Becker

Project Title: Contributions of chromatin remodelling factors CHRAC/ACF to epigenome programming during oogenesis and early embryogenesis in Drosophila melanogaster

We seek to understand the role of the ISWI-containing chromatin remodelling factors CHRAC/ACF during oogenesis and early embryogenesis in Drosophila melanogaster. We found the signature subunit of these remodellers, ACF1, prominently expressed in the female germ line. ACF1 is enriched in the germ stem cells (GSCs) and in the cystoblasts that originate by asymmetric division from a GSC. High levels of ACF1 mark the cystoblast destined to become the oocyte. Preliminary results suggest that overexpression of ACF1 leads to egg chambers containing multiple oocytes and abnormal numbers of nurse cells. A significant number of egg chambers are not functional in acf1 mutant flies. These and other results may indicate a perturbation of stem cell division programmes. In order to explore the physiological context of ACF1 function we will identify molecular interactors (protein, chromatin binding sites and RNA) during oogenesis and embryogenesis. We already generated critical tools for this endeavour. We biochemically identified a novel interaction of ACF with a Domino-containing nucleosome remodelling complex in early embryos. Since Domino, like ISWI, is involved in stem cell fate during oogenesis we will explore functional and physical interactions of both remodelling complexes during oogenesis.