Human urotensin-II potentiates the mitogenic effect of mildly oxidized low-density lipoprotein on vascular smooth muscle cells: comparison with other vasoactive agents and hydrogen peroxide.
Human urotensin-II (U-II) is the most potent vasoactive peptide identified to date, and may be involved in hypertension and atherosclerosis. We investigated the effects of the interactions between U-II or other vasoactive agents and mildly oxidized low-density lipoprotein (mox-LDL) or hydrogen peroxide (H2O2) on the induction of vascular smooth muscle cell (VSMC) proliferation. Growth-arrested rabbit VSMCs were incubated with vasoactive agents (U-II, endothelin-1, angiotensin-II, serotonin, or thromboxane-A2) in the presence or absence of mox-LDL or H2O2. [3H]Thymidine incorporation into DNA was measured as an index of VSMC proliferation. On interaction with mox-LDL or H2O2, U-II induced the greatest increase in [3H]thymidine incorporation among these vasoactive agents. A low concentration of U-II (10 nmol/l) enhanced the potential mitogenic effect of low concentrations of mox-LDL (120 to 337%) and H2O2 (177 to 226%). U-II at 50 nmol/l showed the maximal mitogenic effect (161%), which was abolished by G protein inactivator (GDP-beta-S), c-Src tyrosine kinase inhibitor (radicicol), protein kinase C (PKC) inhibitor (Ro31-8220), extracellular signal-regulated kinase (ERK) kinase inhibitor (PD98059), or Rho kinase inhibitor (Y27632). Mox-LDL at 5 microg/ml showed the maximal mitogenic effect (211%), which was inhibited by free radical scavenger (catalase), intracellular and extracellular antioxidants (N-acetylcysteine and probucol), nicotinamide adenine dinucleotide phosphate oxidase inhibitor (diphenylene iodonium), or c-Jun N-terminal kinase (JNK) inhibitor (SP600125). These results suggested that U-II acts in synergy with mox-LDL in inducing VSMC DNA synthesis at the highest rate among these vasoactive agents. Activation of the G protein/c-Src/PKC/ERK and Rho kinase pathways by U-II together with the redox-sensitive JNK pathway by mox-LDL may explain the synergistic interaction between these agents.
Watanabe
Takuya
T
Department of Biochemistry, Showa University School of Medicine, Tokyo, Japan. watanabemd@med.showa-u.ac.jp
Takahashi
Keiko
K
Kanome
Tomoko
T
Hongo
Shigeki
S
Miyazaki
Akira
A
Koba
Shinji
S
Katagiri
Takashi
T
Pakara
Rajbabu
R
Benedict
Claude R
CR
D000447:Aldehydes / Q000494:pharmacology; D000804:Angiotensin II / Q000494:pharmacology; D000818:Animals; D001013:Aorta, Thoracic / Q000166:cytology; D002478:Cells, Cultured; D004247:DNA / Q000096:biosynthesis; D004357:Drug Synergism; D019332:Endothelin-1 / Q000494:pharmacology; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D008077:Lipoproteins, LDL / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D008244:Lysophosphatidylcholines / Q000378:metabolism / Q000494:pharmacology; D008297:Male; D008934:Mitogens / Q000494:pharmacology*; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D016877:Oxidants / Q000494:pharmacology*; D011817:Rabbits; D012701:Serotonin / Q000494:pharmacology; D018490:Serotonin Agents / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D013928:Thromboxane A2 / Q000494:pharmacology; D014579:Urotensins / Q000494:pharmacology*; D014662:Vasoconstrictor Agents / Q000494:pharmacology
D000447:Aldehydes; D019332:Endothelin-1; D008077:Lipoproteins, LDL; D008244:Lysophosphatidylcholines; D008934:Mitogens; D016877:Oxidants; D018490:Serotonin Agents; D014579:Urotensins; D014662:Vasoconstrictor Agents; C099252:oxidized low density lipoprotein; C462359:tert-4-hydroxy-2-nonenal; D000804:Angiotensin II; D012701:Serotonin; D013928:Thromboxane A2; D004247:DNA; C029677:urotensin II; D006861:Hydrogen Peroxide