TY - JOUR
T1 - Transvection in the Drosophila Abd-B domain
T2 - Extensive upstream sequences are involved in anchoring distant cis-regulatory regions to the promoter
AU - Sipos, László
AU - Mihály, József
AU - Karch, François
AU - Schedl, Paul
AU - Gausz, János
AU - Gyurkovics, Henrik
PY - 1998/6
Y1 - 1998/6
N2 - The Abd-B gene, one of the three homeotic genes in the Drosophila bithorax complex (BX-C), is required for the proper identity of the fifth through the eighth abdominal segments (corresponding to parasegments 10-14) of the fruitfly. The morphological difference between these four segments is due to the differential expression of Abd-B, which is achieved by the action of the parasegment-specific cis-regulatory regions infra-abdominal-5 (iab- 5), -6, -7 and -8. The dominant gain-of-function mutation Frontabdominal-7 (Fab-7) removes a boundary separating two of these cis-regulatory regions, iab-6 and iab-7. As a consequence of the Fab-7 deletion, the parasegment 12- (PS12-) specific iab-7 is ectopically activated in PS11. This results in the transformation of the sixth abdominal segment (A6) into the seventh (A7) in Fab-7 flies. Here we report that point mutations of the Abd-B gene in trans suppress the Fab-7 phenotype in a pairing-dependent manner and thus represent a type of transvection. We show that the observed suppression is the result of trans-regulation of the defective Abd-B gene by the ectopically activated iab-7. Unlike previously, demonstrated cases of trans-regulation in the Abd- B locus, trans-suppression of Fab-7 is sensitive to heterozygosity for chromosomal rearrangements that disturb homologous pairing at the nearby Ubx locus. However, in contrast to Ubx, the transvection we observed in the Abd- B locus is insensitive to the allelic status of zeste. Analysis of different deletion alleles of Abd-B that enhance trans-regulation suggests that an extensive upstream region, different front the sequences required for transcription initiation, mediates interactions between the tab cis- regulatory regions and the proximal Abd-B promoter. Moreover, we find that the amount of DNA deleted in the upstream region is roughly proportional to the strength of trans-interaction, suggesting that this region consists of numerous discrete elements that cooperate in tethering the tab regulatory domains to Abd-B. Possible implications of the tethering complex for the regulation of Abd-B are discussed. In addition, we present evidence that the tenacity, of trans-interactions in the Abd-B gene may vary, depending upon the tissue and stage of development.
AB - The Abd-B gene, one of the three homeotic genes in the Drosophila bithorax complex (BX-C), is required for the proper identity of the fifth through the eighth abdominal segments (corresponding to parasegments 10-14) of the fruitfly. The morphological difference between these four segments is due to the differential expression of Abd-B, which is achieved by the action of the parasegment-specific cis-regulatory regions infra-abdominal-5 (iab- 5), -6, -7 and -8. The dominant gain-of-function mutation Frontabdominal-7 (Fab-7) removes a boundary separating two of these cis-regulatory regions, iab-6 and iab-7. As a consequence of the Fab-7 deletion, the parasegment 12- (PS12-) specific iab-7 is ectopically activated in PS11. This results in the transformation of the sixth abdominal segment (A6) into the seventh (A7) in Fab-7 flies. Here we report that point mutations of the Abd-B gene in trans suppress the Fab-7 phenotype in a pairing-dependent manner and thus represent a type of transvection. We show that the observed suppression is the result of trans-regulation of the defective Abd-B gene by the ectopically activated iab-7. Unlike previously, demonstrated cases of trans-regulation in the Abd- B locus, trans-suppression of Fab-7 is sensitive to heterozygosity for chromosomal rearrangements that disturb homologous pairing at the nearby Ubx locus. However, in contrast to Ubx, the transvection we observed in the Abd- B locus is insensitive to the allelic status of zeste. Analysis of different deletion alleles of Abd-B that enhance trans-regulation suggests that an extensive upstream region, different front the sequences required for transcription initiation, mediates interactions between the tab cis- regulatory regions and the proximal Abd-B promoter. Moreover, we find that the amount of DNA deleted in the upstream region is roughly proportional to the strength of trans-interaction, suggesting that this region consists of numerous discrete elements that cooperate in tethering the tab regulatory domains to Abd-B. Possible implications of the tethering complex for the regulation of Abd-B are discussed. In addition, we present evidence that the tenacity, of trans-interactions in the Abd-B gene may vary, depending upon the tissue and stage of development.
UR - http://www.scopus.com/inward/record.url?scp=2642684572&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=2642684572&partnerID=8YFLogxK
M3 - Article
C2 - 9611211
AN - SCOPUS:2642684572
SN - 0016-6731
VL - 149
SP - 1031
EP - 1050
JO - Genetics
JF - Genetics
IS - 2
ER -