Rab proteins mediate Golgi transport of caveola-internalized glycosphingolipids and correct lipid trafficking in Niemann-Pick C cells

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 clathri...

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Bibliographic Details
Published in:The Journal of clinical investigation 2002-06, Vol.109 (12), p.1541-1550
Main Authors: Choudhury, Amit, Dominguez, Michel, Puri, Vishwajeet, Sharma, Deepak K, Narita, Keishi, Wheatley, Christine L, Marks, David L, Pagano, Richard E
Format: Article
Language:English
Subjects:
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
rab GTP-Binding Proteins - genetics
rab GTP-Binding Proteins - metabolism
Recombinant Fusion Proteins - genetics
Recombinant Fusion Proteins - metabolism
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Summary: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.
ISSN:0021-9738
DOI:10.1172/jci0215420