Epigenetic regulation affects fertility in Drosophila: toward the production of infertility models.

We have revealed that the chorion gene clusters amplify by repeatedly initiating DNA replication from chorion gene amplification origins in the response to developmental signals, through the transcription factors in Drosophila ovarian follicle cells. Orc1, Orc2, and Cdc6 are forms of DNA replication machinery, which are conserved from yeast to humans; and Orc1 and Orc2 mutants are lethal. Overexpression of Orc1 or Orc2 (subunits of the origin recognition complex) led to female sterility, but overexpression of Cdc6 (an Orc family member) or GFP did not. We propose that DNA replication machinery contributes to development.\n\nRecently, we found that H3K4 was trimethylated at chorion gene amplification origins, but not at the Act1 locus. Overexpression of Lsd1H3K4 dimethylase and Lid H3K4 trimethylase are female sterile but not a Lid mutant. These results showed that epigenetic regulation affected fertility. Screening strategies using Drosophila flies could also lead to the development of drugs that reduce sterility and epigenetic effects related histone modification.\n\nSummary statementThere are approximately 470,000 infertile individuals in Japan. We knockowned the prereplicative complex components and demethlases during Drosophila ovary development. In these drospohila, we could be the model of infertile.