The preventive effect of uncarboxylated osteocalcin against free fatty acid-induced endothelial apoptosis through the activation of phosphatidylinositol 3-kinase/Akt signaling pathway: Uncarboxylated osteocalcin and endothelial apoptosis.
OBJECTIVE: Increasing evidence suggests that osteocalcin (OC), one of the osteoblast-specific proteins, has been associated with atherosclerosis, but results are conflicting. The aim of this study was to elucidate the independent effect of uncarboxylated osteocalcin (ucOC), an active form of osteocalcin which has been suggested to have an insulin sensitizing effect, on vascular endothelial cells. MATERIALS AND METHODS: We used human aortic endothelial cells and treated them with ucOC. Linoleic acid (LA) was used as a representative free fatty acid. Apoptosis was evaluated using various methods including a terminal deoxyribonucleotide transferase-mediated deoxyuridine triphosphate nick-end labeling analysis kit and Western blotting for cleaved caspase 3, cleaved poly (ADP-ribose) polymerase and Bcl-xL. The phosphorylations of Akt and endothelial nitric oxide synthase (eNOS) as well as the level of NO were measured to confirm the effect of ucOC on insulin signaling pathway. RESULTS: Pretreatment of ucOC (30ng/ml) prevented LA-induced apoptosis in insulin-stimulated endothelial cells; effects were abolished by pretreatment with the phosphatidylinositol 3-kinase (PI3-kinase) inhibitor, wortmannin. Treatment of ucOC (ranged from 0.3 to 30ng/ml) significantly increased the phosphorylation of Akt and eNOS and nitric oxide secretion from endothelial cells in a PI3-kinase dependent manner. CONCLUSIONS: Our study is the first to demonstrate the independent effect of ucOC on vascular endothelial cells. Our results further suggest that ucOC could have beneficial effects on atherosclerosis.
T10 T11 T12 T13 T14 T15 T16 T17 T18 T19 T1 T20 T21 T22 T23 T24 T25 T26 T27 T28 T29 T2 T30 T31 T32 T33 T34 T35 T36 T37 T38 T39 T3 T40 T41 T42 T43 T4 T5 T6 T7 T8 T9
CHEMICAL CHEMICAL CHEMICAL GENE-Y GENE-Y GENE-N GENE-N GENE-Y GENE-N GENE-Y CHEMICAL GENE-N GENE-Y GENE-Y GENE-Y GENE-Y GENE-Y GENE-Y GENE-Y GENE-Y GENE-Y CHEMICAL GENE-Y GENE-N GENE-Y GENE-N GENE-Y GENE-N GENE-Y GENE-Y GENE-Y GENE-Y CHEMICAL GENE-N GENE-N GENE-Y GENE-Y CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL
NO phosphatidylinositol free fatty acid ucOC insulin phosphatidylinositol 3-kinase PI3-kinase ucOC Akt eNOS phosphatidylinositol PI3-kinase ucOC ucOC uncarboxylated osteocalcin ucOC osteocalcin insulin osteocalcin ucOC OC wortmannin deoxyribonucleotide transferase osteoblast-specific proteins caspase 3 poly (ADP-ribose) polymerase Bcl-xL Akt endothelial nitric oxide synthase eNOS ucOC insulin nitric oxide phosphatidylinositol 3-kinase Akt Uncarboxylated osteocalcin osteocalcin Linoleic acid free fatty acid deoxyribonucleotide deoxyuridine triphosphate poly (ADP-ribose) nitric oxide