Analysis of the mRNA expression of the TGF-Beta family in testicular cells and localization of the splice variant TGF-β2B in testis



The transforming growth factors (TGF)-β, TGF-β1, TGF-β2, and TGF-β3, and their receptors [TβRI, TβRII, TβRIII (betaglycan)] elicit many functions in the testis, for example, they perturb the blood testis barrier (BTB). Although expression of the ligands and receptors have been investigated, the alternative splice variants are incompletely examined. We therefore have analyzed all ligands, the receptors, and the splice variants TβRIB, TβRIIB, and TGF-β2B in testicular cells from rat and mouse. In mouse, the novel transcript variant TGF-β2B was identified and was found in Leydig cells, spermatogonia, pachytene spermatocytes, and in the apical regions of the Sertoli cells in adult testis. Even though expression of the splice variant TβRIB could be shown in mouse and rat, we never found the isoform TβRIIB in the rat cell lines studied. Whereas in all testicular cells expression of all TGF-β ligands could be shown, receptor mRNA expression was slightly more diverse. Furthermore, expression pattern of the splice variants was more heterogeneous, for example, TβRIB was not detectable in adult Sertoli cells, primary peritubular cells, and immortalized peritubular cells. The heterogeneous expression of the receptors and especially of the splice variants might provide possible clues for the different functions of the TGF-β ligands in testicular cells. Mol. Reprod. Dev. © 2006 Wiley-Liss, Inc.