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Bhlhb5::flpo allele uncovers a requirement for Bhlhb5 for the development of the dorsal cochlear nucleus.

Cai X, Kardon AP, Snyder LM, Kuzirian MS, Minestro S, de Souza L, Rubio ME, Maricich SM, Ross SE - Dev. Biol. (2016)

Bottom Line: Using an intersectional genetic strategy, we labeled cartwheel cells, thereby providing proof of concept that subpopulations of Bhlhb5-expressing neurons can be genetically targeted.Moreover, fate-mapping experiments using this allele revealed that Bhlhb5 is required for the proper development of the DCN, since mice lacking Bhlhb5 showed a dramatically diminished number of neurons, including unipolar brush and cartwheel cells.Intriguingly, the Bhlhb5::flpo allele also genetically labels numerous other regions of the nervous system that process sensory input, including the dorsal horn, the retina, and the nucleus of the lateral olfactory tract, hinting at a more general role for Bhlhb5 in the development of neurons that mediate sensory integration.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurobiology, University of Pittsburgh, 200 Lothrop St., Pittsburgh, PA 15213, USA; The Pittsburgh Center for Pain Research, University of Pittsburgh, 200 Lothrop St., Pittsburgh, PA 15213, USA.

No MeSH data available.


Related in: MedlinePlus

Mice lacking Bhlhb5 show a reduced cell number in the DCN. (A and B) Coronal sections from adult mice showing the DCN in control (Bhlhb5flpo/+; RCE::FRT) or Bhlhb5 mutant (Bhlhb5flpo/−; RCE::FRT) mice stained with Hoechst to mark nuclei. (C) Quantification of (A–B) showing a significant reduction in the total cell number in the dorsal cochlear nucleus in Bhlhb5 mutant mice relative to controls. (D–F) Immunostaining (D,E) and quantification (F) of NeuN-positive neurons in the DCN showing a significant loss of neurons in Bhlhb5 mutant mice relative to controls. (G–I) Immunostaining (G–H) and quantification (I) of GFP-expressing neurons, again showing a significant decrease in the absence of Bhlhb5. Representative confocal optical sections are shown. Scale bar = 200 µm. For quantification, n = 4 pairs of control/mutant littermates. Data are presented as mean + SEM and * indicates a significant difference relative to controls (P < 0.05, t-test). All quantification was conducted blind to genotype.
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Figure 5: Mice lacking Bhlhb5 show a reduced cell number in the DCN. (A and B) Coronal sections from adult mice showing the DCN in control (Bhlhb5flpo/+; RCE::FRT) or Bhlhb5 mutant (Bhlhb5flpo/−; RCE::FRT) mice stained with Hoechst to mark nuclei. (C) Quantification of (A–B) showing a significant reduction in the total cell number in the dorsal cochlear nucleus in Bhlhb5 mutant mice relative to controls. (D–F) Immunostaining (D,E) and quantification (F) of NeuN-positive neurons in the DCN showing a significant loss of neurons in Bhlhb5 mutant mice relative to controls. (G–I) Immunostaining (G–H) and quantification (I) of GFP-expressing neurons, again showing a significant decrease in the absence of Bhlhb5. Representative confocal optical sections are shown. Scale bar = 200 µm. For quantification, n = 4 pairs of control/mutant littermates. Data are presented as mean + SEM and * indicates a significant difference relative to controls (P < 0.05, t-test). All quantification was conducted blind to genotype.

Mentions: Given that Bhlhb5 shows prolonged expression in the DCN, we hypothesized that this transcription factor may play a key role in the development of this nucleus. To investigate this idea, we used immunohistochemical and fate-mapping approaches to compare the DCN in control and Bhlhb5 mutant mice. Upon loss of Bhlhb5, we observed a dramatic reduction of the DCN, which showed a ~50% reduction in total cell number (Fig. 5A–C). This cell loss could be almost completely accounted for by the finding that Bhlhb5 mutant mice showed an 80% decrease in the number of NeuN positive neurons (Fig. 5D–F). Approximately 20% of neurons in the DCN are genetically labeled using the Bhlhb5::flpo allele, and these neurons also showed a significant decrease in total number in the DCN of Bhlhb5 mutant mice (Figs. 5G–I and S3). In contrast, there was no obvious defect in the AVCN or the PVCN, which appeared grossly normal in size (Fig. S3). Thus, immunohistochemical and fate-mapping studies reveal an essential role for Bhlhb5 for the proper development of the DCN.


