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The prethalamus is established during gastrulation and influences diencephalic regionalization.

Staudt N, Houart C - PLoS Biol. (2007)

Bottom Line: In this study, we draw an extended expression map of the rostral neural plate that reveals discrete domains inside the presumptive posterior forebrain.Finally, transplantation of these precursors, in the rostral-most neural epithelium, induces changes in cell identity in the surrounding host forebrain.This cell-non-autonomous property led us to propose that these committed prethalamic precursors may play an instructive role in the regionalization of the developing diencephalon.

View Article: PubMed Central - PubMed

Affiliation: Medical Research Council Centre for Developmental Neurobiology, King's College London, London, United Kingdom.

ABSTRACT
The vertebrate neural plate contains distinct domains of gene expression, prefiguring the future brain areas. In this study, we draw an extended expression map of the rostral neural plate that reveals discrete domains inside the presumptive posterior forebrain. We show, by fate mapping, that these well-defined cell populations will develop into specific diencephalic regions. To address whether these early subterritories are already committed to restricted identities, we began to analyse the consequences of ablation and transplantation of these specific cell populations. We found that precursors of the prethalamus are already specified and irreplaceable at late gastrula stage, because ablation of these cells results in loss of prethalamic markers. Moreover, when transplanted into the ectopic environment of the presumptive hindbrain, these cells still pursue their prethalamic differentiation program. Finally, transplantation of these precursors, in the rostral-most neural epithelium, induces changes in cell identity in the surrounding host forebrain. This cell-non-autonomous property led us to propose that these committed prethalamic precursors may play an instructive role in the regionalization of the developing diencephalon.

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Expression Profile of the Rostral Neural Plate(A–G) Rostral neural plate, anterior to the left. Embryos at bud stage (A–D, F, G , I, and K) or 100% epiboly (E) are shown.(A) six3 (red), fezl (blue). (B) six3 (red), arx (blue). (C) barhl2 (red), flh (blue). (D) irx7 (red), arx (blue). (E) irx7 (red), wnt8b (blue). (F) irx7 (red), foxb1.2 (blue). (G) foxb1.2 (red), fezl (blue). (H) Scheme of the different expression domains inside the diencephalon anlage shown in (A–G). (I) Sagittal section, anterior left, foxb1.2 (red), fezl (blue). (J) Scheme of (I). (K) Transverse section, fezl (blue). (L) Scheme of (K). The different domains are the presumptive anteromedial (I), anterolateral (II), and posterior (III) diencephalon, hypothalamus (IV), and eye field (V).
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pbio-0050069-g001: Expression Profile of the Rostral Neural Plate(A–G) Rostral neural plate, anterior to the left. Embryos at bud stage (A–D, F, G , I, and K) or 100% epiboly (E) are shown.(A) six3 (red), fezl (blue). (B) six3 (red), arx (blue). (C) barhl2 (red), flh (blue). (D) irx7 (red), arx (blue). (E) irx7 (red), wnt8b (blue). (F) irx7 (red), foxb1.2 (blue). (G) foxb1.2 (red), fezl (blue). (H) Scheme of the different expression domains inside the diencephalon anlage shown in (A–G). (I) Sagittal section, anterior left, foxb1.2 (red), fezl (blue). (J) Scheme of (I). (K) Transverse section, fezl (blue). (L) Scheme of (K). The different domains are the presumptive anteromedial (I), anterolateral (II), and posterior (III) diencephalon, hypothalamus (IV), and eye field (V).

Mentions: We found that, at bud stage, diencephalic markers like arx [15], fezl [16], and barhl2 [17] are located directly posterior to the eye field (Figure 1A and 1B). Inside that domain, flh [18] is exclusively expressed laterally (domain II in Figure 1C, and unpublished data), overlapping with the telencephalic territory; whereas arx is expressed in the medial part of the barhl2 expression domain at the same developmental stage (domain I in Figure 1B and 1C). In cells posterior to the ones expressing arx, transcripts of irx7 [19] are detected (domain III in Figure 1D). Although irx7 has been described to be expressed in the midbrain and hindbrain, an overlap of the rostral expression domain with that of the forebrain marker pax6a [20] shows that the anterior-most irx7-expressing cells are located within the presumptive forebrain territory (unpublished data). Other genes that we found to be expressed in the posterior diencephalic domain III are wnt8b (Figure 1E) and foxb1.2 (Figure 1F and 1G), which are expressed in an overlapping pattern with irx7 (Figure 1F) and are located posterior to fezl (Figure 1G). The resulting expression map of early forebrain markers shows a subdivision of the forebrain into six different domains (Figure 1H), which expands the previously described map of the rostral neural plate, revealing subdomains inside the diencephalic anlage. Besides the hypothalamic anlage (domain IV in Figure 1) the diencephalon is further partitioned into the anterior medial domain I (arx, fezl, and barhl2), the anterior lateral domain II (flh and barhl2), and the posterior domain III (irx7, foxb1.2, and wnt8b).


