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Inhibin Subunits, Follistatin and Activin Receptors in the Human Teratocarcinoma Cell Line Tera-2

1993; Elsevier BV; Volume: 192; Issue: 3 Linguagem: Inglês

10.1006/bbrc.1993.1562

1090-2104

F.H. deJong, Johan deWinter, Jelle Wesseling, M. A. Timmerman, S. Vangenesen, A.J.M. Vandeneijndenvanraaij, E.J.J. Vanzoelen,

Clusterin in disease pathology

The expression of mRNAs for inhibin subunits was studied in the human teratocarcinoma cell line Tera-2 clone 13 before and after differentiation with retinoic acid (RA). Both α- and βB-subunits of inhibin were expressed. Subsequently, inhibin bio- and immunoactivity in the conditioned media of the Tera-2 cells were determined by studying the release of follicle-stimulating hormone from rat pituitary cells, by immunoassay and by immunoprecipitation using inhibin α- and βB-subunit specific antibodies. Strikingly dissimilar high bio- and low immuno-activities were found. The ensuing hypothesis that the high bioactivity might be due to the presence of the activin-binding protein follistatin was confirmed by immunoprecipitation of 34 and 37 kDa labelled proteins, using a polyclonal anti-follistatin antiserum after culture of the Tera-2 cells with [35S]-methionine. Furthermore, expression of activin receptor types II and 11B mRNA was found in the cells. Addition of 5 μM RA to monolayer cultures of Tera-2 cells resulted in differentiation to flat endoderm-like cells and caused a slight suppression of the expression of the mRNA encoding the inhibin α- and βB-subunits. The expression of follistatin and activin receptor type IIB was strongly suppressed, whereas the expression of the activin receptor type II was not affected. We conclude that Tera-2 cells secrete follistatin and express inhibin subunits and activin receptors differentially during RA-induced differentiation. The role of the decreased expression of follistatin and activin receptor IIB mRNA after addition of RA in the mechanism of RA-induced differentiation remains to be elucidated.