PEX5 regulates autophagy via the mTORC1-TFEB axis during starvation

Defects in the PEX5 gene impair the import of peroxisomal matrix proteins, leading to nonfunctional peroxisomes and other associated pathological defects such as Zellweger syndrome. Although PEX5 regulates autophagy process in a stress condition, the mechanisms controlling autophagy by PEX5 under nutrient deprivation are largely unknown. Herein, we show a novel function of PEX5 in the regulation of autophagy via Transcription Factor EB (TFEB). Under serum-starved conditions, when PEX5 is depleted, the mammalian target of rapamycin (mTORC1) inhibitor TSC2 is downregulated, which results in increased phosphorylation of the mTORC1 substrates, including 70S6K, S6K, and 4E-BP-1. mTORC1 activation further suppresses the nuclear localization of TFEB, as indicated by decreased mRNA levels of TFEB, LIPA, and LAMP1. Interestingly, peroxisomal mRNA and protein levels are also reduced by TFEB inactivation, indicating that TFEB might control peroxisome biogenesis at a transcriptional level. Conversely, pharmacological inhibition of mTOR resulting from PEX5 depletion during nutrient starvation activates TFEB by promoting nuclear localization of the protein. In addition, mTORC1 inhibition recovers the damaged-peroxisome biogenesis. These data suggest that PEX5 may be a critical regulator of lysosomal gene expression and autophagy through the mTOR-TFEB-autophagy axis under nutrient deprivation.

A protein essential for the formation of peroxisomes—cellular organelles that perform diverse metabolic functions—also regulates cellular ‘recycling centers’ that break biomolecules down into nutrients. Researchers led by Raekil Park at the Gwangju Institute of Science and Technology in South Korea have now linked this protein, known as PEX5, to the function of another critical cellular organelle. Lysosomes participate in a process called autophagy, in which non-essential or damaged cellular components and biomolecules are digested to generate nutrients in times of deprivation. Park’s team determined that in the absence of PEX5, starved cells lose the ability to effectively initiate autophagy. They also identified the molecular pathways affected by PEX5 deficiency. These findings indicate a strong functional link between the peroxisome and lysosome, and could aid the development of treatments for certain metabolic disorders.

Diagnostic Significance of Measuring Vascular Endothelial Growth Factor for the Differentiation between Malignant and Tuberculous Pleural Effusion

Malignancy and tuberculosis are common causes of lymphocytic exudative pleural effusion. However, it is occasionally difficult to differentiate malignant pleural effusion from tuberculous pleural effusion. Vascular endothelial growth factor (VEGF) is a critical cytokine in the pathogenesis of malignant pleural effusion. Endocan is a dermatan sulfate proteoglycan that is secreted by endothelial cells. Importantly, endocan mediates the vascular growth-promoting action of VEGF. The aim of this study was to evaluate the diagnostic significance of VEGF and endocan in pleural effusion. We thus measured the levels of VEGF and endocan in the pleural effusion and serum samples of patients with lung cancer (n = 59) and those with tuberculosis (n = 32) by enzyme-linked immunosorbent assay. Lung cancer included 40 cases of adenocarcinoma, 13 of squamous cell carcinoma, and 6 of small cell carcinoma. Pleural effusion VEGF levels were significantly higher in the malignant group than in the tuberculosis group (2,091.47 ± 1,624.80 pg/mL vs. 1,291.05 ± 1,100.53 pg/mL, P < 0.05), whereas pleural effusion endocan levels were similar between the two groups (1.22 ± 0.74 ng/mL vs. 0.87 ± 0.53 ng/mL). The areas under the curve of VEGF and endocan were 0.73 and 0.52, respectively. Notably, the VEGF levels were similar in malignant pleural effusion, irrespective of the histological type of lung cancer. Moreover, no significant difference was found in the serum VEGF and endocan levels between patients with lung cancer and those with tuberculosis. In conclusion, high VEGF levels in pleural effusion are suggestive of malignant pleural effusion.

5-FU Induces Apoptosis of Fas (+), HepG2 Cells Via Activation of Fas-mediated Caspase and Mitochondria Dysfunction

PURPOSE

In order to investigate the role of Fas on the chemosensitivity of cancer cells in regards to chemotherapeutic agents, the Fas/FasL signaling pathway of apoptosis was explored in human hepatoma cells.

MATERIALS AND METHODS

Fas expression of hepatoma cells including Chang, Huh7, HepG2, and Hep3B cells, was determined by RT-PCR and flow cytometry analysis. Cell viability was measured by MTT assay and apoptosis was assessed by DNA fragmentation assay. The catalytic activity of the caspase-family proteases including caspase-3, 6, 8, and 9 proteases, was tested using fluorogenic biosubstrates. The expression of apoptotic mediators including cytochrome c, PARP, and Bcl2 family proteins were measured from cytosolic and mitochondrial compartments. Mitochondrial membrane potential was measured by fluorescence staining with JC-1, rhodamine 123.

RESULTS

Fas mRNA was constitutively expressed in Chang and HepG2 as defined as Fas (+) cells, but not in Huh7 and Hep3B cells, defined as Fas (-) cells. Fas (+) cells were markedly sensitive to 5-FU whereas Fas (-) cells were resistant and able to survive. 5-FU increased Fas expression of Fas (+) HepG2 cells and simultaneously resulted in apoptotic death, characterized by the ladder-pattern fragmentation of genomic DNA. Moreover, it increased the catalytic activity of caspase-8 protease, which eventually cleaved the Bid into truncated Bid which translocated into mitochondria only in Fas (+) cells. It also increased the caspase-9 protease activity with Bax expression, cytosolic release of cytochrome c, and mytochondrial dysfunction only in Fas (+) HepG2 cells. Furthermore, 5-FU increased the enzymatic activity of caspase-3 protease with PARP digestion in HepG2 cells.

CONCLUSION

5-FU exerted cytotoxicity against hepatoma cells via activation of Fas-mediated apoptotic signaling including caspase cascades and mytochondrial dysfunction. Our data suggests that Fas may be an important modulator of the chemosensitivity of cancer cells vis- -vis anticancer chemotherapeutic agents.

Rehmannia glutinosaActivates Intracellular Antioxidant Enzyme Systems in Mouse Auditory Cells

Steamed roots of Rehmannia glutinosa (R. glutinosa) have been traditionally used in Oriental medicine for the treatment of auditory diseases such as tinnitus and hearing loss. To investigate whether the ethanol extract of steamed roots of R. glutinosa (SRG) increases activity of antioxidant enzymes and the level of glutathione (GSH), we measured activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX), and glutathione reductase (GR) and GSH level in HEI-OC1 cells after treatment with 5–50 μg/ml of SRG. The SOD and CAT activities were significantly increased in the presence of SRG compared to the control group. Maximal activities of SOD and CAT were observed in these cells exposed to 10 μg/ml of SRG. The GPX activity also increased dramatically in response to the treatment with SRG in a dose-dependent manner. The GR activity was only increased in the presence of 50 μg/ml of SRG compared to the control group. The level of GSH gradually increased in the presence of 5–50 μg/ml of SRG. In the cytotoxicity test, 5–50 μg/ml of SRG did not show any significant cytotoxicity. These results suggest that the traditional use of R. glutinosa for the treatment of auditory diseases may be explained, in part, by activation of intracellular antioxidant enzyme systems. Further studies are necessary to clarify the active constituents of SRG responsible for such biomolecular activities.

Protective Effect of a Chrysanthemum indicum containing Formulation in Cadmium-Induced Ototoxicity

Chungshinchongyitang (CSCYT) is an herbal drug formula containing Chrysanthemum indicum and 13 other herbs used for treating auditory diseases. Irreversible hearing loss is a characteristic effect of a number of heavy metals. Cadmium ( Cd2+ ) is an environmental contaminant that causes a variety of adverse effects. In the present study, we investigate the protective effects of CSCYT against Cd2+ induced ototoxicity in vitro and ex vivo. The findings of this study show that CSCYT prevents the destruction of hair cell arrays induced by Cd2+ in the rat organ of Corti primary explants. CSCYT inhibited cell death, release of cytochrome c and generation of reactive oxygen species induced by Cd2+ in HEI-OC1 auditory cell line. In addition, we also demonstrated that CSCYT exerted its effect by modulating of apoptosis via the caspase-3 activation and extracellular signal-regulated kinase activation. These results are expected to improve the understanding of the pharmacological mechanism of CSCYT and aid in the development of potential therapeutic strategies against ototoxicity.

