Mitochondria-derived nuclear ATP surge protects against confinement-induced proliferation defects

The physical microenvironment regulates cell behaviour. However, whether physical confinement rewires the subcellular localisation of organelles and affect metabolism is unknown. Proteomics analysis revealed that cellular confinement induces a strong enrichment of mitochondrial proteins within the nuclear compartment. High-resolution microscopy confirmed that mechanical cell confinement leads to a rapid re-localisation of mitochondria to the nuclear periphery. This nuclear-mitochondrial proximity is mediated by an endoplasmic reticulum-based net that entraps the mitochondria in an actin-dependent manner. Functionally, the mitochondrial proximity results in a nuclear ATP surge, which can be reverted by the pharmacological inhibition of mitochondrial ATP production or via actin depolymerisation. Inhibition of the confinement-derived nuclear ATP surge reveals long-term effects on cell fitness which arise from alterations of chromatin states, delayed DNA damage repair, and impaired cell cycle progression. Together, our data describe a confinement-induced metabolic adaptation that is required to enable prompt DNA damage repair and cell cycle progression by allowing chromatin state transitions.