title: Sonic hedgehog signaling in the development of the mouse hypothalamus.
abstract: The expression pattern of Sonic Hedgehog (Shh) in the developing hypothalamus changes over time. Shh is initially expressed in the prechordal mesoderm and later in the hypothalamic neuroepithelium-first medially, and then in two off-medial domains. This dynamic expression suggests that Shh might regulate several aspects of hypothalamic development. To gain insight into them, lineage tracing, (conditional) gene inactivation in mouse, in ovo loss- and gain-of-function approaches in chick and analysis of Shh expression regulation have been employed. We will focus on mouse studies and refer to chick and fish when appropriate to clarify. These studies show that Shh-expressing neuroepithelial cells serve as a signaling center for neighboring precursors, and give rise to most of the basal hypothalamus (tuberal and mammillary regions). Shh signaling is initially essential for hypothalamic induction. Later, Shh signaling from the neuroepithelium controls specification of the lateral hypothalamic area and growth-patterning coordination in the basal hypothalamus. To further elucidate the role of Shh in hypothalamic development, it will be essential to understand how Shh regulates the downstream Gli transcription factors.
authors.affiliation: Neurodevelopmental Genetics, Institute of Reconstructive Neurobiology, University of Bonn Bonn, Germany.
authors.forename: Sandra
authors.initials: S
authors.lastname: Blaess
authors.affiliation: Department of Neurobiology and Development, Institut de Recherches Cliniques de Montréal Montréal, QC, Canada.
authors.forename: Nora
authors.initials: N
authors.lastname: Szabó
authors.affiliation: Department of Medical Cell Biology, Institute of Anatomy and Cell Biology, University of Heidelberg Heidelberg, Germany.
authors.forename: Roberta
authors.initials: R
authors.lastname: Haddad-Tóvolli
authors.affiliation: Department of Medical Cell Biology, Institute of Anatomy and Cell Biology, University of Heidelberg Heidelberg, Germany.
authors.forename: Xunlei
authors.initials: X
authors.lastname: Zhou
authors.affiliation: Department of Medical Cell Biology, Institute of Anatomy and Cell Biology, University of Heidelberg Heidelberg, Germany.
authors.forename: Gonzalo
authors.initials: G
authors.lastname: Álvarez-Bolado
keywords: Gli; Shh; chick; development; hypothalamus; lineage; mouse; phenotype