QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

First published online 6 June 2006
doi: 10.1242/jcs.02993

This Article Figures Only Full Text Full Text (PDF) All Versions of this Article: jcs.02993v1 119/13/2643    most recent Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Related articles in JCS Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Ohsaki, Y. Articles by Ninomiya, H. Search for Related Content PubMed PubMed Citation Articles by Ohsaki, Y. Articles by Ninomiya, H.

Cholesterol depletion facilitates ubiquitylation of NPC1 and its association with SKD1/Vps4

¹ Department of Neurobiology, Tottori University Faculty of Medicine, Yonago 683-8503, Japan
² Department of Intelligence Science and Technology, Graduate School of Informatics, Kyoto University, Kyoto 606-8501, Japan
³ Department of Cell Genetics, National Institute of Genetics, Mishima 411-8540, Japan
⁴ Department of Human Genetics, Mount Sinai School of Medicine, New York, NY 10029, USA
⁵ INSERM Unit 189, Lyon-Sud Medical School and Fondation Gillet-Merieux, Lyon-Sud Hospital, 69921 Oullins, France
⁶ Department of Child Neurology, Tottori University Faculty of Medicine, Yonago 683-8503, Japan

^* Author for correspondence (e-mail: ninomiya{at}grape.med.tottori-u.ac.jp)

Accepted 23 March 2006

Niemann-Pick disease type C (NPC) is an inherited lipid storage disorder caused by mutations in NPC1 or NPC2. NPC1 is a polytopic glycoprotein that contains a sterol-sensing domain, whereas NPC2 is a soluble protein that contains an MD-2-like lipid-recognition domain. In the current study, we addressed the hypothesis that ubiquitylation of NPC1 might be regulated by cholesterol. We found that depletion of cellular cholesterol facilitated ubiquitylation of NPC1 expressed in COS cells. A loss-of-function mutant, NPC1(P691S), which contains an amino acid substitution in the sterol-sensing domain, failed to respond to cholesterol depletion. Another mutant, NPC1(LLNF), which lacks the endosomal-targeting motif, also failed to respond. SKD1(E235Q), a dominant-negative mutant of SKD1/Vps4 that inhibits disassembly of the endosomal sorting complex required for transport (ESCRT), caused an accumulation of ubiquitylated NPC1. SKD1(E235Q) associated with NPC1 on the endosomal membrane, whereas wild-type SKD1 associated with NPC1 only when cells were depleted of cholesterol. Similarly, in control human skin fibroblasts, cholesterol depletion facilitated ubiquitylation of endogenous NPC1. In patient cells that lack NPC2 function, NPC1 was ubiquitylated regardless of cellular cholesterol levels, suggesting that NPC2 is required to prevent NPC1 ubiquitylation under cholesterol-rich conditions. These results suggest that ubiquitylation of NPC1 and its association with the ESCRT complex are controlled by endosomal cholesterol levels utilizing a mechanism that involves NPC2.

Key words: NPC1, NPC2, SKD1, Vps4, Ubiquitin, Cholesterol

Related articles in JCS:

Low cholesterol recipe for Niemann-Pick proteins

JCS 2006 119: 1303. [Full Text]  

This article has been cited by other articles:

				W. S. Garver, D. Jelinek, G. A. Francis, and B. D. Murphy The Niemann-Pick C1 gene is downregulated by feedback inhibition of the SREBP pathway in human fibroblasts J. Lipid Res., May 1, 2008; 49(5): 1090 - 1102. [Abstract] [Full Text] [PDF]

				M. Gentzsch, A. Choudhury, X.-b. Chang, R. E. Pagano, and J. R. Riordan Misassembled mutant {Delta}F508 CFTR in the distal secretory pathway alters cellular lipid trafficking J. Cell Sci., February 1, 2007; 120(3): 447 - 455. [Abstract] [Full Text] [PDF]