Regulation of Inducible Nitric Oxide Synthase Expression in Advanced Glycation End Product–Stimulated RAW 264.7 Cells

Abstract

Advanced glycation end products (AGEs) are closely linked to the development of diabetic atherosclerosis. The current study examines the induction of inducible nitric oxide (NO) synthase (iNOS) and heme oxygenase (HO)-1 expression by AGEs, as well as the signaling pathways involved and the interplay between these two enzymes. The stimulation of RAW 264.7 cells with 6.64 or 33.2 g/ml AGEs leads to HO-1 protein expression, iNOS protein expression, and nitrite accumulation. AGEs lead to the phosphorylation of p42/44 and p38 mitogen-activated protein kinase (MAPK). The inhibition of p42/44 MAPK and protein kinase C prevented, whereas inhibition of p38 MAPK augmented, AGE-induced nitrite release and iNOS expression. In contrast, HO-1 expression was downregulated by inhibition of p38 MAPK. Furthermore, the expression of both proteins was prevented by coincubation with acetovanillone (NADPH oxidase inhibitor). AGE-induced iNOS expression was negatively regulated by stimulation of HO-1 expression with cadmium chloride or endogenous NO. Tin-protoporphyrin IX (HO-1 inhibitor) partially reversed the cadmium chloride-mediated downregulation of iNOS expression. The current study demonstrates that multiple signaling molecules are involved in AGE-stimulated iNOS and HO-1 expression. There also exists a downregulation of iNOS by its own product as well as the products of HO-1.

Heme Oxygenase-1

“…HO-1 is induced by a number of stressors, 7 and one may predict that risk factors for the development of coronary heart disease and other cardiovascular disease processes will mediate HO-1 expression. In fact, this is the case because increased blood pressure 22 and altered laminar flow in blood vessels, 23 advanced glycation end products, 24 cigarette smoke, 25 oxidized lipids, 26 and a multitude of systemic inflammatory processes 7 lead to increased cellular HO-1 expression. Moreover, this constellation of processes that lead to HO-1 induction may suggest a role for HO-1 in mediating the cardiovascular disease processes associated with obesity and metabolic syndrome, 27 which have become significant public health problems.…”

Inhibition of inflammatory nitric oxide production and epidermis damages by Saccharomycopsis Ferment Filtrate

“…Several previous studies have shown the cytoprotective effect of HO-1 in response to various oxidative insults both in vitro and in vivo [29][30][31]. Inhibition of iNOS protein expression by HO-1 has been shown in macrophages and smooth muscle cells, however, the inhibitory mechanisms of HO-1 on iNOS gene expression is still unclear [32][33][34][35][36]. Lee et al [33] reported that HO-1 inhibited LPS-induced phosphorylation of IkBa protein and nuclear translocation of p65 subunit of NF-kB [33].…”

Involvement of the receptor for advanced glycation-end products (RAGE) in β-amyloid-induced toxic effects in rat cerebromicrovascular endothelial cells cultured in vitro

“…In fact, with trypsin pre-treatment and by blocking the interaction to RAGE, we observed significant decreased levels of NO and iNOS immunoreactivity suppression. Currently, to our knowledge, there are no literature data related to RAGE involvement in ßA nitrergic system activation; however, it has been demonstrated that RAGE linkage with other ligands, as advanced glycation-end products (AGE), stimulated iNOS expression in mouse macrophages (37), in murine endothelial cells (38), and in murine macrophages (39). AGE stimulation led to nitrite accumulation and iNOS protein expression, which were partially downregulated by preincubation with anti-RAGE antibody, suggesting the role of RAGE in AGE-induced nitrosative stress activation (39,40).…”