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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.

We generated mice deficient in Lon protease (LONP1), a major enzyme of the mitochondrial quality control machinery. Homozygous deletion of Lonp1 causes early embryonic lethality, whereas its haploinsufficiency protects against colorectal and skin tumors. Furthermore, LONP1 knockdown inhibits cellular proliferation and tumor and metastasis formation, whereas its overexpression increases tumorigenesis. Clinical studies indicate that high levels of LONP1 are a poor prognosis marker in human colorectal cancer and melanoma. Additionally, functional analyses show that LONP1 plays a key role in metabolic reprogramming by remodeling OXPHOS complexes and protecting against senescence. Our findings demonstrate the relevance of LONP1 for cellular and organismal viability and identify this protease as a central regulator of mitochondrial activity in oncogenesis.

The oncogene MLL is frequently translocated in leukemia, resulting in oncogenic fusion proteins. Here, the authors report a temporally controlled mouse model of MLL-ENL driven leukemia AND identify therapeutic targets associated with early MLL-ENL driven leukaemogenesis.

Changes in chromatin structure have been linked to organismal ageing. Here the authors show that altered histone expression and mitochondrial stress during C. elegans development result in chromatin changes and a cytosolic stress response that affects organismal longevity, and depends on HSF-1 and the chromatin remodeller, ISW-1.

In recent years, tetracyclines, such as doxycycline, have become broadly used to control gene expression by virtue of the Tet-on/Tet-off systems. However, the wide range of direct effects of tetracycline use has not been fully appreciated. We show here that these antibiotics induce a mitonuclear protein imbalance through their effects on mitochondrial translation, an effect that likely reflects the evolutionary relationship between mitochondria and proteobacteria. Even at low concentrations, tetracyclines induce mitochondrial proteotoxic stress, leading to changes in nuclear gene expression and altered mitochondrial dynamics and function in commonly used cell types, as well as worms, flies, mice, and plants. Given that tetracyclines are so widely applied in research, scientists should be aware of their potentially confounding effects on experimental results. Furthermore, these results caution against extensive use of tetracyclines in livestock due to potential downstream impacts on the environment and human health.