Novel genes upregulated when NOTCH signalling is disrupted during hypothalamic development

Abstract

BackgroundThe generation of diverse neuronal types and subtypes from multipotent progenitors during development is crucial for assembling functional neural circuits in the adult central nervous system. It is well known that the Notch signalling pathway through the inhibition of proneural genes is a key regulator of neurogenesis in the vertebrate central nervous system. However, the role of Notch during hypothalamus formation along with its downstream effectors remains poorly defined.ResultsHere, we have transiently blocked Notch activity in chick embryos and used global gene expression analysis to provide evidence that Notch signalling modulates the generation of neurons in the early developing hypothalamus by lateral inhibition. Most importantly, we have taken advantage of this model to identify novel targets of Notch signalling, such as Tagln3 and Chga, which were expressed in hypothalamic neuronal nuclei.ConclusionsThese data give essential advances into the early generation of neurons in the hypothalamus. We demonstrate that inhibition of Notch signalling during early development of the hypothalamus enhances expression of several new markers. These genes must be considered as important new targets of the Notch/proneural network.

Regulation of downstream neuronal genes by proneural transcription factors during initial neurogenesis in the vertebrate brain

“…1r), the goal of this study was to determine what regulated the expression of these genes during initial neurogenesis in the rostral brain and during early axon scaffold formation. Having previously shown the involvement of the Notch signalling pathway in the expression of Nhlh1 , Tagln3 , Chga , Cntn2 and Stmn2 in chick, we first looked at the Notch/proneural network [43]. …”

“…Numerous studies support the idea that the Notch signalling pathway and proneural genes act together in a feedback loop to promote initial neurogenesis [5, 10, 29, 43]. However, in the developing brain, this has only been observed in the chick embryo via DAPT treatment [43].…”

“…Anti-sense probes were generated either from plasmids cloned as previously described [43] or plasmids provided as a gift. The protocol for single and double in situ hybridisation has been previously described [43]. For double labelling, Digoxigenin and Fluorescein labelled probes were incubated together.…”

“…Global profiling approaches are beginning to identify a large number of target genes that could be directly regulated by ASCL1 [2, 8, 16, 50, 58]. Recently, by inhibiting the Notch signalling pathway with the chemical inhibitor N-[3.5-difluorophenacetyl-L-alanyl)]-S-phenylglycine t-butyl ester (DAPT) during early chick development, new neuronal markers including Transgelin 3 ( Tagln3 ), Chromogranin A ( Chga ) and Contactin 2 ( Cntn2 ) were identified and introduced to a network of downstream proneural targets genes [43]. Analysis of their expression, as well as the known neuronal markers, Nhlh1 and Stathmin 2 ( Stmn2 ), revealed interesting patterns overlapping with the first neuronal populations of the early axon scaffold in the developing chick brain [44].…”

Differentiation of hypothalamic-like neurons from human pluripotent stem cells

“…Notch signaling controls progenitor maintenance and differentiation of hypothalamic neurons (26,27). Loss of Notch signaling in Nkx2.1 progenitors promotes the differentiation of hypothalamic ARC neurons, and transient inhibition of Notch signaling synchronizes the differentiation of neuron progenitors (26,28).…”