Molecular Genetics of Mammalian Glycosyltransferases 
the control of the Secretor blood group locus). 
We also found inactivating point mutations in the 
H gene in these persons, thus providing strong 
evidence that the human Secretor blood group 
locus corresponds to a distinct a(l ,2)fucosyl- 
transferase gene. 
We have also used glycosyltransferase gene 
segments to identify specific cell surface oligosac- 
charide molecules that play pivotal functional 
roles in the inflammatory process. One of the pri- 
mary events in inflammatory conditions involves 
a process whereby circulating white cells leave 
the interior of blood vessels and become local- 
ized in inflammatory foci outside the vascular 
system. This process begins when the endothelial 
cells lining the blood vessels become "activated" 
by substances that accompany an incipient in- 
flammatory condition. Circulating white cells 
known as neutrophils adhere tightly to activated 
endothelium, insinuate themselves into the endo- 
thelial cell pavement lining the blood vessel, and 
ultimately come to occupy areas outside the vas- 
cular tree. 
Neutrophil adhesion to activated endothelium 
is mediated in part by a protein known as E- 
selectin, or endothelial leukocyte adhesion mole- 
cule 1 (ELAM- 1 ) , which is found on the surface of 
activated endothelium. Structural features exhib- 
ited by this protein suggested that it might inter- 
act with an oligosaccharide molecule specific to 
the surface of neutrophils. By transfecting diff'er- 
ent glycosyltransferase gene segments into mam- 
malian host cells, we were able to recapitulate 
the biosynthesis of several distinct sets of cell sur- 
face oligosaccharide molecules and to demon- 
strate that one set allowed transfected cells to ad- 
here to E-selectin. We further demonstrated that 
the oligosaccharide molecules were one or 
more members of a family of oligosaccharides 
containing sialic acid and fucose and were rep- 
resented by a molecule known as the sialyl Lewis 
X determinant. More recently, we have shown 
that E-selectin maintains a relatively high specific- 
ity for oligosaccharide ligands with a(l,3)- 
linked fucose residues in terminal positions, ver- 
sus subterminal locations. We have also shown 
that terminal «(! ,3)fucosylation may be cata- 
lyzed by some, but not all, human a(l,3)- 
fucosyltransferases . 
Aberrant or overexuberant recruitment of neu- 
trophils to sites of inflammation can contribute, 
after tissue hypoxia and in other pathological cir- 
cumstances, to undesirable tissue damage in au- 
toimmune disease. Initial events in this process 
require adhesive interactions between E-selectin 
and its oligosaccharide counter-receptors on the 
surfaces of neutrophils. It thus seemed possible 
that purified carbohydrate counter-receptors 
might function as anti-inflammatory molecules 
by preventing pathologic neutrophil recruit- 
ment. We have tested this notion in collaboration 
with Peter Ward here at the University of Michi- 
gan. We have prepared therapeutic quantities 
of sialyl Lewis X-containing oligosaccharides, 
using recombinant «(! ,3)fucosyltransferases. 
When tested in an animal model of E-selectin- 
dependent lung inflammation, these carbohy- 
drates exhibit potent anti-inflammatory activity. 
This work suggests that a new class of antiin- 
flammatory pharmaceuticals may be developed 
from such molecules or from their chemical 
analogues. 
These studies have been aided by our recent 
identification of several novel human a(l,3)fu- 
cosyltransferase genes. We have shown that these 
encode enzymes with shared and unique primary 
sequence domains, as well as distinctive and use- 
ful catalytic properties. For example, one of 
these works extremely well for in vitro synthesis 
of the sialyl Lewis X tetrasaccharide, and others 
can efficiently construct analogues of this mole- 
cule. Work is in progress to identify sequence 
domains within the enzymes that dictate their 
distinctive substrate specificities. 
Circumstantial evidence gathered by other in- 
vestigators suggests that oligosaccharides are im- 
portantly involved in cell adhesion during mam- 
malian embryogenesis. We are now directing our 
efi'orts toward exploring this hypothesis and 
characterizing the genes that determine these in- 
teractions, through genetic manipulation of the 
murine genome. 
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