title: Effect of shear stress on asymmetric dimethylarginine release from vascular endothelial cells.
abstract: We demonstrated recently that plasma concentrations of asymmetric dimethylarginine (ADMA), an endogenous inhibitor of nitric oxide (NO) synthase, are increased by high salt intake concomitantly with a decrease in plasma levels of NO in human hypertension. We investigated the effect of shear stress on ADMA release in 2 types of cells: transformed human umbilical vein endothelial cells (HUVECs; cell line ECV-304) and HUVECs. Exposure of ECV-304 cells and HUVECs to shear stress with the use of a cone-plate viscometer enhanced gene expression of protein arginine methyltransferase (PRMT-1), ADMA synthase. In HUVECs, the ratio of PRMT-1 to glyceraldehyde 3-phosphate dehydrogenase mRNA was increased by 2-fold by a shear stress of > or =15 dyne/cm2. A dominant-negative mutant of IkappaB kinase alpha and troglitazone at 8 micromol/L, an activator of peroxisome proliferator-activated receptor gamma, abolished the shear stress-induced increase in PRMT-1 gene expression in parallel with the blockade of nuclear factor (NF)-kappaB translocation into the nucleus. The activity of dimethylarginine dimethylaminohydrolase, the degradation enzyme of ADMA, was unchanged after shear stress < or =15 dyne/cm2 and was enhanced by 1.48+/-0.06-fold (P<0.05) by shear stress at 25 dyne/cm2. The release of ADMA was increased by 1.64+/-0.10-fold (P<0.05) by shear stress at 15 dyne/cm2 but was not affected by shear stress at 25 dyne/cm2. These results indicate that shear stress enhances gene expression of PRMT-1 and ADMA release via activation of the NF-kappaB pathway. Shear stress at higher magnitudes facilitates the degradation of ADMA, thus returning ADMA release levels to baseline.
authors.affiliation: Second Department of Internal Medicine, Hirosaki University School of Medicine, 5 Zaifu-cho, Hirosaki, 036-8562 Japan. osanait@cc.hirosaki-u.ac.jp
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Osanai
authors.forename: Masayuki
authors.initials: M
authors.lastname: Saitoh
authors.forename: Satoko
authors.initials: S
authors.lastname: Sasaki
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Tomita
authors.forename: Toshiro
authors.initials: T
authors.lastname: Matsunaga
authors.forename: Ken
authors.initials: K
authors.lastname: Okumura
mesh_terms: D000581:Amidohydrolases / Q000378:metabolism; D001120:Arginine / Q000031:analogs & derivatives* / Q000378:metabolism*; D002461:Cell Line, Transformed; D004730:Endothelium, Vascular / Q000201:enzymology / Q000378:metabolism*; D005786:Gene Expression Regulation; D006801:Humans; D008856:Microscopy, Fluorescence; D016328:NF-kappa B / Q000032:analysis / Q000276:immunology; D011484:Protein-Arginine N-Methyltransferases / Q000235:genetics / Q000378:metabolism; D013314:Stress, Mechanical; D051996:Transcription Factor RelA
chemical_list: D016328:NF-kappa B; D051996:Transcription Factor RelA; C018524:N,N-dimethylarginine; D001120:Arginine; D011484:Protein-Arginine N-Methyltransferases; D000581:Amidohydrolases; C059999:dimethylargininase