title: The role of transcription in the activation of a Drosophila amplification origin.
abstract: The mechanisms that underlie metazoan DNA replication initiation, especially the connection between transcription and replication origin activation, are not well understood. To probe the role of transcription in origin activation, we exploited a specific replication origin in Drosophila melanogaster follicle cells, ori62, which coincides with the yellow-g2 transcription unit and exhibits transcription-dependent origin firing. Within a 10-kb genomic fragment that contains ori62 and is sufficient for amplification, RNA-sequencing analysis revealed that all detected RNAs mapped solely to the yellow-g2 gene. To determine whether transcription is required in cis for ori62 firing, we generated a set of tagged yellow-g2 transgenes in which we could prevent local transcription across ori62 by deletions in the yellow-g2 promoter. Surprisingly, inhibition of yellow-g2 transcription by promoter deletions did not affect ori62 firing. Our results reveal that transcription in cis is not required for ori62 firing, raising the possibility that a trans-acting factor is required specifically for the activation of ori62. This finding illustrates that a diversity of mechanisms can be used in the regulation of metazoan DNA replication initiation.
authors.affiliation: Whitehead Institute, Massachusetts Institute of Technology, Cambridge, Massachusetts 02142 Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02142.
authors.forename: Brian L
authors.identifier: http://orcid.org/0000-0002-7580-3399
authors.initials: BL
authors.lastname: Hua
authors.affiliation: Whitehead Institute, Massachusetts Institute of Technology, Cambridge, Massachusetts 02142.
authors.forename: Sharon
authors.initials: S
authors.lastname: Li
authors.affiliation: Whitehead Institute, Massachusetts Institute of Technology, Cambridge, Massachusetts 02142 Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02142 weaver@wi.mit.edu.
authors.forename: Terry L
authors.initials: TL
authors.lastname: Orr-Weaver
mesh_terms: D000818:Animals; D004330:Drosophila / Q000235:genetics* / Q000254:growth & development; D029721:Drosophila Proteins / Q000235:genetics; D017353:Gene Deletion; D010063:Ovum / Q000378:metabolism; D011401:Promoter Regions, Genetic; D018741:Replication Origin / Q000235:genetics*; D017423:Sequence Analysis, RNA; D014158:Transcription, Genetic; D019076:Transgenes
chemical_list: D029721:Drosophila Proteins
keywords: DNA replication; gene amplification; promoter deletion; replication initiation; yellow-g2