Cul4 and DDB1 regulate Orc2 localization, BrdU incorporation and Dup stability during gene amplification in Drosophila follicle cells.
In higher eukaryotes, the pre-replication complex (pre-RC) component Cdt1 is the major regulator in licensing control for DNA replication. The Cul4-DDB1-based ubiquitin ligase mediates Cdt1 ubiquitylation for subsequent proteolysis. During the initiation of chorion gene amplification, Double-parked (Dup), the Drosophila ortholog of Cdt1, is restricted to chorion gene foci. We found that Dup accumulated in nuclei in Cul4 mutant follicle cells, and the accumulation was less prominent in DDB1 mutant cells. Loss of Cul4 or DDB1 activity in follicle cells also compromised chorion gene amplification and induced ectopic genomic DNA replication. The focal localization of Orc2, a subunit of the origin recognition complex, is frequently absent in Cul4 mutant follicle cells. Therefore, Cul4 and DDB1 have differential functions during chorion gene amplification.
Lin
Hsiu-Chen
HC
Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan.
Wu
June-Tai
JT
Tan
Bertrand Chin-Ming
BC
Chien
Cheng-Ting
CT
D000818:Animals; D001973:Bromodeoxyuridine / Q000378:metabolism*; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D049109:Cell Proliferation; D002823:Chorion / Q000378:metabolism; D044842:Cullin Proteins / Q000235:genetics / Q000378:metabolism*; D004261:DNA Replication; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D004330:Drosophila / Q000196:embryology / Q000235:genetics* / Q000378:metabolism; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D005260:Female; D005784:Gene Amplification; D018507:Gene Expression Regulation, Developmental; D007814:Larva / Q000378:metabolism; D009154:Mutation; D051738:Origin Recognition Complex / Q000235:genetics / Q000378:metabolism; D006080:Ovarian Follicle / Q000166:cytology / Q000378:metabolism*; D055550:Protein Stability
D018797:Cell Cycle Proteins; D044842:Cullin Proteins; D004268:DNA-Binding Proteins; C411983:DUP protein, Drosophila; D029721:Drosophila Proteins; C497216:Orc2 protein, Drosophila; D051738:Origin Recognition Complex; D001973:Bromodeoxyuridine