Journal: Science translational medicine
Article Title: Targeted apoptosis of myofibroblasts with the BH3 mimetic ABT-263 reverses established fibrosis
doi: 10.1126/scitranslmed.aal3765
Figure Lengend Snippet: (A) Schematic diagram of BH3 profiling assay. HDFs were cultured on matrices with different stiffnesses, permeabilized, and exposed to an array of peptides derived from different proapoptotic BH3-only proteins, and MOMP was measured indirectly using the mitochondrial JC-1 dye (fluorescent dye sensitive to the electropotential gradient across the inner mitochondrial membrane). The decay of DYm was measured as fluorescence at 590 nm over 180 min. (B) Schematic illustrating how BCL-2 family interactions govern MOMP. The terminal execution phase of apoptosis is controlled by BCL-2 family members BAX and BAK, which are required to initiate apoptosis by causing MOMP through their pore-forming activities. MOMP releases caspase-activating factors (cytochrome c) into the cytoplasm, which results in collapse of the DYm and caspase activation. MOMP activation is directly guarded by prosurvival proteins [BCL-2, BCL-XL, BCL-W, MCL-1, and A1 (Bfl-1)], which directly bind and block proapoptotic BAX/BAK. BH3-only activator proteins convey signals to initiate apoptosis by direct activation of BAX/BAK (BIM and BID) or indirectly by binding and inhibiting their prosurvival relatives (PUMA, BAD, NOXA, and HRK), which are known as sensitizers. (C) Interaction map for BH3 peptides and the antiapoptotic BCL-2 members. Red boxes indicate tight binding with a Kd (dissociation constant) of less than 100 nM;green boxes indicate weak or absent interaction, as determined by fluorescence polarization. Diagrams from (A) to (C) are adapted with permission from (23). (D) Heat map of mitochondrial depolarization induced by peptides derived from different proapoptotic BH3-only proteins. HDFs cultured for 48 hours on matrices with stiffness of 1, 4, 8, 25, and 50 kPa were subjected to BH3 profiling assay using BIM and BID (activate proapoptotic effectors BAX and BAK), PUMA (block prosurvival proteins), BAD (selective BCL-2, BCL-XL, and BCL-W sensitizer), and HRK (binds BCL-XL and MS1 and blocks MCL-1) peptides. The concentration of peptides in the assays was 100 μM except for MS1 (10 μM). Data are means ± SD of three replicate wells for each peptide. (E to H) Mitochondrial depolarization caused by the PUMA (E), BAD (F), HRK (G), and MS1 (H) peptides in HDFs cultured on matrices with increasing matrix stiffness. (I) Working model. Matrix stiffness–induced fibroblast-to-myofibroblast transformation increases mitochondrial priming.
Article Snippet: Cell lines and treatments Human foreskin fibroblasts (ATCC SCRC-1041) and primary normal dermal fibroblasts (ATCC PCS-201-010) were purchased from the American Type Culture Collection (ATCC) and cultured according to the vendor’s protocol.
Techniques: Cell Culture, Derivative Assay, Membrane, Fluorescence, Activation Assay, Blocking Assay, Binding Assay, Concentration Assay, Transformation Assay