title: Tetramethylpyrazine attenuates TNF-α-induced iNOS expression in human endothelial cells: Involvement of Syk-mediated activation of PI3K-IKK-IκB signaling pathways.
abstract: Endothelial cells produce nitric oxide (NO) by activation of constitutive nitric oxide synthase (NOS) and transcription of inducible NO synthase (iNOS). We explored the effect of tetramethylpyrazine (TMP), a compound derived from chuanxiong, on tumor necrosis factor (TNF)-α-induced iNOS in human umbilical vein endothelial cells (HUVECs) and explored the signal pathways involved by using RT-PCR and Western blot. TMP suppressed TNF-α-induced expression of iNOS by inhibiting IκB kinase (IKK) phosphorylation, IκB degradation and nuclear factor κB (NF-κB) nuclear translocation, which were required for NO gene transcription. Exposure to wortmannin abrogated IKK/IκB/NF-κB-mediated iNOS expression, suggesting activation of such a signal pathway might be phosphoinositide-3-kinase (PI3K) dependent. Spleen tyrosine kinase (Syk) inhibitor piceatannol significantly inhibited NO production. Furthermore, piceatannol obviously suppressed TNF-α-induced IκB phosphorylation and the downstream NF-κB activation, suggesting that Syk is an upstream key regulator in the activation of PI3K/IKK/IκB-mediated signaling. TMP significantly inhibited TNF-α-induced phosphorylation of Syk and PI3K. Our data indicate that TMP might repress iNOS expression, at least in part, through its inhibitory effect of Syk-mediated PI3K phosphorylation in TNF-α-stimulated HUVECs.
authors.affiliation: Department of Intensive Care Unit, the First Affiliated Hospital, China Medical University, Bei-er Road 92, Shenyang 110001, Liaoning Province, PR China.
authors.forename: Zhen
authors.initials: Z
authors.lastname: Zheng
authors.forename: Zhiliang
authors.initials: Z
authors.lastname: Li
authors.forename: Song
authors.initials: S
authors.lastname: Chen
authors.forename: Jieyi
authors.initials: J
authors.lastname: Pan
authors.forename: Xiaochun
authors.initials: X
authors.lastname: Ma
mesh_terms: D002467:Cell Nucleus / Q000378:metabolism; D042783:Endothelial Cells / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D004730:Endothelium, Vascular / Q000166:cytology; D061307:Human Umbilical Vein Endothelial Cells; D006801:Humans; D051550:I-kappa B Kinase / Q000378:metabolism; D020672:I-kappa B Proteins / Q000378:metabolism; D047908:Intracellular Signaling Peptides and Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II / Q000235:genetics / Q000378:metabolism*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D021381:Protein Transport; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D059748:Proteolysis; D011719:Pyrazines / Q000494:pharmacology*; D015398:Signal Transduction / Q000187:drug effects*; D013267:Stilbenes / Q000494:pharmacology; D000072377:Syk Kinase; D014158:Transcription, Genetic / Q000187:drug effects; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors / Q000494:pharmacology*
chemical_list: D020672:I-kappa B Proteins; D047908:Intracellular Signaling Peptides and Proteins; D016328:NF-kappa B; D011719:Pyrazines; D013267:Stilbenes; D014409:Tumor Necrosis Factor-alpha; C041525:3,3',4,5'-tetrahydroxystilbene; D052247:Nitric Oxide Synthase Type II; D019869:Phosphatidylinositol 3-Kinases; D011505:Protein-Tyrosine Kinases; C000606896:SYK protein, human; D000072377:Syk Kinase; D051550:I-kappa B Kinase; C017953:tetramethylpyrazine
keywords: Endothelial cells; Inducible NO synthase; Phosphoinositide-3-kinase; Spleen tyrosine kinase; Tetramethylpyrazine