Establishing the single-cell molecular architecture of the neurohypophysis to study the development and function of pituicyte

Abstract

The neurohypophysis (NH), located at the posterior lobe of the pituitary, is a major neuro-vasculature interface that connects the brain to the peripheral organs. It mediates blood pressure, osmotic balance, reproduction, lactation, and social bonding through releasing neuropeptides oxytocin (OXT) and arginine-vasopressin (AVP) from the axonal boutons of hypothalamic neurons to the permeable vasculature with fenestrae. Besides the neuronal axons and vasculature endothelial, the pituicyte is the resident astroglia inside the NH and consist of 30-50% of the NH volume. It was reported to assist in the neuropeptide storage and release and cued in the NH permeable vasculature fate. However, its exact molecular identity and hence, “cell type” definition is ambiguous. Hence, we characterized the single-cell transcriptomes of the NH cell types and their organizations in both mouse and zebrafish models. In the mouse model, we discovered novel pituicyte markers with higher specificity than previously reported ones. We also found that the transcriptomes of pituicyte were similar to that of tanycyte bioinformatically. In zebrafish, we defined the pituicyte molecular signatures at different developmental stages. By generating the first pituicyte specific fluorescent reporter and driver transgenic lines, the development of pituicyte and the detailed mechanisms in regulating the formation and maintenance of the NH permeable vasculature fate will then be explored.