MITOL-mediated DRP1 ubiquitylation and degradation promotes mitochondrial hyperfusion in a CMT2A-linked MFN2 mutant

Area of Science:

• Cell Biology
• Neuroscience
• Genetics

Background:

• Mutations in mitofusin 2 (MFN2) are linked to Charcot-Marie-Tooth type 2A (CMT2A) neuropathy and alter mitochondrial morphology.
• The R364W MFN2 mutation leads to elongated, interconnected mitochondria, but the underlying mechanism is unclear.

Purpose of the Study:

• To elucidate the mechanism by which the R364W MFN2 mutation causes mitochondrial hyperfusion.
• To investigate the role of DRP1 (DNM1L) and MITOL (MARCHF5) in MFN2-associated mitochondrial morphology changes.

Main Methods:

• Analysis of MFN2 mutations and their effect on mitochondrial morphology.
• Investigation of DRP1 ubiquitylation and degradation in cells expressing wild-type and mutant MFN2.
• Assessment of MITOL's interaction with MFN2 and DRP1.

Main Results:

• Mitochondrial hyperfusion in R364W-MFN2 cells is caused by increased degradation of DRP1.
• MITOL's interaction and ubiquitylation activity are reduced with R364W-MFN2 compared to wild-type MFN2.
• This differential interaction frees MITOL to ubiquitylate DRP1, leading to its proteasomal degradation and subsequent mitochondrial hyperfusion.

Conclusions:

• MFN2 R364W mutation induces mitochondrial hyperfusion through enhanced DRP1 degradation mediated by MITOL.
• MFN2 indirectly modulates DRP1 activity, a previously unreported mechanism.
• This study provides mechanistic insight into MFN2-associated mitochondrial dysfunction in CMT2A.