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Mutation of pescadillo disrupts oligodendrocyte formation in zebrafish.

Simmons T, Appel B - PLoS ONE (2012)

Bottom Line: During embryogenesis, ventral neural tube precursors give rise to oligodendrocyte progenitor cells, which divide and migrate throughout the central nervous system.We found that pescadillo function is required for both the proper number of oligodendrocyte progenitors to form, by regulating cell cycle progression, and for normal levels of myelin gene expression.Our data provide evidence that neural precursors require pes function to progress through the cell cycle and produce oligodendrocyte progenitor cells and for oligodendrocyte differentiation.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, United States of America.

ABSTRACT

Background: In vertebrates, the myelin sheath is essential for efficient propagation of action potentials along the axon shaft. Oligodendrocytes are the cells of the central nervous system that create myelin sheaths. During embryogenesis, ventral neural tube precursors give rise to oligodendrocyte progenitor cells, which divide and migrate throughout the central nervous system. This study aimed to investigate mechanisms that regulate oligodendrocyte progenitor cell formation.

Methodology/principal findings: By conducting a mutagenesis screen in transgenic zebrafish, we identified a mutation, designated vu166, by an apparent reduction in the number of oligodendrocyte progenitor cells in the dorsal spinal cord. We subsequently determined that vu166 is an allele of pescadillo, a gene known to play a role in ribosome biogenesis and cell proliferation. We found that pescadillo function is required for both the proper number of oligodendrocyte progenitors to form, by regulating cell cycle progression, and for normal levels of myelin gene expression.

Conclusions/significance: Our data provide evidence that neural precursors require pes function to progress through the cell cycle and produce oligodendrocyte progenitor cells and for oligodendrocyte differentiation.

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Related in: MedlinePlus

Markers of cell cycle activity are significantly increased in the spinal cords of pesvu166−/− embryos.(A–H) Transverse sections through the spinal cords of 3 dpf (A,B), 4 dpf (C,D) and 2.5 dpf (E–H) larvae processed for immunohistochemistry. (A,C) Wild type spinal cord (dashed line) section showing BrdU+ (arrows) and BrdU− (arrowheads) olig2+, Sox10+ OPCs. (B,D) pesvu166−/− spinal cord sections. OPCs did not incorporate BrdU but numerous cells lining the central canal and medial septum were BrdU+. (E,F) Representative spinal cord sections showing the M-phase marker PH-3. (G,H) Representative spinal cord sections showing TUNEL labeling (red) to mark apoptotic cells. DAPI labeling (blue) marks cell nuclei. (I) Quantification of the change in total BrdU+ and PH-3+ cells between wild-type and pesvu166−/− spinal cords. (J) Quantification of DAPI+ and TUNEL+ cells in wild-type and mutant spinal cords. Asterisk (*) indicates p≪0.05 by Student's T-test.
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pone-0032317-g004: Markers of cell cycle activity are significantly increased in the spinal cords of pesvu166−/− embryos.(A–H) Transverse sections through the spinal cords of 3 dpf (A,B), 4 dpf (C,D) and 2.5 dpf (E–H) larvae processed for immunohistochemistry. (A,C) Wild type spinal cord (dashed line) section showing BrdU+ (arrows) and BrdU− (arrowheads) olig2+, Sox10+ OPCs. (B,D) pesvu166−/− spinal cord sections. OPCs did not incorporate BrdU but numerous cells lining the central canal and medial septum were BrdU+. (E,F) Representative spinal cord sections showing the M-phase marker PH-3. (G,H) Representative spinal cord sections showing TUNEL labeling (red) to mark apoptotic cells. DAPI labeling (blue) marks cell nuclei. (I) Quantification of the change in total BrdU+ and PH-3+ cells between wild-type and pesvu166−/− spinal cords. (J) Quantification of DAPI+ and TUNEL+ cells in wild-type and mutant spinal cords. Asterisk (*) indicates p≪0.05 by Student's T-test.

Mentions: The reduction in dorsal OPCs and the previously proposed role of pes in cell proliferation [12] raised the possibility that pes function is necessary for the division of OPCs after they migrate out of the pMN domain. To assay the proliferation of OPCs in mutant larvae we exposed the larvae to the thymidine analogue BrdU, an S-phase marker, at various time-points during early development. In wild-type larvae, most OPCs were labeled with BrdU when the pulses were conducted between 52 and 96 hours post fertilization (hpf), and these labeled OPCs represented the vast majority of the BrdU+ cells in the spinal cord (Figure 4A,C and data not shown). Consistent with a requirement for pes in cell division, there were no BrdU positive OPCs in the spinal cords of mutant larvae. However, this experiment revealed that mutant spinal cords had a five-fold increase in the total number of BrdU+ cells, which were mostly adjacent to the central canal and medial septum (Figure 4B,D,I). Additionally, the number of cells that were labeled by the M-phase marker phosphohistone H-3 (PH-3) (Figure 4E,F) was dramatically increased in mutants (Figure 4I). Nevertheless, there was no significant difference in the total number of spinal cord cells between mutant and wild type (Figure 4J).


