The effect of protein and rna synthesis inhibitors on the synthesis and secretion of human chorionic gonadotropin alpha and beta human chorionic gonadotropin subunits in organ culture
Hochberg A.A.
European Journal of Obstetrics and Gynecology and Reproductive Biology 18(1-2): 57-70
1984
ISSN/ISBN: 0301-2115 Accession: 006652679
The relationship between the rate of RNA and protein synthesis, and that of hCG [human chorionic gonadotropin] and its .alpha.- and .beta.-subunits was studied in an organ culture system using RNA and protein synthesis inhibitors. Inhibiting protein synthesis by puromycin or cycloheximide results also in a nearly complete inhibition of the synthesis and/or processing of RNA molecules. Protein synthesis was dependent upon continuous poly A(-) RNA synthesis. The intracelluar content of hCG, .alpha.-hCG and .beta.-hCG remains constant during the entire incubation period, and does not change in response to any of the inhibitors used. In the presence of some inhibitors, changes are observed in the amount of the secreted hormone and its 2 subunits as well as in the association ability of the subunits to form the complete native hormone. Synthesis and secretion of hCG, .alpha.-hCG and .beta.-hCG were almost identically affected by .alpha.-amanitin. The mRNA coding for the 2 subunits have the same relative metabolic stability. These mRNA are mobilized molecules from free cytoplasmic mRNP [messenger ribonucleoprotein] pools. The specific .alpha.- and .beta.-mRNA seem to be less stable, however, than the mRNA coding for the other newly synthesized proteins, since the inhibition of .alpha.- and .beta.-hCG synthesis by .alpha.-amanitin was consistently higher than the corresponding average inhibition of total protein synthesis.