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RAW Cells (raw + cell)
Selected AbstractsTREM-1 expression in macrophages is regulated at transcriptional level by NF-,B and PU.1EUROPEAN JOURNAL OF IMMUNOLOGY, Issue 8 2007Heng Zeng Abstract Triggering receptor expressed on myeloid cells (TREM)-1 is a recently identified immunoglobulin receptor that is expressed on neutrophils and monocytes where it amplifies the acute inflammatory response to bacteria. We examined the transcriptional regulation of TREM-1 in macrophages. Treatment of RAW cells with Escherichia coli LPS or Pseudomonas aeruginosa led to the induction of TREM-1 within 1,h with an expression lasting up to at least 24,h in vitro as detected by RT-PCR. Since the promoter of TREM-1 has multiple binding sites for NF-,B and PU.1 (one of the members of the ets family of transcription factors), we investigated the role of these transcription factors in the induction of TREM-1. Treatment of cells with NF-,B inhibitors abolished the expression of message of TREM-1 induced by LPS and P.,aeruginosa. In contrast, the expression of TREM-1 was increased after stimulation with LPS or P.,aeruginosa in cells that had gene of PU.1 silenced. Additionally, over-expression of PU.1 led to inhibition of TREM-1 induction in response to LPS and P.,aeruginosa. These data suggest that both these transcription factors are involved in the expression of TREM-1. NF-,B functions as a positive regulator whereas PU.1 is a negative regulator of the TREM-1 gene. [source] Osteoclast Differentiation by RANKL Requires NF-,B-Mediated Downregulation of Cyclin-Dependent Kinase 6 (Cdk6),JOURNAL OF BONE AND MINERAL RESEARCH, Issue 7 2004Toru Ogasawara Abstract This study investigated the involvement of cell cycle factors in RANKL-induced osteoclast differentiation. Among the G1 cell cycle factors, Cdk6 was found to be a key molecule in determining the differentiation rate of osteoclasts as a downstream effector of the NF-,B signaling. Introduction: A temporal arrest in the G1 phase of the cell cycle is a prerequisite for cell differentiation, making it possible that cell cycle factors regulate not only the proliferation but also the differentiation of cells. This study investigated cell cycle factors that critically influence differentiation of the murine monocytic RAW264.7 cells to osteoclasts induced by RANKL. Materials and Methods: Growth-arrested RAW cells were stimulated with serum in the presence or absence of soluble RANKL (100 ng/ml). Expressions of the G1 cell cycle factors cyclin D1, D2, D3, E, cyclin-dependent kinase (Cdk) 2, 4, 6, and Cdk inhibitors (p18 and p27) were determined by Western blot analysis. Involvement of NF-,B and c- jun N-terminal kinase (JNK) pathways was examined by overexpressing dominant negative mutants of the I,B kinase 2 (IKKDN) gene and mitogen-activated protein kinase kinase 7 (MKK7DN) gene, respectively, using the adenovirus vectors. To determine the direct effect of Cdk6 on osteoclast differentiation, stable clones of RAW cells transfected with Cdk6 cDNA were established. Osteoclast differentiation was determined by TRACP staining, and cell cycle regulation was determined by BrdU uptake and flow cytometric analysis. Results and Conclusion: Among the cell cycle factors examined, the Cdk6 level was downregulated by RANKL synchronously with the appearance of multinucleated osteoclasts. Inhibition of the NF-,B pathway by IKKDN overexpression, but not that of the JNK pathway by MKK7DN overexpression, caused the decreases in both Cdk6 downregulation and osteoclastogenesis by RANKL. RAW cells overexpressing Cdk6 resist RANKL-induced osteoclastogenesis; however, cell cycle regulation was not affected by the levels of Cdk6 overexpression, suggesting that the inhibitory effect of Cdk6 on osteoclast differentiation was not exerted through cell cycle regulation. These results indicate that Cdk6 is a critical regulator of RANKL-induced osteoclast differentiation and that its NF-,B-mediated downregulation is essential for efficient osteoclast differentiation. [source] Possible Involvement of I,B Kinase 2 and MKK7 in Osteoclastogenesis Induced by Receptor Activator of Nuclear Factor ,B Ligand,JOURNAL OF BONE AND MINERAL RESEARCH, Issue 4 2002Aiichiro Yamamoto Abstract Recent studies have revealed the essential role of the receptor activator of nuclear