Conserved cis-regulatory modules mediate complex neural expression patterns of the eyeless gene in the Drosophila brain.
The Drosophila Pax-6 homologs eyeless (ey) and twin of eyeless (toy) are expressed in the eyes and in the central nervous system (CNS). In addition to the pivotal functions in eye development, previous studies revealed that ey also plays important roles in axonal development of the mushroom bodies, centers for associative learning and memory. It has been reported that a second intron enhancer that contains several Pax-6 binding sites mainly controls the eye-specific expression, but the DNA sequences that control CNS expression are unknown. In this work, we have dissected transcriptional enhancer elements of the ey gene that are required for the CNS expression in various developmental stages. We first show that CNS expression is independent of the eye-specific enhancer of the second intron. By systematic reporter studies, we have identified several discrete DNA elements in the 5' upstream region and in the second intron that cooperatively interact to generate most of the ey expression pattern in the CNS. DNA sequence comparison between the ey genes of distant Drosophila species has identified conserved modules that might be bound by the upstream regulatory factors of the ey gene in CNS development. Furthermore, by RNA interference and mutant studies, we show that ey expression in the brain is independent of the activity of toy and ey itself whereas in the eye primordia it requires both, supporting the notion that ey and toy are regulated by parallel and independent regulatory cascades in brain development.
Institute of Biological Sciences and Tsukuba Advanced Research Alliance, University of Tsukuba, 1-1-1 Tennodai, Tsukuba 305-8572, Japan.
Yoshitsugu
Y
Adachi
Bernd
B
Hauck
Jason
J
Clements
Hiroshi
H
Kawauchi
Mitsuhiko
M
Kurusu
Yoko
Y
Totani
Yuan Yuan
YY
Kang
Tanja
T
Eggert
Uwe
U
Walldorf
Katsuo
K
Furukubo-Tokunaga
Patrick
P
Callaerts
D000818:Animals; D001921:Brain / Q000196:embryology* / Q000378:metabolism; D004251:DNA Transposable Elements; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D004330:Drosophila / Q000196:embryology* / Q000378:metabolism; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D004742:Enhancer Elements, Genetic; D005136:Eye Proteins; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism; D007438:Introns; D051379:Mice; D008969:Molecular Sequence Data; D009928:Organ Specificity; D000071841:PAX6 Transcription Factor; D051761:Paired Box Transcription Factors; D012097:Repressor Proteins; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism
D004251:DNA Transposable Elements; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D005136:Eye Proteins; D018398:Homeodomain Proteins; D000071841:PAX6 Transcription Factor; D051761:Paired Box Transcription Factors; C000605732:Pax6 protein, mouse; D012097:Repressor Proteins; D015534:Trans-Activators; C113278:ey protein, Drosophila; C118464:toy protein, Drosophila