Different mechanisms underlie the long-term regulation of pyruvate dehydrogenase kinase (PDHK) by tri-iodothyronine in heart and liver.
Antibodies to purified recombinant PDHKII were used for ELISAs of PDHKII in mitochondrial extracts. In liver, hyperthyroidism elicited a 2.3-fold increase in PDHK activity (P < 0.01) which was accompanied by a significant 1.5-fold (P < 0.001) increase in the amount of mitochondrial immunoreactive PDHKII. In contrast, despite a stable 2.0-fold increase in cardiac PDHK activity (P < 0.001), the amount of mitochondrial immunoreactive PDHKII in heart was unaffected by hyperthyroidism. The mechanisms for long-term regulation of PDHK activity by thyroid hormones therefore differ fundamentally between heart and liver.
Priestman
D A
DA
Department of Biochemistry, Basic Medical Sciences, St Bartholomew's and the Royal London School of Medicine and Dentistry, Queen Mary and Westfield College, UK.
Donald
E
E
Holness
M J
MJ
Sugden
M C
MC
D000818:Animals; D002457:Cell Extracts; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D005260:Female; D006980:Hyperthyroidism / Q000201:enzymology; D008929:Mitochondria, Heart / Q000201:enzymology*; D008930:Mitochondria, Liver / Q000201:enzymology*; D011494:Protein Kinases / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases; D000081382:Pyruvate Dehydrogenase Acetyl-Transferring Kinase; D051381:Rats; D017208:Rats, Wistar; D014284:Triiodothyronine / Q000494:pharmacology*
D002457:Cell Extracts; D000081382:Pyruvate Dehydrogenase Acetyl-Transferring Kinase; D014284:Triiodothyronine; D011494:Protein Kinases; D017346:Protein Serine-Threonine Kinases