Objective 1

To determine the CoQ concentration and the activities of the mitochondrial respiratory chain (MRC) complexes in muscle biopsies and cultured fibroblasts or even blood samples from patients with different clinical phenotypes of apparent primary CoQ deficiency. The effect of CoQ supplementation in MRC of deficient fibroblasts will be analyzed. Patients with low CoQ are predicted to harbor mutations in one of the genes encoding enzymes of the CoQ biosynthetic pathway. Secondary CoQ deficiencies, such as in dystrophies, neurogenic atrophies, inflammatory myopathies, statin treatment, etc, will be identified with a careful anamnesis and medical examination.

Objective 2

To identify by RNA interference (RNAi) and yeast complementation and to clone the human genes involved in CoQ biosynthesis. The initial selection of potential human coq sequences is based on public human databases and on their high homologies with genes in S. cerevisiae and C. elegans. RNAi of these genes will be monitored by analysis of the CoQ content.

Objective 3

Objective 4

To analyze the CoQ metabolism in CoQ-deficient fibroblasts. The CoQ biosynthesis rate in these cells will be studied by the incorporation of the radiolabeled CoQ precursor p-hydroxybenzoic acid ([14C]pHB). Defective post-translational protein modifications would also result in CoQ-deficiency, therefore the levels of Coq proteins and their post-translational modifications in CoQ-deficient fibroblasts will be also studied. In the case that the in vitro culture of primary fibroblasts is insufficient to run the required assays, immortalized deficient fibroblasts or lymphoblastoid cell lines obtained from the same patients will be used instead.

Objective 5

To study the pattern of expression of genes involved in CoQ-biosynthesis. As it has been proposed above, CoQ deficiency can be a consequence of the mutation of coq genes, but also can be caused by either post-translational modifications of proteins or by mutations on another genes unknown to be involved in CoQ biosynthesis at this time. Besides these considerations, a CoQ deficiency could be also generated by the modification of the expression of the genes required for CoQ biosynthesis.

Ubigenes :: Genetics of coenzyme Q deficiency in humans