2',4',6'-Tris(methoxymethoxy) chalcone (TMMC) attenuates the severity of cerulein-induced acute pancreatitis and associated lung injury

Acute pancreatitis (AP) is an inflammatory disease involving acinar cell injury and rapid production and release of inflammatory cytokines, which play a dominant role in local pancreatic inflammation and systemic complications. 2',4',6'-Tris (methoxymethoxy) chalcone (TMMC), a synthetic chalcone derivative, displays potent anti-inflammatory effects. Therefore, we aimed to investigate whether TMMC might affect the severity of AP and pancreatitis-associated lung injury in mice. We used the cerulein hyperstimulation model of AP. Severity of pancreatitis was determined in cerulein-injected mice by histological analysis and neutrophil sequestration. The pretreatment of mice with TMMC reduced the severity of AP and pancreatitis-associated lung injury and inhibited several biochemical parameters (activity of amylase, lipase, trypsin, trypsinogen, and myeloperoxidase and production of proinflammatory cytokines). In addition, TMMC inhibited pancreatic acinar cell death and production of tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6 by inhibiting NF-κB and extracellular signal-regulated protein kinase 1/2 (ERK1/2) activation. Neutralizing antibodies for TNF-α, IL-1β, and IL-6 inhibited cerulein-induced cell death in isolated pancreatic acinar cells. Moreover, pharmacological blockade of NF-κB/ERK1/2 reduced acinar cell death and production of TNF-α, IL-1β, and IL-6 in isolated pancreatic acinar cells. In addition, posttreatment of mice with TMMC showed reduced severity of AP and lung injury. Our results suggest that TMMC may reduce the complications associated with pancreatitis.

Protective effects of Curcuma longa against cerulein-induced acute pancreatitis and pancreatitis-associated lung injury

Curcuma longa (CL) has been reported to possess a variety of pharmacological activities. However, the effects of CL on acute pancreatitis (AP) have not yet been determined. To this end, we examined the effects of CL on cerulein-induced AP. Cell viability and cytokine productions were measured in pancreatic acini. Mice were divided into 3 groups: i) Normal group, ii) normal saline-treated group, iii) group treated with CL at a dose of 0.05, 0.1, 0.5 and 1 g/kg. CL was administered orally to mice for 7 days. The mice were intraperitoneally injected with the stable cholecystokinin analogue, cerulein (50 μg/kg), every hour for a total of 6 h. The mice were sacrificed 6 h after the completion of the cerulein injections. Blood samples were obtained to determine serum amylase, lipase and cytokine levels. The pancreas was rapidly removed for morphological examination, measurement of tissue myeloperoxidase activity, as well as the level of cytokines and heme oxygenase-1 (HO-1). The CL treatment reduced cerulein-induced cell death and cytokine production in pancreatic acini. The administration of CL significantly ameliorated the severity of pancreatitis and pancreatitis-associated lung injury, as was shown by the reduction in pancreatic edema, neutrophil infiltration, vacuolization, necrosis, serum amylase, lipase and cytokine levels, and mRNA expression of multiple inflammatory mediators such as interleukin (IL)-1ß and -6 and tumor necrosis factor (TNF)-α. In order to identify the regulatory mechanism of CL on cerulein-induced pancreatitis, we examined the level of HO-1 in the pancreas. We found that the administration of CL induced HO-1. Our results suggest that CL plays a protective role in the development of AP and pancreatitis-associated lung injury.

Inhibition of lipopolysaccharide-induced inflammatory responses by piperine

Piperine, a main component of Piper longum Linn. and Piper nigrum Linn., is a plant alkaloid with a long history of medical use. Piperine exhibits anti-inflammatory activity; however, the underlying mechanism remains unknown. We examined the effects of piperine on lipopolysaccharide (LPS)-induced inflammatory responses. Administration of piperine inhibited LPS-induced endotoxin shock, leukocyte accumulation and the production of tumor necrosis factor-alpha (TNF-alpha), but not of interleukin (IL)-1beta and IL-6. In peritoneal macrophages, piperine inhibited LPS/poly (I:C)/CpG-ODN-induced TNF-alpha production. Piperine also inhibited LPS-induced endotoxin shock in TNF-alpha knockout (KO) mice. To clarify the inhibitory mechanism of LPS-induced endotoxin shock, type 1 interferon (IFN) mRNA expression was determined. Piperine inhibited LPS-induced expression of type 1 IFN mRNA. Piperine inhibited the levels of interferon regulatory factor (IRF)-1 and IRF-7 mRNA, and the phosphorylation and nuclear translocation of IRF-3. Piperine also reduced activation of signal transducer and activator of transcription (STAT)-1. In addition, activation of STAT-1 was inhibited in IFN-alpha/beta-treated cells by piperine. These results suggest that piperine inhibits LPS-induced endotoxin shock through inhibition of type 1 IFN production.

Protective effect of ursolic acid from Cornus officinalis on the hydrogen peroxide-induced damage of HEI-OC1 auditory cells

The fruits of Cornus officinalis have been used in traditional oriental medicine for treatment of inner ear diseases, such as tinnitus and hearing loss. In the present study, we investigated the protective effect of C. officinalis on hydrogen peroxide-induced cytotoxicity in HEI-OC1 auditory cells. The results from bioassay-guided fractionation of methanol extract of C. officinalis fruits showed that ursolic acid is a major active component. Ursolic acid (0.05-2 microg/ml) had protective effect against the HEI-OC1 cell damage and reduced lipid peroxidation in a dose-dependent manner. In addition, pre-treatment with ursolic acid significantly attenuated the decrease of activities of catalase (CAT) and glutathione peroxidase (GPX), but superoxide dismutase (SOD) activity was not significantly affected by ursolic acid. These results indicate that ursolic acid protects hydrogen peroxide-induced HEI-OC1 cell damage through inhibition of lipid peroxidation and induction of antioxidant enzymes, CAT and GPX, and may be one of the active components responsible for these effects of C. officinalis fruits.

Induction of nitric oxide & tumour necrosis factor-alpha by Psoralea corylifolia

BACKGROUND & OBJECTIVES

Psoralea corylifolia (PC) is an herb widely used in medicine for the treatment of a variety of ailment. PC is also known to have immunomodulatory activity. However, its mechanism of action is not known. In the present study we investigated effect of PC on nitric oxide (NO) and tumour necrosis factor-alpha (TNF-alpha) production in mouse peritoneal macrophages and also examined the mechanism by which PC regulates NO production.

METHODS

MTT assay performed for cell viability test and nitrite concentration was measured by using Griess reagent. The amount of TNF-alpha secreted by the cells was measured by a modified enzyme-linked immunosorbent assay (ELISA). Expression of iNOS was investigated by western blot analysis.

RESULTS

PC in combination with recombinant interferon-gamma (rIFN-gamma) showed a marked co-operative induction of NO production, with no effect on NO production by itself. The increased production of NO from rIFN-gamma plus PC-stimulated cells was almost completely inhibited by pre-treatment with pyrrolidine dithiocarbamate (PDTC), an inhibitor of nuclear factor kappa B (NF-kappaB). Furthermore, treatment of peritoneal macrophages with rIFN-gamma plus PC caused a significant increase in tumour necrosis factor-alpha (TNF-alpha) production. PDTC also decreased the effect of PC on TNF-alpha production significantly.

INTERPRETATION & CONCLUSION

As NO and TNF-alpha play an important role in immune function and host defense, PC treatment could modulate several aspects of host defense mechanisms due to stimulation of the inducible nitric oxide synthase.

Gardenia jasminoides protects against cerulein-induced acute pancreatitis

AIM: To investigate the effect of Gardenia jasminoides (GJ) on cerulein-induced acute pancreatitis (AP) in mice.

METHODS: C57BL/6 mice weighing 18-20 g were divided into three groups. (1) Normal saline-treated group, (2) treatment with GJ at a dose of 0.1 g/kg, (3) treatment with GJ at a dose of 1 g/kg. GJ was administered orally (n = 6 per group) for 1 wk. Three hours later, the mice were given an intraperitoneal injection of cerulein (50 μg/kg), a stable cholecystokinin (CCK) analogue, every hour for a total of 6 h as described previously. The mice were sacrificed at 6 h after completion of cerulein injections. Blood samples were obtained to determine serum amylase, lipase and cytokine levels. The pancreas was rapidly removed for morphologic examination and scoring. A portion of pancreas was stored at -70°C and prepared for the measurement of tissue myeloperoxidase (MPO) activity, an indicator of neutrophil sequestration, and for reverse-transcriptase PCR (RT-PCR) and real-time PCR measurements.

