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The present study was to see whether echinomycin-induced apoptosis would be NF-kappaB-dependent and if so, whether echinomycin would activate or inhibit NF-kappaB as well as resultant chemokine IL-8 expression. In HT-29 cells echinomycin activated NF-kappaB in time-dependent manner. EMSA in the presence of antibodies specific for p50 and p65 subunits indicated that echinomycin-induces the translocation of p50-p65 heterodimeric subunits of NF-kappaB. Levels of IkappaB were detected at initial echinomycin treatment and thereafter decreased, faintly seen after a 6h treatment. In contrast p-IkappaB levels were clearly detected throughout 6-24h of echinomycin treatment, albeit initially fainted. To clarify the role of NF-kappaB on IL-8 expression in echinomycin-mediated apoptosis of HT-29 cells, ELISA plus RT-PCR clearly showed that IL-8 production is inducible by echinomycin treatment. Using a specific inhibitor, IL-8 regulation at echinomycin treatment in HT-29 cells occurred via both caspase-3 and NF-kappaB-dependent signal pathway. To confirm whether two different pathways (NF-kappaB and caspase) would be coupled, only NF-kappaB inhibitor (PDTC) and caspase-3 specific inhibitor (Z-DEVD-FMK) together significantly attenuated echinomycin-initiated apoptosis of HT-29 cells, pretreatment of HT-29 cells with PDTC rarely affected echinomycin-induced caspase-3 activation. So echinomycin-induced apoptosis in HT-29 cells occurs via NF-kappaB activation independent of caspase-3 activation modulating the resultant-linked key chemokine IL-8 expression and echinomycin-induced apoptosis is NF-kappaB-dependant and directly related to NF-kappaB activation, consequently regulating IL-8 expression.  相似文献   

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  总被引:1,自引:0,他引:1  
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In this work the effect of angiotensin II (AT II) on proximal tubular epithelial cells (pTECs) in vitro was studied. AT II was found to activate the nuclear factor kappaB (NF-kappaB) and its controlled genes, for example, interleukin 6 (IL-6) of pTECs in a time-dependent manner. Two points with maximum NF-kappaB activation were found, the first after 12 h and the second after 3.5 days. The first point may be due to activation of NF-kappaB in pTECs in response to AT II while the second may be due to activation of the advanced glycation end product (AGE)/receptor of the AGE (RAGE) system. Thymoquinone (TQ) was found to decrease NF-kappaB activation in a dose-dependant manner with maximum inhibitory effect at a concentration of 500 nM. Also, pre-incubation of pTECs with TQ leads to disappearance of the second peak of NF-kappaB. These data are consistent with results obtained from IL-6 enzyme-linked immunosorbent assay (ELISA) and transient transfection experiments. The results explain the therapeutic value of TQ which can be used to delay end stage renal diseases in diabetics.  相似文献   

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Inflammatory cell infiltration plays a key role in the pathogenesis of tubulointerstitial damage in chronic renal diseases. In addition to secreting the profibrotic cytokines, monocytes themselves have been demonstrated to be directly associated with renal fibrogenesis. However, how infiltrating monocytes interact with resident cells and the underlying mechanisms remain elusive. In this study we investigated the effects of monocytes on phenotypic changes of human proximal tubular HK-2 cells. The typical epithelial cell morphology of HK-2 cells disappeared after co-culture with monocytes, accompanied by decreased E-cadherin expression, and increased α-SMA and fibronectin expression, suggesting that HK-2 cells undergo epithelial-mesenchymal transition (EMT). Further analysis revealed that the effects were dependent on direct contact of the two types of cells as conditioned medium had no effects. Interestingly, administration of CD18 antibody directly inhibited this process. Furthermore, by microarray and RT-PCR we found that NF-kB signaling may play a role in this process and blockade of this signaling pathway in HK-2 cells could inhibit ICAM-1 expression and EMT phenotypes. Taken together, these findings suggest that monocytes infiltration could directly induce EMT of HK-2 cells via upregulation ICAM-1 through NF-kB signaling pathway.  相似文献   

