Metabolic reorganization in winter: Regulation of pyruvate dehydrogenase (PDH) during long-term freezing and anoxia |
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Affiliation: | 1. Department of Biology, Carleton University, Ottawa, Ontario, Canada;2. Center for Environmental Epigenetics and Development, Biological Sciences, University of Toronto, Toronto, Ontario, Canada |
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Abstract: | Wood frogs, Rana sylvatica, can undergo prolonged periods of whole body freezing during winter, locking as much as 65–70% of total body water into extracellular ice and imposing both anoxia and dehydration on their cells. Metabolic rate depression (MRD) is an adaptation used by R. sylvatica to survive these environmental stresses, where a finite amount of ATP generated through anaerobic metabolism is directed towards maintaining pro-survival functions, while most ATP-expensive cellular processes are temporarily reduced in function. Pyruvate dehydrogenase (PDH) is a vital metabolic enzyme that links anaerobic glycolysis to the aerobic TCA cycle and is an important regulatory site in MRD. PDH enzymatic activity is regulated via reversible protein phosphorylation in response to energetic demands of cells. This study explored the posttranslational regulation of PDH at three serine sites (S232, S293, S300) on the catalytic E1α subunit along with protein expression of four pyruvate dehydrogenase kinases (PDHK1-4) in response to 24 h Freezing, 8 h Thaw, 24 h Anoxia, and 4 h Recovery in the liver and skeletal muscle of R. sylvatica using Luminex multiplex technology and western immunoblotting. Overall, inhibitory regulation of PDH was evident during 24 h Freezing and 24 h Anoxia, which could indicate a notable reduction in glycoytic flux and carbon entry into the tricarboxylic acid cycle as part of MRD. Furthermore, the expression of PDHK1-4 and phosphorylation of PDH at S232, S293, and S300 were highly tissue and stress-specific, indicative of how different tissues respond differently to stress within the same organism. |
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Keywords: | Pyruvate dehydrogenase Pyruvate dehydrogenase kinase Freezing Anoxia Metabolism Reversible protein phosphorylation Metabolic rate depression MRD" },{" #name" :" keyword" ," $" :{" id" :" kwrd0050" }," $$" :[{" #name" :" text" ," _" :" metabolic rate depression RPP" },{" #name" :" keyword" ," $" :{" id" :" kwrd0060" }," $$" :[{" #name" :" text" ," _" :" reversible protein phosphorylation GSK3" },{" #name" :" keyword" ," $" :{" id" :" kwrd0070" }," $$" :[{" #name" :" text" ," _" :" glycogen synthase kinase 3 PDH" },{" #name" :" keyword" ," $" :{" id" :" kwrd0080" }," $$" :[{" #name" :" text" ," _" :" pyruvate dehydrogenase CoA" },{" #name" :" keyword" ," $" :{" id" :" kwrd0090" }," $$" :[{" #name" :" text" ," _" :" Coenzyme A TCA" },{" #name" :" keyword" ," $" :{" id" :" kwrd0100" }," $$" :[{" #name" :" text" ," _" :" tricarboxylic acid PDC" },{" #name" :" keyword" ," $" :{" id" :" kwrd0110" }," $$" :[{" #name" :" text" ," _" :" pyruvate dehydrogenase complex E3BP" },{" #name" :" keyword" ," $" :{" id" :" kwrd0120" }," $$" :[{" #name" :" text" ," _" :" E3-binding protein PDHK" },{" #name" :" keyword" ," $" :{" id" :" kwrd0130" }," $$" :[{" #name" :" text" ," _" :" pyruvate dehydrogenase kinase PDHP" },{" #name" :" keyword" ," $" :{" id" :" kwrd0140" }," $$" :[{" #name" :" text" ," _" :" pyruvate dehydrogenase phosphatase SAPE" },{" #name" :" keyword" ," $" :{" id" :" kwrd0150" }," $$" :[{" #name" :" text" ," _" :" streptavidin-phycoerythrin ECL" },{" #name" :" keyword" ," $" :{" id" :" kwrd0160" }," $$" :[{" #name" :" text" ," _" :" enhanced chemiluminescence MFI" },{" #name" :" keyword" ," $" :{" id" :" kwrd0170" }," $$" :[{" #name" :" text" ," _" :" median fluorescent intensity ANOVA" },{" #name" :" keyword" ," $" :{" id" :" kwrd0180" }," $$" :[{" #name" :" text" ," _" :" analysis of variance F2,6P2" },{" #name" :" keyword" ," $" :{" id" :" kwrd0190" }," $$" :[{" #name" :" text" ," _" :" fructose-2,6-bisphosphate PEPCK" },{" #name" :" keyword" ," $" :{" id" :" kwrd0200" }," $$" :[{" #name" :" text" ," _" :" phosphoenolpyruvate carboxykinase PK" },{" #name" :" keyword" ," $" :{" id" :" kwrd0210" }," $$" :[{" #name" :" text" ," _" :" pyruvate kinase HK" },{" #name" :" keyword" ," $" :{" id" :" kwrd0220" }," $$" :[{" #name" :" text" ," _" :" hexokinase PFK" },{" #name" :" keyword" ," $" :{" id" :" kwrd0230" }," $$" :[{" #name" :" text" ," _" :" phosphofuctokinase |
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