RESULTS: Treatment with GJ decreased significantly the severity of pancreatitis and pancreatitis-associated lung injury. Treatment with GJ attenuated the severity of AP compared with saline-treated mice, as shown by reduction in pancreatic edema, neutrophil infiltration, serum amylase and lipase levels, serum cytokine levels, and mRNA expression of multiple inflammatory mediators.

CONCLUSION: These results suggest that GJ attenuated the severity of AP as well as pancreatitis-associated lung injury.

The protective mechanism of antioxidants in cadmium-induced ototoxicity in vitro and in vivo

BACKGROUND

Several heavy metals have been shown to have toxic effects on the peripheral and central auditory system. Cadmium (Cd2+) is an environmental contaminant showing a variety of adverse effects. Given the current rate of release into the environment, the amount of Cd2+ present in the human body and the incidence of Cd2+-related diseases are expected to increase.

OBJECTIVE

The overall aim of this study was to gain further insights into the mechanism of Cd2+-induced ototoxicity.

METHODS

Cell viability, reactive oxygen species (ROS), mitochondrial membrane potential (MMP), cytochrome c (cyt c), phosphorylated extracellular signal-regulated protein kinase (p-ERK), caspases, morphologic change, and functional changes in HEI-OC1 cells, rat cochlear explants, and mouse cochlea after Cd2+ exposure were measured by flow cytometry, immunohistochemical staining, Western blot analysis, and auditory brainstem response (ABR) recording. Mechanisms underlying Cd2+ototoxicity were studied using inhibitors of different signaling pathways, caspases, and antioxidants.

RESULTS

Cd2+ exposure caused cell death, ROS generation, MMP loss, cyt c release, activation of caspases, ERK activation, apoptosis, and finally auditory threshold shift. Cd2+ toxicity interfered with inhibitors of cellular signaling pathways, such as ERK and c-jun N-terminal kinase, and with caspase inhibitors, especially inhibitors of caspase-9 and caspase-3. The antioxidants N-acetyl-l-cysteine and ebselen showed a significant protective effect on the Cd2+ toxicity.

CONCLUSIONS

Cd2+ is ototoxic with a complex underlying mechanism. However, ROS generation may be the cause of the toxicity, and application of antioxidants can prevent the toxic effect.

Induction of beta defensin 2 by NTHi requires TLR2 mediated MyD88 and IRAK-TRAF6-p38MAPK signaling pathway in human middle ear epithelial cells

Background

All mucosal epithelia, including those of the tubotympanium, are secreting a variety of antimicrobial innate immune molecules (AIIMs). In our previous study, we showed the bactericidal/bacteriostatic functions of AIIMs against various otitis media pathogens. Among the AIIMs, human β-defensin 2 is the most potent molecule and is inducible by exposure to inflammatory stimuli such as bacterial components or proinflammatory cytokines. Even though the β-defensin 2 is an important AIIM, the induction mechanism of this molecule has not been clearly established. We believe that this report is the first attempt to elucidate NTHi induced β-defensin expression in airway mucosa, which includes the middle ear.

Methods

Monoclonal antibody blocking method was employed in monitoring the TLR-dependent NTHi response. Two gene knock down methods – dominant negative (DN) plasmid and small interfering RNA (siRNA) – were employed to detect and confirm the involvement of several key genes in the signaling cascade resulting from the NTHi stimulated β-defensin 2 expression in human middle ear epithelial cell (HMEEC-1). The student's t-test was used for the statistical analysis of the data.

Results

The experimental results showed that the major NTHi-specific receptor in HMEEC-1 is the Toll-like receptor 2 (TLR2). Furthermore, recognition of NTHi component(s)/ligand(s) by TLR2, activated the Toll/IL-1 receptor (TIR)-MyD88-IRAK1-TRAF6-MKK3/6-p38 MAPK signal transduction pathway, ultimately leading to the induction of β-defensin 2.

Conclusion

This study found that the induction of β-defensin 2 is highest in whole cell lysate (WCL) preparations of NTHi, suggesting that the ligand(s) responsible for this up-regulation may be soluble macromolecule(s). We also found that this induction takes place through the TLR2 dependent MyD88-IRAK1-TRAF6-p38 MAPK pathway, with the primary response occurring within the first hour of stimulation. In combination with our previous studies showing that IL-1α-induced β-defensin 2 expression takes place through a MyD88-independent Raf-MEK1/2-ERK MAPK pathway, we found that both signaling cascades act synergistically to up-regulate β-defensin 2 levels. We propose that this confers an essential evolutionary advantage to the cells in coping with infections and may serve to amplify the innate immune response through paracrine signaling.

Fructus Ligustrum lucidi inhibits inflammatory mediator release through inhibition of nuclear factor-kappaB in mouse peritoneal macrophages

Fructus Ligustrum lucidi (FLL) is a widely used herbal medicine for the treatment of a variety of pathologies. We have investigated the anti-inflammatory mechanism of FLL in mouse peritoneal macrophages. FLL exerted an anti-inflammatory action through inhibition of lipopolysaccharide (LPS)-induced tumour necrosis factor (TNF)-alpha production in mouse peritoneal macrophages. The maximal inhibition rate of TNF-alpha production by FLL (0.5 mg mL(-1)) was 60.88 +/- 0.30%. In the inflammatory process, nitric oxide (NO) and prostaglandin E(2) (PGE(2)) increased in peritoneal macrophages. FLL decreased the protein level of NO and PGE(2) in LPS-stimulated mouse peritoneal macrophages. In addition, FLL inhibited nuclear factor-kappaB activation and IkappaB-alpha degradation by the decrease in IkappaB-alpha phosphorylation. Our study suggested that FLL reduced inflammation via an important molecular mechanism, which might explain its beneficial effect in the regulation of inflammatory reactions.

Observations of Forsythia koreana methanol extract on mast cell-mediated allergic reactions in experimental models

To explore effects of Forsythia koreana methanol extract (FKME) on mast cell-mediated allergic and inflammatory properties, the effect of FKME was evaluated on compound 48/80-induced systemic anaphylaxis, ear swelling, and anti-dinitrophenyl (DNP) immunoglobulin E (IgE)-induced passive cutaneous anaphylaxis (PCA). In addition, the effect of FKME was investigated on the histamine release from rat peritoneal mast cells (RPMCs) stimulated by compound 48/80, which promotes histamine release. The human mast cell line HMC-1 was stimulated by phorbol 12-myristate 13-acetate plus calcium ionophore A23187. Activated HMC-1 can produce several proinflammatory and chemotactic cytokines such as tumor necrosis factor-alpha (TNF-alpha), interleukin (IL)-6, and IL-8. Cytokine levels in the culture supernatant were measured by an enzyme-linked immunosorbent assay. Cytotoxicity by FKME was determined by a 3-(4,5-dimethylthiazol-2-yl)-diphenyl-tetrazolium bromide (MTT) assay. FKME inhibited compound 48/80-induced systemic anaphylactic shock and ear swelling in mice. When 1 g/kg FKME was pretreated or posttreated with mice, compound 48/80-induced mice morality was 50 and 66.7%, respectively. One gram per kilogram of FKME pretreatment inhibited ear-swelling responses derived from compound 48/80 by 29.75%. A PCA reaction was inhibited by 17.9%. In an in vitro model, FKME (1 mg/ml) inhibited histamine release from the RPMCs by 13.8% and TNF-alpha, IL-6, and IL-8 production from HMC-1 cells by 71.16% (P < 0.001), 86.72% (P < 0.001), and 44.6%, respectively. However, FKME had no cytotoxic effects on cell viability. In conclusion, FKME inhibited not only systemic anaphylaxis and ear swelling induced by compound 48/80 but also inhibited a PCA reaction induced by anti-DNP IgE in vivo. Treatment with FKME showed significant inhibitory effects on histamine, TNF-alpha, IL-6, and IL-8 release from mast cells.

