title: Negative-feedback regulation of proneural proteins controls the timing of neural precursor division.
abstract: Neurogenesis requires precise control of cell specification and division. In Drosophila, the timing of cell division of the sensory organ precursor (SOP) is under strict temporal control. But how the timing of mitotic entry is determined remains poorly understood. Here, we present evidence that the timing of the G2-M transition is determined by when proneural proteins are degraded from SOPs. This process requires the E3 ubiquitin ligase complex, including the RING protein Sina and the adaptor Phyl. In phyl mutants, proneural proteins accumulate, causing delay or arrest in the G2-M transition. The G2-M defect in phyl mutants is rescued by reducing the ac and sc gene doses. Misexpression of phyl downregulates proneural protein levels in a sina-dependent manner. Phyl directly associates with proneural proteins to act as a bridge between proneural proteins and Sina. As phyl is a direct transcriptional target of Ac and Sc, our data suggest that, in addition to mediating cell cycle arrest, proneural protein initiates a negative-feedback regulation to time the mitotic entry of neural precursors.
authors.affiliation: Department of Life Science, Chang-Gung University, 259 Wen-Hwa 1st Road, Kwei-Shan, Tao-Yuan 333, Taiwan.
authors.forename: Pao-Ju
authors.initials: PJ
authors.lastname: Chang
authors.forename: Yun-Ling
authors.initials: YL
authors.lastname: Hsiao
authors.forename: An-Chi
authors.initials: AC
authors.lastname: Tien
authors.forename: Yi-Chen
authors.initials: YC
authors.lastname: Li
authors.forename: Haiwei
authors.initials: H
authors.lastname: Pi
mesh_terms: D000818:Animals; D004330:Drosophila / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D017344:Genes, Insect; D005982:Glutathione Transferase / Q000378:metabolism; D017403:In Situ Hybridization; D009154:Mutation; D009420:Nervous System / Q000378:metabolism*; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000378:metabolism*; D000098563:Seven in Absentia Proteins
chemical_list: D029721:Drosophila Proteins; D009687:Nuclear Proteins; D011993:Recombinant Fusion Proteins; C092070:phyl protein, Drosophila; D044767:Ubiquitin-Protein Ligases; D000098563:Seven in Absentia Proteins; D005982:Glutathione Transferase