title: Propionyl-L-carnitine induces eNOS activation and nitric oxide synthesis in endothelial cells via PI3 and Akt kinases.
abstract: Propionyl-l-carnitine (PLC) is a natural short-chain derivative of l-carnitine (LC), a natural amino acid that plays an important role in fatty acid metabolism. Recent studies suggest that PLC has vascular protective effects. Because of the importance of endothelial nitric oxide synthase (eNOS) and its product, antiatherogenic molecule nitric oxide (NO), in vascular endothelial function, we sought to elucidate that if PLC would stimulate eNOS and its upstream activators Akt and phosphatidylinositol 3-kinase (PI3 Kinase) in cultured human aortic endothelial cells (HAEC). PLC caused eNOS phosphorylation at Ser-1177, and dominant negative Akt and a novel Akt-selective inhibitor MK-2206 inhibited both PLC-mediated phosphorylation and activation of the enzyme. PI3 kinase inhibition also blocked the phosphorylation and activation of eNOS by PLC. Studies with specific drug inhibitors PD173955 and PP2 showed that the non-receptor tyrosine kinase, src, is an upstream stimulator of the PI3 kinase-Akt pathway in this pathway. In addition, PLC significantly decreased intracellular ATP/ADP ratio and activate AMPK, subsequently leading to Src activation. Finally, we demonstrated that the effects of PLC to augment eNOS activity were associated with a net increase in NO release from endothelial cells. NO production following incubation with PLC was abolished in endothelial cells coincubated with L-NAME, PD173955, LY294002, MK-2206 and compound C. In conclusion, PLC, via AMPK/Src-mediated signaling that leads to activation of PI3 kinase and Akt, stimulates eNOS, leading to increased production of NO.
authors.affiliation: Department of Emergency, the Forth Clinical Hospital, Harbin Medical University, Heilongjiang Harbin 150001, China. Electronic address: wenhuning@163.com.
authors.forename: Wen-hu
authors.initials: WH
authors.lastname: Ning
authors.forename: Kan
authors.initials: K
authors.lastname: Zhao
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000378:metabolism; D001011:Aorta / Q000166:cytology / Q000187:drug effects; D002331:Carnitine / Q000031:analogs & derivatives* / Q000494:pharmacology; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000187:drug effects* / Q000378:metabolism; D006801:Humans; D009569:Nitric Oxide / Q000096:biosynthesis*; D052250:Nitric Oxide Synthase Type III / Q000187:drug effects* / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D019061:src-Family Kinases / Q000378:metabolism
chemical_list: C003223:propionylcarnitine; D009569:Nitric Oxide; D052250:Nitric Oxide Synthase Type III; D019869:Phosphatidylinositol 3-Kinases; D019061:src-Family Kinases; D051057:Proto-Oncogene Proteins c-akt; D055372:AMP-Activated Protein Kinases; D002331:Carnitine
keywords: (PLC); Akt; DN-Akt; Endothelial cells; Endothelial nitric oxide synthase; HAEC; LC; NO; PI3 Kinase; Phosphatidylinositol 3-kinase; Propionyl-l-carnitine; SHR; dominant-negative mutant of protein kinase B (Akt); eNOS; endothelial nitric oxide synthase; human aortic endothelial cells; l-carnitine; nitric oxide; phosphatidylinositol 3-kinase; spontaneously hypertensive rats