Regulation of POU genes by castor and hunchback establishes layered compartments in the Drosophila CNS.
POU transcription factors participate in cell-identity decisions during nervous system development, yet little is known about the regulatory networks controlling their expression. We report all known Drosophila POU genes require castor (cas) for correct CNS expression. drifter and I-POU depend on cas for full expression, whereas pdm-1 and pdm-2 are negatively regulated. cas encodes a zinc finger protein that shares DNA-binding specificity with another pdm repressor: the gap segmentation gene regulator Hunchback (Hb). Our studies reveal that the embryonic CNS contains sequentially generated neuroblast sublineages that can be distinguished by their expression of either Hb, Pdm-1, or Cas. Hb and Cas may directly silence pdm expression in early and late developing sublineages, given that pdm-1 cis-regulatory DNA contains >=32 Hb/Cas-binding sites and its enhancer(s) are ectopically activated in cas- neuroblasts. In addition, the targeted misexpression of Cas in all neuroblast lineages reduces Pdm-1 expression without altering Hb expression. By ensuring correct POU gene expression boundaries, hb and cas maintain temporal subdivisions in the cell-identity circuitry controlling CNS development.
Kambadur
R
R
The Neurogenetics Unit, Laboratory of Neurochemistry, National Institute of Neurological Disorders and Stroke (NINDS), National Institutes of Health (NIH), Bethesda, Maryland 20892 USA.
Koizumi
K
K
Stivers
C
C
Nagle
J
J
Poole
S J
SJ
Odenwald
W F
WF
D000818:Animals; D001483:Base Sequence; D002490:Central Nervous System / Q000196:embryology*; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004330:Drosophila / Q000235:genetics*; D029721:Drosophila Proteins; D004742:Enhancer Elements, Genetic; D019084:Fluorescent Antibody Technique, Indirect; D005786:Gene Expression Regulation; D018398:Homeodomain Proteins / Q000378:metabolism; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D018613:Microscopy, Confocal; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000378:metabolism; D050809:POU Domain Factors; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D018398:Homeodomain Proteins; D009419:Nerve Tissue Proteins; D050809:POU Domain Factors; D014157:Transcription Factors; C110593:cas protein, Drosophila; C061245:hb protein, Drosophila; C104121:nub protein, Drosophila; C072851:pdm2 protein, Drosophila; C091575:vvl protein, Drosophila; C068431:acj6 protein, Drosophila