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Media type:
E-Article
Title:
Y chromosome mediates ribosomal DNA silencing and modulates the chromatin state inDrosophila
Contributor:
Zhou, Jun;
Sackton, Timothy B.;
Martinsen, Lene;
Lemos, Bernardo;
Eickbush, Thomas H.;
Hartl, Daniel L.
Published:
Proceedings of the National Academy of Sciences, 2012
Published in:
Proceedings of the National Academy of Sciences, 109 (2012) 25, Seite 9941-9946
Language:
English
DOI:
10.1073/pnas.1207367109
ISSN:
0027-8424;
1091-6490
Origination:
Footnote:
Description:
Although theDrosophilaY chromosome is degenerated, heterochromatic, and contains few genes, increasing evidence suggests that it plays an important role in regulating the expression of numerous autosomal and X-linked genes. Here we use 15 Y chromosomes originating from a single founder 550 generations ago to study the role of the Y chromosome in regulating rRNA gene transcription, position-effect variegation (PEV), and the link among rDNA copy number, global gene expression, and chromatin regulation. Based on patterns of rRNA gene transcription indicated by transcription of the retrotransposonR2that specifically inserts into the 28S rRNA gene, we show that X-linked rDNA is silenced in males. The silencing of X-linked rDNA expression by the Y chromosome is consistent across populations and independent of genetic background. These Y chromosomes also vary more than threefold in rDNA locus size and cause dramatically different levels of PEV suppression. The degree of suppression is negatively associated with the number and fraction of rDNA units without transposon insertions, but not with total rDNA locus size. Gene expression profiling revealed hundreds of differentially expressed genes among these Y chromosome introgression lines, as well as a divergent global gene expression pattern between the low-PEV and high-PEV flies. Our findings suggest that the Y chromosome is involved in diverse phenomena related to transcriptional regulation including X-linked rDNA silencing and suppression of PEV phenotype. These results further expand our understanding of the role of the Y chromosome in modulating global gene expression, and suggest a link with modifications of the chromatin state.