Abstract
Drosophila neuronal stem cell neuroblasts (NB) constantly change character upon division, to produce a different type of progeny at the next division. Transcription factors Hunchback (HB), Krüppel (KR), Pdm (PDM), etc. are expressed sequentially in each NB and act as determinants of birth-order identity. How a NB switches its expression profile from one transcription factor to the next is poorly understood. We show that the HB-to-KR switch is directed by the nuclear receptor Seven-up (SVP). SVP expression is confined to a temporally restricted subsection within the NB's lineage. Loss of SVP function causes an increase in the number of HB-positive cells within several NB lineages, whereas misexpression of svp leads to the loss of these early-born neurons. Lineage analysis provides evidence that svp is required to switch off HB at the proper time. Thus, svp modifies the self-renewal stem cell program to allow chronological change of cell fates, thereby generating neuronal diversity.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Animals
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Animals, Genetically Modified
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Cell Differentiation
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Cell Division
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Central Nervous System / cytology
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Central Nervous System / embryology
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DNA-Binding Proteins / genetics
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DNA-Binding Proteins / metabolism*
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Drosophila / cytology*
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Drosophila / genetics
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Drosophila / growth & development
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Drosophila / metabolism*
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Drosophila Proteins / genetics
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Drosophila Proteins / metabolism*
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Gene Expression Regulation, Developmental
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Genes, Insect
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Kruppel-Like Transcription Factors
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Multipotent Stem Cells / cytology
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Mutation
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Neurons / cytology*
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Receptors, Steroid / genetics
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Receptors, Steroid / metabolism*
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Repressor Proteins / genetics
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Repressor Proteins / metabolism
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Transcription Factors / genetics
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Transcription Factors / metabolism*
Substances
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DNA-Binding Proteins
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Drosophila Proteins
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Kr protein, Drosophila
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Kruppel-Like Transcription Factors
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Receptors, Steroid
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Repressor Proteins
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Transcription Factors
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hb protein, Drosophila
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svp protein, Drosophila