AUTHOR=Blaess Sandra , Szabó Nora , Haddad-Tóvolli Roberta , Zhou Xunlei , Álvarez-Bolado Gonzalo 

TITLE=Sonic hedgehog signaling in the development of the mouse hypothalamus

JOURNAL=Frontiers in Neuroanatomy

VOLUME=8

YEAR=2015

URL=https://www.frontiersin.org/journals/neuroanatomy/articles/10.3389/fnana.2014.00156

DOI=10.3389/fnana.2014.00156

ISSN=1662-5129

ABSTRACT=<p>The expression pattern of <italic>Sonic Hedgehog</italic> (<italic>Shh</italic>) in the developing hypothalamus changes over time. <italic>Shh</italic> 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, <italic>in ovo</italic> loss- and gain-of-function approaches in chick and analysis of <italic>Shh</italic> 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 <italic>Shh</italic>-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.</p>