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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

Loss of pes function reduces oligodendrocyte gene expression.Transverse sections through spinal cords of 4 dpf wild-type (A–C) and pesvu166−/− (D–F) larvae processed for in situ RNA hybridization. Arrowheads indicate oligodendrocytes. Reaction products are greatly reduced in mutant relative to wild type. (G) Average number of labeled cells in the dorsal and ventral spinal cord. Ten sections from ten larvae of each genotype were counted. Asterisk (*) indicates p≪0.05 by Student's T-test. (H) Relative expression levels of the CNS myelin genes mpz and 36k measured by quantitative PCR.
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pone-0032317-g003: Loss of pes function reduces oligodendrocyte gene expression.Transverse sections through spinal cords of 4 dpf wild-type (A–C) and pesvu166−/− (D–F) larvae processed for in situ RNA hybridization. Arrowheads indicate oligodendrocytes. Reaction products are greatly reduced in mutant relative to wild type. (G) Average number of labeled cells in the dorsal and ventral spinal cord. Ten sections from ten larvae of each genotype were counted. Asterisk (*) indicates p≪0.05 by Student's T-test. (H) Relative expression levels of the CNS myelin genes mpz and 36k measured by quantitative PCR.

Mentions: The deficit of white matter oligodendrocyte lineage cells raised the possibility that pes mutant larvae have a deficit of myelination. To test this, we performed in situ RNA hybridization to detect expression of genes characteristic of differentiating oligodendrocytes. Whereas mutant and wild-type larvae had similar number of ventral mbp+ cells, mutant larvae had significantly fewer dorsal mbp+ cells and fewer ventral and dorsal plp1a+ and cldnk+ cells than wild type (Figure 3A–G). Additionally, the amount of reaction product detected in individual cells of mutant larvae was substantially less that in wild-type larvae for all three probes, including cells that occupied their normal positions near the pial surface (Figure 3A–F). Although the apparent reduction of reaction product could result from decreased probe penetration in mutant larvae, a sox2 RNA probe detected higher levels of gene expression in mutants than in wild-type (see below). To further investigate oligodendrocyte differentiation, we performed quantitative real-time PCR to assay the relative expression levels of the CNS myelin genes myelin protein zero (mpz) and 36K at 4 dpf. Both genes were expressed at levels fourfold lower in mutant larvae relative to wild type (Figure 3H). Therefore, pes function is necessary both for the proper number and distribution of oligodendrocyte lineage cells and for oligodendrocyte differentiation.


Mutation of pescadillo disrupts oligodendrocyte formation in zebrafish.

Simmons T, Appel B - PLoS ONE (2012)

Loss of pes function reduces oligodendrocyte gene expression.Transverse sections through spinal cords of 4 dpf wild-type (A–C) and pesvu166−/− (D–F) larvae processed for in situ RNA hybridization. Arrowheads indicate oligodendrocytes. Reaction products are greatly reduced in mutant relative to wild type. (G) Average number of labeled cells in the dorsal and ventral spinal cord. Ten sections from ten larvae of each genotype were counted. Asterisk (*) indicates p≪0.05 by Student's T-test. (H) Relative expression levels of the CNS myelin genes mpz and 36k measured by quantitative PCR.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3285679&req=5

pone-0032317-g003: Loss of pes function reduces oligodendrocyte gene expression.Transverse sections through spinal cords of 4 dpf wild-type (A–C) and pesvu166−/− (D–F) larvae processed for in situ RNA hybridization. Arrowheads indicate oligodendrocytes. Reaction products are greatly reduced in mutant relative to wild type. (G) Average number of labeled cells in the dorsal and ventral spinal cord. Ten sections from ten larvae of each genotype were counted. Asterisk (*) indicates p≪0.05 by Student's T-test. (H) Relative expression levels of the CNS myelin genes mpz and 36k measured by quantitative PCR.
Mentions: The deficit of white matter oligodendrocyte lineage cells raised the possibility that pes mutant larvae have a deficit of myelination. To test this, we performed in situ RNA hybridization to detect expression of genes characteristic of differentiating oligodendrocytes. Whereas mutant and wild-type larvae had similar number of ventral mbp+ cells, mutant larvae had significantly fewer dorsal mbp+ cells and fewer ventral and dorsal plp1a+ and cldnk+ cells than wild type (Figure 3A–G). Additionally, the amount of reaction product detected in individual cells of mutant larvae was substantially less that in wild-type larvae for all three probes, including cells that occupied their normal positions near the pial surface (Figure 3A–F). Although the apparent reduction of reaction product could result from decreased probe penetration in mutant larvae, a sox2 RNA probe detected higher levels of gene expression in mutants than in wild-type (see below). To further investigate oligodendrocyte differentiation, we performed quantitative real-time PCR to assay the relative expression levels of the CNS myelin genes myelin protein zero (mpz) and 36K at 4 dpf. Both genes were expressed at levels fourfold lower in mutant larvae relative to wild type (Figure 3H). Therefore, pes function is necessary both for the proper number and distribution of oligodendrocyte lineage cells and for oligodendrocyte differentiation.

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