Inhibin subunits, follistatin and activin receptors in the human teratocarcinoma cell line Tera-2.
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 alpha- and beta B-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 alpha- and beta B-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 IIB mRNA was found in the cells. Addition of 5 microM 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 alpha- and beta B-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.
Dept. of Endocrinology & Reproduction, Erasmus University Rotterdam, The Netherlands.
F H
FH
de Jong
J P
JP
de Winter
J G
JG
Wesseling
M A
MA
Timmerman
S
S
van Genesen
A J
AJ
van den Eijnden-van Raaij
E J
EJ
van Zoelen
D029404:Activin Receptors; D028341:Activins; D001681:Biological Assay; D002454:Cell Differentiation; D002478:Cells, Cultured; D002999:Clone Cells; D017077:Culture Media, Conditioned; D015342:DNA Probes; D005640:Follicle Stimulating Hormone / Q000378:metabolism; D038681:Follistatin; D006023:Glycoproteins / Q000096:biosynthesis* / Q000235:genetics; D006801:Humans; D007265:Inhibins / Q000096:biosynthesis* / Q000235:genetics / Q000494:pharmacology; D007986:Luteinizing Hormone / Q000378:metabolism; D046911:Macromolecular Substances; D010902:Pituitary Gland / Q000187:drug effects / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000096:biosynthesis* / Q000235:genetics; D013724:Teratoma; D014212:Tretinoin / Q000494:pharmacology; D014407:Tumor Cells, Cultured
D017077:Culture Media, Conditioned; D015342:DNA Probes; D038681:Follistatin; D006023:Glycoproteins; D046911:Macromolecular Substances; D012333:RNA, Messenger; D011956:Receptors, Cell Surface; D028341:Activins; D014212:Tretinoin; D007265:Inhibins; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone; D029404:Activin Receptors