Targeting CAPN9/CAPNS2 Activity as a Therapeutic Strategy for the Treatment of Transforming Growth Factor Beta-Induced Mesenchymal Transition and Associated Pathologies

Fibrosis;Calpain;TGF beta;epithelial to mesenchy;Cell Biology

Kim, David HoontaeMichaelis, Susan ;

Johns Hopkins University

关键词: Fibrosis;    Calpain;    TGF beta;    epithelial to mesenchy;    Cell Biology;   

Others  :  https://jscholarship.library.jhu.edu/bitstream/handle/1774.2/60549/KIM-DISSERTATION-2015.pdf?sequence=1&isAllowed=y

瑞士|英语

来源: JOHNS HOPKINS DSpace Repository

【 摘 要 】

High expression and/or activity of calpain proteases has been associated with the development of fibrosis, but a mechanistic explanation of their role in this process remains to be defined. In this work, we show that calpain-dependent proteolysis is required for Transforming Growth Factor β (TGFβ)-induced Epithelial-to-Mesenchymal Transition (EMT), Endothelial-to-Mesenchymal Transition (EnMT), and Fibroblast-to-Myofibroblast Transition (FMT). These related cellular processes promote the generation of myofibroblasts, a cell type that has been strongly implicated in driving fibrosis. We show that broad-spectrum calpain inhibitors can suppress EMT or FMT without affecting early TGFβ signaling events, such as phosphorylation of SMAD2. Importantly, calpain activity was also required for maintenance of an established myofibroblast fate. Overexpression of the endogenous dimeric calpain inhibitor, calpastatin, also potently suppressed TGFβ1-induced EMT. RNA interference (RNAi)-mediated knockdown of individual dimeric calpain isoforms, during TGFβ1-induced EMT, showed that only inhibition of CAPN9 or CAPNS2 could suppress generation of myofibroblasts. In epithelial cells, CAPN9 and CAPNS2 were expressed only under high TGFβ signaling conditions. Current data suggests that CAPN9 and CAPNS2 can form a heterodimer, whose activity we hypothesize is necessary for TGFβ-induced mesenchymal transition. We go on to show that expression of CAPN9 is also necessary for TGFβ1-induced cleavage of calcineurin, a known activator of FMT (Davis 2012). In mice, intratracheal delivery of siRNA targeting Capns2 or knockout of Capn9 was able to ameliorate bleomycin-induced lung fibrosis. These data suggest that the selective targeting of the CAPN9/CAPNS2 heterodimer may be a powerful therapeutic strategy for the treatment of fibrotic disorders with minimal side effects.