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The transcription factors Sox10 and Myrf define an essential regulatory network module in differentiating oligodendrocytes.

Hornig J, Fröb F, Vogl MR, Hermans-Borgmeyer I, Tamm ER, Wegner M - PLoS Genet. (2013)

Bottom Line: Once induced, Myrf cooperates with Sox10 to implement the myelination program as evident from the physical interaction between both proteins and the synergistic activation of several myelin-specific genes.This is strongly reminiscent of the situation in Schwann cells where Sox10 first induces and then cooperates with Krox20 during myelination.Our analyses indicate that the regulatory network for myelination in oligodendrocytes is organized along similar general principles as the one in Schwann cells, but is differentially implemented.

View Article: PubMed Central - PubMed

Affiliation: Institut für Biochemie, Emil-Fischer-Zentrum, Universität Erlangen-Nürnberg, Erlangen, Germany.

ABSTRACT
Myelin is essential for rapid saltatory conduction and is produced by Schwann cells in the peripheral nervous system and oligodendrocytes in the central nervous system. In both cell types the transcription factor Sox10 is an essential component of the myelin-specific regulatory network. Here we identify Myrf as an oligodendrocyte-specific target of Sox10 and map a Sox10 responsive enhancer to an evolutionarily conserved element in intron 1 of the Myrf gene. Once induced, Myrf cooperates with Sox10 to implement the myelination program as evident from the physical interaction between both proteins and the synergistic activation of several myelin-specific genes. This is strongly reminiscent of the situation in Schwann cells where Sox10 first induces and then cooperates with Krox20 during myelination. Our analyses indicate that the regulatory network for myelination in oligodendrocytes is organized along similar general principles as the one in Schwann cells, but is differentially implemented.

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Related in: MedlinePlus

ECR9 is an OL enhancer in vivo.(A) Schematic representation of the transgenic constructs consisting of ECR9 in wildtype (ECR9wt) or mutant (ECR9mt) version, the minimal Hsp68 promoter (hsp68), the lacZ marker gene (lacZ) and a SV40 polyA signal (pA). Original Sox binding sites are marked in dark red, inactivated ones in light red. (B) Summary of lacZ expression patterns in ECR9wt-lacZ and ECR9mt-lacZ transgenic animals as determined by X-gal staining and immunohistochemistry on transverse sections at P7. (C,D) Detection of lacZ expression by X-gal staining of transverse sections from the forelimb level of seven day old pups carrying the ECR9wt-lacZ (animal #1) (C) or the ECR9mt-lacZ (animal #2) (D) transgene. Only spinal cord and adjacent tissues are shown. Size bar, 200 µm. (E–J) Co-immunohistochemistry was performed on transverse sections of ECR9wt-lacZ transgenic animal #1 using antibodies directed against β-galactosidase (in red) in combination with antibodies directed against Sox10 (E), Olig2 (F), Myrf (G), Pdgfra (H), Gfap (I), and NeuN (J) (all in green). Pictures were taken from the dorsal funiculus for E–I and from the ventral grey matter for J. Size bars correspond to 10 µm.
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pgen-1003907-g006: ECR9 is an OL enhancer in vivo.(A) Schematic representation of the transgenic constructs consisting of ECR9 in wildtype (ECR9wt) or mutant (ECR9mt) version, the minimal Hsp68 promoter (hsp68), the lacZ marker gene (lacZ) and a SV40 polyA signal (pA). Original Sox binding sites are marked in dark red, inactivated ones in light red. (B) Summary of lacZ expression patterns in ECR9wt-lacZ and ECR9mt-lacZ transgenic animals as determined by X-gal staining and immunohistochemistry on transverse sections at P7. (C,D) Detection of lacZ expression by X-gal staining of transverse sections from the forelimb level of seven day old pups carrying the ECR9wt-lacZ (animal #1) (C) or the ECR9mt-lacZ (animal #2) (D) transgene. Only spinal cord and adjacent tissues are shown. Size bar, 200 µm. (E–J) Co-immunohistochemistry was performed on transverse sections of ECR9wt-lacZ transgenic animal #1 using antibodies directed against β-galactosidase (in red) in combination with antibodies directed against Sox10 (E), Olig2 (F), Myrf (G), Pdgfra (H), Gfap (I), and NeuN (J) (all in green). Pictures were taken from the dorsal funiculus for E–I and from the ventral grey matter for J. Size bars correspond to 10 µm.

Mentions: Both the wildtype ECR9 and the variant with inactivated monomer and dimer sites were combined with the Hsp68 minimal promoter and a lacZ reporter in a transgenic construct and used for the generation of transgenic animals by pronucleus injection (Figure 6A). The Hsp68 minimal promoter was used because it has low activity and causes little ectopic expression in transgenic mice when combined with a lacZ reporter [30], [31]. For wildtype ECR9, eight transgenic animals were obtained and killed for analysis at P7. X-gal staining revealed expression of the lacZ transgene in five of these animals (Figure 6B). All five exhibited transgene expression in oligodendroglial cells despite some variability in expression levels and occurrence of additional expression sites (Figure 6B,C). For four animals there was additional lacZ expression in a subset of spinal cord neurons and/or in PNS glia. One showed transgene expression in cartilage. None of these sites express Myrf normally [19]. The appearance of ectopic expression sites in this kind of analysis is common and likely results from the fact that additional regulatory sequences of the Myrf gene were missing or that the native chromatin context was not preserved in the transgenic construct.