The COX-2 inhibitor SC-236 exerts anti-inflammatory effects by suppressing phosphorylation of ERK in a murine model

SC-236, (4-[5-(4-chlorophenyl)-3-(trifluoromethyl)-1-pyrazol-1-]benzenesulfonamide; C(16)H(11)ClF(3)N(3)O(2)S) is a highly selective cyclooxygenase (COX)-2 inhibitor. Recently, there have been reports that SC-236 protects against cartilage damage in addition to reducing inflammation and pain for those with osteoarthritis. However, the mechanism involved in an inflammatory allergic reaction in a murine model has not been examined. The aim of the present study is to elucidate whether and how SC-236 modulates the inflammatory allergic reaction in a murine model. In this study, the anti-allergic effect was investigated using rat peritoneal mast cells, IgE-induced passive cutaneous anaphylaxis (PCA), and the ear-swelling model in mice. Also, we examined the inhibitory effect of SC-236 on the expression of interleukin (IL)-6 and tumor necrosis factor (TNF)-alpha. SC-236 was found to inhibit the ear-swelling response and histamine release in the murine model. Additionally, SC-236 was revealed to inhibit the PCA response and COX-2 expression. As a final step, the inhibitory mechanism of SC-236 was shown to occur through phosphorylation of extracellular signal-regulated protein kinase (ERK). These in vitro and in vivo results provide new insight into the pharmacological actions of SC-236 as a potential molecule for therapy for inflammatory allergic diseases.

Antiapoptotic mechanism of cannabinoid receptor 2 agonist on cisplatin-induced apoptosis in the HEI-OC1 auditory cell line

Cisplatin is a highly effective chemotherapeutic agent but with significant ototoxic side effects. Apoptosis is an important mechanism of cochlear hair cell loss following exposure to an ototoxic level of cisplatin. The present study investigated the effects of the cannabinoid receptor 2 (CB2) ligand JWH-015 on cisplatin-induced apoptosis. CB2 mRNA was constitutively expressed in the auditory cell line HEI-OC1. By using MTT assay, DNA fragmentation, and FACS analysis, we demonstrated that apoptosis induced by cisplatin was inhibited by treatment with JWH-015 in a dose-dependent manner. Activation of caspase-3, caspase-8, and caspase-9 was detected after treatment with cisplatin, and the cleavage of poly-(ADP)-ribose polymerase (PARP) was observed within cisplatin-treated HEI-OC1 cells. JWH-015 inhibited the activation of caspase-3, caspase-8, and caspase-9; cleavage of PARP; and release of cytochrome c. JWH-015 also inhibited the apoptosis through activation of the extracellular signal-regulated kinase pathway. Finally, JWH-015 inhibited cisplatin-induced reactive oxygen species and tumor necrosis factor-alpha production. Collectively, these findings show that blocking a critical step in apoptosis by using JWH-015 may be a useful strategy to prevent harmful side effects of cisplatin ototoxicity in patients having to undergo chemotherapy.

Selective cyclooxygenase-2 inhibitor ameliorates cholecystokinin-octapeptide-induced acute pancreatitis in rats

AIM: To investigate the effect of selective Cycloo-xygenase-2 (COX-2) inhibitor 4-[5-(4-Chloro-phenyl)-3-(trifluoromethyl)-1H-pyrazol-1-yl] benzenesulfonamide (SC-236), on the cholecystokinin (CCK)-octapeptide-induced acute pancreatitis (AP) in rats.

METHODS: Wistar rat weighing 240 g to 260 g were divided into three groups. (1) Normal DMSO treated group, (2) SC-236 at 4 mg/kg treated group; SC-236 systemically administered via the intravenous (i.v.) catheter, followed by 75 μg/kg CCK octapeptide subcutaneously three times, after 1, 3 and 5 h. This whole procedure was repeated for 5 d. (3) Dimethyl sulfoxide (DMSO) treated group: an identical protocol was used in this group as in the SC-236 cohort (see 2. above). Repeated CCK octapeptide treatment resulted in a typical experimentally induced pancreatitis in the Wistar rats.

RESULTS: SC-236 improved the severity of CCK-octapeptide-induced AP as measured by laboratory criteria [the pancreatic weight/body weight (p.w/b.w) ratio, the level of serum amylase and lipase]. The SC-236 treated group showed minimal histologic evidence of pancreatitis and a significant reduction in myeloperoxidase activity. SC-236 also increased heat shock protein (HSP)-60 and HSP72 compared with the DMSO-treated group in the CCK-octapeptide-induced AP and also reduced the pancreatic levels of COX-2. Furthermore, SC-236 reduced proinflammatory cytokine synthesis and inhibited NF-κB activation compared with the DMSO-treated group in the CCK-octapeptide-induced AP.

CONCLUSION: Our results suggested that COX-2 plays pivotal role in the development of AP and COX-2 inhibitors may play a beneficial role in preventing AP.

The regulatory effect of SC-236 (4-[5-(4-chlorophenyl)-3-(trifluoromethyl)-1-pyrazol-1-l]benzenesulfonamide) on stem cell factor induced migration of mast cells

SC-236, (4-[5-(4-chlorophenyl)-3-(trifluoromethyl)-1-pyrazol-1-]benzenesulfonamide; C(16)H(11)ClF(3)N(3)O(2)S), is a highly selective cyclooxygenase (COX)-2 inhibitor. Recently, there have been reports that SC-236 protects against cartilage damage in addition to reducing inflammation and pain in osteoarthritis. However, the mechanism involved in the inflammatory allergic reaction has not been examined. Mast cells accumulation can be related to inflammatory conditions, including allergic rhinitis, asthma, and rheumatoid arthritis. The aim of the present study is to investigate the effects of SC-236 on stem cell factor (SCF)-induced migration, morphological alteration, and cytokine production of rat peritoneal mast cells (RPMCs). We observed that SCF significantly induced the migration and morphological alteration. The ability of SCF to enhance migration and morphological alteration was abolished by treatment with SC-236. In addition, production of tumor necrosis factor (TNF)-alpha, interleukin (IL)-1beta, and vascular endothelial growth factor (VEGF) production induced by SCF was significantly inhibited by treatment with SC-236. Previous work has demonstrated that SCF-induced migration and cytokine production of mast cells require p38 MAPK activation. We also showed that SC-236 suppresses the SCF-induced p38 MAPK activation in RPMCs. These data suggest that SC-236 inhibits migration and cytokine production through suppression of p38 MAPK activation. These results provided new insight into the pharmacological actions of SC-236 and its potential therapeutic role in the treatment of inflammatory allergic diseases.

Protective effect of Rehmannia glutinosa on the cisplatin-induced damage of HEI-OC1 auditory cells through scavenging free radicals

The steamed root of Rehmannia glutinosa has been used in traditional Oriental Medicine for treatment of inner ear diseases, such as tinnitus and hearing loss. In the present study, we showed that the ethanol extract of steamed roots of Rehmannia glutinosa (SRG) protected HEI-OC1 auditory cells from cisplatin cytotoxicity in a dose-dependent fashion. In addition, to investigate the protection mechanism of SRG on cisplatin cytotoxicity towards HEI-OC1, we measured the effects of SRG on lipid peroxidation of cisplatin treated cells as well as scavenging activities against superoxide radical, hydroxyl radical, hydrogen peroxide, and DPPH radical. SRG (5-100 microg/ml) had protective effect against the cisplatin-induced HEI-OC1 cell damage and reduced lipid peroxidation in a dose-dependent manner. Furthermore, SRG showed strong scavenging activity against superoxide radical, hydroxyl radical, hydrogen peroxide, and DPPH radical. These results indicate that SRG protects cisplatin-induced HEI-OC1 cell damage through inhibition of lipid peroxidation and scavenging activities of free radials.

Hypoxia-induced IL-6 production is associated with activation of MAP kinase, HIF-1, and NF-kappaB on HEI-OC1 cells

In the present study, we investigated the signal transduction pathways of expression of IL-6 in the desferrioxamine (DFX)-stimulated cochlear auditory cell line, HEI-OC1 cells. DFX increased the expression of HIF-1alpha and NF-kappaB in HEI-OC1 cells. DFX significantly increased the production of IL-6 (P<0.05) and expression of IL-6 mRNA but did not affect TNF-alpha production. DFX also induced the activation of mitogen-activated protein kinase (MAPK) including p38, ERK, and JNK on HEI-OC1. Increased IL-6 by DFX was significantly inhibited by p38 inhibitor, SB203580 (about 72% inhibition, P=0.027) but not ERK inhibitor, PD98059 or JNK inhibitor, SP600125. SB203580 inhibited the expression of IL-6 mRNA. Increased IL-6 production was partially inhibited by treatment of iron (HIF-1 inhibitor) or pyrriolidine-dithiocarbamate (PDTC, NF-kappaB inhibitor). DFX also induced IL-6 production and HIF-1alpha expression in the inner ear. We demonstrated the regulatory effects of MAPK, HIF-1alpha, and NF-kappaB on DFX-induced IL-6 production in a HEI-OC1 for the first time. In conclusion, these data indicate that regulation of inflammatory cytokine IL-6 by DFX, through mimicking hypoxic conditions, might explain its beneficial effect in the treatment of hypoxia-induced inner ear diseases.

