The overall goals of this work are to determine mechanisms that regulate expression of mammalian oligosaccharide molecules. Fucosylated oligosaccharides were chosen as an experimental model because their fucose linkages, and the cognate fucosyltransferases responsible for their biosynthesis, are expressed with temporal and spatial precision during mammalian differentiation, and are frequently altered in association with malignant transformation. These properties suggested important functions for these molecules; this has been born out recently by studies demonstrating that one or more members of a specific set of fucosylated oligosaccharides, expressed by cells of the myeloid lineage, mediate adhesion of these leukocytes to endothelial leukocyte adhesion molecule I during inflammation. Moreover, many of these fucosylated oligosaccharides represent molecules whose expression is determined by human blood group genes. To address the regulation of expression of these types of molecules, we have isolated a human gene encoding an alpha(1,2)fucosyltransferase. This gene is thought to correspond to the H blood group locus. This gene, and the techniques used to isolate it, represent tools with which to identify other such alpha(1,2)fucosyltransferase genes, including Secretor blood group locus. Furthermore, these genes represent tools to address transcriptional and post-transcriptional regulatory consideration that determine the types and relative amounts of alpha(1,2)fucosylated glycoconjugates made by tissues and cells. An understanding of these processes will serve to increase the understanding of the functions of these molecules in normal human tissues, and in malignantly transformed tissues.
The SPECIFIC AIMS of this proposal are: 1. To isolate novel human genes that encode alpha(1,2)fucosyltransferases, or genes that otherwise determine expression of such enzymes, using gene transfer methods. 2. To isolate and characterize human DNA sequences that are structurally similar to the human H blood group alpha(1,2)fucosyltransferase gene. 3. To define the biosynthesis of the H blood group alpha(1,2)fucosyltransferase, and other such alpha(1,2)fucosyltransferases that may be isolated in Specific Aims 1 and 2, using biochemical, molecular genetic, and morphological approaches. 4. To define the molecular basis for genetic polymorphism at the human Secretor blood group locus. 5. To define the expression patterns of alpha(1,2)fucosyltransferase genes in normal human tissues.
