Transfer and expression of a murine UDP-Gal:beta-D-Gal-alpha 1,3-galactosyltransferase gene in transfected Chinese hamster ovary cells. Competition reactions between the alpha 1,3-galactosyltransferase and the endogenous alpha 2,3-sialyltransferase.
The cDNA encoding a murine UDP-Gal:beta-D-Gal-alpha 1,3-galactosyltransferase has recently been cloned and sequenced using a transient expression method (Larsen, R.D., Rajan, V.P., Ruff, M.M., Kukowska-Latallo, J., Cummings, R.D., and Lowe, J.B. (1989) Proc. Natl. Acad. Sci. U.S.A. 86, 8227-8231). This report describes the construction and analysis of a Chinese hamster ovary (CHO) cell line in which in vitro expression alpha 1,3-galactosyltransferase activity has been achieved via transfer and expression of the murine alpha 1,3-galactosyltransferase gene. A primary aim of this research was to explore the role of the alpha 1,3-galactosyltransferase in regulating glycoprotein and glycolipid biosynthesis. CHO cells were cotransfected with murine genomic DNA fragments from F9 cells and plasmid DNA containing a resistance gene to the antibiotic G418. Cells resistant to G418 were then selected for expression of surface glycoconjugates containing terminal alpha 1,3-galactosyl residues by isolating cells bound to immobilized Griffonia simplicifolia-I-B4, a lectin which binds to alpha 1,3-galactosyl residues. A positive, stable transfectant clone, designated Clone 3, was obtained and analyzed for expression of the murine of alpha 1,3-galactosyltransferase. Fluorescence-activated cell sorting demonstrated that Clone 3, but not parental, CHO cells bound significant amounts of fluorescein isothiocyanate-labeled G. simplicifolia-I-B4. Southern and Northern blot analyses using the murine alpha 1,3-galactosyltransferase cDNA demonstrated that clone 3, but not parental, CHO cells contain murine alpha 1,3-galactosyltransferase genomic DNA sequences, and express a homologous transcript that comigrates with the authentic 3.6 kilobase alpha 1,3-galactosyltransferase murine mRNA. Enzyme assays confirmed that clone 3, but not parental CHO cells, contained the alpha 1,3-galactosyltransferase activity and that the level of activity is comparable to that found in F9 cells. [3H]Galactose-labeled glycopeptides and glycolipids were obtained from metabolically radiolabeled parental and Clone 3 cells and were analyzed for the presence of terminal alpha 1,3-galactosyl residues. Complex-type, Asn-linked oligosaccharides from both parental and Clone 3 cells contain the repeating disaccharide [3Gal beta 1, 4GlcNAc beta 1]n or poly-N-acetyllactosamine sequences, but only the poly-N-acetyllactosamine chains from clone 3 cells contained the terminal sequence Gal alpha 1,3Gal beta 1,4GlcNAc beta 1-R.(ABSTRACT TRUNCATED AT 400 WORDS)
Smith
D F
DF
Department of Biochemistry, University of Georgia, Athens 30602.
Larsen
R D
RD
Mattox
S
S
Lowe
J B
JB
Cummings
R D
RD
D000818:Animals; D015152:Blotting, Northern; D015139:Blotting, Southern; D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D002460:Cell Line; D006224:Cricetinae; D003412:Cricetulus; D004273:DNA, Neoplasm / Q000235:genetics*; D005260:Female; D005700:Galactosyltransferases / Q000235:genetics* / Q000378:metabolism; D015870:Gene Expression; D005796:Genes; D007700:Kinetics; D037102:Lectins; D051379:Mice; D008969:Molecular Sequence Data; D009844:Oligosaccharides / Q000302:isolation & purification; D010053:Ovary; D011485:Protein Binding; D013724:Teratoma; D014162:Transfection
D004273:DNA, Neoplasm; D037102:Lectins; D009844:Oligosaccharides; D005700:Galactosyltransferases; C047006:N-acetyllactosaminide alpha-1,3-galactosyltransferase