[show abstract][hide abstract] ABSTRACT: Dichloroacetate (DCA) is a structural analog of pyruvate that has been recommended for the treatment of primary lactic acidemia, particularly in patients with pyruvate dehydrogenase (PDHC) deficiency. Recent reports have demonstrated that the response to DCA may depend on the type of molecular abnormality. In this study, we investigated the response to DCA in various PDHC-deficient cell lines and tried to determine the mechanism involved. The effect of chronic 3-d DCA treatment on PDHC activity was assessed in two PDHC-deficient cell lines, each with a different point mutation in the E1alpha subunit gene (R378C and R88C), and one cell line in which an 8-bp tandem repeat was deleted (W383 del). Only two (R378C and R88C) of the three PDHC-deficient cell lines with very low levels of PDHC activity and unstable polypeptides were sensitive to chronic DCA treatment. In these cell lines, DCA treatment resulted in an increase in PDHC activity by 125 and 70%, respectively, with concomitant increases of 121 and 130% in steady-state levels of immunoreactive E1alpha. DCA treatment reduced the turnover of the E1alpha subunit in R378C and R88C mutant cells with no significant effect on the E1beta subunit. Chronic DCA treatment significantly improved the metabolic function of PDHC in digitonin-permeabilized R378C and R88C fibroblasts. The occurrence of DCA-sensitive mutations suggests that DCA treatment is potentially useful as an adjuvant to ketogenic and vitamin treatment in PDHC-deficient patients.
Pediatric Research 06/2003; 53(5):793-9. · 2.67 Impact Factor
[show abstract][hide abstract] ABSTRACT: We report studies of four patients with pyruvate dehydrogenase complex (PDH) deficiency caused by mutations in the E1α subunit.
Two unrelated male patients presented with Leigh syndrome and a R263G missense mutation in exon 8. This mutation has previously
been described in males with the same phenotype. The two other patients had different novel mutations: (1) an 8-bp deletion
at the C-terminus (exon 11) was found in one allele of a young girl suffering from microcephaly and (2) a C88S missense mutation
(exon 3) in a boy who only presented with motor neuropathy. These mutations were not found in the mothers of any of the four
cases. Immunoblot analysis revealed decreased immunoreactivity for the E1α and E1β subunits in three out of the four patients.
These findings confirm that: (1) PDH deficiencies are genetically heterogeneous, (2) the R263G mutation is more frequent in
male cases than are other mutations and this amino acid is a hot spot for gene mutations, (3) the last eight amino acids may
be important for the conformation of the tetrameric E1-PDH enzyme, and (4) the amino acids at positions 88, 263 and 382–387
are essential for the linking of the α subunit with the β subunit and for the activity of the holoenzyme.
Human Genetics 04/1997; 99(6):785-792. · 4.63 Impact Factor