Transcriptional activity of the telomeric retrotransposon HeT-A in Drosophila melanogaster is stimulated as a consequence of subterminal deficiencies at homologous and nonhomologous telomeres.
Drosophila melanogaster telomeres have two DNA domains: a terminal array of retrotransposons and a subterminal repetitive telomere-associated sequence (TAS), a source of telomere position effect (TPE). We reported previously that deletion of the 2L TAS array leads to dominant suppression of TPE by stimulating in trans expression of a telomeric transgene. Here, we compared the transcript activities of a w transgene inserted between the retrotransposon and TAS arrays at the 2L telomere in genotypes with different lengths of the 2L TAS. In contrast to individuals bearing a wild-type 2L homologue, flies with a TAS deficiency showed a significant increase in the level of telomeric w transcript during development, especially in pupae. Moreover, we identified a read-through w transcript initiated from a retrotransposon promoter in the terminal array. Read-through transcript levels also significantly increased with the presence of a 2L TAS deficiency in trans, indicating a stimulating force of the TAS deficiency on retrotransposon promoter activity. The read-through transcript contributes to total w transcript, although most w transcript originates at the w promoter. While silencing of transgenes in nonhomologous telomeres is suppressed by 2L TAS deficiencies, suggesting a global effect, the overall level of HeT-A transcripts is not increased under similar conditions.
Frydrychova
Radmila Capkova
RC
Laboratory of Molecular Genetics, D3-01, P.O. Box 12233, 111 T. W. Alexander Drive, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709-2233, USA.
Biessmann
Harald
H
Konev
Alexander Y
AY
Golubovsky
Mikhail D
MD
Johnson
Jessica
J
Archer
Trevor K
TK
Mason
James M
JM
D000818:Animals; D001483:Base Sequence; D004331:Drosophila melanogaster / Q000235:genetics*; D005786:Gene Expression Regulation; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics; D018626:Retroelements / Q000235:genetics*; D017385:Sequence Homology; D016615:Telomere / Q000235:genetics*; D014158:Transcription, Genetic; D019076:Transgenes
D012333:RNA, Messenger; D018626:Retroelements