Control of e2f1 and PCNA by Drosophila transcription factor DREF.

DREF (DNA replication-related element-binding factor), a zinc finger type transcription factor required for proper cell cycle progression in both mitotic and endocycling cells, is a positive regulator of E2F1, an important transcription factor which regulates genes related to the S-phase of the cell cycle. DREF and E2F1 regulate similar sets of replication-related genes, including proliferating cell nuclear antigen (PCNA), and play roles in the G1 to S phase transition. However, the relationships between dref and e2f1 or PCNA during development are poorly understood.

Temporal and spatial pattern of dref expression during Drosophila bristle development.

The DNA replication-related element-binding factor (DREF) is a BED finger-type transcription factor that has important roles in cell cycle progression. In an earlier study, we showed that DREF is required for endoreplication during posterior scutellar macrochaete development. However, dynamic change in the dref expression in the cell lineage is unclear.

Dynamics of endoreplication during Drosophila posterior scutellar macrochaete development.

Endoreplication is a variant type of DNA replication, consisting only of alternating G1 and S phases. Many types of Drosophila tissues undergo endoreplication. However, the timing and the extent to which a single endocycling macrochaete undergoes temporally programmed endoreplication during development are unclear.

XNP/dATRX interacts with DREF in the chromatin to regulate gene expression.

The ATRX gene encodes a chromatin remodeling protein that has two important domains, a helicase/ATPase domain and a domain composed of two zinc fingers called the ADD domain. The ADD domain binds to histone tails and has been proposed to mediate their binding to chromatin. The putative ATRX homolog in Drosophila (XNP/dATRX) has a conserved helicase/ATPase domain but lacks the ADD domain.

DREF is critical for Drosophila bristle development by regulating endoreplication in shaft cells.

DREF (DNA replication-related element-binding factor) plays important roles in replication and proliferation in vivo by regulating transcription of various genes. However, due to a lack of appropriate cell biological studies in vivo, roles of DREF during a single cell development are poorly understood. To address this question, we focused our attention on macrochaetes bristle development system.

Disappearance of chorion proteins from Bombyx mori eggs treated with HCl solution to prevent diapause.

Bombyx mori eggs enter diapause immediately after completion of mesoderm segregation. HCl treatment of approximately 24-hour-old eggs (germband formation stage) is well known to be the most effective procedure to prevent entry into diapause, although the molecular mechanism remains unclear. In this study, we examined the protein composition of diapausing and nondiapausing eggs after various HCl treatments known to prevent or break diapause and found that proteins of approximately 11 and 8 kDa disappeared immediately after HCl treatment.