Differential expression of adipose- and heart-type fatty acid binding proteins in hibernating ground squirrels.
The up-regulation of heart- and adipose-type fatty acid binding proteins (H-FABPs and A-FABPs) was detected during hibernation in brown adipose tissue (BAT) of 13-lined ground squirrels, Spermophilus tridecemlineatus, using a commercial rat cDNA array. Full length cDNAs encoding H-FABPs and A-FABPs were subsequently retrieved from a BAT cDNA library. These cDNAs were used to probe Northern blots of total RNA from tissues of euthermic versus hibernating ground squirrels. H-FABP mRNA transcripts increased in BAT, skeletal muscle and heart of hibernating animals whereas A-FABP transcripts, which are normally expressed exclusively in adipose tissue, increased in both BAT and heart during torpor. It is proposed that the increased expression of H-FABPs and A-FABPs during hibernation accelerates the rate at which fatty acids can be transported to the mitochondria for oxidization, particularly in support of the huge increase in thermogenesis by BAT and rapid increase in heart rate that are required during arousal from torpor. Comparison of the deduced polypeptide sequence of ground squirrel H-FABP with that from other mammals also revealed three unique amino acid differences which may be important for protein function at low body temperatures during hibernation.
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Institute of Biochemistry and Department of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, ON K1S 5B6, Canada.
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D000273:Adipose Tissue / Q000378:metabolism*; D002001:Adipose Tissue, Brown / Q000737:chemistry / Q000378:metabolism; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D003429:Cross Reactions; D000071438:Fatty Acid-Binding Protein 7; D050556:Fatty Acid-Binding Proteins; D006339:Heart Rate; D006605:Hibernation; D008969:Molecular Sequence Data; D009206:Myocardium / Q000378:metabolism*; D009363:Neoplasm Proteins; D009419:Nerve Tissue Proteins; D020411:Oligonucleotide Array Sequence Analysis; D012119:Respiration; D012589:Sciuridae / Q000378:metabolism*; D016415:Sequence Alignment; D013696:Temperature; D015854:Up-Regulation
D002352:Carrier Proteins; C490174:Fabp7 protein, rat; D000071438:Fatty Acid-Binding Protein 7; D050556:Fatty Acid-Binding Proteins; D009363:Neoplasm Proteins; D009419:Nerve Tissue Proteins