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Nuclear factor -B (NF-B)-regulated inflammatory genes, such as TNF-␣ (tumor necrosis factor-␣), play key roles in the pathogenesis of inflammatory diseases, including diabetes and the metabolic syndrome. However, the nuclear chromatin mechanisms are unclear. We report here that the chromatin histone H3-lysine 4 methyltransferase, SET7/9, is a novel coactivator of NF-B. Gene silencing of SET7/9 with small interfering RNAs in monocytes significantly inhibited TNF-␣-induced inflammatory genes and histone H3-lysine 4 methylation on these promoters, as well as monocyte adhesion to endothelial or smooth muscle cells. Chromatin immunoprecipitation revealed that SET7/9 small interfering RNA could reduce TNF-␣-induced recruitment of NF-B p65 to inflammatory gene promoters. Inflammatory gene induction by ligands of the receptor for advanced glycation end products was also attenuated in SET7/9 knockdown monocytes. In addition, we also observed increased inflammatory gene expression and SET7/9 recruitment in macrophages from diabetic mice. Microarray profiling revealed that, in TNF-␣-stimulated monocytes, the induction of 25% NF-B downstream genes, including the histone H3-lysine 27 demethylase JMJD3, was attenuated by SET7/9 depletion. These results demonstrate a novel role for SET7/9 in inflammation and diabetes.NF-B is a pleiotropic transcription factor that plays a pivotal role in regulating multiple biological functions, such as inflammation, immunity, cell proliferation, and apoptosis (1, 2). NF-B plays an important role in the regulation of proinflammatory genes, such as TNF-␣ (tumor necrosis factor ␣) and MCP-1 (monocyte-chemoattractant protein-1), that are associated with several inflammatory diseases, including atherosclerosis, insulin resistance, metabolic syndrome, and diabetes and its complications (3-7). These genes also lead to monocyte activation associated with these inflammatory diseases.NF-B consists of homo-or heterodimers of different subunits, such as p50, p52, p65/RelA, RelB, and c-Rel, with p65/ RelA and p50 being the most common and well studied (1,8). In most unstimulated cells, NF-B resides in the cytoplasm in an inactive latent form complexed with its inhibitor subunit, IB␣. Multiple extracellular stimuli, including inflammatory cytokines, such as TNF-␣, and ligands of the receptor for advanced glycation end products (RAGE), 2 can induce NF-B activation by promoting IB␣ phosphorylation and its proteasomal degradation (6, 9). The released p65-p50 dimer then translocates to the nucleus, where it binds to the promoters of NF-B-dependent inflammatory genes, such as TNF-␣, MCP-1, and IL-6 (interleukin-6), to induce their expression (2). p65 protein is a key transcriptionally active component of NF-B whose transactivation potential is enhanced by several coactivators, including CREB-binding protein/p300, p/CAF, and SRC1 (10), which have histone acetyltransferase activity, and CARM1, which has arginine methyltransferase activity (11,12). Recently, we showed that histone H3 lysine acetylation is enriched...

Cyclooxygenase-2 (COX-2) enzyme and its inflammatory products such as prostaglandin E 2 (PGE 2 ) have been implicated in the pathogenesis of several inflammatory diseases. However their role in diabetic vascular disease is unclear. Advanced glycation end products (AGEs) act via their receptor, RAGE, to play a major role in diabetic complications. In this study, we investigated the effect of AGEs and S100b, a specific RAGE ligand, on the expression of COX-2 and the molecular mechanisms involved in cultured THP-1 monocytes and human peripheral blood monocytes. S100b treatment of THP-1 cells led to a significant 3-5-fold induction of COX-2 mRNA (p < 0.001). COX-2 protein and its product PGE 2 were also increased, whereas COX-1 expression was unaffected. In vitro prepared AGE also induced COX-2 mRNA. S100b-induced COX-2 mRNA was blocked by an anti-RAGE antibody and by inhibitors of NF-B (Bay11-7082), oxidant stress, protein kinase C, ERK, and p38 MAPKs. S100b (4-h treatment) significantly increased transcription from a human COX-2 promoter-luciferase construct (4-fold, p < 0.001). Promoter deletion analyses and inhibition of transcription by an NF-B superrepressor mutant confirmed NF-B involvement. This was further supported by inhibition of S100b-induced PGE 2 by Bay11-7082. Additionally, S100b-induced adherence of THP-1 monocytes to vascular smooth muscle cells was blocked by the COX-2 inhibitor NS-398, Bay11-7082, inhibitors of ERK and p38 MAPK, and protein kinase C thereby indicating functional relevance. S100b also increased COX-2 mRNA expression in human peripheral blood monocytes from healthy donors. Moreover, COX-2 mRNA levels were clearly evident in monocytes obtained from diabetic patients but not from normal subjects. These results show for the first time that AGEs can augment inflammatory responses by up-regulating COX-2 via RAGE and multiple signaling pathways, thereby leading to monocyte activation and vascular cell dysfunction.

The cyclooxygenase (COX)-2 enzyme has been implicated in the pathogenesis of several inflammatory diseases. However, its role in diabetic vascular disease is unclear. In this study, we evaluated the hypothesis that diabetic conditions can induce COX-2 in monocytes. High glucose treatment of THP-1 monocytic cells led to a significant three-to fivefold induction of COX-2 mRNA and protein expression but not COX-1 mRNA. High glucose-induced COX-2 mRNA was blocked by inhibitors of nuclear factor-B (NF-〉), protein kinase C, and p38 mitogen-activated protein kinase. In addition, an antioxidant and inhibitors of mitochondrial superoxide, NADPH oxidase, and glucose metabolism to glucosamine also blocked high glucose-induced COX-2 expression to varying degrees. High glucose significantly increased transcription from a human COX-2 promoterluciferase construct (twofold, P < 0.001). Promoter deletion analyses and inhibition of transcription by NF-〉 superrepressor and cAMP-responsive element binding (CREB) mutants confirmed the involvement of NF-〉 and CREB transcription factors in high glucoseinduced COX-2 regulation. In addition, isolated peripheral blood monocytes from type 1 and type 2 diabetic patients had high levels of COX-2 mRNA, whereas those from normal volunteers showed no expression. These results show that high glucose and diabetes can augment inflammatory responses by upregulating COX-2 via multiple signaling pathways, leading to monocyte activation relevant to the pathogenesis of diabetes complications. Diabetes 53: [795][796][797][798][799][800][801][802] 2004

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