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Conserved Noncoding Sequences Regulate lhx5 Expression in the Zebrafish Forebrain.

Sun L, Chen F, Peng G - PLoS ONE (2015)

Bottom Line: We found a proximately located enhancer gave rise to robust reporter EGFP expression in the forebrain regions.We also identify an enhancer located approximately 40 kb upstream of the lhx5 coding region that is required for expression in the prethalamus (ventral thalamus).Together our results suggest discrete enhancer elements control lhx5 expression in different regions of the forebrain.

View Article: PubMed Central - PubMed

Affiliation: Institutes of Brain Science, State Key Laboratory of Medical Neurobiology and Collaborative Innovation Center for Brain Science, Fudan University, Shanghai, China.

ABSTRACT
The LIM homeobox family protein Lhx5 plays important roles in forebrain development in the vertebrates. The lhx5 gene exhibits complex temporal and spatial expression patterns during early development but its transcriptional regulation mechanisms are not well understood. Here, we have used transgenesis in zebrafish in order to define regulatory elements that drive lhx5 expression in the forebrain. Through comparative genomic analysis we identified 10 non-coding sequences conserved in five teleost species. We next examined the enhancer activities of these conserved non-coding sequences with Tol2 transposon mediated transgenesis. We found a proximately located enhancer gave rise to robust reporter EGFP expression in the forebrain regions. In addition, we identified an enhancer located at approximately 50 kb upstream of lhx5 coding region that is responsible for reporter gene expression in the hypothalamus. We also identify an enhancer located approximately 40 kb upstream of the lhx5 coding region that is required for expression in the prethalamus (ventral thalamus). Together our results suggest discrete enhancer elements control lhx5 expression in different regions of the forebrain.

No MeSH data available.


Schematic overview of the lhx5 locus.(A) Genomic regions surrounding lhx5 genes from vertebrate species. The teleost lhx5 gene is flanked by adjacent upstream gene mzt2b (Fugu, Medaka, Tilapia, cavefish and zebrafish). The cartilaginous elephant shark, the lobe-finned coelacanth, and the tetrapod species show the same rbm19-lhx5-sdsl gene co-localization. The spotted gar mzt2b-rbm19-lhx5 gene co-localization is partially similar to both the tetrapod and the teleost fishes. (B) Conserved non-coding sequences (CNS) in the upstream genomic sequence of lhx5 locus in eight representative vertebrate species. Eight of the ten CNSs are teleost-specific, and two CNSs (CNS3 and CNS5) are found in all eight species.
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pone.0132525.g001: Schematic overview of the lhx5 locus.(A) Genomic regions surrounding lhx5 genes from vertebrate species. The teleost lhx5 gene is flanked by adjacent upstream gene mzt2b (Fugu, Medaka, Tilapia, cavefish and zebrafish). The cartilaginous elephant shark, the lobe-finned coelacanth, and the tetrapod species show the same rbm19-lhx5-sdsl gene co-localization. The spotted gar mzt2b-rbm19-lhx5 gene co-localization is partially similar to both the tetrapod and the teleost fishes. (B) Conserved non-coding sequences (CNS) in the upstream genomic sequence of lhx5 locus in eight representative vertebrate species. Eight of the ten CNSs are teleost-specific, and two CNSs (CNS3 and CNS5) are found in all eight species.

Mentions: Conserved non-coding sequences (CNSs) are evolutionary conserved intergenic or intronic sequence elements derived from a common ancestor. We carried out comparative sequence analysis of the lhx5 loci to look for CNSs with putative roles in lhx5 gene transcriptional regulation. Twelve vertebrate species representing major groups of the jawed vertebrate lineage were included in our analyses, including genomic sequences from human, mouse, chicken, frog, coelacanth, elephant shark, spotted gar, and five teleost fishes (Fig 1). The shared synteny analyses indicated lhx5 genomic regions in zebrafish and other teleost species showed conserved syntenies. In all teleosts, the mzt2a gene is located upstream to the lhx5 gene. The LHX5 loci in tetrapods didn’t show conserved synteny with the corresponding regions in the teleost fishes. Nevertheless, conserved syntenies were observed between the tetrapods and other fish species (Fig 1A). Thus the cartilaginous elephant shark and the lobe-finned coelacanth showed the same rbm19-lhx5-sdsl gene co-localization as in the tetrapods. Interestingly, the spotted gar mzt2b-rbm19-lhx5 gene co-localization was partially similar to both the tetrapod and the teleost fishes. These conserved synteny results suggested the genomic sequences in the lhx5 regions were conserved through evolution but speciation in teleost lineage has diversified the gene co-localizations.


