Decoding gene networks controlling hypothalamic and prethalamic neuron development.

The hypothalamus and prethalamus regulate diverse physiological and behavioral processes, yet the gene regulatory networks guiding their development remain poorly defined. Using single-cell RNA and ATAC sequencing, we profile over 660,000 cells in the developing mouse hypothalamus and prethalamus between embryonic day 11 and postnatal day 8. This resource maps key transcriptional and chromatin dynamics underlying regionalization, neurogenesis, and neuronal subtype differentiation. We identify distinct neurogenic progenitor populations and uncover gene regulatory networks controlling their spatial and temporal identity. Integration with genome-wide association study data reveals that transcription factors active in supramammillary and prethalamic lineages are associated with metabolic and neuropsychiatric traits. Cross-repressive interactions among regional transcription factors reinforce hypothalamic boundaries. Functional analysis of Dlx1/2 shows that their loss disrupts GABAergic neuron specification, leading to impaired thalamic inhibition and hyperactivity. This study provides a foundational atlas of hypothalamic and prethalamic development and highlights the importance of early gene regulatory programs in health and disease.