Cell Biologists Find That Certain Mitochondrial Diseases Stem from Coenzyme Q10 Depletion

A team of German cell biologists has linked the development of certain mitochondrial-linked diseases to depletion of the organelles' pool of coenzyme Q10 brought about by mutation in the MFN2 gene, which encodes the fusion protein mitofusin 2.

Despite the established role of mitofusins (Mfn1 and Mfn2) in mitochondrial fusion, only Mfn2 had been associated with metabolic and neurodegenerative diseases, which suggests that this protein is needed to maintain mitochondrial energy metabolism. Mice lacking the MFN1 gene, which encodes mitofusin 1, seem perfectly healthy, but MFN2-deficient mice die soon after birth. Furthermore, mutations in the MFN2 gene cause human diseases, including the peripheral neuropathy Charcot-Marie-Tooth type 2A. The molecular basis for the mitochondrial dysfunction encountered in the absence of Mfn2 has not been explained.

In the current study, investigators at the Max Planck Institute for Biology of Ageing (Cologne, Germany) worked with cultures of mouse heart muscle cells lacking the MFN2 gene.

They reported in the February 16, 2015, online edition of the Journal of Cell Biology that energy metabolism in the cells was impaired compared to that of healthy heart cells or of heart cells that lacked only Mfn1. The energy metabolic process in the Mfn2-deficient cells was found to have been disrupted by reduced levels of coenzyme Q, a key component of the mitochondrial respiratory chain that generates cellular energy in the form of ATP.

The reduced respiratory chain function in the mitochondria of cells lacking Mfn2 could be partially restored by supplementation with coenzyme Q10, which suggested a possible therapeutic strategy for patients with diseases caused by mutations in the MFN2 gene.

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Max Planck Institute for Biology of Ageing