Specification of neurotransmitter identity by Tal1 in thalamic nuclei

Abstract

Our results demonstrate that Tal1 plays an essential role in regulating neurotransmitter phenotype in the developing thalamic nuclei. Developmental Dynamics 246:749-758, 2017. © 2017 Wiley Periodicals, Inc.

Defining developmental diversification of diencephalon neurons through single cell gene expression profiling

“…8H). As expected based on previous studies (Lee et al, 2017a;Sellers et al, 2014;Song et al, 2015;Virolainen et al, 2012), most cells fell along the bifurcation from progenitors into rostral thalamic and prethalamic fates with sequential gene expression changes corresponding to the progression of lineage development (Fig. 8H).…”

“…This is in agreement with the notion that these two regions may share a common pool of progenitors but give rise to different subtypes of GABAergic neurons (Kataoka and Shimogori, 2008). Indeed, GABAergic precursors that arise from the rostral thalamus or pretectum retain latent plasticity for subtype identity upon cell cycle exit; removal of various transcription factors, such as Gata2, Helt and Ascl1, Tal2, and Dlx1/2 results in cell fate switching between rostral thalamus and prethalamus (Delogu et al, 2012;Lee et al, 2017a;Sellers et al, 2014;Song et al, 2015;Virolainen et al, 2012). Furthermore, the predicted close relationship between the epithalamus and the thalamus is also in line with the fact that they both arise from the p2 domain (Puelles and Rubenstein, 2003;Rubenstein et al, 1994).…”

“…Remarkably, the predicted temporal expression profile of these genes recapitulated their known expression behavior in vivo (Delogu et al, 2012;Sellers et al, 2014;Virolainen et al, 2012). It has been demonstrated that many of these proteins play an essential role in GABAergic neuron differentiation in the rostral thalamus or in other brain regions Delogu et al, 2012;Lee et al, 2017a;Sellers et al, 2014;Song et al, 2015;Virolainen et al, 2012). Our analyses also revealed dynamic expression of several transcription factors, such as Otx1, Emx2, Six3, Uncx, Nr4a2 and Irx1, without described roles in the rostral thalamus.…”

Amphibian thalamic nuclear organization during larval development and in the adult frog Xenopus laevis: Genoarchitecture and hodological analysis

“…As development proceeds, GABA/Nkx2.2 cells are found in the Ar2, the GdN, and the IGL, similarly to the situation described in mice, where both GABA and Nkx2.2 were expressed in the ventral lateral geniculate nucleus (vLG) and in the external medullary lamina IGL (Vue et al, ), suggesting that in Xenopus at least a subpopulation of the GdN and IGL is originated in the intermediate stratum and then migrates radially to the final adult positions in the superficial stratum. Supporting this idea is the fact that in Xenopus both markers are very scarce in superficial derivatives such as the La, in contrast to the abundance noted in the Ar and Ac, (derivatives of the intermediate stratum) and that most NPY cells, specifically located in the IGL of most amniotes studied (Botchkina & Morin, ; Güntürkün & Karten, ; Kenigfest et al, ; Lee et al, ; Pinato, Frazao, Cruz‐Rizzolo, Cavalcante, & Nogueira, ) express also Nkx2.2. The nucleus of the zona limitans (described in Milán & Puelles, ) seemed to be also a pure rostral derivative in Xenopus , since it expresses exclusively rostral markers such as Nkx2.2 and GABA.…”

Tcf7l2 transcription factor is required for the maintenance, but not the initial specification, of the neurotransmitter identity in the caudal thalamus

“…Furthermore, Ascl1 and Helt act cooperatively to regulate Gata2 in GABAergic thalamic neurons. Recently, we demonstrated that Tal1 is not required for regional patterning in the caudal diencephalon, but essential for regulating post‐mitotic GABAergic neurotransmitter identity in the rTH and IGL/vLG . By contrast, loss‐ and/or gain‐of‐function analyses revealed the roles for Neurog1/2 and Pax6 in promoting glutamatergic lineage fate in the cTH .…”