factor ,B (NF-,B) ligand (RANKL) in osteoclast differentiation and activation. Adenovirus vector could efficiently transduce genes into RAW264.7 cells, which differentiate into osteoclast-like multinucleated cells in the presence of RANKL. The role of NF-,B and c- jun N-terminal kinase (JNK) activation in RANKL-induced osteoclast differentiation was investigated using an adenovirus vector carrying the dominant negative I,B kinase 2 gene (AxIKK2DN) or dominant negative MKK7 gene (AxMKK7DN). IKK2DN and MKK7DN overexpression in RAW cells specifically suppressed the NF-,B activation and JNK activation in response to RANKL, respectively, without affecting other signaling pathways. Either inhibition of NF-,B or JNK pathways dose-dependently inhibited osteoclast formation induced by RANKL. These results suggest that both NF-,B and JNK activation are independently required for osteoclast differentiation. [source] Regulation of osteoclastogenesis and RANK expression by TGF-,1JOURNAL OF CELLULAR BIOCHEMISTRY, Issue 2 2001Tao Yan Abstract Transforming growth factor-, (TGF-,) has been shown to both inhibit and to stimulate bone resorption and osteoclastogenesis. This may be due, in part, to differential effects on bone marrow stromal cells that support osteoclastogenesis vs. direct effects on osteoclastic precursor cells. In the present study, we used the murine monocytic cell line, RAW 264.7, to define direct effects of TGF-, on pre-osteoclastic cells. In the presence of macrophage-colony stimulating factor (M-CSF) (20 ng/ml) and receptor activator of NF-,B ligand (RANK-L) (50 ng/ml), TGF-,1 (0.01,5 ng/ml) dose-dependently stimulated (by up to 120-fold) osteoclast formation (assessed by the presence of tartrate-resistant acid phosphatase (TRAP) positive multinucleated cells and expression of calcitonin and vitronectin receptors). In addition, TGF-,1 also increased steady state RANK mRNA levels in a time- (by up to 3.5-fold at 48 h) and dose-dependent manner (by up to 2.2-fold at 10 ng/ml). TGF-,1 induction of RANK mRNA levels was present both in undifferentiated RAW cells as well as in cells that had been induced to differentiate into osteoclasts by a 7-day treatment with M-CSF and RANK-L. Using a fluorescence-labeled RANK-L probe, we also demonstrated by flow cytometry that TGF-,1 resulted in a significant increase in the percentage of RANK+ RAW cells (P,<,0.05), as well as an increase in the fluorescence intensity per cell (P,<,0.05), the latter consistent with an increase in RANK protein expression per cell. These data thus indicate that TGF-, directly stimulates osteoclastic differentiation, and this is accompanied by increased RANK mRNA and protein expression. J. Cell. Biochem. 83: 320,325, 2001. © 2001 Wiley-Liss, Inc. [source] Anti-inflammatory activity of the synthetic C-C biflavonoidsJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 12 2006Haeil Park To find anti-inflammatory agents based on plant constituents, the effects of six synthetic C-C biflavonoids connecting with different positions of C-C bond between flavone monomers (a: 4,-4,, b: 4,-3,, c: 4,-6, d: 3,-6, e: 6-6, f: 4,-3) were examined on PGE2 and nitric oxide (NO) production from lipopolysaccharide (LPS)-treated macrophages, RAW 264.7. Among the compounds tested, the biflavonoids d, e, and f showed a considerable inhibition of cyclooxygenase-2 (COX-2)-mediated PGE2 production at concentrations up to 50 ,M, while the derivative c exerted cytotoxic effects on RAW cells. Especially, the biflavonoid e possessed the most potent inhibitory activity of PGE2 production with an IC50 of 3.7 ,M, compared with an IC50 of 8.2,20.7 ,M by ginkgetin (natural biflavonoid). Western blot and reverse transcriptase-polymerase chain reaction analyses have shown that the inhibition of PGE2 production by these synthetic derivatives was mediated at least in part by COX-2 inhibition, but not by COX-2 down-regulation. Meanwhile, these synthetic biflavonoids did not considerably inhibit inducible nitric oxide synthase-mediated NO production at concentrations up to 50 ,M. When intraperitoneally administered, the biflavonoid e showed a significant anti-inflammatory activity (22.2% inhibition) against rat carrageenan-induced paw oedema at 5 mg kg,1. The biflavonoid e may be used as a synthetic lead for developing new anti-inflammatory agents. [source] | ||||||||||