Regulation of Lipopolysaccharide-Induced Inducible Nitric-Oxide Synthase Expression through the Nuclear Factor-κB Pathway and Interferon-β/Tyrosine Kinase 2/Janus Tyrosine Kinase 2-Signal Transducer and Activator of Transcription-1 Signaling Cascades by 2-Naphthylethyl-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline (THI 53), a New Synthetic Isoquinoline Alkaloid

Abstract

The effects of 2-naphthylethyl-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline (THI 53), on nitric oxide (NO) production and inducible nitric-oxide synthase (iNOS) protein induction by lipopolysaccharide (LPS) were investigated in RAW 264.7 cells and mice. In cells, THI 53 concentration dependently reduced NO production and iNOS protein induction by LPS. In addition, THI 53 inhibited NO production and iNOS protein induction in LPS-treated mice. LPS-mediated iNOS protein induction was inhibited significantly by the specific tyrosine kinase inhibitor ␣-cyano-(3-hydroxy-4-nitro)cinnamonitrile (AG126) as well as by THI 53. In addition, a c-Jun NH 2 -terminal kinase (JNK) inhibitor anthra[1,9-cd]pyrazole-6 (2H)-one) (SP600125) but not an extracellular regulated kinase inhibitor [2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one (PD98029)] or a p38 inhibitor [4-(4-fluorophenyl)-2-(4-methylsulfinylphenyl)-5-(4-pyridyl)1H-imidazole (SB230580)] reduced the iNOS protein level induced by LPS. Moreover, a Janus kinase 2 (JAK2) inhibitor ␣-cyano-(3,4-dihydroxy)-N-benzylcinnamide (AG490) dose-dependently prevented LPS-mediated iNOS protein induction. LPS activated phosphorylations of tyrosine kinases, especially tyrosine kinase 2 (Tyk2) and signal transducer and activator of transcription-1 (STAT-1); these were reduced by THI 53. LPS also phosphorylated the JNK pathway; however, this phosphorylation was unaffected by THI 53. Interestingly, a JNK inhibitor (SP600125) and another tyrosine kinase inhibitor (genistein) significantly inhibited STAT-1 phosphorylation, suggesting that the LPS-activated JNK pathway and a tyrosine kinase pathway (especially Tyk2) may link to the STAT-1 pathway, which is involved in iNOS induction. However, THI 53 regulates LPS-mediated iNOS protein induction by affecting the Tyk2/JAK2-STAT-1 pathway, not the JNK pathway. The inhibition by THI 53 of LPS-induced NO production was recovered by a tyrosine phosphatase inhibitor (Na 3 VO 4 ), which supports the possibility that THI 53 inhibits the LPS-induced inflammatory response through regulation of tyrosine kinase pathways. THI 53 also inhibited LPS-mediated interferon (IFN)-␤ production and nuclear factor-B (NF-B) activation. Thus, THI 53 may regulate LPS-mediated inflammatory response through both the NF-B and IFN-␤/Tyk2/JAK2-STAT-1 pathways.The expression of inducible nitric-oxide synthase (iNOS) and the production of large quantities of nitric oxide (NO) may contribute to the pathophysiology of endotoxemia or sepsis (Thiemermann and Vane, 1990). Moreover, mice carrying the null mutant gene for iNOS are resistant to the hypotension and death caused by lipopolysaccharide (LPS) This study was supported by the Korea Science and Engineering Foundation (R13-2005-005-01003-0).H.J.K. and K.T. contributed equally to this work.

Dendritic Cells Infected withvpr-Positive Human Immunodeficiency Virus Type 1 Induce CD8+T-Cell Apoptosis via Upregulation of Tumor Necrosis Factor Alpha

“…On the other hand, Nef-induced killing of bystander CD8 ϩ T cells by monocytes has been shown to be through the activation of p38-MAPK (34). It is interesting that p38 is upstream of STAT-1 signaling, as demonstrated recently in primary cells and a transformed macrophage cell line in the context of LPS stimulation (25), thereby suggesting its role in regulating common downstream events. Lysates from infected DC cultures were tested by Western blotting for various signaling molecules.…”

Upregulations of Glucocorticoid-Induced Leucine Zipper by Hypoxia and Glucocorticoid Inhibit Proinflammatory Cytokines under Hypoxic Conditions in Macrophages

“…The inhibitor concentrations were decided according to previous studies in RAW264.7 cells (42)(43)(44). In these experiments, RAW264.7 cells were incubated with wortmannin (PI3K inhibitor), SB203580 (p38 inhibitor), SP600125 (JNK inhibitor), or PD098059 (ERK inhibitor) 1 h before hypoxic stimulation, and then the expression of GILZ was detected by Western blot.…”

Sphingosine 1-Phosphate 1 and TLR4 Mediate IFN-β Expression in Human Gingival Epithelial Cells

“…IFN-␤ elicits multifaceted effects in the host innate immune system by inducing other molecules such as CXCL-10 via a pathway requiring Jak proteins (7), including Jak2 or Jak1 (6,34). To examine the biological effect of IFN-␤ induced by LPS/S1P stimuli, we, FIGURE 2.…”