Neuronal Precurser Gene Function in the Regulation of Cell Proliferation and Neuronal Differentiation

Ohio State University Research Foundation -Do Not Use, Columbus OH

Investigators

Abstract

During development of multicellular organisms, regulatory systems governing cell proliferation and developmental programs regulating the formation of specific organs, tissues or cell types, have to interface to ensure that an appropriate number of cells are generated for every tissue and organ. Equally important is the regulated termination of cell proliferation and initiation of lineage appropriate differentiation. A substantial body of work has provided a rather detailed picture of the regulatory systems controlling cell proliferation and cell cycle arrest. In contrast rather little is known, how tissue or lineage specific developmental programs functionally interact with cell cycle regulatory system. In the fruit fly Drosophila melanogaster, the pan-neural expressed neuronal precursor gene prospero (pros) is critical for proper termination of cell proliferation and initiation of neuronal differentiation during embryonic neurogenesis. In this role, pros activity is required for the proper transcriptional regulation of multiple key cell cycle regulatory genes, including the cyclin dependent kinase (cdk) inhibitor gene dacapo, the cdc25 gene string, E2F and cyclin E. Two additional pan-neural neuronal precursor genes, deadpan (dpn) and asense (ase), have been shown to be critical for cell proliferation during larval optic lobe development and proper expression of the cdk inhibitor gene dacapo. This group of pan-neural transcription factor encoding genes represent, or are part of, a critical regulatory link between neuronal lineage specific developmental programs and cell proliferation and/or neuronal differentiation. Experiments conducted under this project will firstly determine, using a range of developmental-genetic approaches, the regulatory capacity and genetic interactions of Pros in the regulation of cell proliferation and differentiation during embryonic and larval neurogenesis. Secondly, functional in vivo and in vitro analysis of transcriptional regulatory regions of dacapo, string and cyclinE will be performed to determine the specific sequence motifs involved in the pros mediated transcriptional regulation of these genes. To this end reporter gene constructs will be used to map and functionally define Pros response elements in transgenic flies. In vitro DNA binding analysis and in vitro mutagenesis experiments will complement the in vivo approaches. These experiments will provide an initial understanding of the functional mode and interactions of this newly emerging regulatory system. As all genes involved in this study are evolutionarily conserved from Drosophila to humans, the information gained from this analysis should have direct relevance for the understanding of similar developmental processes in a number of other organisms.