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B1 SOX coordinate cell specification with patterning and morphogenesis in the early zebrafish embryo.

Okuda Y, Ogura E, Kondoh H, Kamachi Y - PLoS Genet. (2010)

Bottom Line: Chromatin immunoprecipitation analysis of the her3, hesx1, neurog1, pcdh18a, and cyp26a1 genes further suggests a direct regulation of these genes by B1 SOX.We also found an interesting overlap between the early phenotypes of the B1 sox quadruple knockdown embryos and the maternal-zygotic spg embryos that are devoid of pou5f1 activity.These findings indicate that the B1 SOX proteins control a wide range of developmental regulators in the early embryo through partnering in part with Pou5f1 and possibly with other factors, and suggest that the B1 sox functions are central to coordinating cell fate specification with patterning and morphogenetic processes occurring in the early embryo.

View Article: PubMed Central - PubMed

Affiliation: Graduate School of Frontier Biosciences, Osaka University, Suita, Japan.

ABSTRACT
The B1 SOX transcription factors SOX1/2/3/19 have been implicated in various processes of early embryogenesis. However, their regulatory functions in stages from the blastula to early neurula remain largely unknown, primarily because loss-of-function studies have not been informative to date. In our present study, we systematically knocked down the B1 sox genes in zebrafish. Only the quadruple knockdown of the four B1 sox genes sox2/3/19a/19b resulted in very severe developmental abnormalities, confirming that the B1 sox genes are functionally redundant. We characterized the sox2/3/19a/19b quadruple knockdown embryos in detail by examining the changes in gene expression through in situ hybridization, RT-PCR, and microarray analyses. Importantly, these phenotypic analyses revealed that the B1 SOX proteins regulate the following distinct processes: (1) early dorsoventral patterning by controlling bmp2b/7; (2) gastrulation movements via the regulation of pcdh18a/18b and wnt11, a non-canonical Wnt ligand gene; (3) neural differentiation by regulating the Hes-class bHLH gene her3 and the proneural-class bHLH genes neurog1 (positively) and ascl1a (negatively), and regional transcription factor genes, e.g., hesx1, zic1, and rx3; and (4) neural patterning by regulating signaling pathway genes, cyp26a1 in RA signaling, oep in Nodal signaling, shh, and mdkb. Chromatin immunoprecipitation analysis of the her3, hesx1, neurog1, pcdh18a, and cyp26a1 genes further suggests a direct regulation of these genes by B1 SOX. We also found an interesting overlap between the early phenotypes of the B1 sox quadruple knockdown embryos and the maternal-zygotic spg embryos that are devoid of pou5f1 activity. These findings indicate that the B1 SOX proteins control a wide range of developmental regulators in the early embryo through partnering in part with Pou5f1 and possibly with other factors, and suggest that the B1 sox functions are central to coordinating cell fate specification with patterning and morphogenetic processes occurring in the early embryo.

