title: The RanGEF Bj1 promotes prospero nuclear export and neuroblast self-renewal.
abstract: Drosophila larval neuroblasts are a model system for studying stem cell self-renewal and differentiation. Here, we report a novel role for the Drosophila gene Bj1 in promoting larval neuroblast self-renewal. Bj1 is the guanine-nucleotide exchange factor for Ran GTPase, which regulates nuclear import/export. Bj1 transcripts are highly enriched in larval brain neuroblasts (in both central brain and optic lobe), while Bj1 protein is detected in both neuroblasts and their neuronal progeny. Loss of Bj1 using both mutants or RNAi causes a progressive loss of larval neuroblasts, showing that Bj1 is required to maintain neuroblast numbers. Loss of Bj1 does not result in neuroblast apoptosis, but rather leads to abnormal nuclear accumulation of the differentiation factor Prospero, and premature neuroblast differentiation. We conclude that the Bj1 RanGEF promotes Prospero nuclear export and neuroblast self-renewal.
authors.affiliation: Institute of Molecular Biology, Institute of Neuroscience, Howard Hughes Medical Institute, University of Oregon, Eugene, Oregon, 97403.
authors.forename: Tasha
authors.initials: T
authors.lastname: Joy
authors.forename: Keiko
authors.initials: K
authors.lastname: Hirono
authors.forename: Chris Q
authors.initials: CQ
authors.lastname: Doe
mesh_terms: D021581:Active Transport, Cell Nucleus; D000818:Animals; D001921:Brain / Q000378:metabolism; D002454:Cell Differentiation / Q000502:physiology*; D004268:DNA-Binding Proteins / Q000378:metabolism*; D029721:Drosophila Proteins / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000166:cytology / Q000254:growth & development / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental / Q000502:physiology; D020662:Guanine Nucleotide Exchange Factors / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D058953:Neural Stem Cells / Q000378:metabolism*; D009474:Neurons / Q000166:cytology*; D009687:Nuclear Proteins / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism*
chemical_list: D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D020662:Guanine Nucleotide Exchange Factors; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; D014157:Transcription Factors; C073099:pros protein, Drosophila; C068687:RCC1 protein, Drosophila
keywords: Drosophila; RanGEF; differentiation; neuroblast; self-renewal