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Fgf16 is required for specification of GABAergic neurons and oligodendrocytes in the zebrafish forebrain.

Miyake A, Chitose T, Kamei E, Murakami A, Nakayama Y, Konishi M, Itoh N - PLoS ONE (2014)

Bottom Line: The knockdown of fgf16 decreased cell proliferation in the forebrain and midbrain. fgf16 was also essential for development of the ventral telencephalon and diencephalon, whereas fgf16 was not required for dorsoventral patterning in the midbrain. fgf16 was additionally required for the specification and differentiation of γ-aminobutyric acid (GABA)ergic interneurons and oligodendrocytes, but not for those of glutamatergic neurons in the forebrain.The fgf16 morphant phenotype was similar to that of the fgf19 morphant and embryos blocked Hh signaling.The results of the present study indicate that Fgf16 signaling, which is regulated by the downstream pathways of Hh-Fgf19 in the forebrain, is involved in forebrain development.

View Article: PubMed Central - PubMed

Affiliation: Department of Genetic Biochemistry, Kyoto University Graduate School of Pharmaceutical Sciences, Sakyo, Kyoto, Japan.

ABSTRACT
Fibroblast growth factor (Fgf) signaling plays crucial roles in various developmental processes including those in the brain. We examined the role of Fgf16 in the formation of the zebrafish brain. The knockdown of fgf16 decreased cell proliferation in the forebrain and midbrain. fgf16 was also essential for development of the ventral telencephalon and diencephalon, whereas fgf16 was not required for dorsoventral patterning in the midbrain. fgf16 was additionally required for the specification and differentiation of γ-aminobutyric acid (GABA)ergic interneurons and oligodendrocytes, but not for those of glutamatergic neurons in the forebrain. Cross talk between Fgf and Hedgehog (Hh) signaling was critical for the specification of GABAergic interneurons and oligodendrocytes. The expression of fgf16 in the forebrain was down-regulated by the inhibition of Hh and Fgf19 signaling, but not by that of Fgf3/Fgf8 signaling. The fgf16 morphant phenotype was similar to that of the fgf19 morphant and embryos blocked Hh signaling. The results of the present study indicate that Fgf16 signaling, which is regulated by the downstream pathways of Hh-Fgf19 in the forebrain, is involved in forebrain development.

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Comparison of cell proliferation and cell death patterns in control embryos and fgf16 morphants.(A, B) Control embryos (A) and embryos injected with fgf16 MO (B) were stained using an anti-H3P antibody. Panels show representative horizontal sections of the head region at 24 hpf. (C, D) The percentage of proliferating cells labelled with the anti-pH3 antibody in the forebrain (C) and midbrain (D) of control embryos and embryos injected with fgf16 MO. Results are the mean ± S.D. for three independent sections from three embryos. The significance of differences in mean values was assessed with the Student’s t-test. Asterisks indicate significant differences from the control (*P<0.05). The forebrain (fb) and midbrain (mb) regions, which we defined in the sections, are separated by black lines. Scale bar: 25 µm.
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pone-0110836-g003: Comparison of cell proliferation and cell death patterns in control embryos and fgf16 morphants.(A, B) Control embryos (A) and embryos injected with fgf16 MO (B) were stained using an anti-H3P antibody. Panels show representative horizontal sections of the head region at 24 hpf. (C, D) The percentage of proliferating cells labelled with the anti-pH3 antibody in the forebrain (C) and midbrain (D) of control embryos and embryos injected with fgf16 MO. Results are the mean ± S.D. for three independent sections from three embryos. The significance of differences in mean values was assessed with the Student’s t-test. Asterisks indicate significant differences from the control (*P<0.05). The forebrain (fb) and midbrain (mb) regions, which we defined in the sections, are separated by black lines. Scale bar: 25 µm.

Mentions: Fgf signaling has been shown to regulate cell proliferation and cell survival in the brains of mice and zebrafish [8], [55], [56]. fgf16 is also required for cell proliferation in the mesenchyme of fin buds [29]. Therefore, the morphological abnormalities observed in the forebrain and midbrain of fgf16 morphants at 24 hpf may have been due to a defect in cell proliferation and/or cell survival in these regions. To examine this, we compared the number of mitotic cells in wild-type embryos and fgf16 morphants. Phosphorylated histone H3 (pH3) was specifically detected in the mitotic cells in mitotic phase (M-phase) [57]. We identified proliferating cells as pH3-positive cells. The rate of pH3-positive cells in the forebrain of fgf16 morphants was significantly lower than that in wild-type embryos at 24 hpf (Fig. 3A–C). In addition, the rate of pH3-positive cells in the midbrain was significantly decreased in fgf16 morphants (Fig. 3A, B, D). These results suggested that fgf16 may promote cell proliferation in the forebrain and midbrain. fgf16 morphants were also assayed for apoptotic cells via TUNEL labeling at 24 hpf. The number of apoptotic cells in the forebrain and midbrain was slightly higher in the fgf16 morphants than in the wild-type embryos (n = 6/6)(Fig. S1A, B).


