Retinoic acid decreases nitric oxide production in endothelial cells: a role of phosphorylation of endothelial nitric oxide synthase at Ser(1179).
The effects of retinoic acid (RA) on nitric oxide (NO) production are controversial. Furthermore, it has never been studied whether these effects are mediated by direct modulation of phosphorylation of endothelial nitric oxide synthase (eNOS). Using bovine aortic endothelial cells, we found that all-trans RA (atRA) dose- and time-dependently decreased NO production without alteration in eNOS expression. This decrease was accompanied by reduction in eNOS-Ser(1179) phosphorylation. However, atRA did not alter the phosphorylation of eNOS-Ser(116) or eNOS-Thr(497). Concurrently, atRA also decreased the expressions of vascular endothelial growth factor (VEGF) and its receptor KDR/Flk-1, and Akt phosphorylation. Co-treatment with troglitazone, an activator of VEGF expression, reversed the atRA-induced reductions in eNOS-Ser(1179) phosphorylation and NO production, with concomitant restoration in VEGF expression. Direct treatment with VEGF also reversed these inhibitory effects, suggesting an important role for VEGF. Nonetheless, the RARalpha antagonist Ro 41-5253 did not block all the inhibitory effects of atRA, indicating that these inhibitory effects are not mediated by the RA response element (RARE). Thus, atRA decreases eNOS-Ser(1179) phosphorylation through a mechanism that depends on VEGF-KDR/Flk-1-mediated Akt phosphorylation but is independent of RARE, leading to reduction in NO production.
Cho
Du-Hyong
DH
Department of Biomedical Sciences, National Institute of Health, 5 Nokbun-dong, Eunpyung-gu, Seoul 122-701, Republic of Korea.
Choi
Yoon Jung
YJ
Jo
Sangmee Ahn
SA
Nam
Jae-Hwan
JH
Jung
Sung-Chul
SC
Jo
Inho
I
D000818:Animals; D002417:Cattle; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation / Q000187:drug effects; D042783:Endothelial Cells / Q000187:drug effects* / Q000378:metabolism*; D009569:Nitric Oxide / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000187:drug effects / Q000378:metabolism*; D052250:Nitric Oxide Synthase Type III; D010766:Phosphorylation / Q000187:drug effects; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D018168:Receptors, Retinoic Acid / Q000378:metabolism; D020218:Response Elements / Q000502:physiology; D012694:Serine / Q000378:metabolism*; D014212:Tretinoin / Q000494:pharmacology*; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism*
D011518:Proto-Oncogene Proteins; D018168:Receptors, Retinoic Acid; D042461:Vascular Endothelial Growth Factor A; D009569:Nitric Oxide; D012694:Serine; D014212:Tretinoin; D019001:Nitric Oxide Synthase; D052250:Nitric Oxide Synthase Type III; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt