Document Detail

Activin receptor inhibition by Smad2 regulates Drosophila wing disc patterning through BMP-response elements.
MedLine Citation:
PMID:  23293296     Owner:  NLM     Status:  MEDLINE    
Imaginal disc development in Drosophila requires coordinated cellular proliferation and tissue patterning. In our studies of TGFβ superfamily signaling components, we found that a protein null mutation of Smad2, the only Activin subfamily R-Smad in the fruit fly, produces overgrown wing discs that resemble gain of function for BMP subfamily signaling. The wing discs are expanded specifically along the anterior-posterior axis, with increased proliferation in lateral regions. The morphological defect is not observed in mutants for the TGFβ receptor baboon, and epistasis tests showed that baboon is epistatic to Smad2 for disc overgrowth. Rescue experiments indicate that Baboon binding, but not canonical transcription factor activity, of Smad2 is required for normal disc growth. Smad2 mutant discs generate a P-Mad stripe that is narrower and sharper than the normal gradient, and activation targets are correspondingly expressed in narrowed domains. Repression targets of P-Mad are profoundly mis-regulated, with brinker and pentagone reporter expression eliminated in Smad2 mutants. Loss of expression requires a silencer element previously shown to be controlled by BMP signaling. Epistasis experiments show that Baboon, Mad and Schnurri are required to mediate the ectopic silencer output in the absence of Smad2. Taken together, our results show that loss of Smad2 permits promiscuous Baboon activity, which represses genes subject to control by Mad-dependent silencer elements. The absence of Brinker and Pentagone in Smad2 mutants explains the compound wing disc phenotype. Our results highlight the physiological relevance of substrate inhibition of a kinase, and reveal a novel interplay between the Activin and BMP pathways.
Aidan J Peterson; Michael B O'Connor
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural    
Journal Detail:
Title:  Development (Cambridge, England)     Volume:  140     ISSN:  1477-9129     ISO Abbreviation:  Development     Publication Date:  2013 Feb 
Date Detail:
Created Date:  2013-01-07     Completed Date:  2013-03-07     Revised Date:  2014-04-08    
Medline Journal Info:
Nlm Unique ID:  8701744     Medline TA:  Development     Country:  England    
Other Details:
Languages:  eng     Pagination:  649-59     Citation Subset:  IM    
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MeSH Terms
Activin Receptors / genetics,  metabolism*
Body Patterning
Bone Morphogenetic Proteins / metabolism
Cell Proliferation
Cell Size
Crosses, Genetic
Drosophila / genetics,  metabolism*,  physiology
Drosophila Proteins / genetics,  metabolism*
Epistasis, Genetic
Extracellular Matrix Proteins / genetics,  metabolism
Gene Expression Regulation, Developmental*
Imaginal Discs / metabolism,  physiology*
Mutagenesis, Site-Directed
Organ Size
RNA Interference
Receptors, Transforming Growth Factor beta / genetics,  metabolism
Repressor Proteins / genetics,  metabolism
Signal Transduction
Smad2 Protein / genetics,  metabolism*
Time Factors
Wing / metabolism,  physiology*
Grant Support
Reg. No./Substance:
0/Bone Morphogenetic Proteins; 0/Drosophila Proteins; 0/Extracellular Matrix Proteins; 0/Magu protein, Drosophila; 0/Receptors, Transforming Growth Factor beta; 0/Repressor Proteins; 0/Smad2 Protein; 0/Smad2 protein, Drosophila; 0/brinker protein, Drosophila; EC Receptors; EC protein, Drosophila

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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