SHH and Notch regulate SOX9+ progenitors to govern arcuate POMC neurogenesis

Casein kinase 1α is required to maintain murine hypothalamic pro-opiomelanocortin expression

Hypothalamic pro-opiomelanocortin (POMC) neuron development is considered to play an essential role in the development of obesity. However, the underlying mechanisms remain unclear. Casein kinase 1α (CK1α) was expressed in the embryonic mouse hypothalamus at high levels and colocalized with POMC neurons. CK1α deletion in POMC neurons caused weight gain, metabolic defects, and increased food intake. The number of POMC-expressing cells was considerably decreased in Csnk1a1^fl/fl;POMC^cre (PKO) mice from embryonic day 15.5 to postnatal day 60, while apoptosis of POMC neurons was not affected. Furthermore, unchanged POMC progenitor cells and a decreased POMC phenotype established CK1α function in hypothalamic POMC neuron development. CK1α deletion led to elevated Notch intracellular domain (NICD) protein expression, and NICD inhibition rescued the PKO mouse phenotype. In summary, CK1α is involved in hypothalamic POMC expression via NICD-POMC signaling, deepening our understanding of POMC neuron development and control of systemic metabolic functions.

A neuroepithelial wave of BMP signalling drives anteroposterior specification of the tuberal hypothalamus

The tuberal hypothalamus controls life-supporting homeostatic processes, but despite its fundamental role, the cells and signalling pathways that specify this unique region of the central nervous system in embryogenesis are poorly characterised. Here, we combine experimental and bioinformatic approaches in the embryonic chick to show that the tuberal hypothalamus is progressively generated from hypothalamic floor plate-like cells. Fate-mapping studies show that a stream of tuberal progenitors develops in the anterior-ventral neural tube as a wave of neuroepithelial-derived BMP signalling sweeps from anterior to posterior through the hypothalamic floor plate. As later-specified posterior tuberal progenitors are generated, early specified anterior tuberal progenitors become progressively more distant from these BMP signals and differentiate into tuberal neurogenic cells. Gain- and loss-of-function experiments in vivo and ex vivo show that BMP signalling initiates tuberal progenitor specification, but must be eliminated for these to progress to anterior neurogenic progenitors. scRNA-Seq profiling shows that tuberal progenitors that are specified after the major period of anterior tuberal specification begin to upregulate genes that characterise radial glial cells. This study provides an integrated account of the development of the tuberal hypothalamus.