A family of snail-related zinc finger proteins regulates two distinct and parallel mechanisms that mediate Drosophila neuroblast asymmetric divisions.
Three snail family genes snail, escargot and worniu, encode related zinc finger transcription factors that mediate Drosophila central nervous system (CNS) development. We show that simultaneous removal of all three genes causes defective neuroblast asymmetric divisions; inscuteable transcription/translation is delayed/suppressed in the segmented CNS. Further more, defects in localization of cell fate determinants and orientation of the mitotic spindle in dividing neuroblasts are much stronger than those associated with inscuteable loss of function. In inscuteable neuroblasts, cell fate determinants are mislocalized during prophase and metaphase, yet during anaphase and telophase the great majority of mutant neuroblasts localize these determinants as cortical crescents overlying one of the spindle poles. This phenomenon, known as 'telophase rescue', does not occur in the absence of the snail family genes; moreover, in contrast to inscuteable mutants, mitotic spindle orientation is completely randomized. Our data provide further evidence for the existence of two distinct asymmetry-controlling mechanisms in neuroblasts both of which require snail family gene function: an inscuteable-dependent mechanism that functions throughout mitosis and an inscuteable-independent mechanism that acts during anaphase/telophase.
Cai
Y
Y
Institute of Molecular and Cell Biology, 30 Medical Drive, Singapore.
Chia
W
W
Yang
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X
D000818:Animals; D019521:Body Patterning / Q000502:physiology*; D002352:Carrier Proteins / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000378:metabolism; D002490:Central Nervous System / Q000196:embryology / Q000378:metabolism; D003598:Cytoskeletal Proteins / Q000235:genetics* / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D004330:Drosophila / Q000196:embryology / Q000235:genetics / Q000502:physiology; D029721:Drosophila Proteins; D005786:Gene Expression Regulation; D017344:Genes, Insect; D019476:Insect Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D008938:Mitosis; D016296:Mutagenesis; D009419:Nerve Tissue Proteins / Q000378:metabolism; D009474:Neurons / Q000166:cytology / Q000378:metabolism / Q000502:physiology; D009479:Neuropeptides; D009687:Nuclear Proteins / Q000378:metabolism; D000071250:Snail Family Transcription Factors; D013234:Stem Cells / Q000166:cytology / Q000378:metabolism / Q000502:physiology; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D016335:Zinc Fingers / Q000235:genetics / Q000502:physiology*
D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D003598:Cytoskeletal Proteins; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D019476:Insect Proteins; C107613:Mira protein, Drosophila; D009419:Nerve Tissue Proteins; D009479:Neuropeptides; D009687:Nuclear Proteins; C115164:PON protein, Drosophila; D000071250:Snail Family Transcription Factors; D014157:Transcription Factors; C098678:insc protein, Drosophila; C073099:pros protein, Drosophila; C000604451:sna protein, Drosophila; C402787:wor protein, Drosophila