Analysis of Homogeneous Populations of Anterior Pituitary Folliculostellate Cells by Laser Capture Microdissection and Reverse Transcription-Polymerase Chain Reaction

Abstract

Pituitary folliculostellate (FS) cells are usually located between the secretory cells in the anterior pituitary, and they produce many peptides that exert a paracrine effect on hormone-producing pituitary cells. Previous approaches have been unsuccessful in obtaining homogeneous populations of FS cells. We used a combination of immunostaining with S100 protein followed by laser capture microdissection (Immuno-LCM) to obtain purified populations of rat FS cells. These cells were analyzed along with a mouse FS cell line (TtT/GF) by RT-PCR for gene expression. RT-PCR analyses showed that both FS cell populations expressed the mRNAs for glial fibrillary acidic protein, S100 protein, transforming growth factor-β1 (TGFβ1), TGFβ receptor, interleukin-6, leptin, leptin receptor, pituitary adenylate cyclase-activating polypeptide (PACAP), and PACAP receptors. Both FS cell populations were negative for PRL, GH, and POMC, supporting the homogeneity of the rat FS cell population. TGFβ1, but not PACAP-38, treatment stimulated cell proliferation in both FS cell populations. TGFβ1 increased leptin, but not interleukin-6, mRNA expression in rat FS cells. However, TGFβ1 inhibited leptin RNA expression in the TtT/GF cell line, as shown by RT-PCR and Northern blot analysis. These results indicate that 1) homogeneous populations of FS cells can be prepared by Immuno-LCM; 2) TGFβ1 stimulates the proliferation of normal rat FS cells and the TtT/GF cell line; and 3) the effects of TGFβ1 to stimulate leptin mRNA expression in rat FS cells but inhibit leptin mRNA expression in TtT/GF cells probably reflect alterations in signal transduction in the TtT/GF cell line.