Fgf16 is required for specification of GABAergic neurons and oligodendrocytes in the zebrafish forebrain.

Miyake A, Chitose T, Kamei E, Murakami A, Nakayama Y, Konishi M, Itoh N - PLoS ONE (2014)

Comparison of cell proliferation and cell death patterns in control embryos and fgf16 morphants.(A, B) Control embryos (A) and embryos injected with fgf16 MO (B) were stained using an anti-H3P antibody. Panels show representative horizontal sections of the head region at 24 hpf. (C, D) The percentage of proliferating cells labelled with the anti-pH3 antibody in the forebrain (C) and midbrain (D) of control embryos and embryos injected with fgf16 MO. Results are the mean ± S.D. for three independent sections from three embryos. The significance of differences in mean values was assessed with the Student’s t-test. Asterisks indicate significant differences from the control (*P<0.05). The forebrain (fb) and midbrain (mb) regions, which we defined in the sections, are separated by black lines. Scale bar: 25 µm.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4214708&req=5

pone-0110836-g003: Comparison of cell proliferation and cell death patterns in control embryos and fgf16 morphants.(A, B) Control embryos (A) and embryos injected with fgf16 MO (B) were stained using an anti-H3P antibody. Panels show representative horizontal sections of the head region at 24 hpf. (C, D) The percentage of proliferating cells labelled with the anti-pH3 antibody in the forebrain (C) and midbrain (D) of control embryos and embryos injected with fgf16 MO. Results are the mean ± S.D. for three independent sections from three embryos. The significance of differences in mean values was assessed with the Student’s t-test. Asterisks indicate significant differences from the control (*P<0.05). The forebrain (fb) and midbrain (mb) regions, which we defined in the sections, are separated by black lines. Scale bar: 25 µm.
Mentions: Fgf signaling has been shown to regulate cell proliferation and cell survival in the brains of mice and zebrafish [8], [55], [56]. fgf16 is also required for cell proliferation in the mesenchyme of fin buds [29]. Therefore, the morphological abnormalities observed in the forebrain and midbrain of fgf16 morphants at 24 hpf may have been due to a defect in cell proliferation and/or cell survival in these regions. To examine this, we compared the number of mitotic cells in wild-type embryos and fgf16 morphants. Phosphorylated histone H3 (pH3) was specifically detected in the mitotic cells in mitotic phase (M-phase) [57]. We identified proliferating cells as pH3-positive cells. The rate of pH3-positive cells in the forebrain of fgf16 morphants was significantly lower than that in wild-type embryos at 24 hpf (Fig. 3A–C). In addition, the rate of pH3-positive cells in the midbrain was significantly decreased in fgf16 morphants (Fig. 3A, B, D). These results suggested that fgf16 may promote cell proliferation in the forebrain and midbrain. fgf16 morphants were also assayed for apoptotic cells via TUNEL labeling at 24 hpf. The number of apoptotic cells in the forebrain and midbrain was slightly higher in the fgf16 morphants than in the wild-type embryos (n = 6/6)(Fig. S1A, B).

Bottom Line: The knockdown of fgf16 decreased cell proliferation in the forebrain and midbrain. fgf16 was also essential for development of the ventral telencephalon and diencephalon, whereas fgf16 was not required for dorsoventral patterning in the midbrain. fgf16 was additionally required for the specification and differentiation of γ-aminobutyric acid (GABA)ergic interneurons and oligodendrocytes, but not for those of glutamatergic neurons in the forebrain.The fgf16 morphant phenotype was similar to that of the fgf19 morphant and embryos blocked Hh signaling.The results of the present study indicate that Fgf16 signaling, which is regulated by the downstream pathways of Hh-Fgf19 in the forebrain, is involved in forebrain development.

View Article: PubMed Central - PubMed

Affiliation: Department of Genetic Biochemistry, Kyoto University Graduate School of Pharmaceutical Sciences, Sakyo, Kyoto, Japan.

ABSTRACT
Fibroblast growth factor (Fgf) signaling plays crucial roles in various developmental processes including those in the brain. We examined the role of Fgf16 in the formation of the zebrafish brain. The knockdown of fgf16 decreased cell proliferation in the forebrain and midbrain. fgf16 was also essential for development of the ventral telencephalon and diencephalon, whereas fgf16 was not required for dorsoventral patterning in the midbrain. fgf16 was additionally required for the specification and differentiation of γ-aminobutyric acid (GABA)ergic interneurons and oligodendrocytes, but not for those of glutamatergic neurons in the forebrain. Cross talk between Fgf and Hedgehog (Hh) signaling was critical for the specification of GABAergic interneurons and oligodendrocytes. The expression of fgf16 in the forebrain was down-regulated by the inhibition of Hh and Fgf19 signaling, but not by that of Fgf3/Fgf8 signaling. The fgf16 morphant phenotype was similar to that of the fgf19 morphant and embryos blocked Hh signaling. The results of the present study indicate that Fgf16 signaling, which is regulated by the downstream pathways of Hh-Fgf19 in the forebrain, is involved in forebrain development.

Show MeSH
Related in: MedlinePlus