TGF-beta signaling activates steroid hormone receptor expression during neuronal remodeling in the Drosophila brain.
Metamorphosis of the Drosophila brain involves pruning of many larval-specific dendrites and axons followed by outgrowth of adult-specific processes. From a genetic mosaic screen, we recovered two independent mutations that block neuronal remodeling in the mushroom bodies (MBs). These phenotypically indistinguishable mutations affect Baboon function, a Drosophila TGF-beta/activin type I receptor, and dSmad2, its downstream transcriptional effector. We also show that Punt and Wit, two type II receptors, act redundantly in this process. In addition, knocking out dActivin around the mid-third instar stage interferes with remodeling. Binding of the insect steroid hormone ecdysone to distinct ecdysone receptor isoforms induces different metamorphic responses in various larval tissues. Interestingly, expression of the ecdysone receptor B1 isoform (EcR-B1) is reduced in activin pathway mutants, and restoring EcR-B1 expression significantly rescues remodeling defects. We conclude that the Drosophila Activin signaling pathway mediates neuronal remodeling in part by regulating EcR-B1 expression.
Zheng
Xiaoyan
X
Department of Cell and Structural Biology, University of Illinois, Urbana, IL 61801, USA.
Wang
Jian
J
Haerry
Theodor E
TE
Wu
Ann Y-H
AY
Martin
Josephine
J
O'Connor
Michael B
MB
Lee
Ching-Hsien J
CH
Lee
Tzumin
T
D030201:Activin Receptors, Type I / Q000172:deficiency / Q000235:genetics; D030301:Activin Receptors, Type II / Q000172:deficiency / Q000235:genetics; D000818:Animals; D001921:Brain / Q000166:cytology / Q000254:growth & development* / Q000378:metabolism; D002454:Cell Differentiation / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000172:deficiency / Q000235:genetics; D004330:Drosophila / Q000166:cytology / Q000254:growth & development* / Q000378:metabolism; D029721:Drosophila Proteins / Q000172:deficiency / Q000235:genetics; D005260:Female; D005804:Genes, Lethal / Q000235:genetics; D007814:Larva / Q000166:cytology / Q000254:growth & development / Q000378:metabolism; D008297:Male; D024521:Mushroom Bodies / Q000166:cytology / Q000254:growth & development / Q000378:metabolism; D020125:Mutation, Missense / Q000235:genetics; D009434:Neural Pathways / Q000166:cytology / Q000254:growth & development* / Q000378:metabolism; D009473:Neuronal Plasticity / Q000235:genetics*; D009474:Neurons / Q000166:cytology / Q000378:metabolism; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D011506:Proteins; D011956:Receptors, Cell Surface / Q000172:deficiency / Q000235:genetics; D011987:Receptors, Steroid / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000235:genetics; D051899:Smad2 Protein; D015534:Trans-Activators / Q000172:deficiency / Q000235:genetics; D016212:Transforming Growth Factor beta / Q000378:metabolism*
D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D020033:Protein Isoforms; D011506:Proteins; D011956:Receptors, Cell Surface; D011987:Receptors, Steroid; D051899:Smad2 Protein; D015534:Trans-Activators; D016212:Transforming Growth Factor beta; C055469:ecdysone receptor; C449821:wit protein, Drosophila; D030201:Activin Receptors, Type I; D030301:Activin Receptors, Type II; C425583:put protein, Drosophila