Ethanol induces the production of cytokines via the Ca2+, MAP kinase, HIF-1α, and NF-κB pathway

In the present study, we sought to investigate the signal transduction pathways of expression of cytokines in the ethanol-stimulated human mast cell line, HMC-1. Ethanol significantly increased the intracellular calcium level in HMC-1. Ethanol also significantly enhanced IL-6, TNF-alpha, and TGF-beta1 production compared with media control, but did not significantly affect the IL-1beta production. After 8 h of stimulation, ethanol increased mRNA and protein expression levels of TNF-alpha and TGF-beta1 in HMC-1. The increased cytokine level was significantly inhibited by BAPTA-AM, PD98059, and SB203580. These inhibitors also inhibited ethanol-induced ERK and p38 MAPK phosphorylation. Ethanol resulted in a great increase in protein levels and promoter activity driving luciferase expression of HIF-1alpha and NF-kappaB in HMC-1 cells, but it did not affect on HIF-1alpha mRNA expression. Our observations show that calcium, MAPK activation, HIF-1alpha, and NF-kappaB are necessary for ethanol-induced TNF-alpha and TGF-beta1 expression. These results may have important implications for the study of alcohol-related diseases.

Vascular endothelial growth factor is regulated by hypoxic stress via MAPK and HIF-1 alpha in the inner ear

Vascular endothelial growth factor (VEGF) is a key regulator of angiogenesis. The iron-chelator desferrioxamine (DFX) increased the expression of hypoxia-inducible factor (HIF)-1alpha in the hair cell line, HEI-OC1. The increased VEGF production by DFX was inhibited by iron. DFX also induced the activation of mitogen-activated protein kinase (MAPK) on HEI-OC1. The increased VEGF production by DFX was inhibited by a specific inhibitor of MAPK. In addition, DFX induced the VEGF production and HIF-1alpha stabilization in vivo. These results indicate that VEGF production is regulated via MAPK and HIF-1alpha under hypoxic condition in the inner ear.

Cyclooxygenase-2 inhibitor SC-236 [4-[5-(4-chlorophenyl)-3-(trifluoromethyl)-1-pyrazol-1-l] benzenesulfonamide] suppresses nuclear factor-kappaB activation and phosphorylation of p38 mitogen-activated protein kinase, extracellular signal-regulated kinase, and c-Jun N-terminal kinase in human mast cell line cells

SC-236 [4-[5-(4-chlorophenyl)-3-(trifluoromethyl)-1-pyrazol-1-l] benzenesulfonamide; C16H11ClF3N3O2S] is a highly selective cyclooxygenase (COX)-2 inhibitor. However, the exact mechanism that accounts for the anti-inflammatory effect of SC-236 is not completely understood. The aim of the present study was to elucidate whether and how SC-236 modulates the inflammatory reaction in a stimulated human mast cell (HMC) line, HMC-1. SC-236 inhibited the expression of tumor necrosis factor-alpha, interleukin (IL)-6, IL-8, vascular endothelial growth factor, COX-2, inducible nitric-oxide synthase, and hypoxia-inducible factor-1alpha in phorbol 12-myristate 13-acetate plus calcium ionophore A23187 (PMACI)-stimulated HMC-1. SC-236 suppressed nuclear factor (NF)-kappaB activation induced by PMACI, leading to suppression of IkappaB-alpha phosphorylation and degradation. SC-236 also suppressed strong induction of NF-kappaB promoter-mediated luciferase activity. In addition, SC-236 suppressed PMACI-induced phosphorylation of the mitogen-activated protein kinase p38, the extracellular-regulated kinase p44, and the c-Jun N-terminal kinase and induced expression of mitogen-activated protein kinase phosphatase-1. These results provide new insight into the pharmacological actions of SC-236 as a potential molecule for therapy of mast cell-mediated inflammatory diseases.

Regulatory effect of dosiinpartner on high-fat diet-induced obesity in C57BL/6J mice

Dosiinpartner (DSP) is a newly developed dietary functional food to help control weight. The aim of this study was to evaluate whether DSP combined with a high-fat (HF) diet could influence body weight, fat accumulation, and plasma glucose levels. Mice were fed for 8 weeks with normal diet, HF diet, and HF+10% or 20% DSP diet. Body weight was recorded at 1 week, and plasma levels of total cholesterol, low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol, and glucose were analyzed at the end of the study. Weight increases in the 10% or 20% DSP group were significantly less than in the HF diet group (p<0.05). Plasma total cholesterol and LDL cholesterol levels decreased by 48.3% and 26.8% in the 10% DSP group and by 42.9% and 34.9% in the 20% DSP group, respectively. However, the HDL cholesterol level was unchanged. Glucose levels also decreased by 80.6% in the 10% DSP group but was almost the same in the HF and 20% DSP groups. Our findings indicate that DSP may be beneficial in the regulation of high-fat diet-induced overweight and other complications such as circulatory disorders and diabetes mellitus.

Effect of disodium cromoglycate on mast cell-mediated immediate-type allergic reactions

We investigated the effect of disodium cromoglycate (DSCG) on mast cell-mediated immediate-type hypersensitivity. DSCG inhibited systemic allergic reaction induced by compound 48/80 dose-dependently. Passive cutaneous anaphylaxis was inhibited by 71.6% by oral administration of DSCG (1 g/kg). When DSCG was pretreated at concentration rang from 0.01-1000 g/kg, the serum histamine levels were reduced in a dose dependent manner. DSCG also significantly inhibited histamine release from rat peritoneal mast cell (RPMC) by compound 48/80. We confirmed that DSCG inhibited compound 48/80-induced degranulation of RPMC by alcian blue/nuclear fast red staining. In addition, DSCG showed a significant inhibitory effect on anti-dinitrophenyl IgE-mediated tumor necrosis factor-alpha production. These results indicate that DSCG inhibits mast cell-mediated immediate-type allergic reaction.

Quercetin protects the hydrogen peroxide-induced apoptosis via inhibition of mitochondrial dysfuntion in H9c2 cardiomyoblast cells

Quercetin possesses a broad range of pharmacological properties, including protection of LDL from oxidation. However, little is known about the mechanism by which quercetin rescues cardiomyoblasts from oxidative damage. This study was designed to investigate the protective mechanism of quercetin on H(2)O(2)-induced toxicity of H9c2 cardiomyoblasts. Oxidative stress, such as H(2)O(2), ZnCl(2), and menadione, significantly decreased the viability of H9c2 cells, which was accompanied with apparent apoptotic features, including fragmentation of genomic DNA as well as activation of caspase protease. However, quercetin markedly inhibited the apoptotic characteristics via reduction of intracellular reactive oxygen species generation. Also, it prevented the H(2)O(2)-mediated mitochondrial dysfunction, including disruption of mitochondria membrane permeability transition as well as an increase in expression of apoptogenic Bcl-2 proteins, Bcl-2 and Bcl-X(L). Furthermore, pretreatment of quercetin inhibited the activation of caspase-3, thereby both cleavage of poly(ADP-ribose) polymerase and degradation of inhibitor of caspase-activated DNase/DNA fragmentation factor by H(2)O(2) were completely abolished. Taken together, these data suggest that protective effects of quercetin against oxidative injuries of H9c2 cardiomyoblasts may be achieved via modulation of mitochondrial dysfunction and inhibition of caspase activity.

Effects of flavonoids isolated from Scutellariae radix on cytochrome P-450 activities in human liver microsomes

A series of flavonoids isolated from Scutellariae radix were evaluated for their effects on cytochrome P-450 (CYP) activities in human liver microsomes. All flavonoids did not substantially inhibit pentoxyresorufin O-deethylation (CYP2B 1), mephenytoin 4-hydroxylation (CYP2C19), dextromethorphan O-demethylation (CYP2D6), and chlorzoxazone 6-hydroxylation (CYP2E1) activities (IC50: >50 microM). Baicalein and 2',5,6',7-tetrahydroxyflavone inhibited hepatic testosterone 6beta-hydroxylation (CYP3A4) activity with a IC50 of 17.4 and 7.8 microM, respectively. Oroxylin A inhibited diclofenac 4-hydroxylation (CYP2C9) activity with a IC50 of 6.7 microM. In contrast, all flavonoids tested inhibited hepatic caffeine N'-demethylation (CYP1A2) with IC50 values ranging from 0.7 to 51.3 microM. Kinetic analysis revealed that the mechanism of inhibition varied according to the flavonoids. These results suggest that flavonoids tested are inhibitors of hepatic CYP1A2 and that the extracts of Scutellariae radix, widely used as a hepatoprotective agent, may protect the liver through the prevention of CYPIA2-induced metabolic activation of protoxicants.

