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Lhx5 controls mamillary differentiation in the developing hypothalamus of the mouse.

Heide M, Zhang Y, Zhou X, Zhao T, Miquelajáuregui A, Varela-Echavarría A, Alvarez-Bolado G - Front Neuroanat (2015)

Bottom Line: Microarray analysis and chromatin immunoprecipitation indicated that Lhx5 appears to be involved in Shh downregulation through Tbx3 and activates several MBO-specific regulator and effector genes.Finally, by tracing the caudal hypothalamic cell lineage we show that, in the Lhx5 mutant, at least some MBO cells are present but lack characteristic marker expression.Our work shows how the Lhx5 locus contributes to integrate regional specification pathways with downstream acquisition of neuronal identity in the MBO.

View Article: PubMed Central - PubMed

Affiliation: Institute of Anatomy and Cell Biology, University of Heidelberg Heidelberg, Germany.

ABSTRACT
Acquisition of specific neuronal identity by individual brain nuclei is a key step in brain development. However, how the mechanisms that confer neuronal identity are integrated with upstream regional specification networks is still mysterious. Expression of Sonic hedgehog (Shh), is required for hypothalamic specification and is later downregulated by Tbx3 to allow for the differentiation of the tubero-mamillary region. In this region, the mamillary body (MBO), is a large neuronal aggregate essential for memory formation. To clarify how MBO identity is acquired after regional specification, we investigated Lhx5, a transcription factor with restricted MBO expression. We first generated a hypomorph allele of Lhx5-in homozygotes, the MBO disappears after initial specification. Intriguingly, in these mutants, Tbx3 was downregulated and the Shh expression domain abnormally extended. Microarray analysis and chromatin immunoprecipitation indicated that Lhx5 appears to be involved in Shh downregulation through Tbx3 and activates several MBO-specific regulator and effector genes. Finally, by tracing the caudal hypothalamic cell lineage we show that, in the Lhx5 mutant, at least some MBO cells are present but lack characteristic marker expression. Our work shows how the Lhx5 locus contributes to integrate regional specification pathways with downstream acquisition of neuronal identity in the MBO.

No MeSH data available.


Generation of a novel Lhx5 mutant allele. (A–C)Lhx5 wild type allele, floxed allele and recombined allele, as indicated. Exons 2–4 were flanked by loxP sites. (D–L) Upper two rows: In situ detection of Lhx5 mRNA on sagittal sections of E12.5 embryo brains (genotypes as indicated). Scale bar in (G), 500 μm. Arrows show the localization of the MBO. (E,H,K) High-magnification of the areas framed in (D,G,J). Lower row (F,I,L): Antibody detection of LHX5 protein on parallel sections to those shown in (D,G,J). Scale bar in (I), 100 μm. Arrows show the localization of the MBO.
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Figure 2: Generation of a novel Lhx5 mutant allele. (A–C)Lhx5 wild type allele, floxed allele and recombined allele, as indicated. Exons 2–4 were flanked by loxP sites. (D–L) Upper two rows: In situ detection of Lhx5 mRNA on sagittal sections of E12.5 embryo brains (genotypes as indicated). Scale bar in (G), 500 μm. Arrows show the localization of the MBO. (E,H,K) High-magnification of the areas framed in (D,G,J). Lower row (F,I,L): Antibody detection of LHX5 protein on parallel sections to those shown in (D,G,J). Scale bar in (I), 100 μm. Arrows show the localization of the MBO.

Mentions: We generated a novel conditional allele of Lhx5 by homologous recombination. We cloned the conditional Lhx5 targeting construct by inserting loxP sites into the Lhx5 locus spanning a region from intron 1 to intron 4 including exons 2–4 (Figures 2A–C).


Lhx5 controls mamillary differentiation in the developing hypothalamus of the mouse.

Heide M, Zhang Y, Zhou X, Zhao T, Miquelajáuregui A, Varela-Echavarría A, Alvarez-Bolado G - Front Neuroanat (2015)

Generation of a novel Lhx5 mutant allele. (A–C)Lhx5 wild type allele, floxed allele and recombined allele, as indicated. Exons 2–4 were flanked by loxP sites. (D–L) Upper two rows: In situ detection of Lhx5 mRNA on sagittal sections of E12.5 embryo brains (genotypes as indicated). Scale bar in (G), 500 μm. Arrows show the localization of the MBO. (E,H,K) High-magnification of the areas framed in (D,G,J). Lower row (F,I,L): Antibody detection of LHX5 protein on parallel sections to those shown in (D,G,J). Scale bar in (I), 100 μm. Arrows show the localization of the MBO.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4536661&req=5

Figure 2: Generation of a novel Lhx5 mutant allele. (A–C)Lhx5 wild type allele, floxed allele and recombined allele, as indicated. Exons 2–4 were flanked by loxP sites. (D–L) Upper two rows: In situ detection of Lhx5 mRNA on sagittal sections of E12.5 embryo brains (genotypes as indicated). Scale bar in (G), 500 μm. Arrows show the localization of the MBO. (E,H,K) High-magnification of the areas framed in (D,G,J). Lower row (F,I,L): Antibody detection of LHX5 protein on parallel sections to those shown in (D,G,J). Scale bar in (I), 100 μm. Arrows show the localization of the MBO.
Mentions: We generated a novel conditional allele of Lhx5 by homologous recombination. We cloned the conditional Lhx5 targeting construct by inserting loxP sites into the Lhx5 locus spanning a region from intron 1 to intron 4 including exons 2–4 (Figures 2A–C).

Bottom Line: Microarray analysis and chromatin immunoprecipitation indicated that Lhx5 appears to be involved in Shh downregulation through Tbx3 and activates several MBO-specific regulator and effector genes.Finally, by tracing the caudal hypothalamic cell lineage we show that, in the Lhx5 mutant, at least some MBO cells are present but lack characteristic marker expression.Our work shows how the Lhx5 locus contributes to integrate regional specification pathways with downstream acquisition of neuronal identity in the MBO.

View Article: PubMed Central - PubMed

Affiliation: Institute of Anatomy and Cell Biology, University of Heidelberg Heidelberg, Germany.

ABSTRACT
Acquisition of specific neuronal identity by individual brain nuclei is a key step in brain development. However, how the mechanisms that confer neuronal identity are integrated with upstream regional specification networks is still mysterious. Expression of Sonic hedgehog (Shh), is required for hypothalamic specification and is later downregulated by Tbx3 to allow for the differentiation of the tubero-mamillary region. In this region, the mamillary body (MBO), is a large neuronal aggregate essential for memory formation. To clarify how MBO identity is acquired after regional specification, we investigated Lhx5, a transcription factor with restricted MBO expression. We first generated a hypomorph allele of Lhx5-in homozygotes, the MBO disappears after initial specification. Intriguingly, in these mutants, Tbx3 was downregulated and the Shh expression domain abnormally extended. Microarray analysis and chromatin immunoprecipitation indicated that Lhx5 appears to be involved in Shh downregulation through Tbx3 and activates several MBO-specific regulator and effector genes. Finally, by tracing the caudal hypothalamic cell lineage we show that, in the Lhx5 mutant, at least some MBO cells are present but lack characteristic marker expression. Our work shows how the Lhx5 locus contributes to integrate regional specification pathways with downstream acquisition of neuronal identity in the MBO.

No MeSH data available.