Repair of UV-induced pyrimidine dinners in the individual genesGart, NotchandwhitefromDrosophila melanogastercell lines

Cock, J.G.R. de; Klink, E.C.; Ferro, W.; Lohman, P.H.M.; Eeken, J.C.J.

doi:10.1093/nar/19.12.3289

Cited by 20 publications

(8 citation statements)

References 38 publications

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“…Using this value, we calculate from our immunoprecipitation results that not more than 1.5% of the Ubx promoter sequences could have bound TBP or Pol II. This value is indistinguishable from the background level represented by precipitation of the white coding region (34).…”

Section: Chromatin Of the Repressed Ubx Gene Is Enriched In Methy-mentioning

confidence: 67%

“…Using antibodies against TBP and against the C-terminal domain of RNA polymerase II (Pol II), we performed ChIP and compared the precipitation of the Ubx promoter with that of the hsp26 promoter, which, in the uninduced, pre-set condition, is known to bind both TBP and paused Pol II (33). As a negative control we took a DNA fragment from the third exon of the white gene, which is inactive in SL2 cells (34). Very little TBP or Pol II, if any, is associated with the inactive Ubx promoter in SL2 cells (Table 1).…”

Section: Chromatin Of the Repressed Ubx Gene Is Enriched In Methy-mentioning

confidence: 99%

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Polycomb Complexes and the Propagation of the Methylation Mark at the Drosophila Ubx Gene

Kahn

Schwartz

Dellino

et al. 2006

Journal of Biological Chemistry

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Polycomb group proteins are transcriptional repressors that control many developmental genes. The Polycomb group protein Enhancer of Zeste has been shown in vitro to methylate specifically lysine 27 and lysine 9 of histone H3 but the role of this modification in Polycomb silencing is unknown. We show that H3 trimethylated at lysine 27 is found on the entire Ubx gene silenced by Polycomb. However, Enhancer of Zeste and other Polycomb group proteins stay primarily localized at their response elements, which appear to be the least methylated parts of the silenced gene. Our results suggest that, contrary to the prevailing view, the Polycomb group proteins and methyltransferase complexes are recruited to the Polycomb response elements independently of histone methylation and then loop over to scan the entire region, methylating all accessible nucleosomes. We propose that the Polycomb chromodomain is required for the looping mechanism that spreads methylation over a broad domain, which in turn is required for the stability of the Polycomb group protein complex. Both the spread of methylation from the Polycomb response elements, and the silencing effect can be blocked by the gypsy insulator.

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Section: Chromatin Of the Repressed Ubx Gene Is Enriched In Methy-mentioning

confidence: 67%

Section: Chromatin Of the Repressed Ubx Gene Is Enriched In Methy-mentioning

confidence: 99%

Polycomb Complexes and the Propagation of the Methylation Mark at the Drosophila Ubx Gene

Kahn

Schwartz

Dellino

et al. 2006

Journal of Biological Chemistry

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“…3D, E, and F). In contrast, the promoters of the white and Ubx genes, which are inactive in SL2 cells (2,5), are found in the same fractions as bulk chromatin (Fig. 3G and H).…”

Section: Resultsmentioning

confidence: 91%

Characteristic Low Density and Shear Sensitivity of Cross-Linked Chromatin Containing Polycomb Complexes

Schwartz

Kahn

Pirrotta

2005

Molecular and Cellular Biology

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Chromatin cross-linking is widely used for mapping the distribution of chromosomal proteins by immunoprecipitation, but our knowledge of the physical properties of chromatin complexes remains rudimentary. Density gradients have been long used to separate fragments of cross-linked chromatin with their bound proteins from free protein or free DNA. We find that the association of DNA fragments with very-highmolecular-weight protein complexes shifts their buoyant density to values much lower then that of bulk chromatin. We show that in a CsCl gradient, Polycomb response elements, promoters of active genes, and insulator or boundary elements are found at buoyant densities similar to those of free protein and are depleted from the bulk chromatin fractions. In these regions, the low density is associated with the presence of large protein complexes and with high sensitivity to sonication. Our results suggest that separation of different chromatin regions according to their buoyant density may bias chromatin immunoprecipitation results. Density centrifugation of cross-linked chromatin may provide a simple approach to investigate the properties of large chromatin complexes in vivo.

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“…The negative correlation between these two mutation frequencies could indicate a differential repair of the vermilion locus in relation to the X-chromosome genes measured in the RL assay. To date, no preferential repair has been found in Drosophila [de Cock et al, 1991[de Cock et al, , 1992avan der Helm et al, 1997] and transcription coupled repair is not expected in this organism [Sekelsky et al, 2000]. Nevertheless, several facts still point to the occurrence of differential repair: 1) The vermilion gene is not essential for viable gametes and is expressed only in later developmental stages [Baillie and Chovnik, 1971;O'Brien and MacIntyre, 1978], whereas other X-chromosome genes are necessary for germ cell viability and may possibly be preferentially repaired.…”

Section: Discussionmentioning

confidence: 99%

O‐ethylthymidine adducts are the most relevant damages for mutation induced by N‐ethyl‐N‐nitrosourea in female germ cells of Drosophila melanogaster

Álvarez¹,

Comendador²,

Sierra³

2002

Environ and Mol Mutagen

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Responses to genotoxic agents vary not only among organisms, test systems, and cellular stages, but also between sexes; little, however, is known about the mutagenic consequences of chemical exposures to female germ cells. In this study, the mutagenicity of N-ethyl-N-nitrosourea (ENU) was analyzed in female germ cells of Drosophila melanogaster using the recessive-lethal test and the vermilion system, which simultaneously generates information on induced mutation frequency and mutation spectrum. ENU was mutagenic in all stages of oogenesis, although there were differences among the stages. In mature and immature oocytes, ENU-induced mutations in the vermilion locus were 43.5% A:T-->G:C transitions, 39.1% A:T-->T:A transversions, 8.7% G:C-->A:T transitions, and 8.7% A:T-->C:G transversions, indicating that the most important premutagenic lesions induced by this chemical are O(4)-ethylthymine and O(2)-ethylthymine. The low frequency of mutation involving O(6)-ethylguanine (i.e., G:C-->A:T transitions) could be a consequence of the repair of these lesions by O(6)-methylguanine DNA methyltransferase. Comparison of these results with those previously obtained in male germ cells stresses the importance of the repair activity of the analyzed cells, because the mutation spectrum in female germ cells was similar to the spectrum obtained with repair-proficient spermatogonial cells and different from repair-deficient postmeiotic cells. The results also indicate that studies with female germ cells could be an alternative to the use of premeiotic male germ cells, especially when the analysis of these cells is difficult or almost impossible and when studies of in vivo DNA repair in premeiotic germ cells are performed.

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Repair of UV-induced pyrimidine dinners in the individual genesGart, NotchandwhitefromDrosophila melanogastercell lines

Cited by 20 publications

References 38 publications

Polycomb Complexes and the Propagation of the Methylation Mark at the Drosophila Ubx Gene

Polycomb Complexes and the Propagation of the Methylation Mark at the Drosophila Ubx Gene

Characteristic Low Density and Shear Sensitivity of Cross-Linked Chromatin Containing Polycomb Complexes

O‐ethylthymidine adducts are the most relevant damages for mutation induced by N‐ethyl‐N‐nitrosourea in female germ cells of Drosophila melanogaster

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