Activation of caspase-8 during N-(4-hydroxyphenyl)retinamide-induced apoptosis in Fas-defective hepatoma cells

We observed that N-(4-hydroxyphenyl)retinamide (4HPR), a chemopreventive and chemotherapeutic agent, effectively induced apoptosis in hepatoma cells. Interestingly, Fas-negative (Hep 3B and PLC/PRF/5) hepatoma cells were shown to be more susceptible to apoptosis induced by 4HPR than were Fas-positive (Hep G2 and SK-HEP-1) hepatoma cells. Thus, we explored the mechanisms underlying 4HPR-induced apoptosis in Fas-defective hepatoma cells. Hep 3B cells stably expressing the dominant-negative Fas-associated death domain (dnFADD) showed no alteration in 4HPR drug susceptibility, but when stably expressing E1B19K, Crm A, or dominant-negative FLICE (dnFLICE), Hep 3B cells were resistant, suggesting that 4HPR-induced apoptosis was mediated by caspase-8 activation. Furthermore, apoptosis could be completely blocked by Z-VAD-FMK (a general caspase inhibitor) or by IETD-CHO (a caspase-8 inhibitor), but was only partially blocked by Ac-DEVD-CMK (a caspase-3 inhibitor), by N-acetyl-L-cysteine (NAC) (an antioxidant), by N-acetyl-leucyl-leucyl-norleucinal (ALLN) (a calpain inhibitor I), or by Z-LEHD-FMK (a caspase-9 inhibitor). Time-sequence analysis of the induction of apoptosis by 4HPR revealed that an initial caspase-8 activation was followed by late mitochondrial cytochrome c release and minor caspase-9 activation, which suggested that caspase-8 activation is the primary upstream regulatory point. Activation of Bid or induction of proapoptotic Bax was not observed during apoptosis. In contrast, Bcl-xL expression was decreased during 4HPR-induced apoptosis. Taken together, these results indicate that 4HPR may be a potential chemotherapeutic drug, which is able to induce apoptosis in Fas-defective hepatoma cells through caspase-8 activation.

Sodium nitroprusside induces apoptosis of H9C2 cardiac muscle cells in a c-Jun N-terminal kinase-dependent manner

Sodium nitroprusside (SNP) induces apoptosis in H9C2 cardiac muscle cells. Treatment with an exogenous NO donor SNP (2 mM) to H9C2 cells resulted in apoptotic morphological changes; a bright blue-fluorescent condensed nuclei and chromatin fragmentation by fluorescence microscope of Hoechst 33258-staining. The activity of caspase-3 like protease was increased during SNP-induced cell death. However, the activity of caspase-1 like protease was not affected by SNP. Pretreatment with Z-VAD-FMK (a pan-caspase inhibitor) or Ac-DEVD-CHO (a specific caspase-3 inhibitor) abrogated the SNP-induced cell death. SNP markedly activated three MAP kinases (JNK/SAPK, ERK and p38 MAP kinase) in the cardiac muscle cells. In this study, selective inhibition of the ERK or p38 MAPK pathway (by PD98059 or SB203580, respectively) had no effect on the extent of SNP-induced apoptosis in cardiac muscle cells. In contrast, inhibition of the JNK pathway by transfection of a dominant negative mutant of JNK markedly reduced the extent of SNP-induced cell death. Taken together, we suggest that JNK/SAPK will be related to SNP-induced apoptosis of H9C2 cardiac muscle cells.

Dexamethasone suppresses tumor necrosis factor-alpha-induced apoptosis in osteoblasts: possible role for ceramide

Ceramide has been proposed as a second messenger molecule implicated in a variety of biological processes, including apoptosis. Recently, it has been reported that tumor necrosis factor-alpha (TNF-alpha) activates the release of ceramide and that ceramide acts as a mediator for the TNF-alpha-induced stimulation of the binding affinity of nuclear factor-KB (NF-KB), a ubiquitous transcription factor of particular importance in immune and inflammatory responses. In this study we demonstrate that dexamethasone, which reduces the production of ceramide, significantly inhibits TNF-alpha-induced activation of NF-KB, c-Jun N-terminal kinase, also known as stress-activating protein kinase, caspase-3-like cysteine protease, redistribution of cytochrome c, and apoptosis in MC3T3E1 osteoblasts. Compared with TNF-alpha-induced JNK activation, ceramide elicits a more rapid activation of JNK within 30 min. C2-ceramide activates NF-KB and caspase-3 like protease to the same degree and with kinetics similar to those of TNF-alpha. This study provides evidence that the release of ceramide may be required as a second messenger in TNF-alpha-induced apoptosis. These results also suggest a regulatory role for dexamethasone in TNF-alpha-induced apoptosis via inhibition of ceramide release. Therefore, our in vitro results suggest that therapies targeted at the inhibition of ceramide release may abrogate inflammatory processes in TNF-alpha-related diseases, including rheumatoid arthritis and periodontitis.

Effect of ionizing radiation on the differentiation of ROS 17/2.8 osteoblasts through free radicals

Although the acceleration of bone regeneration by radiation has been reported, the mechanisms of action of radiation on bone are unclear. The present results indicate that ionizing radiation-stimulated differentiation could result from the generation of reactive oxygen species during radiation exposure. The free radical release is considered as the most important mechanism of bone effect by radiation treatment. In addition, we report that radiation induced transient activation of c-Jun N-terminal kinase/stress-activated protein kinase (JNK/SAPK) activation and the transcription factor, AP-1. The JNK and AP-1 activation is mediated with radiation-released free radicals in ROS 17/2.8 osteoblasts. These results indicate that ionizing radiation at a single dose of up to 5 Gray stimulates differentiation of ROS 17/2.8 osteoblasts via free radial release which may affect JNK/SAPK and AP-1 activities.

High Affinity IgG Receptor Activation of Src Family Kinases Is Required for Modulation of the Shc-Grb2-Sos Complex and the Downstream Activation of the Nicotinamide Adenine Dinucleotide Phosphate (Reduced) Oxidase

We used the U937 cell line to examine the modulation of adaptor protein interactions (Shc, Grb2, and Cbl) after high affinity IgG receptor (FcγRI) cross-linking, leading to the formation of the Grb2-Sos complex, the activation of Ras, and the regulation of the respiratory burst. Cross-linking of FcγRI induced the conversion of GDP-Ras to GTP-Ras reaching a maximum 5 min after stimulation. Concomitant with Ras activation, Sos underwent an electrophoretic mobility shift and the Sos-Grb2 association was increased (6-fold). The Grb2-Sos complex was present only in the membrane fraction and was augmented after FcγRI stimulation. Tyrosine-phosphorylated Shc, mainly the p52 isoform, was observed to transiently onload to the membrane Grb2-Sos complex on FcγRI stimulation. Cross-linking of FcγRI induces the tyrosine phosphorylation of Cbl, which forms a complex with Grb2 and Shc via the Cbl C terminus. Kinetic experiments confirm that Cbl-Grb2 is relatively stable, whereas Grb2-Sos, Grb2-Shc, and Cbl-Shc interactions are highly inducible. The Src family tyrosine kinase inhibitor, PP1, was shown to completely inhibit Shc tyrosine phosphorylation, the Shc-Grb2 interaction, and the FcγR-induced respiratory burst. Our results provide the first evidence that the upstream activation of Src kinases is required for the modulation of the Shc-Grb2 interaction and the myeloid NADPH oxidase response.

