Chorionic Gonadotropin Synthesized in Cultivated Trophoblast

Abstract

Using ³H-proline as a marker of synthesized hCG, human chorionic tissue of the first trimester of pregnancy was cultivated in a synthetic medium which contained no serum component. By a combination of Sephadex G-100 gel filtration and DEAE-cellulose chromatography, biosynthesized ³H-labeled hCG in the medium was purified.
On DEAE-cellulose chromatography immunoreactive hCG was eluted at a conductivity of 4.2-6.5 and 7.8-11.3 mmhos, whereas native hCG had been eluted only at a conductivity of 1.5-4.2 mmhos. On polyacrylamide disc gel electrophoresis 3H-radioactivity and immunoreactivity of hCG showed a peak in the same segment of the disc which corresponded to the migration area of native hCG. Sialic acid content of the biosynthesized ³H-labeled hCG was 0.04-0.05% whereas it was 3.0-3.8% in native hCG. In Ouchterlony immunodiffusion the biosynthesized hCG fraction eluted at a lower conductivity of 4.2-6.5 mmhos on DEAE-cellulose clearly made a precipitation line only with anti-hCG serum. On the other hand the fraction eluted at a higher conductivity of 7.8-11.3 mmhos made precipitation lines against both anti-hCG and anti-hCFSH serum. These results certified that hCG labeled with ³H-proline was biosynthesized actively in our culture system and it might be suspected that the biosynthesized hCG had some different properties from native hCG, and that hCFSH could be biosynthesized in vitro, too.