The prethalamus is established during gastrulation and influences diencephalic regionalization.

Staudt N, Houart C - PLoS Biol. (2007)

Expression Profile of the Rostral Neural Plate(A–G) Rostral neural plate, anterior to the left. Embryos at bud stage (A–D, F, G , I, and K) or 100% epiboly (E) are shown.(A) six3 (red), fezl (blue). (B) six3 (red), arx (blue). (C) barhl2 (red), flh (blue). (D) irx7 (red), arx (blue). (E) irx7 (red), wnt8b (blue). (F) irx7 (red), foxb1.2 (blue). (G) foxb1.2 (red), fezl (blue). (H) Scheme of the different expression domains inside the diencephalon anlage shown in (A–G). (I) Sagittal section, anterior left, foxb1.2 (red), fezl (blue). (J) Scheme of (I). (K) Transverse section, fezl (blue). (L) Scheme of (K). The different domains are the presumptive anteromedial (I), anterolateral (II), and posterior (III) diencephalon, hypothalamus (IV), and eye field (V).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC1808486&req=5

pbio-0050069-g001: Expression Profile of the Rostral Neural Plate(A–G) Rostral neural plate, anterior to the left. Embryos at bud stage (A–D, F, G , I, and K) or 100% epiboly (E) are shown.(A) six3 (red), fezl (blue). (B) six3 (red), arx (blue). (C) barhl2 (red), flh (blue). (D) irx7 (red), arx (blue). (E) irx7 (red), wnt8b (blue). (F) irx7 (red), foxb1.2 (blue). (G) foxb1.2 (red), fezl (blue). (H) Scheme of the different expression domains inside the diencephalon anlage shown in (A–G). (I) Sagittal section, anterior left, foxb1.2 (red), fezl (blue). (J) Scheme of (I). (K) Transverse section, fezl (blue). (L) Scheme of (K). The different domains are the presumptive anteromedial (I), anterolateral (II), and posterior (III) diencephalon, hypothalamus (IV), and eye field (V).
Mentions: We found that, at bud stage, diencephalic markers like arx [15], fezl [16], and barhl2 [17] are located directly posterior to the eye field (Figure 1A and 1B). Inside that domain, flh [18] is exclusively expressed laterally (domain II in Figure 1C, and unpublished data), overlapping with the telencephalic territory; whereas arx is expressed in the medial part of the barhl2 expression domain at the same developmental stage (domain I in Figure 1B and 1C). In cells posterior to the ones expressing arx, transcripts of irx7 [19] are detected (domain III in Figure 1D). Although irx7 has been described to be expressed in the midbrain and hindbrain, an overlap of the rostral expression domain with that of the forebrain marker pax6a [20] shows that the anterior-most irx7-expressing cells are located within the presumptive forebrain territory (unpublished data). Other genes that we found to be expressed in the posterior diencephalic domain III are wnt8b (Figure 1E) and foxb1.2 (Figure 1F and 1G), which are expressed in an overlapping pattern with irx7 (Figure 1F) and are located posterior to fezl (Figure 1G). The resulting expression map of early forebrain markers shows a subdivision of the forebrain into six different domains (Figure 1H), which expands the previously described map of the rostral neural plate, revealing subdomains inside the diencephalic anlage. Besides the hypothalamic anlage (domain IV in Figure 1) the diencephalon is further partitioned into the anterior medial domain I (arx, fezl, and barhl2), the anterior lateral domain II (flh and barhl2), and the posterior domain III (irx7, foxb1.2, and wnt8b).

Bottom Line: In this study, we draw an extended expression map of the rostral neural plate that reveals discrete domains inside the presumptive posterior forebrain.Finally, transplantation of these precursors, in the rostral-most neural epithelium, induces changes in cell identity in the surrounding host forebrain.This cell-non-autonomous property led us to propose that these committed prethalamic precursors may play an instructive role in the regionalization of the developing diencephalon.

View Article: PubMed Central - PubMed

Affiliation: Medical Research Council Centre for Developmental Neurobiology, King's College London, London, United Kingdom.

ABSTRACT
The vertebrate neural plate contains distinct domains of gene expression, prefiguring the future brain areas. In this study, we draw an extended expression map of the rostral neural plate that reveals discrete domains inside the presumptive posterior forebrain. We show, by fate mapping, that these well-defined cell populations will develop into specific diencephalic regions. To address whether these early subterritories are already committed to restricted identities, we began to analyse the consequences of ablation and transplantation of these specific cell populations. We found that precursors of the prethalamus are already specified and irreplaceable at late gastrula stage, because ablation of these cells results in loss of prethalamic markers. Moreover, when transplanted into the ectopic environment of the presumptive hindbrain, these cells still pursue their prethalamic differentiation program. Finally, transplantation of these precursors, in the rostral-most neural epithelium, induces changes in cell identity in the surrounding host forebrain. This cell-non-autonomous property led us to propose that these committed prethalamic precursors may play an instructive role in the regionalization of the developing diencephalon.

Show MeSH
Related in: MedlinePlus