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Toll-like receptors (TLRs) recognize pathogen-associated molecular patterns (PAMPS) leading to the activation of the innate immune response and subsequently to the shaping of the adaptive immune response. Of the known human TLRs, TLR3, 7, 8, and 9 were shown to recognize nucleic acid ligands. TLR3 signaling is induced by double-stranded (ds)RNA, a molecular signature of viruses, and is mediated by the TRIF (TIR domain-containing adaptor-inducing IFNbeta) adaptor molecule. Thus, TLR3 plays an important role in the host response to viral infections. The liver is constantly exposed to a large variety of foreign substances, including pathogens such as HBV (hepatitis B virus) and HCV (hepatitis C virus), which frequently establish persistent liver infections. In this work, we investigated the expression and signaling pathway of TLR3 in different hepatoma cell lines. We show that hepatocyte lineage cells express relatively low levels of TLR3 mRNA. TLR3 signaling in HEK293 cells (human embryonic kidney cells) activated NF-kappaB and IRF3 (interferon regulatory factor 3) and induced IFNbeta (interferon beta) promoter expression, which are known to lead to pro-inflammatory cytokine secretion. In Huh7 cells, there was only a short-term IRF3 activation, and a very low level of IFNbeta expression. In HepG2 cells on the other hand, while no induction of pro-inflammatory factors was observed, signaling by TLR3 was skewed towards the induction of apoptosis. These results indicate preferential induction of the apoptotic pathway over the cytokine induction pathway by TLR3 signaling in hepatocellular carcinoma cells with potential implications for therapeutic strategies.  相似文献   

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Liu J  Zou L  Zheng Y  Zhao Z  Li Y  Yang P  Luo S 《Cell biology international》2007,31(10):1220-1224
This study was to examine the early responses of nuclear factor kappa B (NF-kappaB) to mechanical strains in MG-63. MG-63 cells were subjected to cyclic uniaxial compressive or tensile strain, produced by a four-point bending system, at 1000 microstrain or 4000 microstrain for 5 min, 15 min, 30 min and 1h, respectively. Control cells received the same treatment with no mechanical stress loading. Expression of NF-kappaB (p60) was measured by Western blotting. NF-kappaB responded rapidly to mechanical stimuli in MG-63 cells. NF-kappaB was activated by cyclic uniaxial stretch at 1000 microstrain while it was restrained under a compressive strain environment at 1000 microstrain (P<0.001). The effects reversed for tension and compression at 4000 microstrain (P<0.001). Furthermore, strains at 1000 microstrain affected NF-kappaB expression much easier than those at 4000 microstrain. This indicates that there may be different responding mechanisms or mechanotransduction pathways for different mechanical stimuli.  相似文献   

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Recent in vitro studies suggest that adenosine monophosphate (AMP)-activated protein kinase (AMPK) exerts inhibitory effects on cardiac hypertrophy. However, it is unclear whether long-term activation of AMPK will affect cardiac hypertrophy in vivo. In these reports, we investigate the in vivo effects of long-term AMPK activation on cardiac hypertrophy and the related molecular mechanisms. To examine the effects of AMPK activation in the development of pressure overload-induced cardiac hypertrophy, we administered 5-aminoimidazole 1 carboxamide ribonucleoside (AICAR, 0.5 mg/g body wt), a specific activator of AMPK, to rats with transaortic constriction (TAC) for 7 weeks. We found that long-term AMPK activation attenuated cardiac hypertrophy, and improved cardiac function in rats subjected to TAC. Furthermore, long-term AMPK activation attenuated protein synthesis, diminished calcineurin-nuclear factor of activated T cells (NFAT) and nuclear factor kappaB (NF-kappaB) signaling in pressure overload-induced hypertrophic hearts. Our in vitro experiments further proved that activation of AMPK by infection of AdAMPK blocked cardiac hypertrophy and NFAT, NF-kappaB, and MAPK signal pathways. The present study demonstrates for the first time that pharmacological activation of AMPK inhibits cardiac hypertrophy in through blocking signaling transduction pathways that are involved in cardiac growth. It presents a potential therapy strategy to inhibit pathological cardiac hypertrophy by increasing the activity of AMPK.  相似文献   

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Jurkat T leukemic cells respond to Etoposide, antineoplastic agent which targets the DNA unwinding enzyme, Topoisomerase II, and TNF-Related-Apoptosis-Inducing-Ligand (TRAIL), 34 kDa transmembrane protein, which displays minimal or no toxicity on normal cells and tissues, not only disclosing the occurrence of apoptosis but also a kind of resistance. A similar rate of viability upon the exposure to these two drugs up to 24 h has been evidenced, followed by the occurrence of a rescue process against TRAIL, not performed against Etoposide, along with an higher number of dead cells upon Etoposide exposure, in comparison with TRAIL treatment. These preliminary results let us to speculate on the possible involvement of PI-3-kinase in TRAIL resistance disclosed by surviving cells (20%), may be phosphorylating Akt-1 and, in parallel, IkappaB alpha on both serine and tyrosine residues. On the other hand, in Etoposide Jurkat exposed cells Ser 32-36 phosphorylation of IkappaB alpha is not sufficient to overbalance the apoptotic fate of the cells, since Bax increase, IAP decrease, and caspase-3 activation determine the persistence of the apoptotic state along with the occurrence of cell death by necrosis. Thus, the existence of a balance between apoptotic and rescue response in 20% of cells surviving to TRAIL suggests the possibility of pushing it in favor of cell death in order to improve the yield of pharmacological strategies.  相似文献   

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