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LEM domain-containing protein 3 antagonizes TGFß-SMAD2/3 signaling in a stiffness-dependent manner in both the nucleus and cytosol.
Chambers, Dwight M; Moretti, Leandro; Zhang, Jennifer J; Cooper, Spencer W; Chambers, Davis M; Santangelo, Philip J; Barker, Thomas H.
Afiliação
  • Chambers DM; From the Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University School of Medicine, Atlanta, Georgia 30332.
  • Moretti L; Biomedical Engineering, University of Virginia, Charlottesville, Virginia 22908, and.
  • Zhang JJ; From the Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University School of Medicine, Atlanta, Georgia 30332.
  • Cooper SW; From the Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University School of Medicine, Atlanta, Georgia 30332.
  • Chambers DM; the College of Arts and Sciences, Georgia State University, Atlanta, Georgia 30303.
  • Santangelo PJ; From the Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University School of Medicine, Atlanta, Georgia 30332.
  • Barker TH; Biomedical Engineering, University of Virginia, Charlottesville, Virginia 22908, and thomas.barker@virginia.edu.
J Biol Chem ; 293(41): 15867-15886, 2018 10 12.
Article em En | MEDLINE | ID: mdl-30108174
ABSTRACT
Transforming growth factor-ß (TGFß) signaling through SMAD2/3 is an important driver of pathological fibrosis in multiple organ systems. TGFß signaling and extracellular matrix (ECM) stiffness form an unvirtuous pathological circuit in which matrix stiffness drives activation of latent TGFß, and TGFß signaling then drives cellular stress and ECM synthesis. Moreover, ECM stiffness also appears to sensitize cells to exogenously activated TGFß through unknown mechanisms. Here, using human fibroblasts, we explored the effect of ECM stiffness on a putative inner nuclear membrane protein, LEM domain-containing protein 3 (LEMD3), which is physically connected to the cell's actin cytoskeleton and inhibits TGFß signaling. We showed that LEMD3-SMAD2/3 interactions are inversely correlated with ECM stiffness and TGFß-driven luciferase activity and that LEMD3 expression is correlated with the mechanical response of the TGFß-driven luciferase reporter. We found that actin polymerization but not cellular stress or LEMD3-nuclear-cytoplasmic couplings were necessary for LEMD3-SMAD2/3 interactions. Intriguingly, LEMD3 and SMAD2/3 frequently interacted in the cytosol, and we discovered LEMD3 was proteolytically cleaved into protein fragments. We confirmed that a consensus C-terminal LEMD3 fragment binds SMAD2/3 in a stiffness-dependent manner throughout the cell and is sufficient for antagonizing SMAD2/3 signaling. Using human lung biopsies, we observed that these nuclear and cytosolic interactions are also present in tissue and found that fibrotic tissues exhibit locally diminished and cytoplasmically shifted LEMD3-SMAD2/3 interactions, as noted in vitro Our work reveals novel LEMD3 biology and stiffness-dependent regulation of TGFß by LEMD3, providing a novel target to antagonize pathological TGFß signaling.
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Texto completo: 1 Base de dados: MEDLINE Assunto principal: Proteínas Nucleares / Fator de Crescimento Transformador beta / Mecanotransdução Celular / Proteína Smad2 / Proteína Smad3 / Proteínas de Membrana Idioma: En Ano de publicação: 2018 Tipo de documento: Article

Texto completo: 1 Base de dados: MEDLINE Assunto principal: Proteínas Nucleares / Fator de Crescimento Transformador beta / Mecanotransdução Celular / Proteína Smad2 / Proteína Smad3 / Proteínas de Membrana Idioma: En Ano de publicação: 2018 Tipo de documento: Article