EXPRESSION AND LOCALIZATION OF ACTIVIN BETA-A-SUBUNIT AND ACTIVIN RECEPTORS IN TM3, A MOUSE LEYDIG-CELL LINE

We have determined whether TM3 cells, a cell line derived from a murin e Leydig cell tumor, (a) transcribe messenger RNAs encoding the beta A -subunits of inhibin/activin, and activin receptors I, II, and IIB, an d (b) produce activin-A protein. Messenger RNAs for inhibin/activin be ta A-subunits and activin receptors II, and IIB in TM3 cells were loca lized and expressed using in situ hybridization and the reverse transc ription-polymerase chain reaction (RT-PCR) analysis, respectively. The identity of the RT-PCR products was confirmed by DNA sequencing of PC R products. Immunocytochemically, activin-A was localized in these cel ls. We observed that messenger RNAs encoding activin beta(A)-subunit a s well as activin receptors II, and IIB were expressed and activin pro tein was produced by TM3 cells. These findings suggest that activin-A may have autocrine functions in TM3 cells and that activin-A may be in volved in regulating the growth and differentiation of mouse Leydig