Bhlhb5::flpo allele uncovers a requirement for Bhlhb5 for the development of the dorsal cochlear nucleus.

Cai X, Kardon AP, Snyder LM, Kuzirian MS, Minestro S, de Souza L, Rubio ME, Maricich SM, Ross SE - Dev. Biol. (2016)

Mice lacking Bhlhb5 show a reduced cell number in the DCN. (A and B) Coronal sections from adult mice showing the DCN in control (Bhlhb5flpo/+; RCE::FRT) or Bhlhb5 mutant (Bhlhb5flpo/−; RCE::FRT) mice stained with Hoechst to mark nuclei. (C) Quantification of (A–B) showing a significant reduction in the total cell number in the dorsal cochlear nucleus in Bhlhb5 mutant mice relative to controls. (D–F) Immunostaining (D,E) and quantification (F) of NeuN-positive neurons in the DCN showing a significant loss of neurons in Bhlhb5 mutant mice relative to controls. (G–I) Immunostaining (G–H) and quantification (I) of GFP-expressing neurons, again showing a significant decrease in the absence of Bhlhb5. Representative confocal optical sections are shown. Scale bar = 200 µm. For quantification, n = 4 pairs of control/mutant littermates. Data are presented as mean + SEM and * indicates a significant difference relative to controls (P < 0.05, t-test). All quantification was conducted blind to genotype.
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Related In: Results  -  Collection

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Figure 5: Mice lacking Bhlhb5 show a reduced cell number in the DCN. (A and B) Coronal sections from adult mice showing the DCN in control (Bhlhb5flpo/+; RCE::FRT) or Bhlhb5 mutant (Bhlhb5flpo/−; RCE::FRT) mice stained with Hoechst to mark nuclei. (C) Quantification of (A–B) showing a significant reduction in the total cell number in the dorsal cochlear nucleus in Bhlhb5 mutant mice relative to controls. (D–F) Immunostaining (D,E) and quantification (F) of NeuN-positive neurons in the DCN showing a significant loss of neurons in Bhlhb5 mutant mice relative to controls. (G–I) Immunostaining (G–H) and quantification (I) of GFP-expressing neurons, again showing a significant decrease in the absence of Bhlhb5. Representative confocal optical sections are shown. Scale bar = 200 µm. For quantification, n = 4 pairs of control/mutant littermates. Data are presented as mean + SEM and * indicates a significant difference relative to controls (P < 0.05, t-test). All quantification was conducted blind to genotype.
Mentions: Given that Bhlhb5 shows prolonged expression in the DCN, we hypothesized that this transcription factor may play a key role in the development of this nucleus. To investigate this idea, we used immunohistochemical and fate-mapping approaches to compare the DCN in control and Bhlhb5 mutant mice. Upon loss of Bhlhb5, we observed a dramatic reduction of the DCN, which showed a ~50% reduction in total cell number (Fig. 5A–C). This cell loss could be almost completely accounted for by the finding that Bhlhb5 mutant mice showed an 80% decrease in the number of NeuN positive neurons (Fig. 5D–F). Approximately 20% of neurons in the DCN are genetically labeled using the Bhlhb5::flpo allele, and these neurons also showed a significant decrease in total number in the DCN of Bhlhb5 mutant mice (Figs. 5G–I and S3). In contrast, there was no obvious defect in the AVCN or the PVCN, which appeared grossly normal in size (Fig. S3). Thus, immunohistochemical and fate-mapping studies reveal an essential role for Bhlhb5 for the proper development of the DCN.

Bottom Line: Using an intersectional genetic strategy, we labeled cartwheel cells, thereby providing proof of concept that subpopulations of Bhlhb5-expressing neurons can be genetically targeted.Moreover, fate-mapping experiments using this allele revealed that Bhlhb5 is required for the proper development of the DCN, since mice lacking Bhlhb5 showed a dramatically diminished number of neurons, including unipolar brush and cartwheel cells.Intriguingly, the Bhlhb5::flpo allele also genetically labels numerous other regions of the nervous system that process sensory input, including the dorsal horn, the retina, and the nucleus of the lateral olfactory tract, hinting at a more general role for Bhlhb5 in the development of neurons that mediate sensory integration.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurobiology, University of Pittsburgh, 200 Lothrop St., Pittsburgh, PA 15213, USA; The Pittsburgh Center for Pain Research, University of Pittsburgh, 200 Lothrop St., Pittsburgh, PA 15213, USA.

No MeSH data available.


Related in: MedlinePlus