OMA1 mediates local and global stress responses against protein misfolding in CHCHD10 mitochondrial myopathy
Mario K. Shammas, … , Joanna Poulton, Derek P. Narendra
Mario K. Shammas, … , Joanna Poulton, Derek P. Narendra
Published June 14, 2022
Citation Information: J Clin Invest. 2022;132(14):e157504. https://doi.org/10.1172/JCI157504.
View: Text | PDF
Research Article Cell biology Genetics Article has an altmetric score of 1

OMA1 mediates local and global stress responses against protein misfolding in CHCHD10 mitochondrial myopathy

Abstract

Mitochondrial stress triggers a response in the cell’s mitochondria and nucleus, but how these stress responses are coordinated in vivo is poorly understood. Here, we characterize a family with myopathy caused by a dominant p.G58R mutation in the mitochondrial protein CHCHD10. To understand the disease etiology, we developed a knockin (KI) mouse model and found that mutant CHCHD10 aggregated in affected tissues, applying a toxic protein stress to the inner mitochondrial membrane. Unexpectedly, the survival of CHCHD10-KI mice depended on a protective stress response mediated by the mitochondrial metalloendopeptidase OMA1. The OMA1 stress response acted both locally within mitochondria, causing mitochondrial fragmentation, and signaled outside the mitochondria, activating the integrated stress response through cleavage of DAP3-binding cell death enhancer 1 (DELE1). We additionally identified an isoform switch in the terminal complex of the electron transport chain as a component of this response. Our results demonstrate that OMA1 was critical for neonatal survival conditionally in the setting of inner mitochondrial membrane stress, coordinating local and global stress responses to reshape the mitochondrial network and proteome.

Authors

Mario K. Shammas, Xiaoping Huang, Beverly P. Wu, Evelyn Fessler, Insung Y. Song, Nicholas P. Randolph, Yan Li, Christopher K.E. Bleck, Danielle A. Springer, Carl Fratter, Ines A. Barbosa, Andrew F. Powers, Pedro M. Quirós, Carlos Lopez-Otin, Lucas T. Jae, Joanna Poulton, Derek P. Narendra

×

Figure 6

C10 G58R activates OMA1 in mouse and patient tissues and localizes to mitochondria.

Options: View larger image (or click on image) Download as PowerPoint
C10 G58R activates OMA1 in mouse and patient tissues and localizes to mi...
(A) Western blot showing WT and C10 WT/G58R/S59L dox-inducible HEK293 cell lines at the 8- and 16-hour dox (1 μg/mL) treatment time points. r1, replicate 1. (B) Quantification of OMA1 S-OPA1 (top) and C10 (bottom) levels from A and Supplemental Figure 7C (n = 4–5 biological replicates). (C) Protein differential abundance between HEK293 WT C10 G58R dox-inducible cells treated overnight with DMSO or dox (n = 4 biological replicates). nDNA, nuclear DNA. (D) Tetramethylrhodamine ethyl ester (TMRE) and MitoTracker Green (MTG) signal intensities in DMSO- and dox-treated HEK293 WT C10 G58R dox-inducible cells treated for over 24 hours (n = 6 biological replicates total on at least 2 occasions). (E) TMRE intensities in HEK293 WT (293 WT) and C2/C10-DKO cells transduced with WT C10 or C10 G58R (n = 7 biological replicates total on at least 2 occasions). (F) MitoSOX and CM-H2DCFDA fluorescence intensities in HEK293 WT C10 G58R dox-inducible cells treated overnight with DMSO or dox (n = at least 7 biological replicates on at least 2 occasions). (G) Representative confocal time series images of Tet-On HEK293 cells overexpressing C10 G58R. Arrows indicate a mitochondrial flicker event. Scale bar: 5 μm. mitomEm, mito-mEmerald. (H) Normalized SD of ΔΨm in mitochondria followed for 85 seconds (n = 60 mitochondria analyzed from 3 biological replicates). (I) Fluctuations in normalized ΔΨm of individual mitochondria followed for 85 seconds (n = 60 mitochondria analyzed from 3 biological replicates; each line represents an individual mitochondrion). ΔF/Favg, change in fluorescence intensity divided by the average fluorescence intensity. (J) Representative oxygen consumption rate (OCR) plots from Seahorse assays using HEK293 WT and OMA1-KO cells transduced with an empty vector or C10 G58R. (K) Quantification of basal and maximum oxygen consumption from the experiments in J (n = 6 biological replicates). Ctrl, control. Error bars represent the SEM. *P < 0.05, **P < 0.01, ***P < 0.001, and ****P < 0.0001, by 1-way ANOVA with Dunnett’s T3 multiple comparisons (B and H), permutation-based FDR with s0 = 0 (C), t test with Welch’s correction (D and F) and 2-way ANOVA with Sidak’s multiple comparisons (E and K). See also Supplemental Figures 7 and 8 and Supplemental data set 2.