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Objective:To observe the molecular mechanism involved in expression of hemeoxygenase -1 (HO-1) induced by a macrophage-activating lipopeptide-2 (MALP-2).Methods:THP-1 cells were cultured in vitro and stimulated by MALP-2 for 12 h, expression of HO-1 was detected by Western blot .TLR2 and TLR6 neutralizing antibodies incubation , dominant negative plasmids transfection were used to assess the functional of TLR 2,6 in mediating HO-1 expression.Phosphorylation of c-Src and Akt were detec-ted by Western blot, and c-Src siRNA and PI3K inhibitor LY294002 were used to investigate the role of c-Src and PI3K in HO-1 ex-pression.Results:MALP-2 induced c-Src phosphorylation , and TLR2 and TLR6 neutralizing antibodies , or their dominant negatively plasmids could abrogate this effect .In addition, siRNA of c-Src could decrease the phosphorylation level of Akt , and the PI3K inhibi-tor could inhibit HO-1 expression.Conclusion: MALP-2 can induce THP-1 cells expression of HO-1 through TLR2,6/c-Src/PI3K pathways .
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Objective To investigate whether macrophage-activating lipopeptide-2 ( MALP-2) in-duces the expression of heme oxygenase-1 ( HO-1 ) in THP-1 cells and its possible mechanism .Methods Human monocyte cells THP-1 were cultured in vitro and then were incubated with various concentrations (0, 0.01, 0.1, 1.0 or 5.0 ng/ml) of MALP-2 for 16 h, or were stimulated by 5.0 ng/ml MALP-2 for different length of time (0 h, 4 h, 8 h, 12 h, 16 h or 24 h).The expression of HO-1 at mRNA and protein levels were detected by real-time PCR analysis and Western blot assay .The enzyme activity of HO-1 was detected by colorimetric analysis.THP-1 cells were pre-incubated with 30 μmol/L of SB203580, PD98059 and SP600125 for 30 min and then were cultured with 5.0 ng/ml MALP-2 for 16 h to investigate the role of mito-gen-activated protein kinases (MAPKs) signaling pathway in HO-1 production.After incubating THP-1 cells with 5.0 ng/ml MALP-2 for different periods of time, NF-E2-related factor 2 (Nrf2) protein was detected by Western blot assay to study the effects of Nrf2 pathway on MALP-2-induced HO-1 expression.Nrf2 and HO-1 proteins were measured by Western blot assay after transfecting THP-1 cells (1×106/well) with Nrf2 siRNA at a final concentration of 100 nmol/L.Results MALP-2 enhanced the expression of HO-1 at mRNA and protein levels as well as the enzyme activity of HO-1 in THP-1 cells in a concentration-dependent manner.The expression of HO-1 protein induced by MALP-2 was significantly inhibited by 30 μmol/L MAPKs specific inhibitors ( SB203580 , PD98059 and SP600125 ) .MALP-2 induced Nrf2 translocation at a concentration of 5.0 ng/ml.The expression of Nrf2 and HO-1 proteins were significantly decreased in Nrf 2 siRNA-transfected THP-1 cells.Conclusion MAPKs and Nrf2 signaling pathways were involved in the MALP-2 induced HO-1 expression .
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Objective To investigate whether macrophage-activating lipopeptide-2 ( MALP-2) in-duces the expression of hemoxygenase-1 ( HO-1 ) in THP-1 cells and to further elucidate its possible regulatory mechanism for a better understanding of protective response upon mycoplasma infection .Methods THP-1 cells were cultured in vitro and stimulated by MALP-2 at different concentrations for 12 h.THP-1 cells were incubated with TLR 2 or TLR6 neutralizing antibodies , or transfected with their dominant negative plasmids to evaluate the effects of TLR 2 and TLR6 on HO-1 expression .Phosphorylation of Akt was detected by Western blot.PI3K inhibitor LY294002 was used to investigate the role of PI3K in HO-1 expression.Im-munofluorescence and electrophoretic mobility shift assay ( EMSA ) were performed to observe the nuclear translocation and DNA-binding activity of nuclear factor Nrf 2.Small interfering RNA ( siRNA) was used to silence the genes encoding Nrf2 and HO-1.Cobalt protoporphyrin (CoPP), an inducer of HO-1, was used to treat THP-1 cells.The expression of HO-1 was detected by Western blot .The secretion of TNF-αand IL-1βby THP-1 cells were measured by ELISA .Results MALP-2 induced the expression of HO-1 in THP-1 cells.However, the expression of HO-1 was inhibited by TLR2 and TLR6 neutralizing antibodies and expres-sion of their dominant negative plasmids .Moreover, PI3K pathway was activated by MALP-2, and with the use of PI3K inhibitor, the expression of HO-1 was decreased.The translocation of Nrf2 to the nucleus and itsDNA-binding activity were enhanced by MALP-2, but were inhibited by the treatment of PI3K inhibitor.Theexpression of HO-1 was significantly down-regulated upon the interference of Nrf2 gene expression withsiRNA.Silenced expression of HO-1 increased the level of TNF-αand IL-1β, while CoPP treatment decreasedthe secretion of MALP-2-induced cytokines.Conclusion MALP-2 might induce the expression ofHO-1 in THP-1 cells through TLR2,6/PI3K/Nrf2 pathways.The expression of HO-1 could negatively regulatethe hyper-secretion of cytokines.