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DNA methyltransferase 3b is dispensable for mouse neural crest development.

Jacques-Fricke BT, Roffers-Agarwal J, Gammill LS - PLoS ONE (2012)

Bottom Line: In both neural crest-specific and fully DNMT3b-mutant embryos, cranial neural crest cells exhibited only subtle migration defects, with increased numbers of dispersed cells trailing organized streams in the head.In spite of this, the resulting cranial ganglia, craniofacial skeleton, and heart developed normally when neural crest cells lacked DNMT3b.We conclude that defects in neural crest derivatives in DNMT3b mutant mice reflect a requirement for DNMT3b in lineages such as the branchial arch mesendoderm or the cardiac mesoderm that interact with neural crest cells during formation of these structures.

View Article: PubMed Central - PubMed

Affiliation: Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, Minnesota, United States of America.

ABSTRACT
The neural crest is a population of multipotent cells that migrates extensively throughout vertebrate embryos to form diverse structures. Mice mutant for the de novo DNA methyltransferase DNMT3b exhibit defects in two neural crest derivatives, the craniofacial skeleton and cardiac ventricular septum, suggesting that DNMT3b activity is necessary for neural crest development. Nevertheless, the requirement for DNMT3b specifically in neural crest cells, as opposed to interacting cell types, has not been determined. Using a conditional DNMT3b allele crossed to the neural crest cre drivers Wnt1-cre and Sox10-cre, neural crest DNMT3b mutants were generated. In both neural crest-specific and fully DNMT3b-mutant embryos, cranial neural crest cells exhibited only subtle migration defects, with increased numbers of dispersed cells trailing organized streams in the head. In spite of this, the resulting cranial ganglia, craniofacial skeleton, and heart developed normally when neural crest cells lacked DNMT3b. This indicates that DNTM3b is not necessary in cranial neural crest cells for their development. We conclude that defects in neural crest derivatives in DNMT3b mutant mice reflect a requirement for DNMT3b in lineages such as the branchial arch mesendoderm or the cardiac mesoderm that interact with neural crest cells during formation of these structures.

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The conditional allele DNMT3b−/− phenotype.Embryos homozygous for the recombined conditional DNMT3b allele (DNMT3b−/−; left) were compared to wildtype littermates (+/+; right) at E13.5. DNMT3b−/− animals were smaller, had small faint livers (line), and exhibited subcutaneous edema (arrow). These are the same defects exhibited by embryos homozygous for the DNMT3b targeted mutation [16].
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pone-0047794-g002: The conditional allele DNMT3b−/− phenotype.Embryos homozygous for the recombined conditional DNMT3b allele (DNMT3b−/−; left) were compared to wildtype littermates (+/+; right) at E13.5. DNMT3b−/− animals were smaller, had small faint livers (line), and exhibited subcutaneous edema (arrow). These are the same defects exhibited by embryos homozygous for the DNMT3b targeted mutation [16].

Mentions: To define the requirement for DNMT3b specifically in neural crest cells, we took advantage of a line of mice with a conditional DNMT3b allele. In these mice, exons 6 through 9 are flanked by loxP sites (floxed, or fl), and when recombined, the essential PC and ENV motifs of the DNMT3b methyltransferase catalytic domain are deleted [25]. Like the targeted DNMT3b allele in which the last half of exon 7 through exon 9 are deleted, the conditional DNMT3b allele is presumed to be a [12], [25]. As the conditional allele is nevertheless a distinct mutation, to validate its utility for studying embryonic development, we used DDX4(Vasa)-cre germline deleter mice [24] to recombine the loxP sites and generate DNMT3b−/− mice. Like the DNMT3b−/− targeted mutation [16], conditional allele DNMT3b−/− embryos are smaller than their wildtype littermates, exhibit subcutaneous edema, and have pale, stunted livers at E13.5 (Fig. 2). Moreover, after dozens of crosses, we have never obtained conditional allele DNMT3b−/− pups, indicating the deletion is embryonic lethal. Thus, mice with the recombined DNMT3b conditional allele have the same developmental defects as those with a DNMT3b targeted allele.


