Human glycolipid transfer protein - intracellular localization and effects on the sphingolipid synthesis

A1 Originalartikel i en vetenskaplig tidskrift (referentgranskad)


Interna författare/redaktörer


Publikationens författare: Tuuf J, Mattjus P
Publiceringsår: 2007
Tidskrift: Biochimica et Biophysica Acta Molecular and Cell Biology of Lipids
Tidskriftsakronym: BBA-MOL CELL BIOL L
Volym: 1771
Nummer: 11
Artikelns första sida, sidnummer: 1353
Artikelns sista sida, sidnummer: 1363
Antal sidor: 11
ISSN: 1388-1981


Abstrakt

Glycolipid transfer proteins (GLTPs) are small proteins that specifically transfer glycolipids from one bilayer membrane to another in vitro. However, the precise biological function is still unknown. In this study the intracellular distribution of GLTP was determined. We have used several independent methods, including differential and discontinuous density gradient centrifugation, plasma membrane permeabilization and confocal microscopy imaging, and we demonstrate that GLTP has a cytosolic location. The GLTP is not located in the Golgi apparatus, endoplasmic reticulum, nucleus, lysosomes, mitochondria or peroxisomes in HeLa cells. We have also used a fluorescence resonance energy transfer assay to detect transfer of fluorescently labeled BODIPY-glucosylceramide in the cytosolic fraction from both wild-type and GLTP-overexpressing HeLa cells. Furthermore, we have studied de novo sphingolipid changes in cells overexpressing GLTP using sphinganine metabolic labeling. The results show a significant increase in the synthesis of glucosylceramide (GlcCer) and a decrease in the sphingomyelin (SM) synthesis. However, no changes were detected in the de novo sphingolipid synthesis in GLTP-knockdown cells compared to control cells. We propose that GLTP is not likely involved in the de novo synthesis of glycosphingolipids, but could rather have a role as a glycolipid sensor for the cellular levels of glucosylceramide.


Nyckelord

confocal microscopy, cytosolic localization, GLTP, glucosylceramide, RNAi, subcellular fractionation

Senast uppdaterad 2019-11-12 vid 03:04