PROCEEDINGS |
Pituitary homeobox1 (Ptx1) was isolated as a pituitary-restricted transcription factor for the proopiomelanocortin (POMC) gene. In order to elucidate the expression of Ptx1 protein, we investigated the localization of Ptx1 protein in the adult rat pituitary glands and the pituitary cell lines. We made the specific antibody for Ptx1 protein, and confirmed the specificity by Western blot analysis. Immunohistochemically, many nuclei in the anterior pituitary cells as well as those of the intermediate cells were positive for Ptx1 by using this specific antibody. By immunohistochemical double staining, Ptx1 was observed not only in all types of hormone secreting cells but also in some of folliculo-stellate (FS) cells. Furthermore, the expression of Ptx1 mRNA was confirmed in various pituitary cell lines and FS cell line by using reverse transcriptase-polymerase chain reaction (RT-PCR) method. Our studies indicated that Ptx1 may not only play a role as a basic transcriptional factor for various hormone production, but it may play some important roles in FS cells. The synergistic action with other factors remains to be further investigated. It was also hitherto unreported finding of particular interest that Ptx1 was identified in FS cells suggesting the possibility that FS cells derives from common ancestor with hormone secreting cells.