Oleic acid stimulates glucose uptake into adipocytes by enhancing insulin receptor signaling.
The present study investigated cis-unsaturated free fatty acid (FFA)-regulated glucose uptake. In the cell-free assay of protein tyrosine phosphatase 1B (PTP1B), cis-unsaturated FFAs such as linoleic, linolenic, and oleic acid significantly suppressed PTP1B activity in a concentration (1 - 100 μM)-dependent manner, with the highest potential for oleic acid. Oleic acid (1 μM) stimulated insulin (0.1 nM)-induced phosphorylation of the insulin receptor at Tyr1185 and increased insulin (0.1 nM)-induced phosphorylation of Akt at Thr308 and Ser473 in differentiated 3T3-L1-GLUT4myc adipocytes. In the föerster resonance energy transfer analysis, oleic acid activated Rac1 in PC-12 cells, which is inhibited by the phosphatidylinositol 3-kinase (PI3K) inhibitor wortmannin, the 3-phosphoinositide-dependent protein kinase-1 (PDK1) inhibitor BX912, or the Akt inhibitor MK2206. Oleic acid (1 μM) significantly increased insulin (0.1 nM)-stimulated glucose uptake in 3T3-L1-GLUT4myc adipocytes, although oleic acid by itself had no effect on the glucose uptake. Taken together, the results of the present study show that oleic acid enhances insulin receptor signaling through a pathway along an insulin receptor/PI3K/PDK1/Akt/Rac1 axis in association with PTP1B inhibition and facilitates insulin-induced glucose uptake into adipocytes.
Division of Bioinformation, Department of Physiology, Institute for Advanced Medical Sciences, Hyogo College of Medicine, Japan.
Ayako
A
Tsuchiya
Hisao
H
Nagaya
Takeshi
T
Kanno
Tomoyuki
T
Nishizaki
D017667:Adipocytes / Q000378:metabolism*; D000730:Androstadienes / Q000494:pharmacology; D000818:Animals; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D006575:Heterocyclic Compounds, 3-Ring / Q000494:pharmacology; D006801:Humans; D007328:Insulin / Q000502:physiology; D019301:Oleic Acid / Q000494:pharmacology*; D010766:Phosphorylation; D054562:Protein Tyrosine Phosphatase, Non-Receptor Type 1 / Q000037:antagonists & inhibitors; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D051381:Rats; D011972:Receptor, Insulin / Q000378:metabolism / Q000502:physiology*; D015398:Signal Transduction / Q000187:drug effects* / Q000502:physiology; D013268:Stimulation, Chemical; D000077191:Wortmannin; D020830:rac1 GTP-Binding Protein / Q000378:metabolism
D000730:Androstadienes; D006575:Heterocyclic Compounds, 3-Ring; D007328:Insulin; C548887:MK 2206; D019301:Oleic Acid; D011972:Receptor, Insulin; D051057:Proto-Oncogene Proteins c-akt; D054562:Protein Tyrosine Phosphatase, Non-Receptor Type 1; C516610:Ptpn1 protein, rat; C499134:Rac1 protein, rat; D020830:rac1 GTP-Binding Protein; D000077191:Wortmannin