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Mitochondrial membrane tension governs fission

Why do some mitochondria divide while others constrict without dividing? The NCCR Chemical Biology is proud to announce a new open access publication in Cell Reports stemming from the collaboration of 3 NCCR labs (Manley, Roux and Matile). Interdisciplinary collaboration strikes again!

 

Highlights from the publication:

  • Mitochondria constricted by canonical fission factors do not invariably divide.
  • The average tension for mitochondria that divide is higher than for those that do not.
  • Depolymerizing microtubules or inhibiting myosin II reduces mitochondrial tension.
  • Probability of division, but not of constriction, depends on mitochondrial tension.

 

Summary

During mitochondrial fission, key molecular and cellular factors assemble on the outer mitochondrial membrane, where they coordinate to generate constriction. Constriction sites can eventually divide or reverse upon disassembly of the machinery. However, a role for membrane tension in mitochondrial fission, although speculated, has remained undefined. The authors capture the dynamics of constricting mitochondria in mammalian cells using live-cell structured illumination microscopy (SIM). By analyzing the diameters of tubules that emerge from mitochondria and implementing a fluorescence lifetime-based mitochondrial membrane tension sensor, they discovered that mitochondria are indeed under tension. Under perturbations that reduce mitochondrial tension, constrictions initiate at the same rate, but are less likely to divide. The authors propose a model based on our estimates of mitochondrial membrane tension and bending energy in living cells which accounts for the observed probability distribution for mitochondrial constrictions to divide.

Reference

Dora Mahecic, Lina Carlini, Tatjana Kleele, Adai Colom, Antoine Goujon, Stefan Matile, Aurélien Roux, Suliana Manley, “Mitochondrial membrane tension governs fission”, Cell Reports, 35, 2, 108947, 2021.