GLYCOSYLATION OF CD4: EXPRESSION IN CHINESE HAMSTER OVARY CELLS AND PARTIAL CHARACTERIZATION OF THE OLIGOSACCHARIDES.

Important note: Information in this article was accurate in 1991. The state of the art may have changed since the publication date.

GLYCOSYLATION OF CD4: EXPRESSION IN CHINESE HAMSTER OVARY CELLS AND PARTIAL CHARACTERIZATION OF THE OLIGOSACCHARIDES.

Serono Symp Publ Raven Press; 64:89-107 1989. Unique Identifier : AIDSLINE ICDB/91670912
Konig R; Ashwell G; Hanover JA; Lab. of Biochemistry and Metabolism, NIDDKD, NIH, Bethesda, MD; 20892

Abstract: The T-cell surface glycoprotein CD4 plays an important role in cellular immunity and serves as a receptor for HIV. To study the biosynthesis and assembly of CD4, CD4 was overexpressed in wild-type and glycosylation-deficient Chinese hamster ovary (CHO) cells by cotransfection of a human CD4 cDNA and a cDNA encoding the human multiple drug resistance (MDR1) gene. The transfected DNA sequences were coamplified by selection with sequentially increasing concentrations of colchicine. In cloned recombinant cells, the glycoprotein was expressed in large amounts on the surface of the transfected cells. Transfected 4B-77 cells expressed CD4 1.9-fold higher on the surface than did the human acute lymphoblastic leukemia cells of the CEM-CM3 cell line. Much of the CD4 in 4B-77 cells resided intracellularly, whereas no intracellular CD4 was found in CEM cells. Treatment of these transfected cells (4B-77) with tunicamycin resulted in a drastic reduction of CD4 surface expression and the production of an unstable unglycosylated form. These findings suggest a rapid degradation of unglycosylated CD4 in a pre-Golgi compartment. Partial characterization of the oligosaccharides of CD4 from transfected wild-type CHO cells, from cells of the glycosylation-deficient mutant Lec2, which does not add sialic acid to oligosaccharides, and from CEM cells suggested the presence of biantennary, unsialylated complex-type oligosaccharides. The experiments demonstrate the importance of glycosylation for the stability of CD4 and the usefulness of recombinant CHO cell lines overexpressing CD4 for generating large amounts of this glycoprotein and for elucidating the cell biology of CD4 and the mechanism for degradation of unglycosylated CD4. (34 Refs)

Keywords: Animal Antigens, CD4/*GENETICS Cell Line, Transformed Cloning, Molecular Cricetulus Gene Expression Regulation, Neoplastic/*PHYSIOLOGY Glycosylation Hamsters Human Leukemia, Lymphocytic, Acute Oligosaccharides/*GENETICS Proteins/*GENETICS Tumor Cells, Cultured/*CHEMISTRY MEETING PAPER
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