Conserved Noncoding Sequences Regulate lhx5 Expression in the Zebrafish Forebrain.

Sun L, Chen F, Peng G - PLoS ONE (2015)

Schematic overview of the lhx5 locus.(A) Genomic regions surrounding lhx5 genes from vertebrate species. The teleost lhx5 gene is flanked by adjacent upstream gene mzt2b (Fugu, Medaka, Tilapia, cavefish and zebrafish). The cartilaginous elephant shark, the lobe-finned coelacanth, and the tetrapod species show the same rbm19-lhx5-sdsl gene co-localization. The spotted gar mzt2b-rbm19-lhx5 gene co-localization is partially similar to both the tetrapod and the teleost fishes. (B) Conserved non-coding sequences (CNS) in the upstream genomic sequence of lhx5 locus in eight representative vertebrate species. Eight of the ten CNSs are teleost-specific, and two CNSs (CNS3 and CNS5) are found in all eight species.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4492605&req=5

pone.0132525.g001: Schematic overview of the lhx5 locus.(A) Genomic regions surrounding lhx5 genes from vertebrate species. The teleost lhx5 gene is flanked by adjacent upstream gene mzt2b (Fugu, Medaka, Tilapia, cavefish and zebrafish). The cartilaginous elephant shark, the lobe-finned coelacanth, and the tetrapod species show the same rbm19-lhx5-sdsl gene co-localization. The spotted gar mzt2b-rbm19-lhx5 gene co-localization is partially similar to both the tetrapod and the teleost fishes. (B) Conserved non-coding sequences (CNS) in the upstream genomic sequence of lhx5 locus in eight representative vertebrate species. Eight of the ten CNSs are teleost-specific, and two CNSs (CNS3 and CNS5) are found in all eight species.
Mentions: Conserved non-coding sequences (CNSs) are evolutionary conserved intergenic or intronic sequence elements derived from a common ancestor. We carried out comparative sequence analysis of the lhx5 loci to look for CNSs with putative roles in lhx5 gene transcriptional regulation. Twelve vertebrate species representing major groups of the jawed vertebrate lineage were included in our analyses, including genomic sequences from human, mouse, chicken, frog, coelacanth, elephant shark, spotted gar, and five teleost fishes (Fig 1). The shared synteny analyses indicated lhx5 genomic regions in zebrafish and other teleost species showed conserved syntenies. In all teleosts, the mzt2a gene is located upstream to the lhx5 gene. The LHX5 loci in tetrapods didn’t show conserved synteny with the corresponding regions in the teleost fishes. Nevertheless, conserved syntenies were observed between the tetrapods and other fish species (Fig 1A). Thus the cartilaginous elephant shark and the lobe-finned coelacanth showed the same rbm19-lhx5-sdsl gene co-localization as in the tetrapods. Interestingly, the spotted gar mzt2b-rbm19-lhx5 gene co-localization was partially similar to both the tetrapod and the teleost fishes. These conserved synteny results suggested the genomic sequences in the lhx5 regions were conserved through evolution but speciation in teleost lineage has diversified the gene co-localizations.

Bottom Line: We found a proximately located enhancer gave rise to robust reporter EGFP expression in the forebrain regions.We also identify an enhancer located approximately 40 kb upstream of the lhx5 coding region that is required for expression in the prethalamus (ventral thalamus).Together our results suggest discrete enhancer elements control lhx5 expression in different regions of the forebrain.

View Article: PubMed Central - PubMed

Affiliation: Institutes of Brain Science, State Key Laboratory of Medical Neurobiology and Collaborative Innovation Center for Brain Science, Fudan University, Shanghai, China.

ABSTRACT
The LIM homeobox family protein Lhx5 plays important roles in forebrain development in the vertebrates. The lhx5 gene exhibits complex temporal and spatial expression patterns during early development but its transcriptional regulation mechanisms are not well understood. Here, we have used transgenesis in zebrafish in order to define regulatory elements that drive lhx5 expression in the forebrain. Through comparative genomic analysis we identified 10 non-coding sequences conserved in five teleost species. We next examined the enhancer activities of these conserved non-coding sequences with Tol2 transposon mediated transgenesis. We found a proximately located enhancer gave rise to robust reporter EGFP expression in the forebrain regions. In addition, we identified an enhancer located at approximately 50 kb upstream of lhx5 coding region that is responsible for reporter gene expression in the hypothalamus. We also identify an enhancer located approximately 40 kb upstream of the lhx5 coding region that is required for expression in the prethalamus (ventral thalamus). Together our results suggest discrete enhancer elements control lhx5 expression in different regions of the forebrain.

No MeSH data available.