ABSTRACT
I. Introduction................................................................................... 73 II. How Pit-1 Progenitor Cells Differentiate into
Hormone-Secreting Cells.............................................................. 74 III. Transdiffentiation of PRL Cells from GH Cells ......................... 75 IV. Prolactin-Producing Cells Differentiated from
G0/G1-Arrested Somatotrophs.................................................... 76 V. Glucocorticoids Promote the Maturation of GH Cells .............. 78
References ............................................................................................... 80
Anterior pituitary hormones are individually produced and secreted by five types of glandular cells. These specialized types of cells, which produce different hormones, are believed to arise from common stem cells. However, the mechanism by which these anterior pituitary glandular cells differentiate is still under discussion. Recent advances in molecular biology have revealed many transcription factors that promote pituitary hormone gene expression. The Pit-1 gene is an example of such a transcription factor. The Pit-1 gene is known to affect growth hormone (GH), prolactin (PRL), and thyrotropin (TSH) cell differentiation. This suggests that all three cell types may arise from a common progenitor cell. However, how these cell types differentiate and then mature into individual cell types in the adult anterior pituitary gland is still unknown. We were especially interested in the differentiation of Pit-1 lineage cells.
