prostaglandin-d2 and pyrazolanthrone

Angiotensin II (Ang II) plays a critical role in regulating vascular inflammatory diseases, such as atherosclerosis and hypertension. Early growth response-1 (Egr-1) is an immediate early gene that acts as a master switch for the inflammatory response. However, the role of Ang II in regulating Egr-1 expression in macrophages, and the effect of peroxisome proliferators-activated receptor-γ (PPAR-γ) ligand 15d-PGJ2 in this process remain to be investigated.. We showed that Ang II significantly up-regulated the expression of Egr-1 in RAW264.7 macrophages, and this effect was markedly attenuated by Eprosartan (an AT1R blocker), SP600125 (a JNK-specific inhibitor) and PD98059 (an ERK-specific inhibitor). Moreover, treatment of macrophages with 15d-PGJ2, a natural PPAR-γ ligand, significantly reduced Ang II-induced expression of Egr-1 and its inflammatory gene targets (IL-1β, TNF-α, TGF-β, MCP-1 and ICAM-1) through PPAR-γ activation and ROS formation. In addition, 15d-PGJ2 treatment markedly inhibited Ang II-induced macrophage migration and proliferation.. This study for the first time demonstrates that Ang II can induce the expression of Egr-1 via AT1R/JNK and ERK signaling pathways. Activation of PPAR-γ by 15d-PGJ2 suppresses Egr-1-mediated proinflammatory response, and may be a novel therapeutic strategy for treatment of vascular inflammatory diseases.

Topics: Acrylates; Angiotensin II; Animals; Anthracenes; Cell Line; Cell Movement; Cell Proliferation; Cytokines; Early Growth Response Protein 1; Flavonoids; Gene Expression Regulation; Imidazoles; Macrophages; Male; MAP Kinase Signaling System; Mice; Prostaglandin D2; Thiophenes; Up-Regulation

Inorganic phosphate (Pi) transport probably represents an important function of bone-forming cells in relation to extracellular matrix mineralization. In the present study, we investigated the effect of prostaglandin D2 (PGD2) on Pi transport activity and its intracellular signaling mechanism in MC3T3-E1 osteoblast-like cells. PGD2 stimulated Na-dependent Pi uptake time- and dose-dependently in MC3T3-E1 cells during their proliferative phase. A protein kinase C (PKC) inhibitor calphostin C partially suppressed the stimulatory effect of PGD2 on Pi uptake. The selective inhibitors of mitogen-activated protein (MAP) kinase pathways such as ERK, p38 and Jun kinases suppressed PGD2-induced Pi uptake. The inhibitors of phosphatidylinositol (PI) 3-kinase and S6 kinase reduced this effect of PGD2, while Akt kinase inhibitor did not. These results suggest that PGD2 stimulates Na-dependent Pi transport activity in the phase of proliferation of osteoblasts. The mechanisms responsible for this effect are activation of PKC, MAP kinases, PI 3-kinase and S6 kinase.

Topics: 3T3 Cells; Animals; Anthracenes; Butadienes; Cells, Cultured; Chromones; Dose-Response Relationship, Drug; Imidazoles; Mice; Morpholines; Naphthalenes; Nitriles; Osteoblasts; Phosphates; Prostaglandin D2; Pyridines; Signal Transduction; Sirolimus; Sodium

We previously reported that prostaglandin D(2) (PGD(2)) stimulates the induction of heat shock protein 27 (HSP27) in osteoblast-like MC3T3-E1 cells. In the present study, we investigated whether PGD(2) stimulates the phosphorylation of HSP27 in MC3T3-E1 cells exposed to heat shock. In the cultured MC3T3-E1 cells, PGD(2) markedly stimulated the phosphorylation of HSP27 at Ser-15 and Ser-85 in a time-dependent manner. Among the mitogen-activated protein (MAP) kinase superfamily, p44/p42 MAP kinase and p38 MAP kinase were phosphorylated by PGD(2) which had little effect on the phosphorylation of stress-activated protein kinase (SAPK)/c-Jun N-terminal kinase (JNK). The PGD(2)-induced phosphorylation of HSP27 was attenuated by PD169316, an inhibitor of p38 MAP kinase or PD98059, a MEK inhibitor. SP600125, a SAPK/JNK inhibitor did not affect the HSP27 phosphorylation. In addition, PD169316 suppressed the PGD(2)-induced phosphorylation of MAPKAP kinase 2. These results strongly suggest that PGD(2) stimulates HSP27 phosphorylation via p44/p42 MAP kinase and p38 MAP kinase but not SAPK/JNK in osteoblasts.

Topics: Animals; Anthracenes; Cell Line; Enzyme Inhibitors; Flavonoids; Heat-Shock Proteins; Imidazoles; Intracellular Signaling Peptides and Proteins; Mice; Mitogen-Activated Protein Kinases; Osteoblasts; Phosphorylation; Prostaglandin D2; Protein Kinases; Protein Serine-Threonine Kinases

As for the pathogenesis of rheumatoid arthritis (RA), prostaglandins (PGs) act as important mediators of inflammation and joint destruction. Among them, PGD2 is well recognized as a potent regulator of osteoblastic functions. We previously showed that PGD2 stimulates the induction of heat shock protein 27 (HSP27) via protein kinase C (PKC)-dependent p38 mitogen-activated protein (MAP) kinase and p44/p42 MAP kinase in osteoblast-like MC3T3-E1 cells. Therefore, it is a current topic to clarify how HSP27 plays a role for regulating osteoblastic functions in the lesion of RA. On the other hand, methotrexate (MTX) is one of the most effective medicines for the treatment of RA. Here, we examined the effect of MTX on PGD2-stimulated HSP27 induction in MC3T3-E1 cells. The cells were pretreated with various doses of MTX including therapeutic dosage for RA, and then stimulated by PGD2. MTX significantly enhanced the PGD2- increased levels of HSP27 in a dose-dependent manner, although MTX alone had no effect on the levels of HSP27. In addition, MTX amplified the PGD2-increased levels of HSP27 mRNA. On the contrary, MTX had little effect on PGD2-induced formation of inositol phosphates, PKC activation and phosphorylations of MAP kinases. Our results strongly suggest that MTX enhances PGD2-stimulated HSP27 induction at a point downstream from MAP kinases in osteoblasts.

Topics: Animals; Anthracenes; Blotting, Northern; Cells, Cultured; Cycloheximide; Dactinomycin; DNA; DNA-Binding Proteins; Enzyme Activation; Heat Shock Transcription Factors; Heat-Shock Proteins; HSP27 Heat-Shock Proteins; HSP70 Heat-Shock Proteins; HSP90 Heat-Shock Proteins; Inositol Phosphates; Methotrexate; Mice; Mitogen-Activated Protein Kinases; Osteoblasts; Phosphorylation; Prostaglandin D2; Protein Binding; Protein Kinase C; Protein Kinase Inhibitors; Response Elements; RNA, Messenger; Transcription Factors