High affinity IgG receptor activation of Src family kinases is required for modulation of the Shc-Grb2-Sos complex and the downstream activation of the nicotinamide adenine dinucleotide phosphate (reduced) oxidase

We used the U937 cell line to examine the modulation of adaptor protein interactions (Shc, Grb2, and Cbl) after high affinity IgG receptor (FcgammaRI) cross-linking, leading to the formation of the Grb2-Sos complex, the activation of Ras, and the regulation of the respiratory burst. Cross-linking of FcgammaRI induced the conversion of GDP-Ras to GTP-Ras reaching a maximum 5 min after stimulation. Concomitant with Ras activation, Sos underwent an electrophoretic mobility shift and the Sos-Grb2 association was increased (6-fold). The Grb2-Sos complex was present only in the membrane fraction and was augmented after FcgammaRI stimulation. Tyrosine-phosphorylated Shc, mainly the p52 isoform, was observed to transiently onload to the membrane Grb2-Sos complex on FcgammaRI stimulation. Cross-linking of FcgammaRI induces the tyrosine phosphorylation of Cbl, which forms a complex with Grb2 and Shc via the Cbl C terminus. Kinetic experiments confirm that Cbl-Grb2 is relatively stable, whereas Grb2-Sos, Grb2-Shc, and Cbl-Shc interactions are highly inducible. The Src family tyrosine kinase inhibitor, PP1, was shown to completely inhibit Shc tyrosine phosphorylation, the Shc-Grb2 interaction, and the FcgammaR-induced respiratory burst. Our results provide the first evidence that the upstream activation of Src kinases is required for the modulation of the Shc-Grb2 interaction and the myeloid NADPH oxidase response.

Role of Src in the modulation of multiple adaptor proteins in FcalphaRI oxidant signaling

Cross-linking of Fc receptors for IgA, FcalphaR (CD89), on monocytes/macrophages is known to enhance phagocytic activity and generation of oxygen free radicals. We provide evidence here that the FcalphaR signals through the gamma subunit of FcepsilonRI in U937 cells differentiated with interferon gamma (IFNgamma). Our results provide the first evidence that FcalphaR-mediated signals modulate a multimolecular adaptor protein complex containing Grb2, Shc, SHIP, CrkL, Cbl, and SLP-76. Cross-linking of FcalphaRI using anti-FcalphaRI induces the phosphorylation of the gamma subunit as detected by mobility retardation on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Stimulation of FcalphaRI induced the tyrosine phosphorylation of Shc and increased the association of Grb2 with Shc and CrkL. Grb2 associates constitutively with Sos, and the latter undergoes mobility shift upon FcalphaRI stimulation. The complex adapter proteins, Cbl and SLP-76, are physically associated in myeloid cells and both proteins undergo tyrosine phosphorylation upon FcalphaR stimulation. These data indicate that the stimulation of FcalphaR results in the modulation of adaptor complexes containing tyrosine-phosphorylated Cbl, Shc, SHIP, Grb2, and Crkl. Experiments performed with the Src kinase inhibitor, PP1, provide the first evidence that Src kinase activation is required for FcalphaRI-induced production of superoxide anions and provide insight into the mechanism for FcalphaR-mediated activation of downstream oxidant signaling in myeloid cells.

Overexpression of Protein Kinase C Isoforms Protects RAW 264.7 Macrophages from Nitric Oxide-Induced Apoptosis: Involvement of c-Jun N-Terminal Kinase/Stress-Activated Protein Kinase, p38 Kinase, and CPP-32 Protease Pathways

Nitric oxide (NO) induces apoptotic cell death in murine RAW 264.7 macrophages. To elucidate the inhibitory effects of protein kinase C (PKC) on NO-induced apoptosis, we generated clones of RAW 264.7 cells that overexpress one of the PKC isoforms and explored the possible interactions between PKC and three structurally related mitogen-activated protein (MAP) kinases in NO actions. Treatment of RAW 264.7 cells with sodium nitroprusside (SNP), a NO-generating agent, activated both c-Jun N-terminal kinase/stress-activated protein kinase (JNK/SAPK) and p38 kinase, but did not activate extracellular signal-regulated kinase (ERK)-1 and ERK-2. In addition, SNP-induced apoptosis was slightly blocked by the selective p38 kinase inhibitor (SB203580) but not by the MAP/ERK1 kinase inhibitor (PD098059). PKC transfectants (PKC-βII, -δ, and -η) showed substantial protection from cell death induced by the exposure to NO donors such as SNP and S-nitrosoglutathione (GSNO). In contrast, in RAW 264.7 parent or in empty vector-transformed cells, these NO donors induced internucleosomal DNA cleavage. Moreover, overexpression of PKC isoforms significantly suppressed SNP-induced JNK/SAPK and p38 kinase activation, but did not affect ERK-1 and -2. We also explored the involvement of CPP32-like protease in the NO-induced apoptosis. Inhibition of CPP32-like protease prevented apoptosis in RAW 264.7 parent cells. In addition, SNP dramatically activated CPP32 in the parent or in empty vector-transformed cells, while slightly activated CPP32 in PKC transfectants. Therefore, we conclude that PKC protects NO-induced apoptotic cell death, presumably nullifying the NO-mediated activation of JNK/SAPK, p38 kinase, and CPP32-like protease in RAW 264.7 macrophages.

Overexpression of protein kinase C isoforms protects RAW 264.7 macrophages from nitric oxide-induced apoptosis: involvement of c-Jun N-terminal kinase/stress-activated protein kinase, p38 kinase, and CPP-32 protease pathways

Nitric oxide (NO) induces apoptotic cell death in murine RAW 264.7 macrophages. To elucidate the inhibitory effects of protein kinase C (PKC) on NO-induced apoptosis, we generated clones of RAW 264.7 cells that overexpress one of the PKC isoforms and explored the possible interactions between PKC and three structurally related mitogen-activated protein (MAP) kinases in NO actions. Treatment of RAW 264.7 cells with sodium nitroprusside (SNP), a NO-generating agent, activated both c-Jun N-terminal kinase/stress-activated protein kinase (JNK/SAPK) and p38 kinase, but did not activate extracellular signal-regulated kinase (ERK)-1 and ERK-2. In addition, SNP-induced apoptosis was slightly blocked by the selective p38 kinase inhibitor (SB203580) but not by the MAP/ERK1 kinase inhibitor (PD098059). PKC transfectants (PKC-beta II, -delta, and -eta) showed substantial protection from cell death induced by the exposure to NO donors such as SNP and S-nitrosoglutathione (GSNO). In contrast, in RAW 264.7 parent or in empty vector-transformed cells, these NO donors induced internucleosomal DNA cleavage. Moreover, overexpression of PKC isoforms significantly suppressed SNP-induced JNK/SAPK and p38 kinase activation, but did not affect ERK-1 and -2. We also explored the involvement of CPP32-like protease in the NO-induced apoptosis. Inhibition of CPP32-like protease prevented apoptosis in RAW 264.7 parent cells. In addition, SNP dramatically activated CPP32 in the parent or in empty vector-transformed cells, while slightly activated CPP32 in PKC transfectants. Therefore, we conclude that PKC protects NO-induced apoptotic cell death, presumably nullifying the NO-mediated activation of JNK/SAPK, p38 kinase, and CPP32-like protease in RAW 264.7 macrophages.

Differential interaction of Crkl with Cbl or C3G, Hef-1, and gamma subunit immunoreceptor tyrosine-based activation motif in signaling of myeloid high affinity Fc receptor for IgG (Fc gamma RI)

Cbl-Crkl and Crkl-C3G interactions have been implicated in T cell and B cell receptor signaling and in the regulation of the small GTPase, Rap1. Recent evidence suggests that Rap1 plays a prominent role in the regulation of immunoreceptor tyrosine-based activation motif (ITAM) signaling. To gain insight into the role of Crkl in myeloid ITAM signaling, we investigated Cbl-Crkl and Crkl-C3G interactions following Fc gamma RI aggregation in U937IF cells. Fc gamma RI cross-linking of U937IF cells results in the tyrosine phosphorylation of Cbl, Crkl, and Hef-1, an increase in the association of Crkl with Cbl via direct SH2 domain interaction and increased Crkl-Hef-1 binding. Crkl constitutively binds to the guanine nucleotide-releasing protein, C3G, via direct SH3 domain binding. Our data show that distinct Cbl-Crkl and Crkl-C3G complexes exist in myeloid cells, suggesting that these complexes may modulate distinct signaling events. Anti-Crkl immunoprecipitations demonstrate that the ITAM-containing gamma subunit of Fc gamma RI is induced to form a complex with the Crkl protein, and Crkl binds to the cytoskeletal protein, Hef-1. The induced association of Crkl with Cbl, Hef-1, and Fc gamma RI gamma after Fc gamma RI activation and the constitutive association between C3G and Crkl provide the first evidence that a Fc gamma RI gamma-Crkl-C3G complex may link ITAM receptors to the activation of Rap1 in myeloid cells.

