Induction of surface glycoprotein expression by cyclic AMP in Chinese hamster ovary cells

Abstract

Surface expression of a membrane glycoprotein of 135 000 molecular weight (P135) was inducible by adenosine 3′,5′-cyclic monophosphate in Chinese hamster ovary cells, CHO-K1 clone. Cells were cultured in the presence or absence of cyclic AMP derivatives, chemicals influencing cytoplasmic cyclic AMP levels, or inhibitors of protein or RNA synthesis. Surface proteins were radiolabeled by a lactoperoxidase-catalyzed iodination reaction and analyzed by two-dimensional polyacrylamide gel electrophoresis. Surface expression of P135 increased 3–5-fold in the presence of N 6, O 2′-dibutyryl cyclic AMP or 8-parachlorophenylthio cyclic AMP. Induction was also observed after treatment with prostaglandins E 1 and F 2α, but not with sodium butyrate. Phosphodiesterase inhibitor, Roche compound Ro20-1724, enhanced the effect of N 6, O 2′-dibutyryl cyclic AMP. Metabolic incorporation of [ 35S]methionine into P135 was increased by N 6, O 2′-dibutyryl cyclic AMP. The induction was sensitive to inhibitors of protein and RNA biosynthesis. These results are consistent with a proposal that cyclic AMP controls the synthesis of this protein. Metabolic incorporation of a radioactive precursor suggested that P135 was a glucosamine-containing glycoprotein. P135 appeared to be strongly associated with cell membrane because it was resistant to extraction of plasma membrane by cold 0.1 N NaOH.