Abundant expression of uncoupling protein-2 in the small intestine: up-regulation by dietary fish oil and fibrates.
Mitochondrial uncoupling protein-2 (UCP-2) is widely expressed in various mammalian tissues, although its physiological functions are not well understood. We examined the effects of dietary fish oil on UCP-2 expression in the rat small intestine, in which UCP-2 mRNA levels are higher than in other organs. Feeding with fish oil (20%) up-regulated UCP-2 mRNA within 6 days in the small intestine as well as the liver, compared to feeding with soybean oil. This was mimicked by feeding with agonists for peroxisome proliferator-activated receptor alpha (PPARalpha) such as fenofibrate and bezafibrate, but not the PPARgamma agonist troglitazone. The bezafibrate-induced increase in UCP-2 expression was found within 2 days in the small intestine, but only after 6 days in the liver. The up-regulation of UCP-2 was also found in cultured intestinal epithelial cells (IEC-6) treated for 24 h with various long-chain fatty acids and PPARalpha agonists. These results indicated that intestinal UCP-2 is up-regulated through direct activation of PPARalpha by dietary fatty acids.
Murase
T
T
Biological Science Laboratories, Kao Corporation, Tochigi, Japan.
Kondo
H
H
Hase
T
T
Tokimitsu
I
I
Saito
M
M
D000818:Animals; D002460:Cell Line; D004042:Dietary Fats, Unsaturated / Q000008:administration & dosage / Q000494:pharmacology*; D004847:Epithelial Cells / Q000187:drug effects; D005395:Fish Oils / Q000008:administration & dosage / Q000494:pharmacology*; D005786:Gene Expression Regulation / Q000187:drug effects; D007421:Intestine, Small / Q000378:metabolism*; D007473:Ion Channels; D008297:Male; D026901:Membrane Transport Proteins; D024101:Mitochondrial Proteins; D014176:Protein Biosynthesis; D011506:Proteins / Q000378:metabolism*; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D017208:Rats, Wistar; D018160:Receptors, Cytoplasmic and Nuclear / Q000819:agonists / Q000187:drug effects; D014157:Transcription Factors / Q000819:agonists / Q000187:drug effects; D014475:Uncoupling Agents / Q000378:metabolism*; D000071246:Uncoupling Protein 2; D015854:Up-Regulation
D004042:Dietary Fats, Unsaturated; D005395:Fish Oils; D007473:Ion Channels; D026901:Membrane Transport Proteins; D024101:Mitochondrial Proteins; D011506:Proteins; D012333:RNA, Messenger; D018160:Receptors, Cytoplasmic and Nuclear; D014157:Transcription Factors; C000604391:Ucp2 protein, rat; D014475:Uncoupling Agents; D000071246:Uncoupling Protein 2