Insulin receptors of human term placental cells and choriocarcinoma (JEG-3) cells: characteristics and regulation.

Abstract

Insulin has been implicated as a regulator of placental growth and function. In order to probe hormoneplacental interactions, an in vitro human placental cell culture model was employed in conjunction with the human choriocarcinoma cell line, JEG-3. Short term monolayer cultures of human term placentae were established from trypsinized chorionic villi and were presumed to be predominantly of syncytial origin on the basis of their electron microscopic morphology, their capacity to produce placental hormones, and their loss of replicative potential. Specific binding of [125I]iodoinsulin to both cell types was examined using whole cell radioreceptor assays, and was found to be a saturable process, time and temperature dependent, and proportional to cell protein and ligand concentration. At 4 C, a steady state was reached by 18 h and was maintained for 6 h. Specificity of the insulin receptor was evidenced by the inability of structurally unrelated hormones to inhibit [125I]iodoinsulin binding. Scatchard plot...