polyhomeotic appears to be a target of engrailed regulation in Drosophila.
In Drosophila, Engrailed is a nuclear regulatory protein with essential roles in embryonic segmentation and in normal development of posterior compartments. One of its regulatory targets appears to be polyhomeotic (ph), a Polycomb group gene. We observed, by immunostaining, that Engrailed protein binds to the site of the polyhomeotic locus in region 2D of polytene chromosomes. The same analysis carried out on a transgenic line containing one copy of a P(ph-lacZ) construct shows an additional Engrailed-binding site at the location of the insert. In vivo, polyhomeotic depends on engrailed function in germ-band-elongated embryos, when engrailed and polyhomeotic genes are expressed in similar patterns. By in vitro immunoprecipitations and gel shift assays, we identified two classes of high affinity Engrailed-binding sites upstream of each of the two polyhomeotic transcription units. DNA fragments containing these sites were also immunoprecipitated from embryonic UV crosslinked chromatin in presence of anti-Engrailed antibody. These results suggest that polyhomeotic activation in germ-band-elongated embryos could be mediated by Engrailed-binding to these sites.
Serrano
N
N
Département de Biologie du Développement, Institut Jacques Monod, CNRS et Université Paris 7, France.
Brock
H W
HW
Demeret
C
C
Dura
J M
JM
Randsholt
N B
NB
Kornberg
T B
TB
Maschat
F
F
D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D004268:DNA-Binding Proteins / Q000235:genetics*; D004330:Drosophila / Q000196:embryology / Q000235:genetics*; D029721:Drosophila Proteins; D018507:Gene Expression Regulation, Developmental; D005801:Genes, Homeobox; D017344:Genes, Insect; D018398:Homeodomain Proteins / Q000235:genetics*; D007150:Immunohistochemistry; D007301:Insect Hormones / Q000235:genetics*; D008969:Molecular Sequence Data; D009698:Nucleoproteins / Q000235:genetics*; D063150:Polycomb Repressive Complex 1; D011233:Precipitin Tests; D012469:Salivary Glands / Q000196:embryology; D014157:Transcription Factors / Q000235:genetics*
D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; C063459:En protein, Drosophila; D018398:Homeodomain Proteins; D007301:Insect Hormones; D009698:Nucleoproteins; D014157:Transcription Factors; C072820:ph-d protein, Drosophila; D063150:Polycomb Repressive Complex 1