Localization of α1,3-fucosyltransferase VI in Weibel–Palade bodies of human endothelial cells

Localization of α1,3-fucosyltransferase VI in Weibel–Palade bodies of human endothelial cells

^*Institute of Physiology, University of Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland; and ^§Institute for Biopharmaceutical Research, Incorporated, CH-9545 Waengi, Switzerland

Communicated by Ewald R. Weibel, University of Bern, Herrenschwanden, Switzerland (received for review December 12, 1999)

Abstract

Surface glycosylation of endothelial cells is relevant to various processes including coagulation, inflammation, metastasis, and lymphocyte homing. One of the essential sugars involved in these processes is fucose linked α1→3 to N-acetylglucosamine. A family of α1,3-fucosyltransferases (FucTs) called FucT-III, IV, V, VI, VII, and IX is able to catalyze such fucosylations. Reverse transcription–PCR analysis revealed that human umbilical vein endothelial cells express all of the FucTs except FucT-IX. The predominant activity, as inferred by acceptor specificity of enzyme activity in cell lysates, is compatible with the presence of FucT-VI. By using an antibody to recombinant soluble FucT-VI, the enzyme colocalized with β4-galactosyltransferase-1 to the Golgi apparatus. By using a polyclonal antiserum raised against a 17-aa peptide of the variable (stem) region of the FucT-VI, immunocytochemical staining of FucT-VI was restricted to Weibel–Palade bodies, as determined by colocalization with P-selectin and von Willebrand factor. SDS/PAGE immunoblotting and amino acid sequencing of internal peptides confirmed the identity of the antigen isolated by the peptide-specific antibody as FucT-VI. Storage of a fucosyltransferase in Weibel–Palade bodies suggests a function independent of Golgi-associated glycosylation.

Footnotes

↵ † Present address: Institute of Physiology, University of Fribourg, Rue du Musée 5, CH-1700 Fribourg, Switzerland.
↵ ‡ Present address: Glycobiology Research and Training Center, Divisions of Hematology–Oncology and Cellular and Molecular Medicine, University of California San Diego, La Jolla, CA.
↵ ¶ To whom reprint requests should be addressed. E-mail: egberger{at}physiol.unizh.ch.
Abbreviations:

FucT,

α1,3-fucosyltransferase;

GalT-1,

galactosyltransferase-1;

LacNAc,

N-acetyllactosamine;

LNB-I,

lacto-N-biose I;

sLacNAc,

sialyl-N-acetyllactosamine;

WP,

Weibel–Palade;

HUVECs,

human umbilical vein endothelial cells;

RT-PCR,

reverse transcription–PCR;

vWF,

von Willebrand factor