Octanoate stimulates cytosolic triacylglycerol accumulation and CD36 mRNA expression but inhibits acetyl coenzyme A carboxylase activity in primary cultured bovine mammary epithelial cells.
Mammary epithelial cells, which express and secrete leptin into milk, accumulate triacylglycerol (TAG). We examined effects on the accumulation of cytosolic TAG of addition of short- (acetate and butyrate) or medium- (octanoate) chain fatty acids to the medium bathing bovine mammary epithelial cells (bMEC). Octanoate stimulated the accumulation of TAG in a concentration-dependent manner from 1 to 10 mM and increased lipid droplet formation and mRNA expression of CD36 (a fatty acid translocase). Additionally, expression of a peroxisome proliferator activated receptor (PPAR) gamma 2 protein that is a lipid-activated transcription factor, was increased by the addition of acetate or octanoate. However, leptin mRNA expression was significantly reduced by addition of acetate or butyrate. Both short- and medium-chain fatty acids inhibited acetyl coenzyme A carboxylase (ACC) activities, which is pivotal in lipid synthesis, but elevated expression of uncoupling protein 2 (UCP2) mRNA, which is important in energy expenditure. These results suggest that octanoate induces cytosolic TAG accumulation and the formation of lipid droplets, and that acetate and butyrate inhibit leptin expression and lipid synthesis in bMEC.
Yonezawa
Tomo
T
Department of Animal Physiology, Graduate School of Agricultural Science, Tohoku University, Amamiyamachi, Sendai 981-8555, Japan. yonet@bios.tohoku.ac.jp
Yonekura
Shinichi
S
Sanosaka
Masato
M
Hagino
Akihiko
A
Katoh
Kazuo
K
Obara
Yoshiaki
Y
D000103:Acetyl-CoA Carboxylase / Q000037:antagonists & inhibitors*; D000818:Animals; D018955:CD36 Antigens / Q000235:genetics*; D002210:Caprylates / Q000494:pharmacology*; D002417:Cattle; D002478:Cells, Cultured; D003600:Cytosol / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism; D005260:Female; D015870:Gene Expression / Q000187:drug effects; D007473:Ion Channels; D020738:Leptin / Q000235:genetics; D008321:Mammary Glands, Animal / Q000187:drug effects* / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000235:genetics; D024101:Mitochondrial Proteins / Q000235:genetics; D047495:PPAR gamma / Q000235:genetics; D012333:RNA, Messenger / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014280:Triglycerides / Q000378:metabolism*; D000071246:Uncoupling Protein 2
D018955:CD36 Antigens; D002210:Caprylates; D004791:Enzyme Inhibitors; D007473:Ion Channels; D020738:Leptin; D026901:Membrane Transport Proteins; D024101:Mitochondrial Proteins; D047495:PPAR gamma; D012333:RNA, Messenger; D014280:Triglycerides; D000071246:Uncoupling Protein 2; D000103:Acetyl-CoA Carboxylase; C031492:octanoic acid