Salmonella survival (Marsman et al, 2004;Harrison et al, 2004;Guignot et al, 2004). Dynein motor recruitment to RAB7-RILP is controlled by interactions between the cholesterol sensor ORP1L and the ER protein VAP-A and this mechanism is responsible for vesicle clustering observed in lysosomal storage diseases characterized by accumulation of cholesterol in the late endosomal compartments (Rocha et al, 2009;Vihervaara et al, 2011).…”