An N-ethyl-N-nitrosourea screen for genes involved in variegation in the mouse

ME Blewitt, NK Vickaryous, SJ Hemley, Alyson Ashe, TJ Bruxner, JI Preis, R Arkell, Emma Whitelaw

Research output: Contribution to journalArticleResearchpeer-review

Abstract

We have developed a sensitized screen to identify genes involved in gene silencing, using random N-ethyl-N-nitrosourea mutagenesis on mice carrying a variegating GFP transgene. The dominant screen has produced six mutant lines, including both suppressors and enhancers of variegation. All are semidominant and five of the six are homozygous embryonic lethal. In one case, the homozygous lethality depends on sex: homozygous females die at midgestation and display abnormal DNA methylation of the X chromosome, whereas homozygous males are viable. Linkage analysis reveals that the mutations map to unique chromosomal locations. We have studied the effect of five of the mutations on expression of an endogenous allele known to be sensitive to epigenetic state, agouti viable yellow. In all cases, there is an effect on penetrance, and in most cases, parent of origin and sex-specific effects are detected. This screen has identified genes that are involved in epigenetic reprogramming of the genome, and the behavior of the mutant lines suggests a common mechanism between X inactivation and transgene and retrotransposon silencing. Our findings raise the possibility that the presence or absence of the X chromosome in mammals affects the establishment of the epigenetic state at autosomal loci by acting as a sink for proteins involved in gene silencing. The study demonstrates the power of sensitized screens in the mouse not only for the discovery of novel genes involved in a particular process but also for the elucidation of the biology of that process.

LanguageEnglish
Pages7629-7634
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume102
Issue number21
DOIs
Publication statusPublished - 24 May 2005
Externally publishedYes

Keywords

  • epigenetics
  • mutagenesis
  • X inactivation
  • POSITION-EFFECT VARIEGATION
  • DROSOPHILA-MELANOGASTER
  • AGOUTI LOCUS
  • EXPRESSION
  • MUTATIONS
  • MICE
  • DIFFERENTIATION
  • LOCALIZATION
  • METHYLATION
  • INHERITANCE

Cite this

Blewitt, ME ; Vickaryous, NK ; Hemley, SJ ; Ashe, Alyson ; Bruxner, TJ ; Preis, JI ; Arkell, R ; Whitelaw, Emma. / An N-ethyl-N-nitrosourea screen for genes involved in variegation in the mouse. In: Proceedings of the National Academy of Sciences of the United States of America. 2005 ; Vol. 102, No. 21. pp. 7629-7634.
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An N-ethyl-N-nitrosourea screen for genes involved in variegation in the mouse. / Blewitt, ME; Vickaryous, NK; Hemley, SJ; Ashe, Alyson; Bruxner, TJ; Preis, JI; Arkell, R; Whitelaw, Emma.

In: Proceedings of the National Academy of Sciences of the United States of America, Vol. 102, No. 21, 24.05.2005, p. 7629-7634.

Research output: Contribution to journalArticleResearchpeer-review

TY - JOUR

T1 - An N-ethyl-N-nitrosourea screen for genes involved in variegation in the mouse

AU - Blewitt, ME

AU - Vickaryous, NK

AU - Hemley, SJ

AU - Ashe, Alyson

AU - Bruxner, TJ

AU - Preis, JI

AU - Arkell, R

AU - Whitelaw, Emma

PY - 2005/5/24

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N2 - We have developed a sensitized screen to identify genes involved in gene silencing, using random N-ethyl-N-nitrosourea mutagenesis on mice carrying a variegating GFP transgene. The dominant screen has produced six mutant lines, including both suppressors and enhancers of variegation. All are semidominant and five of the six are homozygous embryonic lethal. In one case, the homozygous lethality depends on sex: homozygous females die at midgestation and display abnormal DNA methylation of the X chromosome, whereas homozygous males are viable. Linkage analysis reveals that the mutations map to unique chromosomal locations. We have studied the effect of five of the mutations on expression of an endogenous allele known to be sensitive to epigenetic state, agouti viable yellow. In all cases, there is an effect on penetrance, and in most cases, parent of origin and sex-specific effects are detected. This screen has identified genes that are involved in epigenetic reprogramming of the genome, and the behavior of the mutant lines suggests a common mechanism between X inactivation and transgene and retrotransposon silencing. Our findings raise the possibility that the presence or absence of the X chromosome in mammals affects the establishment of the epigenetic state at autosomal loci by acting as a sink for proteins involved in gene silencing. The study demonstrates the power of sensitized screens in the mouse not only for the discovery of novel genes involved in a particular process but also for the elucidation of the biology of that process.

AB - We have developed a sensitized screen to identify genes involved in gene silencing, using random N-ethyl-N-nitrosourea mutagenesis on mice carrying a variegating GFP transgene. The dominant screen has produced six mutant lines, including both suppressors and enhancers of variegation. All are semidominant and five of the six are homozygous embryonic lethal. In one case, the homozygous lethality depends on sex: homozygous females die at midgestation and display abnormal DNA methylation of the X chromosome, whereas homozygous males are viable. Linkage analysis reveals that the mutations map to unique chromosomal locations. We have studied the effect of five of the mutations on expression of an endogenous allele known to be sensitive to epigenetic state, agouti viable yellow. In all cases, there is an effect on penetrance, and in most cases, parent of origin and sex-specific effects are detected. This screen has identified genes that are involved in epigenetic reprogramming of the genome, and the behavior of the mutant lines suggests a common mechanism between X inactivation and transgene and retrotransposon silencing. Our findings raise the possibility that the presence or absence of the X chromosome in mammals affects the establishment of the epigenetic state at autosomal loci by acting as a sink for proteins involved in gene silencing. The study demonstrates the power of sensitized screens in the mouse not only for the discovery of novel genes involved in a particular process but also for the elucidation of the biology of that process.

KW - epigenetics

KW - mutagenesis

KW - X inactivation

KW - POSITION-EFFECT VARIEGATION

KW - DROSOPHILA-MELANOGASTER

KW - AGOUTI LOCUS

KW - EXPRESSION

KW - MUTATIONS

KW - MICE

KW - DIFFERENTIATION

KW - LOCALIZATION

KW - METHYLATION

KW - INHERITANCE

U2 - 10.1073/pnas.0409375102

DO - 10.1073/pnas.0409375102

M3 - Article

VL - 102

SP - 7629

EP - 7634

JO - Proceedings of the National Academy of Sciences of the United States of America

T2 - Proceedings of the National Academy of Sciences of the United States of America

JF - Proceedings of the National Academy of Sciences of the United States of America

SN - 0027-8424

IS - 21

ER -