title: Omega-3 fatty acids attenuate constitutive and insulin-induced CD36 expression through a suppression of PPAR α/γ activity in microvascular endothelial cells.
abstract: Microvascular dysfunction occurs in insulin resistance and/or hyperinsulinaemia. Enhanced uptake of free fatty acids (FFA) and oxidised low-density lipoproteins (oxLDL) may lead to oxidative stress and microvascular dysfunction interacting with CD36, a PPARα/γ-regulated scavenger receptor and long-chain FFA transporter. We investigated CD36 expression and CD36-mediated oxLDL uptake before and after insulin treatment in human dermal microvascular endothelial cells (HMVECs), ± different types of fatty acids (FA), including palmitic, oleic, linoleic, arachidonic, eicosapentaenoic (EPA), and docosahexaenoic (DHA) acids. Insulin (10(-8) and 10(-7) M) time-dependently increased DiI-oxLDL uptake and CD36 surface expression (by 30 ± 13%, p<0.05 vs. untreated control after 24 hours incubation), as assessed by ELISA and flow cytometry, an effect that was potentiated by the PI3-kinase inhibitor wortmannin and reverted by the ERK1/2 inhibitor PD98059 and the PPARα/γ antagonist GW9662. A ≥ 24 hour exposure to 50 μM DHA or EPA, but not other FA, blunted both the constitutive (by 23 ± 3% and 29 ± 2%, respectively, p<0.05 for both) and insulin-induced CD36 expressions (by 45 ± 27 % and 12 ± 3 %, respectively, p<0.05 for both), along with insulin-induced uptake of DiI-oxLDL and the downregulation of phosphorylated endothelial nitric oxide synthase (P-eNOS). At gel shift assays, DHA reverted insulin-induced basal and oxLDL-stimulated transactivation of PPRE and DNA binding of PPARα/γ and NF-κB. In conclusion, omega-3 fatty acids blunt the increased CD36 expression and activity promoted by high concentrations of insulin. Such mechanisms may be the basis for the use of omega-3 fatty acids in diabetic microvasculopathy.
authors: G d'Annunzio University, Chieti, Italy.
authors: Rosalinda
authors: R
authors: Madonna
authors: Sara
authors: S
authors: Salerni
authors: Deborah
authors: D
authors: Schiavone
authors: Jan F
authors: JF
authors: Glatz
authors: Yong-Jian
authors: YJ
authors: Geng
authors: Raffaele
authors: R
authors: De Caterina
mesh_terms: D000730:Androstadienes / Q000494:pharmacology; D000813:Anilides / Q000494:pharmacology; D018955:CD36 Antigens / Q000235:genetics / Q000378:metabolism*; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000037:antagonists & inhibitors; D002460:Cell Line; D020405:Dermis / Q000473:pathology; D042783:Endothelial Cells / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D015525:Fatty Acids, Omega-3 / Q000378:metabolism*; D005419:Flavonoids / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D007328:Insulin / Q000494:pharmacology; D007333:Insulin Resistance / Q000502:physiology; D018384:Oxidative Stress; D047493:PPAR alpha / Q000037:antagonists & inhibitors; D047495:PPAR gamma / Q000037:antagonists & inhibitors; D000081082:Phosphoinositide-3 Kinase Inhibitors; D051116:Receptors, Scavenger / Q000235:genetics / Q000378:metabolism*; D000077191:Wortmannin
chemical_list: C457499:2-chloro-5-nitrobenzanilide; D000730:Androstadienes; D000813:Anilides; D018955:CD36 Antigens; D015525:Fatty Acids, Omega-3; D005419:Flavonoids; D007328:Insulin; D047493:PPAR alpha; D047495:PPAR gamma; D000081082:Phosphoinositide-3 Kinase Inhibitors; D051116:Receptors, Scavenger; D017871:Calcium-Calmodulin-Dependent Protein Kinases; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one; D000077191:Wortmannin