The clinical heterogeneity of coenzyme Q10 deficiency results from genotypic differences in the Coq9 gene.

Marta Luna‐Sánchez,Luis Carlos López,Emanuele Barca,Catarina M Quinzii,Ángeles Montilla‐García,Dario Acuña‐Castroviejo,Germaine Escames,Elena Díaz‐Casado,Miguel Ángel Tejada,Enrique Javier Cobos

doi:10.15252/emmm.201404632

Abstract

Primary coenzyme Q10 (CoQ10) deficiency is due to mutations in genes involved in CoQ biosynthesis. The disease has been associated with five major phenotypes, but a genotype–phenotype correlation is unclear. Here, we compare two mouse models with a genetic modification in Coq9 gene (Coq9Q95X and Coq9R239X), and their responses to 2,4-dihydroxybenzoic acid (2,4-diHB). Coq9R239X mice manifest severe widespread CoQ deficiency associated with fatal encephalomyopathy and respond to 2,4-diHB increasing CoQ levels. In contrast, Coq9Q95X mice exhibit mild CoQ deficiency manifesting with reduction in CI+III activity and mitochondrial respiration in skeletal muscle, and late-onset mild mitochondrial myopathy, which does not respond to 2,4-diHB. We show that these differences are due to the levels of COQ biosynthetic proteins, suggesting that the presence of a truncated version of COQ9 protein in Coq9R239X mice destabilizes the CoQ multiprotein complex. Our study points out the importance of the multiprotein complex for CoQ biosynthesis in mammals, which may provide new insights to understand the genotype–phenotype heterogeneity associated with human CoQ deficiency and may have a potential impact on the treatment of this mitochondrial disorder.

Highlights

Primary coenzyme Q10 (CoQ10) deficiency is due to mutations in genes involved in Coenzyme Q (CoQ) biosynthesis
Our work describes the first mouse model of mitochondrial myopathy with exercise intolerance associated to CoQ deficiency, providing new insights to understand the genotype–phenotype disparity associated to CoQ deficiency
Contrary to Coq9R239X, which manifests severe widespread CoQ10 deficiency associated with fatal encephalomyopathy, Coq9Q95X mice exhibited mild CoQ deficiency manifesting with reduction in CI+III activity and mitochondrial respiration in skeletal muscle, leading to a lateonset mild mitochondrial myopathy with decreased locomotor activity

Summary

Introduction

Primary coenzyme Q10 (CoQ10) deficiency is due to mutations in genes involved in CoQ biosynthesis. Coq9R239X mice manifest severe widespread CoQ deficiency associated with fatal encephalomyopathy and respond to 2,4-diHB increasing CoQ levels. Coq9Q95X mice exhibit mild CoQ deficiency manifesting with reduction in CI+III activity and mitochondrial respiration in skeletal muscle, and late-onset mild mitochondrial myopathy, which does not respond to 2,4-diHB. We show that these differences are due to the levels of COQ biosynthetic proteins, suggesting that the presence of a truncated version of COQ9 protein in Coq9R239X mice destabilizes the CoQ multiprotein complex. Our study points out the importance of the multiprotein complex for CoQ biosynthesis in mammals, which may provide new insights to understand the genotype– phenotype heterogeneity associated with human CoQ deficiency and may have a potential impact on the treatment of this mitochondrial disorder

Methods

Results

Conclusion