Rab Proteins Mediate Golgi Transport of Caveola-Internalized Glycosphingolipids and Correct Lipid Trafficking in Niemann-Pick C Cells

J Clin Invest. 2002 Jun;109(12):1541-50. doi: 10.1172/JCI15420.

Abstract

We recently showed that human skin fibroblasts internalize fluorescent analogues of the glycosphingolipids lactosylceramide and globoside almost exclusively by a clathrin-independent mechanism involving caveolae. In contrast, a sphingomyelin analogue is internalized approximately equally via clathrin-dependent and caveolar routes. Here, we further characterized the caveolar pathway for glycosphingolipids, showing that Golgi targeting of sphingolipids internalized via caveolae required microtubules and phosphoinositol 3-kinases and was inhibited in cells expressing dominant-negative Rab7 and Rab9 constructs. In addition, overexpression of wild-type Rab7 or Rab9 (but not Rab11) in Niemann-Pick type C (NP-C) lipid storage disease fibroblasts resulted in correction of lipid trafficking defects, including restoration of Golgi targeting of fluorescent lactosylceramide and endogenous GM(1) ganglioside, and a dramatic reduction in intracellular cholesterol stores. Our results demonstrate a role for Rab7 and Rab9 in the Golgi targeting of glycosphingolipids and suggest a new therapeutic approach for restoring normal lipid trafficking in NP-C cells.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Antigens, CD*
  • Biological Transport
  • Boron Compounds / metabolism
  • Caveolae / metabolism*
  • Cell Line
  • Cholera Toxin / metabolism
  • Cholesterol / metabolism
  • Fibroblasts / cytology
  • Fibroblasts / metabolism
  • Fluorescent Dyes / metabolism
  • Gene Expression
  • Golgi Apparatus / metabolism*
  • Green Fluorescent Proteins
  • HeLa Cells
  • Humans
  • Lactosylceramides / metabolism*
  • Lipid Metabolism
  • Luminescent Proteins / genetics
  • Luminescent Proteins / metabolism
  • Niemann-Pick Diseases / metabolism*
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism
  • rab GTP-Binding Proteins / genetics
  • rab GTP-Binding Proteins / metabolism*

Substances

  • 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene
  • Antigens, CD
  • Boron Compounds
  • Fluorescent Dyes
  • Lactosylceramides
  • Luminescent Proteins
  • Recombinant Fusion Proteins
  • fluorescent protein 583
  • Green Fluorescent Proteins
  • rab7 protein
  • CDw17 antigen
  • Cholera Toxin
  • Cholesterol
  • RAB9A protein, human
  • rab GTP-Binding Proteins