DNA methyltransferase 3b is dispensable for mouse neural crest development.

Jacques-Fricke BT, Roffers-Agarwal J, Gammill LS - PLoS ONE (2012)

The conditional allele DNMT3b−/− phenotype.Embryos homozygous for the recombined conditional DNMT3b allele (DNMT3b−/−; left) were compared to wildtype littermates (+/+; right) at E13.5. DNMT3b−/− animals were smaller, had small faint livers (line), and exhibited subcutaneous edema (arrow). These are the same defects exhibited by embryos homozygous for the DNMT3b targeted mutation [16].
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3475715&req=5

pone-0047794-g002: The conditional allele DNMT3b−/− phenotype.Embryos homozygous for the recombined conditional DNMT3b allele (DNMT3b−/−; left) were compared to wildtype littermates (+/+; right) at E13.5. DNMT3b−/− animals were smaller, had small faint livers (line), and exhibited subcutaneous edema (arrow). These are the same defects exhibited by embryos homozygous for the DNMT3b targeted mutation [16].
Mentions: To define the requirement for DNMT3b specifically in neural crest cells, we took advantage of a line of mice with a conditional DNMT3b allele. In these mice, exons 6 through 9 are flanked by loxP sites (floxed, or fl), and when recombined, the essential PC and ENV motifs of the DNMT3b methyltransferase catalytic domain are deleted [25]. Like the targeted DNMT3b allele in which the last half of exon 7 through exon 9 are deleted, the conditional DNMT3b allele is presumed to be a [12], [25]. As the conditional allele is nevertheless a distinct mutation, to validate its utility for studying embryonic development, we used DDX4(Vasa)-cre germline deleter mice [24] to recombine the loxP sites and generate DNMT3b−/− mice. Like the DNMT3b−/− targeted mutation [16], conditional allele DNMT3b−/− embryos are smaller than their wildtype littermates, exhibit subcutaneous edema, and have pale, stunted livers at E13.5 (Fig. 2). Moreover, after dozens of crosses, we have never obtained conditional allele DNMT3b−/− pups, indicating the deletion is embryonic lethal. Thus, mice with the recombined DNMT3b conditional allele have the same developmental defects as those with a DNMT3b targeted allele.

Bottom Line: In both neural crest-specific and fully DNMT3b-mutant embryos, cranial neural crest cells exhibited only subtle migration defects, with increased numbers of dispersed cells trailing organized streams in the head.In spite of this, the resulting cranial ganglia, craniofacial skeleton, and heart developed normally when neural crest cells lacked DNMT3b.We conclude that defects in neural crest derivatives in DNMT3b mutant mice reflect a requirement for DNMT3b in lineages such as the branchial arch mesendoderm or the cardiac mesoderm that interact with neural crest cells during formation of these structures.

View Article: PubMed Central - PubMed

Affiliation: Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, Minnesota, United States of America.

ABSTRACT
The neural crest is a population of multipotent cells that migrates extensively throughout vertebrate embryos to form diverse structures. Mice mutant for the de novo DNA methyltransferase DNMT3b exhibit defects in two neural crest derivatives, the craniofacial skeleton and cardiac ventricular septum, suggesting that DNMT3b activity is necessary for neural crest development. Nevertheless, the requirement for DNMT3b specifically in neural crest cells, as opposed to interacting cell types, has not been determined. Using a conditional DNMT3b allele crossed to the neural crest cre drivers Wnt1-cre and Sox10-cre, neural crest DNMT3b mutants were generated. In both neural crest-specific and fully DNMT3b-mutant embryos, cranial neural crest cells exhibited only subtle migration defects, with increased numbers of dispersed cells trailing organized streams in the head. In spite of this, the resulting cranial ganglia, craniofacial skeleton, and heart developed normally when neural crest cells lacked DNMT3b. This indicates that DNTM3b is not necessary in cranial neural crest cells for their development. We conclude that defects in neural crest derivatives in DNMT3b mutant mice reflect a requirement for DNMT3b in lineages such as the branchial arch mesendoderm or the cardiac mesoderm that interact with neural crest cells during formation of these structures.

Show MeSH
Related in: MedlinePlus