Ledoux, B. | Search bioRxiv

bioRxiv2024

In-depth study of MPV17: a molecular travel unveiling a mitochondrial calcium regulation function

Mitochondrial DNA depletion syndromes are severe genetic disorders associated with mutations in a variety of genes including MPV17, encoding a protein of the inner mitochondrial membrane with an unclear function. In this study, using BioID technology, we identified MPV17 interacting partners among which proteins from the MICOS complex. However, MPV17 knockout did not impact mitochondrial ultrastructure, but led to increased mitochondria-derived vesicles formation and altered mitochondrial permeability transition pore. Furthermore, MPV17 KO cells exhibited higher mitochondrial calcium levels and reactive oxygen species, leading to mtDNA degradation, a phenomenon prevented by blocking mitochondrial calcium entry or treating cells with antioxidant. We thus propose a function for MPV17 as a potential additional member of the mitochondrial permeability transition pore, whereas in the absence of the protein, the build-up of calcium inside the mitochondria would lead to mtDNA degradation caused by increased oxidative damages.

cell biology↗

bioRxiv2022

Plasma membrane nanodeformations promote actin polymerisation through CIP4/CDC42 recruitment and regulate type II IFN signaling

In their environment, cells have to cope with mechanical stresses constantly. Among those, nanoscale deformations of plasma membrane induced by substrate nanotopography are now largely accepted as a biophysical stimulus influencing cell behaviour and function. However, the mechanotransduction cascades involved and their precise molecular effects on cellular physiology are still poorly understood. Here, using homemade fluorescent nanostructured cell culture surfaces, we explored the role of Bin/Amphiphysin/Rvs (BAR) domain proteins as mechanosensors of plasma membrane geometry. Our data reveal that distinct subsets of BAR proteins bind to plasma membrane deformations in a membrane curvature radius-dependent manner. Furthermore, we show that membrane curvature promotes the formation of dynamic actin structures mediated by the Rho GTPase CDC42, the F-BAR protein CIP4 and the presence of PI(4,5)P2, independently of clathrin. In addition, these actin-enriched nanodomains can serve as platforms to regulate receptor signaling as they appear to contain Interferon {gamma} receptor (IFN{gamma}-R) and to lead to the partial inhibition of IFN{gamma}-induced Janus-activated tyrosine kinase/signal transducer and activator of transcription (JAK/STAT) signaling.

cell biology↗