Gene regulation and genetic defects in the pyruvate dehydrogenase complex.

The mammalian pyruvate dehydrogenase complex (PDC) is subject to both short-term (product inhibition and covalent modification) and long-term (increases in total activity and protein mass) regulation mediated by dietary and hormonal treatments. Recent advances in the isolation and characterization of the complementary DNAs as well as genes encoding several components of mammalian PDC have facilitated studies concerning long-term regulation of PDC. Analyses of the promoter-regulatory regions of the two human PDC genes show characteristics of both facultative and housekeeping gene promoters, indicating complex transcriptional regulation. Deficiency of PDC activity causes a wide range of neurological disabilities. A spectrum of genetic defects in PDC components has been reported; however, the most frequent defects are associated with the pyruvate dehydrogenase component. Heterogeneity in pyruvate dehydrogenase deficiency has been shown to occur at both protein and messenger RNA levels, and several mutations in pyruvate dehydrogenase have been identified. Dietary treatments such as ketogenic diets and vitamin supplements as well as dichloroacetate treatment have been utilized to treat PDC deficiency, but their efficacy requires further evaluation.