The transcription factors Sox10 and Myrf define an essential regulatory network module in differentiating oligodendrocytes.

Hornig J, Fröb F, Vogl MR, Hermans-Borgmeyer I, Tamm ER, Wegner M - PLoS Genet. (2013)

ECR9 is an OL enhancer in vivo.(A) Schematic representation of the transgenic constructs consisting of ECR9 in wildtype (ECR9wt) or mutant (ECR9mt) version, the minimal Hsp68 promoter (hsp68), the lacZ marker gene (lacZ) and a SV40 polyA signal (pA). Original Sox binding sites are marked in dark red, inactivated ones in light red. (B) Summary of lacZ expression patterns in ECR9wt-lacZ and ECR9mt-lacZ transgenic animals as determined by X-gal staining and immunohistochemistry on transverse sections at P7. (C,D) Detection of lacZ expression by X-gal staining of transverse sections from the forelimb level of seven day old pups carrying the ECR9wt-lacZ (animal #1) (C) or the ECR9mt-lacZ (animal #2) (D) transgene. Only spinal cord and adjacent tissues are shown. Size bar, 200 µm. (E–J) Co-immunohistochemistry was performed on transverse sections of ECR9wt-lacZ transgenic animal #1 using antibodies directed against β-galactosidase (in red) in combination with antibodies directed against Sox10 (E), Olig2 (F), Myrf (G), Pdgfra (H), Gfap (I), and NeuN (J) (all in green). Pictures were taken from the dorsal funiculus for E–I and from the ventral grey matter for J. Size bars correspond to 10 µm.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3814293&req=5

pgen-1003907-g006: ECR9 is an OL enhancer in vivo.(A) Schematic representation of the transgenic constructs consisting of ECR9 in wildtype (ECR9wt) or mutant (ECR9mt) version, the minimal Hsp68 promoter (hsp68), the lacZ marker gene (lacZ) and a SV40 polyA signal (pA). Original Sox binding sites are marked in dark red, inactivated ones in light red. (B) Summary of lacZ expression patterns in ECR9wt-lacZ and ECR9mt-lacZ transgenic animals as determined by X-gal staining and immunohistochemistry on transverse sections at P7. (C,D) Detection of lacZ expression by X-gal staining of transverse sections from the forelimb level of seven day old pups carrying the ECR9wt-lacZ (animal #1) (C) or the ECR9mt-lacZ (animal #2) (D) transgene. Only spinal cord and adjacent tissues are shown. Size bar, 200 µm. (E–J) Co-immunohistochemistry was performed on transverse sections of ECR9wt-lacZ transgenic animal #1 using antibodies directed against β-galactosidase (in red) in combination with antibodies directed against Sox10 (E), Olig2 (F), Myrf (G), Pdgfra (H), Gfap (I), and NeuN (J) (all in green). Pictures were taken from the dorsal funiculus for E–I and from the ventral grey matter for J. Size bars correspond to 10 µm.
Mentions: Both the wildtype ECR9 and the variant with inactivated monomer and dimer sites were combined with the Hsp68 minimal promoter and a lacZ reporter in a transgenic construct and used for the generation of transgenic animals by pronucleus injection (Figure 6A). The Hsp68 minimal promoter was used because it has low activity and causes little ectopic expression in transgenic mice when combined with a lacZ reporter [30], [31]. For wildtype ECR9, eight transgenic animals were obtained and killed for analysis at P7. X-gal staining revealed expression of the lacZ transgene in five of these animals (Figure 6B). All five exhibited transgene expression in oligodendroglial cells despite some variability in expression levels and occurrence of additional expression sites (Figure 6B,C). For four animals there was additional lacZ expression in a subset of spinal cord neurons and/or in PNS glia. One showed transgene expression in cartilage. None of these sites express Myrf normally [19]. The appearance of ectopic expression sites in this kind of analysis is common and likely results from the fact that additional regulatory sequences of the Myrf gene were missing or that the native chromatin context was not preserved in the transgenic construct.

Bottom Line: Once induced, Myrf cooperates with Sox10 to implement the myelination program as evident from the physical interaction between both proteins and the synergistic activation of several myelin-specific genes.This is strongly reminiscent of the situation in Schwann cells where Sox10 first induces and then cooperates with Krox20 during myelination.Our analyses indicate that the regulatory network for myelination in oligodendrocytes is organized along similar general principles as the one in Schwann cells, but is differentially implemented.

View Article: PubMed Central - PubMed

Affiliation: Institut für Biochemie, Emil-Fischer-Zentrum, Universität Erlangen-Nürnberg, Erlangen, Germany.

ABSTRACT
Myelin is essential for rapid saltatory conduction and is produced by Schwann cells in the peripheral nervous system and oligodendrocytes in the central nervous system. In both cell types the transcription factor Sox10 is an essential component of the myelin-specific regulatory network. Here we identify Myrf as an oligodendrocyte-specific target of Sox10 and map a Sox10 responsive enhancer to an evolutionarily conserved element in intron 1 of the Myrf gene. Once induced, Myrf cooperates with Sox10 to implement the myelination program as evident from the physical interaction between both proteins and the synergistic activation of several myelin-specific genes. This is strongly reminiscent of the situation in Schwann cells where Sox10 first induces and then cooperates with Krox20 during myelination. Our analyses indicate that the regulatory network for myelination in oligodendrocytes is organized along similar general principles as the one in Schwann cells, but is differentially implemented.

Show MeSH
Related in: MedlinePlus