Localization of the murine niemann-pick C1 protein to two distinct intracellular compartments

William S. Garver, Randall A. Heidenreich, Robert P. Erickson, Mitchell A. Thomas, Jean M. Wilson

Research output: Contribution to journalArticle

87 Scopus citations

Abstract

Niemann-Pick type C (NPC) disease is characterized by an accumulation of cholesterol and other lipids in the lysosomal compartment. In this report, we use subcellular fractionation and microscopy to determine the localization of the murine Niemann-Pick C1 (NPC1) protein. Fractionation of mouse liver homogenates indicates that some NPC1 cosediments with lysosome-associated membrane protein 1 (LAMP1)-containing membranes. However, a significant amount of NPC1 is also found in membranes that do not contain LAM1. Moreover, fractionation of liver membranes and fibroblasts in the presence of a nonionic detergent showed that a fraction of NPC1 cosediments with caveolin-1 in rafts. Immunofluorescence microscopy of cultured mouse fibroblasts showed that NPC1 is found in two morphologically distinct structures. The first population is characterized by large punctate structures that do not colocalize with major organelle protein markers, but do colocalize with filipin and a small fraction of caveolin-1. Examination of these large NPC1- containing compartments using electron microscopy shows that these structures contain extensive internal membranes. The second population is represented by smaller, more diffuse structures, a fraction of which colocalize will LAMP1- positive compartments. Incubation of fibroblasts with low density lipoprotein (LDL) increases colocalization of NPC1 with LAMP1-containing compartments. This colocalization can be further enhanced by treating fibroblasts with progesterone or chloroquine. The results indicate that NPC1 is associated with an unique vesicular compartment enriched with cholesterol and containing caveolin-l, and that NPC1 cycles to LAMP1-positive compartments, presumably to facilitate the processing of LDL-derived cholesterol.

Original languageEnglish (US)
Pages (from-to)673-687
Number of pages15
JournalJournal of Lipid Research
Volume41
Issue number5
StatePublished - May 2000

Keywords

  • Cholesterol
  • Niemann-Pick C1 protein
  • Niemann-Pick type C

ASJC Scopus subject areas

  • Biochemistry
  • Endocrinology
  • Cell Biology

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    Garver, W. S., Heidenreich, R. A., Erickson, R. P., Thomas, M. A., & Wilson, J. M. (2000). Localization of the murine niemann-pick C1 protein to two distinct intracellular compartments. Journal of Lipid Research, 41(5), 673-687.