Correcting mitochondrial fusion by manipulating mitofusin conformations

Area of Science:

• Cell Biology
• Neuroscience
• Genetics

Background:

• Mitochondria are essential dynamic organelles involved in cellular life and death, undergoing fusion and fission.
• Mutations in Mitofusin 2 (MFN2) disrupt mitochondrial fusion, leading to Charcot-Marie-Tooth disease type 2A (CMT2A), a neurodegenerative disorder.
• Directly modulating mitochondrial fusion has been challenging due to an incomplete understanding of mitofusin structural functions.

Purpose of the Study:

• To elucidate the structural basis of mitofusin function and its role in mitochondrial fusion.
• To investigate whether targeting mitofusin conformational transitions can regulate mitochondrial fusion.
• To develop a therapeutic strategy for CMT2A by manipulating mitochondrial dynamics.

Main Methods:

• Structural analysis of mitofusins to identify distinct molecular conformations (fusion-constrained and fusion-permissive).
• Development of a cell-permeant minipeptide designed to target and alter mitofusin conformations.
• In vitro studies using cultured mouse fibroblasts and neurons with CMT2A-associated genetic defects.

Main Results:

• Mitofusins exist in at least two conformations, regulated by intramolecular interactions, influencing mitochondrial fusion.
• The engineered minipeptide successfully destabilized the fusion-constrained conformation and promoted the fusion-permissive state.
• Treatment with the minipeptide reversed mitochondrial abnormalities in cultured cells and neurons relevant to CMT2A.

Conclusions:

• Mitofusin conformational plasticity is a key regulator of mitochondrial fusion and overall mitochondrial dynamism.
• Targeting these conformational transitions offers a novel strategy for therapeutic intervention in mitochondrial diseases.
• This approach successfully corrected mitochondrial pathology in CMT2A models, highlighting its potential for treating related neurodegenerative conditions.