Sonic hedgehog signaling pathway in normal and adenomatous pituitary
type: CreativeWork
description: This work investigates for the first time the expression and the role of Sonic hedgehog signaling pathway in adult pituitary and in pituitary tumors. Shh is a signaling protein, important in regulating patterning and proliferation in the embryo and the adult. It has a crucial role in pituitary development and Shh deficient mice do not even have a rudimentary Rathke's pouch (the development structure that gives rise to anterior pituitary). This study reveals the presence of an active Shh pathway in the post-developmental pituitary gland, with major impacts on hormone secretion and cell proliferation. After embryonic development, Shh continues to be expressed in the normal adult pituitary, being mainly co-localized in corticotrophs. These cells express also the receptor Ptc2 and the Shh induced transcription factor Gli1, being so Shh-producing and Shh-responsive cells. Shh acts in an autocrine way inside corticotrophs, inducing a major stimulation of ACTH secretion in the normal rat pituitary and in the AtT-20 cell line. The Shh induced ACTH secretion effect is synergistic with CRH. Shh stimulation increases CRH-R1 levels, up-regulating so the response of corticotrophs to CRH. At the same time, Gli1 is not only activated by Shh, but also by CRH and PKA. Gli1 itself activates POMC-transcription and acts in parallel upstream to CREB and AP-1. A major increase in Shh protein levels is seen as a result of CRH stimulation. All these results put in evidence a multiple cross-talk between these two important pathways acting at different levels to insure the final ACTH stimulation. Other types of hormone-secreting adenohypophysial cells possess one of Shh receptors (Ptc1 or Ptc2) and the transcription factor Gli1, so they have an active Shh pathway. Shh produced in the corticotrophs is a signaling protein, so it diffuses and acts also in distance. Shh increases GH secretion from the rat pituitary somatotrophs and from the GH3 cell line, while the effect on Prolactin is not sta…
abstract: This work investigates for the first time the expression and the role of Sonic hedgehog signaling pathway in adult pituitary and in pituitary tumors. Shh is a signaling protein, important in regulating patterning and proliferation in the embryo and the adult. It has a crucial role in pituitary development and Shh deficient mice do not even have a rudimentary Rathke's pouch (the development structure that gives rise to anterior pituitary). This study reveals the presence of an active Shh pathway in the post-developmental pituitary gland, with major impacts on hormone secretion and cell proliferation. After embryonic development, Shh continues to be expressed in the normal adult pituitary, being mainly co-localized in corticotrophs. These cells express also the receptor Ptc2 and the Shh induced transcription factor Gli1, being so Shh-producing and Shh-responsive cells. Shh acts in an autocrine way inside corticotrophs, inducing a major stimulation of ACTH secretion in the normal rat pituitary and in the AtT-20 cell line. The Shh induced ACTH secretion effect is synergistic with CRH. Shh stimulation increases CRH-R1 levels, up-regulating so the response of corticotrophs to CRH. At the same time, Gli1 is not only activated by Shh, but also by CRH and PKA. Gli1 itself activates POMC-transcription and acts in parallel upstream to CREB and AP-1. A major increase in Shh protein levels is seen as a result of CRH stimulation. All these results put in evidence a multiple cross-talk between these two important pathways acting at different levels to insure the final ACTH stimulation. Other types of hormone-secreting adenohypophysial cells possess one of Shh receptors (Ptc1 or Ptc2) and the transcription factor Gli1, so they have an active Shh pathway. Shh produced in the corticotrophs is a signaling protein, so it diffuses and acts also in distance. Shh increases GH secretion from the rat pituitary somatotrophs and from the GH3 cell line, while the effect on Prolactin is not sta…
author: Vila, Greisa
date published: 2004-03-18
date modified: 2026-07-24T02:51:56Z
provider: Ludwig Maxmilians Universität München
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: Ludwig-Maximilians-Universität