Cholesterol sensor ORP1L contacts the ER protein VAP to control Rab7-RILP-p150 Glued and late endosome positioning. – ScienceOpen
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      Cholesterol sensor ORP1L contacts the ER protein VAP to control Rab7-RILP-p150 Glued and late endosome positioning.

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          Abstract

          Late endosomes (LEs) have characteristic intracellular distributions determined by their interactions with various motor proteins. Motor proteins associated to the dynactin subunit p150(Glued) bind to LEs via the Rab7 effector Rab7-interacting lysosomal protein (RILP) in association with the oxysterol-binding protein ORP1L. We found that cholesterol levels in LEs are sensed by ORP1L and are lower in peripheral vesicles. Under low cholesterol conditions, ORP1L conformation induces the formation of endoplasmic reticulum (ER)-LE membrane contact sites. At these sites, the ER protein VAP (VAMP [vesicle-associated membrane protein]-associated ER protein) can interact in trans with the Rab7-RILP complex to remove p150(Glued) and associated motors. LEs then move to the microtubule plus end. Under high cholesterol conditions, as in Niemann-Pick type C disease, this process is prevented, and LEs accumulate at the microtubule minus end as the result of dynein motor activity. These data explain how the ER and cholesterol control the association of LEs with motor proteins and their positioning in cells.

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          Most cited references53

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          Role of cholesterol and lipid organization in disease.

          Membrane lipids are essential for biological functions ranging from membrane trafficking to signal transduction. The composition of lipid membranes influences their organization and properties, so it is not surprising that disorders in lipid metabolism and transport have a role in human disease. Significant recent progress has enhanced our understanding of the molecular and cellular basis of lipid-associated disorders such as Tangier disease, Niemann-Pick disease type C and atherosclerosis. These insights have also led to improved understanding of normal physiology.
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            • Record: found
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            Niemann-Pick C1 disease gene: homology to mediators of cholesterol homeostasis.

            Niemann-Pick type C (NP-C) disease, a fatal neurovisceral disorder, is characterized by lysosomal accumulation of low density lipoprotein (LDL)-derived cholesterol. By positional cloning methods, a gene (NPC1) with insertion, deletion, and missense mutations has been identified in NP-C patients. Transfection of NP-C fibroblasts with wild-type NPC1 cDNA resulted in correction of their excessive lysosomal storage of LDL cholesterol, thereby defining the critical role of NPC1 in regulation of intracellular cholesterol trafficking. The 1278-amino acid NPC1 protein has sequence similarity to the morphogen receptor PATCHED and the putative sterol-sensing regions of SREBP cleavage-activating protein (SCAP) and 3-hydroxy-3-methyl-glutaryl coenzyme A (HMG-CoA) reductase.
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              The Rab7 effector protein RILP controls lysosomal transport by inducing the recruitment of dynein-dynactin motors.

              Many intracellular compartments, including MHC class II-containing lysosomes, melanosomes, and phagosomes, move along microtubules in a bidirectional manner and in a stop-and-go fashion due to the alternating activities of a plus-end directed kinesin motor and a minus-end directed dynein-dynactin motor. It is largely unclear how motor proteins are targeted specifically to different compartments. Rab GTPases recruit and/or activate several proteins involved in membrane fusion and vesicular transport. They associate with specific compartments after activation, which makes Rab GTPases ideal candidates for controlling motor protein binding to specific membranes. We and others [7] have identified a protein, called RILP (for Rab7-interacting lysosomal protein), that interacts with active Rab7 on late endosomes and lysosomes. Here we show that RILP prevents further cycling of Rab7. RILP expression induces the recruitment of functional dynein-dynactin motor complexes to Rab7-containing late endosomes and lysosomes. Consequently, these compartments are transported by these motors toward the minus end of microtubules, effectively inhibiting their transport toward the cell periphery. This signaling cascade may be responsible for timed and selective dynein motor recruitment onto late endosomes and lysosomes.
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                Author and article information

                Journal
                J Cell Biol
                The Journal of cell biology
                Rockefeller University Press
                1540-8140
                0021-9525
                Jun 29 2009
                : 185
                : 7
                Affiliations
                [1 ] Division of Cell Biology, The Netherlands Cancer Institute, 1066CX Amsterdam, Netherlands.
                Article
                jcb.200811005
                10.1083/jcb.200811005
                2712958
                19564404
                9bf4129d-2676-410b-a87a-078933a288a4
                History

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