Cloning and characterization of PDK4 on 7q21.3 encoding a fourth pyruvate dehydrogenase kinase isoenzyme in human.
Different isoenzymes of pyruvate dehydrogenase kinase (PDK) inhibit the mitochondrial pyruvate dehydrogenase complex by phosphorylation of the E1alpha subunit, thus contributing to the regulation of glucose metabolism. By positional cloning in the 7q21.3-q22.1 region linked with insulin resistance and non-insulin-dependent diabetes mellitus in the Pima Indians, we identified a gene encoding an additional human PDK isoform, as evidenced by its amino acid sequence identity (>65%) with other mammalian PDKs, and confirmed by biochemical analyses of the recombinant protein. We performed detailed comparative analyses of the gene, termed PDK4, in insulin-resistant and insulin-sensitive Pima Indians, and detected five DNA variants with comparable frequencies in both subject groups. Using quantitative reverse transcription polymerase chain reaction, we found that the variants identified in the promoter and 5'-untranslated region did not correlate with differences in mRNA level in skeletal muscle and adipose tissue. We conclude that alterations in PDK4 are unlikely to be the molecular basis underlying the observed linkage at 7q21.3-q22.1 in the Pima Indians. Information about the genomic organization and promoter sequences of PDK4 will be useful in studies of other members of this family of mitochondrial protein kinases that are important for the regulation of glucose metabolism.
Rowles
J
J
Clinical Diabetes and Nutrition Section, Phoenix Epidemiology and Clinical Research Branch, NIDDK, National Institutes of Health, Phoenix, Arizona 85016, USA.
Scherer
S W
SW
Xi
T
T
Majer
M
M
Nickle
D C
DC
Rommens
J M
JM
Popov
K M
KM
Harris
R A
RA
Riebow
N L
NL
Xia
J
J
Tsui
L C
LC
Bogardus
C
C
Prochazka
M
M
D000273:Adipose Tissue / Q000737:chemistry; D000595:Amino Acid Sequence; D001483:Base Sequence; D002897:Chromosomes, Human, Pair 7; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000737:chemistry; D003924:Diabetes Mellitus, Type 2 / Q000201:enzymology / Q000235:genetics; D006801:Humans; D007198:Indians, North American; D007527:Isoenzymes / Q000235:genetics*; D008969:Molecular Sequence Data; D018482:Muscle, Skeletal / Q000737:chemistry; D016133:Polymerase Chain Reaction; D011494:Protein Kinases / Q000235:genetics*; D017346:Protein Serine-Threonine Kinases; D000081382:Pyruvate Dehydrogenase Acetyl-Transferring Kinase; D012333:RNA, Messenger / Q000032:analysis; D017386:Sequence Homology, Amino Acid; D014018:Tissue Distribution
D018076:DNA, Complementary; D007527:Isoenzymes; C000631432:PDK4 protein, human; D000081382:Pyruvate Dehydrogenase Acetyl-Transferring Kinase; D012333:RNA, Messenger; D011494:Protein Kinases; D017346:Protein Serine-Threonine Kinases