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Impairment of neural development in the QKD embryos.(A) Altered expression of genes involved in neural differentiation. RT-PCR analysis of the indicated genes was performed as described in Figure 4C. (B) Effects of B1 sox QKD on neural bHLH gene expression. The her3 expression is totally lost in the QKD embryos (a–c), whereas ascl1a is transiently upregulated at 75%E in a broad area of the neuroectoderm (d–f). (C) The loss of cyp26a1 expression in the anterior neuroectoderm (a, b) and evidence of hindbrain patterning defects: expansion of hoxb1a expression (c) and a severe reduction of mafba expression (d). (D) The loss of expression of oep and shha/b in the neuroectoderm of the QKD embryos. (a–d) In the QKD embryos, the expression of oep is lost in the ectoderm at the shield stage (b) and the neuroectoderm at the 75%E and tailbud stages (c, d) (marked by open arrowheads in b’–d’), whereas its initial zygotic expression (a) and mesodermal expression (b–d) are maintained (closed arrowheads in a’–d’). (e) ndr2 is also expressed in the QKD mesoderm at normal levels. (f–i) The expression of shha/b in the neuroectoderm is lost (marked by open arrowheads in f’–i’), whereas that in the mesoderm is retained (closed arrowheads in f’–i’). (E) The loss of mdkb expression in the neuroectoderm and severe reduction of foxd3 expression in the neural crest cells of QKD embryos.
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pgen-1000936-g005: Impairment of neural development in the QKD embryos.(A) Altered expression of genes involved in neural differentiation. RT-PCR analysis of the indicated genes was performed as described in Figure 4C. (B) Effects of B1 sox QKD on neural bHLH gene expression. The her3 expression is totally lost in the QKD embryos (a–c), whereas ascl1a is transiently upregulated at 75%E in a broad area of the neuroectoderm (d–f). (C) The loss of cyp26a1 expression in the anterior neuroectoderm (a, b) and evidence of hindbrain patterning defects: expansion of hoxb1a expression (c) and a severe reduction of mafba expression (d). (D) The loss of expression of oep and shha/b in the neuroectoderm of the QKD embryos. (a–d) In the QKD embryos, the expression of oep is lost in the ectoderm at the shield stage (b) and the neuroectoderm at the 75%E and tailbud stages (c, d) (marked by open arrowheads in b’–d’), whereas its initial zygotic expression (a) and mesodermal expression (b–d) are maintained (closed arrowheads in a’–d’). (e) ndr2 is also expressed in the QKD mesoderm at normal levels. (f–i) The expression of shha/b in the neuroectoderm is lost (marked by open arrowheads in f’–i’), whereas that in the mesoderm is retained (closed arrowheads in f’–i’). (E) The loss of mdkb expression in the neuroectoderm and severe reduction of foxd3 expression in the neural crest cells of QKD embryos.

Mentions: Several neuronal genes were found to be abnormally upregulated in the QKD embryos. stmn2a is strongly expressed in CNS neurons from mid-somitogenesis stages in wild-type embryos [45] and also weakly expressed throughout the embryo at epiboly stages (Figure 5A and Figure S7A). The latter early stage expression was found to be aberrantly upregulated in the QKD embryos (Figure 5A and Figure S7A). The neuronal tuba1 gene was also upregulated from 75%E (Figure 5A). These observations suggest that a portion of the neuronal differentiation programs is precociously initiated in the QKD embryos.


B1 SOX coordinate cell specification with patterning and morphogenesis in the early zebrafish embryo.

Okuda Y, Ogura E, Kondoh H, Kamachi Y - PLoS Genet. (2010)

Impairment of neural development in the QKD embryos.(A) Altered expression of genes involved in neural differentiation. RT-PCR analysis of the indicated genes was performed as described in Figure 4C. (B) Effects of B1 sox QKD on neural bHLH gene expression. The her3 expression is totally lost in the QKD embryos (a–c), whereas ascl1a is transiently upregulated at 75%E in a broad area of the neuroectoderm (d–f). (C) The loss of cyp26a1 expression in the anterior neuroectoderm (a, b) and evidence of hindbrain patterning defects: expansion of hoxb1a expression (c) and a severe reduction of mafba expression (d). (D) The loss of expression of oep and shha/b in the neuroectoderm of the QKD embryos. (a–d) In the QKD embryos, the expression of oep is lost in the ectoderm at the shield stage (b) and the neuroectoderm at the 75%E and tailbud stages (c, d) (marked by open arrowheads in b’–d’), whereas its initial zygotic expression (a) and mesodermal expression (b–d) are maintained (closed arrowheads in a’–d’). (e) ndr2 is also expressed in the QKD mesoderm at normal levels. (f–i) The expression of shha/b in the neuroectoderm is lost (marked by open arrowheads in f’–i’), whereas that in the mesoderm is retained (closed arrowheads in f’–i’). (E) The loss of mdkb expression in the neuroectoderm and severe reduction of foxd3 expression in the neural crest cells of QKD embryos.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2865518&req=5

