Induction of nitric oxide synthase in raw 264.7 macrophages by lipoteichoic acid fromStaphylococcus aureus: Involvement of protein kinase C- and nuclear factor-kB-dependent mechanisms

Abstract

This study investigates the signaling pathway involved in inducible nitric oxide synthase (iNOS) expression and nitric oxide (NO) release caused by Staphylococcus aureus lipoteichoic acid (LTA) in RAW 264.7 macrophages. A phosphatidylcholine-phospholipase C (PC-PLC) inhibitor (D-609) and a phosphatidylinositol-phospholipase C (PI-PLC) inhibitor (U-73122) attenuated LTA-induced iNOS expression and NO release. Two PKC inhibitors (Go 6976 and Ro 31-8220), an NF-kappaB inhibitor (pyrrolidine dithiocarbamate; PDTC), and long-term (24 h) 12-phorbol-13-myristate acetate (PMA) treatment each also inhibited LTA-induced iNOS expression and NO release. Treatment of cells with LTA caused an increase in PKC activity; this stimulatory effect was inhibited by D-609, U-73122, or Ro 31-8220. Stimulation of cells with LTA caused IkappaB-alpha phosphorylation and IkappaB-alpha degradation in the cytosol, and translocation of p65 and p50 NF-kappaB from the cytosol to the nucleus. Treatment of cells with LTA caused NF-kappaB activation by detecting the formation of NF-kappaB-specific DNA-protein complexes in the nucleus; this effect was inhibited by Go 6976, Ro 31-8220, long-term PMA treatment, PDTC, L-1-tosylamido-2-phenylethyl chloromethyl ketone (TPCK), and calpain inhibitor I. These results suggest that LTA might activate PC-PLC and PI-PLC to induce PKC activation, which in turn initiates NF-kappaB activation, and finally induces iNOS expression and NO release in RAW 264.7 macrophages.

Lipoteichoic acid promotes nuclear accumulation of β-catenin via AKT in human gingival fibroblasts

“…AKT activates many pathways induced by growth factor receptor-activated PI3K and signaling pathways that regulate NF-κB [10]. PI3K is an enzyme that regulates multiple cellular processes, including cell growth, transformation, differentiation, and survival [11][12][13].…”

The flavonoids luteolin and quercetagetin inhibit lipoteichoic acid actions on H9c2 cardiomyocytes

“…The intracellular signaling pathways through which LTA causes iNOS expression in macrophages involves two separate pathways: the phosphatidylcholine-phospholipase C (PC-PLC), phosphatidylinositol-phospholipase C (PI-PLC)/protein kinase C (PKC)/NFkB pathway and the tyrosine kinase/phosphatidylinositol 3-kinase (PI3K)/p38 mitogen-activated protein kinase (p38 MAPK) pathway [23]. Previous …”

Nitric oxide and the control of catecholamine secretion in rainbow trout Oncorhynchus mykiss

“…However, because removal of the endothelium did not affect NO production during electrical field stimulation, it would appear that the neuronal form of NOS (nNOS) is the key isoform modulating catecholamine secretion from trout chromaffin cells. physiological processes ranging from vascular regulation to immunological responses (Kuo et al, 2003;Mungrue et al, 2003). NO is produced in various tissues by the nitric oxide synthase (NOS) family of enzymes.…”