Identification and functional analysis of mutations in FAD-binding domain of mitochondrial glycerophosphate dehydrogenase in caucasian patients with type 2 diabetes mellitus.
Ca2+-responsive mitochondrial FAD-linked glycerophosphate dehydrogenase (mGPDH) is a key component of the pancreatic beta-cell glucose-sensing device. The purpose of this study was to examine the association of mutations in the cDNA coding for the FAD-binding domain of mGPDH and to explore the functional consequences of these mutations in vitro. To investigate this association in type 2 diabetes mellitus, we studied a cohort of 168 patients with type 2 diabetes and 179 glucose-tolerant control subjects of Spanish Caucasian origin by single-stranded conformational polymorphism analysis. In vitro site-directed mutagenesis was performed in the mGPDH cDNA sequence to reproduce those mutations that produce amino acid changes in a patient with type 2 diabetes. We detected mutations in the mGPDH FAD-binding domain in a single patient, resulting in a Gly to Arg amino acid change at positions 77, 78, and 81 and a Thr to Pro at position 90. In vitro expression of the mutated constructs in Xenopus oocytes resulted in a significantly lower enzymatic activity than in cells expressing the wild-type form of the enzyme. Our results indicate that although mutations in the mGPDH gene do not appear to have a major role in type 2 diabetes mellitus, the reduction in mGPDH enzymatic activity associated with the newly described mGPDH mutations suggests that they may contribute to the disease in some patients.
Gudayol
M
M
Endocrinology and Diabetes Unit, Hospital Clinic de Barcelona, Spain.
Vidal
J
J
Usac
E F
EF
Morales
A
A
Fabregat
M E
ME
Fernández-Checa
J C
JC
Novials
A
A
Gomis
R
R
D000368:Aged; D000818:Animals; D002478:Cells, Cultured; D015331:Cohort Studies; D018076:DNA, Complementary / Q000235:genetics; D003924:Diabetes Mellitus, Type 2 / Q000235:genetics*; D005260:Female; D005182:Flavin-Adenine Dinucleotide / Q000378:metabolism*; D005993:Glycerolphosphate Dehydrogenase / Q000235:genetics* / Q000378:metabolism*; D006801:Humans; D008297:Male; D008875:Middle Aged; D008928:Mitochondria / Q000201:enzymology*; D009154:Mutation; D009865:Oocytes; D017434:Protein Structure, Tertiary / Q000235:genetics; D014981:Xenopus
D018076:DNA, Complementary; D005182:Flavin-Adenine Dinucleotide; D005993:Glycerolphosphate Dehydrogenase