Self-regulatory circuits in dorsoventral axis formation of the short-germ beetle Tribolium castaneum.
The rel/NF-kappaB transcription factor Dorsal controls dorsoventral (DV) axis formation in Drosophila. A stable nuclear gradient of Dorsal directly regulates approximately 50 target genes. In Tribolium castaneum (Tc), a beetle with an ancestral type of embryogenesis, the Dorsal nuclear gradient is not stable, but rapidly shrinks and disappears. We find that negative feedback accounts for this dynamic behavior: Tc-Dorsal and one of its target genes activate transcription of the IkB homolog Tc-cactus, terminating Dorsal function. Despite its transient role, Tc-Dorsal is strictly required to initiate DV polarity, as in Drosophila. However, unlike in Drosophila, embryos lacking Tc-Dorsal display a periodic pattern of DV cell fates along the AP axis, indicating that a self-organizing ectodermal patterning system operates independently of mesoderm or maternal DV polarity cues. Our results also elucidate how extraembryonic tissues are organized in short-germ embryos, and how patterning information is transmitted from the early embryo to the growth zone.
Nunes da Fonseca
Rodrigo
R
Institute of Developmental Biology, University of Cologne, Gyrhofstrasse 17, 50931 Cologne, Germany.
von Levetzow
Cornelia
C
Kalscheuer
Patrick
P
Basal
Abidin
A
van der Zee
Maurijn
M
Roth
Siegfried
S
D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D019521:Body Patterning / Q000502:physiology*; D002467:Cell Nucleus / Q000378:metabolism; D025461:Feedback, Physiological; D018507:Gene Expression Regulation, Developmental; D017403:In Situ Hybridization; D019476:Insect Proteins / Q000235:genetics / Q000378:metabolism; D009024:Morphogenesis / Q000502:physiology; D034622:RNA Interference; D051193:Toll-Like Receptors / Q000235:genetics / Q000378:metabolism; D014231:Tribolium / Q000033:anatomy & histology / Q000196:embryology / Q000235:genetics
D015415:Biomarkers; D019476:Insect Proteins; D051193:Toll-Like Receptors