Dynamic expression of Notch-dependent neurogenic markers in the chick embryonic nervous system

Abstract

The establishment of a functional nervous system requires a highly orchestrated process of neural proliferation and differentiation. The evolutionary conserved Notch signaling pathway is a key regulator of this process, regulating basic helix-loop-helix (bHLH) transcriptional repressors and proneural genes. However, little is known about downstream Notch targets and subsequently genes required for neuronal specification. In this report, the expression pattern of Transgelin 3 (Tagln3), Chromogranin A (Chga) and Contactin 2 (Cntn2) was described in detail during early chick embryogenesis. Expression of these genes was largely restricted to the nervous system including the early axon scaffold populations, cranial ganglia and spinal motor neurons. Their temporal and spatial expression were compared with the neuronal markers Nescient Helix-Loop-Helix 1 (Nhlh1), Stathmin 2 (Stmn2) and HuC/D. We show that Tagln3 is an early marker for post-mitotic neurons whereas Chga and Cntn2 are expressed in mature neurons. We demonstrate that inhibition of Notch signaling during spinal cord neurogenesis enhances expression of these markers. This data demonstrates that Tagln3, Chga and Cntn2 represent strong new candidates to contribute to the sequential progression of vertebrate neurogenesis.

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

“…The conservation of gene expression was analysed by comparison with chick data (Table 2). Similar to the expression patterns observed in the chick embryo [44], these neuronal markers were differentially expressed throughout the early neuronal populations in the brain (Fig. 1 and Table 2), cranial ganglia and spinal cord (data not shown) in the developing mouse embryo.…”

“…Recently, a number of neuronal markers, described as part of the Notch/proneural network, were shown to be specifically expressed in the early neuronal populations of the chick brain [44]. To investigate the role of this network during formation of these neuronal populations in the developing mouse brain, the expression patterns of those markers, Nhlh1 , Tagln3 , Chga , Cntn2 and Stmn2 were analysed between E8.5 and E10.5 (Fig.…”

“…Expression in the mouse brain between E9.5 and E10.5, compared in the chick brain between HH12 and HH17 (taken from [44] and Fig. 7)…”

“…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]. …”

The DNA methylation profile of activated human natural killer cells

“…One study found the MAML2 promoter became hypermethylated in senescent mesenchymal stem cells after long term culture. 64 We found another Notch related gene, the actin-binding protein involved in cytoskeletal organization, 65 TAGLN3, demethylated in activated NK cells.…”