Transcriptional regulation of growth hormone gene expression by growth hormone-releasing factor

Abstract

Production and release of hormones by the pituitary is known to be under complex hormonal control. Prolactin, for example, is both positively and negatively regulated by steroid and thyroid hormones as well as by peptide hormones1–5. Some hypothalamic releasing factors have been shown to regulate both hormone biosynthesis and hormone release6–11. In the case of growth hormone (GH), glucocorticoids and thyroid hormone stimulate its production12–14, at least in part by stimulating transcription of the GH gene12, and somatostatin inhibits6,15,16 and growth hormone-releasing factor (GRF) stimulates17–19 its release. So far, however, polypeptide hormone regulation of GH biosynthesis has not been demonstrated. Recently a peptide with GH-releasing activity has been characterized from human pancreatic islet tumours14,20,21. We report here that pure human pancreatic GRF (hpGRF) stimulates transcription of the GH gene, as well as stimulating GH release.