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Inner-membrane proteins PMI/TMEM11 regulate mitochondrial morphogenesis independently of the DRP1/MFN fission/fusion

Thomas Rival1, Marc Macchi, Laetitia Arnauné-Pelloquin

  • 1Institut de Biologie du Développement de Marseille-Luminy, CNRS UMR 6216/Aix-Marseille Universités, F-13288 Marseille, France.

EMBO Reports
|January 29, 2011
PubMed

Insights

Mitochondrial networks are shaped by fusion and fission. A novel protein, PMI, regulates mitochondrial shape independently of known DRP1 and MFN pathways, revealing a new mechanism for mitochondrial remodeling.

Area of Science:

  • Cell Biology
  • Mitochondrial Dynamics
  • Organelle Morphology

Background:

  • Mitochondria exhibit dynamic changes in number and morphology, crucial for cellular functions.
  • These dynamics are regulated by opposing fusion and fission pathways involving proteins like Mitofusins (MFNs), OPA1, and dynamin-related protein 1 (DRP1).
  • Understanding the complete machinery governing mitochondrial shape is essential for comprehending cellular health and disease.

Purpose of the Study:

  • To identify and characterize novel proteins involved in mitochondrial morphogenesis.
  • To elucidate the molecular mechanisms by which mitochondrial shape is regulated.
  • To investigate whether additional pathways, independent of DRP1 and MFN, contribute to mitochondrial network organization.

Main Methods:

  • Genetic screening in Drosophila to identify genes regulating mitochondrial morphology.
  • Analysis of mitochondrial morphology in cells with mutations in the Drosophila PMI gene and its human orthologue TMEM11.
  • Epistatic experiments to determine the relationship between PMI and known fission/fusion regulators (DRP1, MFNs).

Main Results:

  • The Drosophila PMI gene and its human orthologue TMEM11 encode inner-mitochondrial membrane proteins that regulate mitochondrial morphogenesis.
  • PMI-mutant cells display a highly condensed mitochondrial network, suggesting a role in mitochondrial shape regulation.
  • Epistatic experiments revealed that PMI controls mitochondrial shape through a mechanism independent of DRP1 and MFN, indicating a novel pathway.

Conclusions:

  • Mitochondrial networks in higher eukaryotes are shaped by at least two distinct pathways.
  • One pathway involves the previously known DRP1 and MFN proteins.
  • A second, novel pathway for mitochondrial remodeling is dependent on PMI (or TMEM11).

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