Foxd1 is required for terminal differentiation of anterior hypothalamic neuronal subtypes

Although the hypothalamus functions as a master homeostat for many behaviors, little is known about the transcriptional networks that control its development. To investigate this question, we analyzed mice deficient for the Forkhead domain transcription factor Foxd1. Foxd1 is selectively expressed in neuroepithelial cells of the prethalamus and hypothalamus prior to the onset of neurogenesis, and is later restricted to neural progenitors of the prethalamus and anterior hypothalamus. During early stages of neurogenesis, we observed that Foxd1-deficient mice showed reduced expression of Six3 and Vax1 in anterior hypothalamus, but overall patterning of the prethalamus and hypothalamus is unaffected. After neurogenesis is complete, however, a progressive reduction and eventual loss of expression of molecular markers of the suprachiasmatic, paraventricular and periventricular hypothalamic is observed. These findings demonstrate that Foxd1 acts in hypothalamic progenitors to allow sustained expression of a subset of genes selectively expressed in mature neurons of the anterior hypothalamus. Highlights Foxd1 is broadly expressed in neuroepithelial cells of the hypothalamus and prethalamus. Foxd1 mutants show severe defects in anterior hypothalamic development, although prethalamic development is only modestly affected. Loss of Foxd1 results does not affect initial patterning of the hypothalamus, but leads to a progressive loss of expression of markers specific to neurons of the suprachiasmatic, paraventricular and periventricular nuclei. Foxd1 regulates expression of multiple transcription factors expressed in developing anterior hypothalamus.