pgen-1000936-g005: Impairment of neural development in the QKD embryos.(A) Altered expression of genes involved in neural differentiation. RT-PCR analysis of the indicated genes was performed as described in Figure 4C. (B) Effects of B1 sox QKD on neural bHLH gene expression. The her3 expression is totally lost in the QKD embryos (a–c), whereas ascl1a is transiently upregulated at 75%E in a broad area of the neuroectoderm (d–f). (C) The loss of cyp26a1 expression in the anterior neuroectoderm (a, b) and evidence of hindbrain patterning defects: expansion of hoxb1a expression (c) and a severe reduction of mafba expression (d). (D) The loss of expression of oep and shha/b in the neuroectoderm of the QKD embryos. (a–d) In the QKD embryos, the expression of oep is lost in the ectoderm at the shield stage (b) and the neuroectoderm at the 75%E and tailbud stages (c, d) (marked by open arrowheads in b’–d’), whereas its initial zygotic expression (a) and mesodermal expression (b–d) are maintained (closed arrowheads in a’–d’). (e) ndr2 is also expressed in the QKD mesoderm at normal levels. (f–i) The expression of shha/b in the neuroectoderm is lost (marked by open arrowheads in f’–i’), whereas that in the mesoderm is retained (closed arrowheads in f’–i’). (E) The loss of mdkb expression in the neuroectoderm and severe reduction of foxd3 expression in the neural crest cells of QKD embryos.
Mentions: Several neuronal genes were found to be abnormally upregulated in the QKD embryos. stmn2a is strongly expressed in CNS neurons from mid-somitogenesis stages in wild-type embryos [45] and also weakly expressed throughout the embryo at epiboly stages (Figure 5A and Figure S7A). The latter early stage expression was found to be aberrantly upregulated in the QKD embryos (Figure 5A and Figure S7A). The neuronal tuba1 gene was also upregulated from 75%E (Figure 5A). These observations suggest that a portion of the neuronal differentiation programs is precociously initiated in the QKD embryos.

Bottom Line: Chromatin immunoprecipitation analysis of the her3, hesx1, neurog1, pcdh18a, and cyp26a1 genes further suggests a direct regulation of these genes by B1 SOX.We also found an interesting overlap between the early phenotypes of the B1 sox quadruple knockdown embryos and the maternal-zygotic spg embryos that are devoid of pou5f1 activity.These findings indicate that the B1 SOX proteins control a wide range of developmental regulators in the early embryo through partnering in part with Pou5f1 and possibly with other factors, and suggest that the B1 sox functions are central to coordinating cell fate specification with patterning and morphogenetic processes occurring in the early embryo.

View Article: PubMed Central - PubMed

Affiliation: Graduate School of Frontier Biosciences, Osaka University, Suita, Japan.

ABSTRACT
The B1 SOX transcription factors SOX1/2/3/19 have been implicated in various processes of early embryogenesis. However, their regulatory functions in stages from the blastula to early neurula remain largely unknown, primarily because loss-of-function studies have not been informative to date. In our present study, we systematically knocked down the B1 sox genes in zebrafish. Only the quadruple knockdown of the four B1 sox genes sox2/3/19a/19b resulted in very severe developmental abnormalities, confirming that the B1 sox genes are functionally redundant. We characterized the sox2/3/19a/19b quadruple knockdown embryos in detail by examining the changes in gene expression through in situ hybridization, RT-PCR, and microarray analyses. Importantly, these phenotypic analyses revealed that the B1 SOX proteins regulate the following distinct processes: (1) early dorsoventral patterning by controlling bmp2b/7; (2) gastrulation movements via the regulation of pcdh18a/18b and wnt11, a non-canonical Wnt ligand gene; (3) neural differentiation by regulating the Hes-class bHLH gene her3 and the proneural-class bHLH genes neurog1 (positively) and ascl1a (negatively), and regional transcription factor genes, e.g., hesx1, zic1, and rx3; and (4) neural patterning by regulating signaling pathway genes, cyp26a1 in RA signaling, oep in Nodal signaling, shh, and mdkb. Chromatin immunoprecipitation analysis of the her3, hesx1, neurog1, pcdh18a, and cyp26a1 genes further suggests a direct regulation of these genes by B1 SOX. We also found an interesting overlap between the early phenotypes of the B1 sox quadruple knockdown embryos and the maternal-zygotic spg embryos that are devoid of pou5f1 activity. These findings indicate that the B1 SOX proteins control a wide range of developmental regulators in the early embryo through partnering in part with Pou5f1 and possibly with other factors, and suggest that the B1 sox functions are central to coordinating cell fate specification with patterning and morphogenetic processes occurring in the early embryo.

Show MeSH
Related in: MedlinePlus