A distinct type of heterochromatin at the telomeric region of the Drosophila melanogaster Y chromosome.
Heterochromatin assembly and its associated phenotype, position effect variegation (PEV), provide an informative system to study chromatin structure and genome packaging. In the fruit fly Drosophila melanogaster, the Y chromosome is entirely heterochromatic in all cell types except the male germline; as such, Y chromosome dosage is a potent modifier of PEV. However, neither Y heterochromatin composition, nor its assembly, has been carefully studied. Here, we report the mapping and characterization of eight reporter lines that show male-specific PEV. In all eight cases, the reporter insertion sites lie in the telomeric transposon array (HeT-A and TART-B2 homologous repeats) of the Y chromosome short arm (Ys). Investigations of the impact on the PEV phenotype of mutations in known heterochromatin proteins (i.e., modifiers of PEV) show that this Ys telomeric region is a unique heterochromatin domain: it displays sensitivity to mutations in HP1a, EGG and SU(VAR)3-9, but no sensitivity to Su(z)2 mutations. It appears that the endo-siRNA pathway plays a major targeting role for this domain. Interestingly, an ectopic copy of 1360 is sufficient to induce a piRNA targeting mechanism to further enhance silencing of a reporter cytologically localized to the Ys telomere. These results demonstrate the diversity of heterochromatin domains, and the corresponding variation in potential targeting mechanisms.
Department of Biology, Washington University, St. Louis, Missouri, United States of America.
Sidney H
SH
Wang
Department of Biology, Washington University, St. Louis, Missouri, United States of America.
Ruth
R
Nan
Dipartimento di Biologia e Biotecnologie "Charles Darwin" and Istituto Pasteur Fondazione Cenci-Bolognetti, Sapienza Università di Roma, Roma, Italy.
Maria C
MC
Accardo
Department of Biology, Washington University, St. Louis, Missouri, United States of America.
Monica
M
Sentmanat
Dipartimento di Biologia e Biotecnologie "Charles Darwin" and Istituto Pasteur Fondazione Cenci-Bolognetti, Sapienza Università di Roma, Roma, Italy.
Patrizio
P
Dimitri
Department of Biology, Washington University, St. Louis, Missouri, United States of America.
Sarah C R
SC
Elgin
D000818:Animals; D042002:Chromatin Assembly and Disassembly; D000090266:Chromobox Protein Homolog 5; D055012:Chromosomal Position Effects; D002868:Chromosomal Proteins, Non-Histone / Q000235:genetics / Q000378:metabolism; D002874:Chromosome Mapping; D004251:DNA Transposable Elements; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism; D004331:Drosophila melanogaster / Q000235:genetics* / Q000378:metabolism; D006570:Heterochromatin / Q000737:chemistry* / Q000378:metabolism; D008297:Male; D009154:Mutation; D010641:Phenotype; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism; D016615:Telomere / Q000737:chemistry*; D014998:Y Chromosome / Q000737:chemistry*
D002868:Chromosomal Proteins, Non-Histone; D004251:DNA Transposable Elements; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D006570:Heterochromatin; D034741:RNA, Small Interfering; D012097:Repressor Proteins; C089148:Su(var)3-9 protein, Drosophila; C071051:Su(z)2 protein, Drosophila; D000090266:Chromobox Protein Homolog 5