Journal: bioRxiv
Article Title: Mitochondrial Respiratory Chain Function is crucial for Muscle Toxicity in Facioscapulohumeral Muscular Dystrophy
doi: 10.1101/2025.11.25.690559
Figure Lengend Snippet: (A) Left: longitudinal quantitation of DUX4 and ZSCAN4-tdTomato containing nuclei in iDUX4 ZSCAN4-tdT reporter myoblasts at 2h intervals after DOX (62.5 ng/mL). Right: immunofluorescence micrographs of iDUX4 ZSCAN4-tdT reporter myoblasts before (0h), and 4h and 16h after exposure to DOX (62.5 ng/mL; green=DUX4, red=ZSCAN4-tdTomato, blue=nuclei; scale bar=100μm). (B) Normalised oxygen consumption rate (OCR) curves of iDUX4 control (CTRL) and DOX-induced (62.5 ng/mL DOX for 4h and 16h) myoblasts. (C) Respirometric assessment of mitochondrial respiration reveals reduction of basal, maximal and ATP-linked respiration in iDUX4 myoblasts 4h after DOX (62.5 ng/mL). (D) Normalised extracellular acidification rate (ECAR) curves of iDUX4 control (CTRL) and DOX-induced (62.5 ng/mL DOX for 4h and 16h) myoblasts. (E) ATP production rates demonstrating reduction of ATP in iDUX4 myoblasts 4h after DOX (62.5 ng/mL), mainly arising from defective oxidative phosphorylation (OXPHOS; mitoATP), while glycoATP is unaffected before 16h. (F) Assaying of Casp9 (red; onset 4h after DOX) and Casp3/7 activation (grey; onset 8h after DOX), measured at 2h intervals over 16h. (G) Assaying Annexin V as a marker of apoptosis in iDUX4 myoblasts after DOX (62.5 ng/mL), measured at 2h intervals over 16h. (H) Casp3/7 activation in iDUX4 myoblasts 8h after DOX (62.5 ng/mL) is prevented by a Casp9 inhibitor (Z-LEHD-FMK TFA; 10 μM). (I) Casp3/7 and Casp9 activation in iDUX4 myoblasts 8h after DOX (62.5 ng/mL) with non-targeted (Q10; 20 μM) or mitochondria-targeted (mitoQ10; 20μM) Coenzyme Q10. [n=3-6, data is mean ± s.d., where * p <0.05, ** p <0.01, *** p <0.001, **** p <0.0001].
Article Snippet: Caspase 9 inhibitor Z-LEHD-FMK TFA (S7313) and mitoQ10 (mesylate; S8978) were from Selleckchem (Houston, TX, USA).
Techniques: Quantitation Assay, Immunofluorescence, Control, Phospho-proteomics, Activation Assay, Marker