Studies on the Mechanism of Synthesis, Release and Regulation of Human Chronic Gonadotrophin in Syncitiotrophoblast Cells of Placenta: Characterization of MRNA, Polyribosomal Complex and Other Factors Involved

Abstract

Using clonal lines of human choriocarcinoma cells in culture, kohler et al. (1971) examined the physio-chemical characteristics of chorionic gonadotrophin produced by different clones and assayed the biological and immunological potencies of various HCG species. Biosynthesis of HCG was studied by incubating placental tissue in a C14 labelled amino acid mixture, and then submitting the concentrated culture fluids to immunoelectrophoresis (Gitlin and Biasucci, 1969). We have studied the protein synthesizing machinery involved in the synthesis of HCG by the placental tissue. For this purpose the following experiments were designed and conducted: 1. Isolation of syncitiotrophoblast by cell dispersion technique using enzymatic methods (collagenase, viocase). 2. Isolation of polyribosomal complex from cells synthesizing HCG. 3. Extraction of tRNA from ribosomes free cytoplasm. 4. Extraction and purification of mRNA 5. In vitro studies of the incorporation of labelled amino acids in newly synthesized protein by placental tissue and cell free system. 6. Identification of HCG in the newly synthesized protein by column chromatography, polyacrylamide gel electrophoresis and radioimmunoassay. 7. In victor translation of HCG mRNA 8. Effect of estrogen, progesterone, and prostaglandin on HCG synthesis in cell free system. 9. Effect of cyclic AMP and adenylcyclase on HCG synthesis. The results obtained have been discussed in report. The task has been very difficult because of many technical difficulties involved specifically the availability of radioimmunoassay material and hormones. We consider that our accomplishments have supplemented the knowledge of HCG synthesis and the information obtained in the course of this project will go long way in helping us find ways and means to understand the nature of HCG synthesis and its regulation under normal conditions. Certainly it would be desirable to extend similar studies to abnormal tissue like chriocatcinoma which synthesize huge quantities of HCG and in cases of HCG deficient placenta.