title: Activation of Smad2 but not Smad3 is required to mediate TGF-β signaling during axolotl limb regeneration.
abstract: Axolotls are unique among vertebrates in their ability to regenerate tissues, such as limbs, tail and skin. The axolotl limb is the most studied regenerating structure. The process is well characterized morphologically; however, it is not well understood at the molecular level. We demonstrate that TGF-β1 is highly upregulated during regeneration and that TGF-β signaling is necessary for the regenerative process. We show that the basement membrane is not prematurely formed in animals treated with the TGF-β antagonist SB-431542. More importantly, Smad2 and Smad3 are differentially regulated post-translationally during the preparation phase of limb regeneration. Using specific antagonists for Smad2 and Smad3 we demonstrate that Smad2 is responsible for the action of TGF-β during regeneration, whereas Smad3 is not required. Smad2 target genes (Mmp2 and Mmp9) are inhibited in SB-431542-treated limbs, whereas non-canonical TGF-β targets (e.g. Mmp13) are unaffected. This is the first study to show that Smad2 and Smad3 are differentially regulated during regeneration and places Smad2 at the heart of TGF-β signaling supporting the regenerative process.
authors.affiliation: Department of Biochemistry and Molecular Medicine, Faculty of Medicine, Université de Montréal, Montréal, Québec, H3C-3J7, Canada.
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Denis
authors.affiliation: Department of Biochemistry and Molecular Medicine, Faculty of Medicine, Université de Montréal, Montréal, Québec, H3C-3J7, Canada.
authors.forename: Fadi
authors.initials: F
authors.lastname: Sader
authors.affiliation: Department of Biochemistry and Molecular Medicine, Faculty of Medicine, Université de Montréal, Montréal, Québec, H3C-3J7, Canada.
authors.forename: Samuel
authors.initials: S
authors.lastname: Gatien
authors.affiliation: Department of Stomatology, Faculty of Dentistry, Université de Montréal, Montréal, Québec, H3C-3J7, Canada.
authors.forename: Éric
authors.initials: É
authors.lastname: Villiard
authors.affiliation: Department of Surgery, Faculty of Medicine, McGill University, Montréal, Québec, H3G-1A4, Canada.
authors.forename: Anie
authors.initials: A
authors.lastname: Philip
authors.affiliation: Department of Biochemistry and Molecular Medicine, Faculty of Medicine, Université de Montréal, Montréal, Québec, H3C-3J7, Canada Department of Stomatology, Faculty of Dentistry, Université de Montréal, Montréal, Québec, H3C-3J7, Canada stephane.roy@umontreal.ca.
authors.forename: Stéphane
authors.identifier: 0000-0002-4504-0968
authors.initials: S
authors.lastname: Roy
mesh_terms: D000558:Ambystoma mexicanum / Q000378:metabolism / Q000502:physiology; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D001485:Basement Membrane / Q000187:drug effects / Q000378:metabolism; D001549:Benzamides / Q000494:pharmacology; D015153:Blotting, Western; D004149:Dioxoles / Q000494:pharmacology; D005121:Extremities / Q000502:physiology*; D005455:Fluorescent Antibody Technique; D012038:Regeneration / Q000187:drug effects* / Q000502:physiology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects; D051899:Smad2 Protein / Q000235:genetics / Q000378:metabolism*; D051900:Smad3 Protein / Q000235:genetics / Q000378:metabolism*; D016212:Transforming Growth Factor beta / Q000037:antagonists & inhibitors / Q000378:metabolism
chemical_list: C459179:4-(5-benzo(1,3)dioxol-5-yl-4-pyridin-2-yl-1H-imidazol-2-yl)benzamide; D001549:Benzamides; D004149:Dioxoles; D051899:Smad2 Protein; D051900:Smad3 Protein; D016212:Transforming Growth Factor beta
keywords: Ambystoma mexicanum; Axolotl; Epimorphic; Limb; Regeneration; Salamander; Smad2; Smad3; TGF-β signaling; Urodeles