TY - JOUR T1 - Altered protein homeostasis in pulmonary fibrosis indicates a role for proteasomal activator 200 JF - European Respiratory Journal JO - Eur Respir J VL - 44 IS - Suppl 58 SP - P3903 AU - Nora Semren AU - Vanessa Welk AU - Martina Korfei AU - Isis Fernandez AU - Andreas Günther AU - Oliver Eickelberg AU - Silke Meiners Y1 - 2014/09/01 UR - http://erj.ersjournals.com/content/44/Suppl_58/P3903.abstract N2 - The proteasome, a multicatalytic protease complex, is essential for maintaining cellular function and protein homeostasis. Proteasome activator 200 (PA200) associates with the proteasome thereby activating its protease activities. Fibrotic lung disease involves alterations of protein homeostasis but regulation of proteasomal function is unknown. Here, we investigated the role of PA200 for proteasome function in pulmonary fibrosis.We first analyzed expression of PA200 and its association to proteasome core complexes in TGF-β1 treated lung fibroblasts (CCL206) as well as in experimental lung fibrosis and human IPF tissue by various approaches. mRNA and protein levels of the activator remained unchanged in TGF-β1 treated CCL206 despite an increase in overall proteasome activity. However, we observed an enhanced association of PA200 with the 26S proteasome as determined by native gel analysis and following separation of the proteasome complexes by SDS-PAGE. This correlated with an increased activation of the proteasome complexes. Moreover, PA200 protein levels were increased in fibrotic lungs of bleomycin-treated mice and human IPF lungs. Immunohistochemistry staining of IPF lungs identified myofibroblasts and ciliated bronchial cells as the main cell types overexpressing PA200 in fibroblast foci of IPF lungs.Concluding, these results suggest a participation of PA200 in induction of proteasome activity in the course of myofibroblast differentiation in pulmonary fibrosis and provide a new aspect on regulation of protein homeostasis in lung fibrosis. ER -