Mutation of pescadillo disrupts oligodendrocyte formation in zebrafish.

Simmons T, Appel B - PLoS ONE (2012)

Markers of cell cycle activity are significantly increased in the spinal cords of pesvu166−/− embryos.(A–H) Transverse sections through the spinal cords of 3 dpf (A,B), 4 dpf (C,D) and 2.5 dpf (E–H) larvae processed for immunohistochemistry. (A,C) Wild type spinal cord (dashed line) section showing BrdU+ (arrows) and BrdU− (arrowheads) olig2+, Sox10+ OPCs. (B,D) pesvu166−/− spinal cord sections. OPCs did not incorporate BrdU but numerous cells lining the central canal and medial septum were BrdU+. (E,F) Representative spinal cord sections showing the M-phase marker PH-3. (G,H) Representative spinal cord sections showing TUNEL labeling (red) to mark apoptotic cells. DAPI labeling (blue) marks cell nuclei. (I) Quantification of the change in total BrdU+ and PH-3+ cells between wild-type and pesvu166−/− spinal cords. (J) Quantification of DAPI+ and TUNEL+ cells in wild-type and mutant spinal cords. Asterisk (*) indicates p≪0.05 by Student's T-test.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3285679&req=5

pone-0032317-g004: Markers of cell cycle activity are significantly increased in the spinal cords of pesvu166−/− embryos.(A–H) Transverse sections through the spinal cords of 3 dpf (A,B), 4 dpf (C,D) and 2.5 dpf (E–H) larvae processed for immunohistochemistry. (A,C) Wild type spinal cord (dashed line) section showing BrdU+ (arrows) and BrdU− (arrowheads) olig2+, Sox10+ OPCs. (B,D) pesvu166−/− spinal cord sections. OPCs did not incorporate BrdU but numerous cells lining the central canal and medial septum were BrdU+. (E,F) Representative spinal cord sections showing the M-phase marker PH-3. (G,H) Representative spinal cord sections showing TUNEL labeling (red) to mark apoptotic cells. DAPI labeling (blue) marks cell nuclei. (I) Quantification of the change in total BrdU+ and PH-3+ cells between wild-type and pesvu166−/− spinal cords. (J) Quantification of DAPI+ and TUNEL+ cells in wild-type and mutant spinal cords. Asterisk (*) indicates p≪0.05 by Student's T-test.
Mentions: The reduction in dorsal OPCs and the previously proposed role of pes in cell proliferation [12] raised the possibility that pes function is necessary for the division of OPCs after they migrate out of the pMN domain. To assay the proliferation of OPCs in mutant larvae we exposed the larvae to the thymidine analogue BrdU, an S-phase marker, at various time-points during early development. In wild-type larvae, most OPCs were labeled with BrdU when the pulses were conducted between 52 and 96 hours post fertilization (hpf), and these labeled OPCs represented the vast majority of the BrdU+ cells in the spinal cord (Figure 4A,C and data not shown). Consistent with a requirement for pes in cell division, there were no BrdU positive OPCs in the spinal cords of mutant larvae. However, this experiment revealed that mutant spinal cords had a five-fold increase in the total number of BrdU+ cells, which were mostly adjacent to the central canal and medial septum (Figure 4B,D,I). Additionally, the number of cells that were labeled by the M-phase marker phosphohistone H-3 (PH-3) (Figure 4E,F) was dramatically increased in mutants (Figure 4I). Nevertheless, there was no significant difference in the total number of spinal cord cells between mutant and wild type (Figure 4J).

Bottom Line: During embryogenesis, ventral neural tube precursors give rise to oligodendrocyte progenitor cells, which divide and migrate throughout the central nervous system.We found that pescadillo function is required for both the proper number of oligodendrocyte progenitors to form, by regulating cell cycle progression, and for normal levels of myelin gene expression.Our data provide evidence that neural precursors require pes function to progress through the cell cycle and produce oligodendrocyte progenitor cells and for oligodendrocyte differentiation.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, United States of America.

ABSTRACT

Background: In vertebrates, the myelin sheath is essential for efficient propagation of action potentials along the axon shaft. Oligodendrocytes are the cells of the central nervous system that create myelin sheaths. During embryogenesis, ventral neural tube precursors give rise to oligodendrocyte progenitor cells, which divide and migrate throughout the central nervous system. This study aimed to investigate mechanisms that regulate oligodendrocyte progenitor cell formation.

Methodology/principal findings: By conducting a mutagenesis screen in transgenic zebrafish, we identified a mutation, designated vu166, by an apparent reduction in the number of oligodendrocyte progenitor cells in the dorsal spinal cord. We subsequently determined that vu166 is an allele of pescadillo, a gene known to play a role in ribosome biogenesis and cell proliferation. We found that pescadillo function is required for both the proper number of oligodendrocyte progenitors to form, by regulating cell cycle progression, and for normal levels of myelin gene expression.

Conclusions/significance: Our data provide evidence that neural precursors require pes function to progress through the cell cycle and produce oligodendrocyte progenitor cells and for oligodendrocyte differentiation.

Show MeSH
Related in: MedlinePlus