Inhibition of nitric oxide synthesis by butanol fraction of the methanol extract of Ulmus davidiana in murine macrophages

Since there is increasing evidence that nitric oxide (NO) plays a crucial role in the pathogenesis of inflammatory diseases, this study was undertaken to address whether the methanol (MeOH) extract and its fractions of the bark of Ulmus davidiana Planch (Ulmaceae) could modulate the expression of inducible NO synthase (iNOS) in thioglycollate-elicited murine peritoneal macrophages and murine macrophage cell line, RAW264.7 cells. Stimulation of the peritoneal macrophages and RAW264.7 cells with interferon-gamma (IFN-gamma) and lipopolysaccharide (LPS) resulted in increased production of NO in the medium. However, the butanol (BuOH) fraction of the MeOH extract of U. davidiana barks showed marked inhibition of NO synthesis in a dose-dependent manner. The inhibition of NO synthesis was reflected in the decreased amount of iNOS protein, as determined by Western blotting. The BuOH fraction did not affect the viability of RAW264.7 cells, as assessed by methylthiazol-2-yl-2, 5-diphenyl tetrazolium bromide (MTT) assay; rather, it reduced endogenous NO-induced apoptotic cell death via inhibition of NO synthesis in RAW264.7 cells. On the other hand, the BuOH fraction showed no inhibitory effect on the synthesis of NO by RAW264.7 cells, when iNOS was already expressed by the stimulation with IFN-gamma and LPS. Collectively, these results demonstrate that the BuOH fraction inhibits NO synthesis by inhibition of the induction of iNOS in murine macrophages.

The role of inducible 70-kDa heat shock protein in cell cycle control, differentiation, and apoptotic cell death of the human myeloid leukemic HL-60 cells

Several studies have suggested a role for heat shock proteins (hsps) during development and differentiation. However, relatively little is known about the role of hsp70 in controlling human hematopoietic cell differentiation and death. Here, we show that constitutive expression of human inducible 70-kDa heat shock protein (hsp70) promotes differentiation of HL-60 cells and prevents apoptosis that occurred after terminal differentiation or directly by apoptotic agents. After treatment with phorbol 12-myristate 13-acetate (PMA), hsp70-overexpressing cells (HL-60/hsp70) underwent rapid growth arrest and plastic adherence and expressed more CD14 than parental HL-60 or empty vector-transformed cells (HL-60/puro). HL-60/hsp70 cells also rapidly differentiated into granulocytes by addition of all-trans-retinoic acid, as assessed by phenotypic changes after staining with Wright-Giemsa. After differentiation into monocyte/macrophage-like cells or granulocytes, hsp70-overexpressing cells showed little evidence for apoptosis and had a prolonged survival, indicating that the survival-enhancing properties of hsp70 counteract programmed cell death that accompanies terminal differentiation. HL-60/hsp70 cells also showed more resistance than parental cells against apoptotic agents such as sodium nitroprusside, a NO-generating agent, or Taxol, a microtubule stabilizing agent. Further, heat shock of parental HL-60 cells at 42 degrees C for 3 h increased hsp70 levels, promoted plastic adherence (< 6 h) of the cells in respond to PMA, and protected cells from SNP or Taxol. Taken together, these studies demonstrate that hsp70 plays a crucial role in the differentiation of myeloid cells, participating in cell cycle controls and phenotypic changes, with protecting effects on apoptosis induced by different pathways.

Nitric oxide inhibits c-Jun N-terminal kinase 2 (JNK2) via S-nitrosylation

S-nitrosylation by S-nitrosoglutathione (GSNO), a nitric oxide (NO) donor, suppresses the phosphotransferase activity of cJun N-terminal kinase 2 (JNK2)/stress activated protein kinase (SAPK) in dose- and time-dependent manners in vitro. JNK2 activity is significantly decreased at 10 microM of GSNO, which is dramatically reversed by adding 10 mM of DTT. Reduced form of glutathione protects the GSNO-induced suppression of JNK2 activation in a dose-dependent fashion. However, GSNO-treated Sek1 does not affect the JNK2 activity of phosphotransferation toward c-Jun N-terminal1-79 protein. These results indicate that NO may exert a regulatory role of JNK2 activity by S-nitrosylation of the protein in apoptotic signaling pathway. Suppression of JNK2 phosphotransferase activity by NO is also supported by the observation that NO plays an important anti-apoptotic roles in heptocytes, splenocytes, eosinophils and B lymphocytes.

CBL-GRB2 interaction in myeloid immunoreceptor tyrosine activation motif signaling

In this study, we provide the first evidence for role of the CBL adapter protein interaction in Fc gammaRI receptor signal transduction. We study the Fc gammaRI receptor, an immunoreceptor tyrosine activation motif (ITAM)-linked signaling pathway, using IFN-gamma-differentiated U937 myeloid cells, termed U937IF cells. CBL is constitutively associated with both GRB2 and the ITAM-containing receptor subunit, Fc gammaRIgamma of Fc gammaRI, providing direct evidence that CBL functions in myeloid ITAM signaling. Fc gammaRI cross-linking of U937IF cells induces the tyrosine phosphorylation of CBL that is associated with an altered CBL-GRB2 interaction. Both GRB2-SH3 and SH2 domains bind CBL in resting cell lysates; upon Fc gammaRI stimulation, phosphorylated CBL binds exclusively to the GRB2-SH2 domain. Glutathione-S-transferase fusion protein data demonstrate that the constitutive interaction of CBL with GRB2 and CRKL is mediated via two discrete regions of the CBL C terminus. The proximal C terminus (residues 461-670) binds to GRB2 constitutively, and under conditions of receptor activation binds to the tyrosine-phosphorylated SHC adapter molecule. The distal C terminus of CBL (residues 671-906) binds the CRKL adapter protein. The data demonstrate that the CBL-GRB2 and GRB2-SOS protein complexes are distinct and mutually exclusive in U937IF cells, supporting a model by which the CBL-GRB2 and GRB2-SOS complexes function in separate pathways for myeloid Fc gammaRI signaling.

Effect of stem cell factor, interleukin-6, nitric oxide and transforming growth factor-beta on the osteoclast differentiation induced by 1 alpha,25-(OH)2D3 in primary murine bone marrow cultures

Osteotropic hormones and cytokines are involved in the differentiation of osteoclast progenitors from haematopoietic stem cells to multinucleated osteoclasts which mediate bone resorption. Stem cell factor, interleukin-6, nitric oxide, and transforming growth factor-beta are implicated in the regulation of bone resorption by osteoclast. We test whether stem cell factor, interleukin-6, nitric oxide, and transforming growth factor-beta affect the generation of osteoclast-like multi-nucleated cells induced by 1 alpha,25-(OH)2D3. 1 alpha,25-(OH)2D3 increase the generation of osteoclast-like cells retaining osteoclast characteristics including multinuclearity and positive staining for tartrate-resistant acid phosphatase. Combined treatment of stem cell factor with interleukin-6 synergistically potentiates the ability of 1 alpha,25-(OH)2D3 to generate tartrate-resistant acid phosphatase-positive multinucleated cells. However, either stem cell factor or interleukin-6 alone does not induce the generation of tartrate-resistant acid phosphatase-positive multinucleated cells. Transforming growth factor-beta produces a biphasic effect on osteoclast generation induced by 1 alpha,25-(OH)2D3. Transforming growth factor-beta stimulates osteoclast generation at low concentration (0.1 ng/ml) whereas it suppresses the formation of osteoclast-like cell at higher concentration (1 ng/ml). Sodium nitroprusside, a donor of nitric oxide, almost completely inhibits the generation of 1 alpha,25-(OH)2D3-induced osteoclast at high concentration (100 microM), but it significantly enhances the osteoclast generation at low concentrations (3 microM). These results suggest that stem cell factor, interleukin-6, transforming growth factor-beta, and nitric oxide interact with 1 alpha,25-(OH)2D3 to modulate the differentiation of hematopoietic precursors toward committed osteoclast precursors.

Enhancing and priming of macrophages for superoxide anion production by taxol

Taxol, an anticancer drug, has been known not only to block cell division by stabilizing microtubules but also to activate murine macrophages to express TNF-alpha, interleukin-1, and to produce nitric oxide (NO). We therefore reasoned that taxol could activate murine macrophages to generate reactive oxygen intermediates, such as superoxide anion (O2-), which are responsible for intracellular killing of pathogenic microbes. Treatment of RAW264.7 cells, murine macrophage cell line, with taxol increased phorbol ester-induced O2- production in a dose dependent manner (approximately 2 fold). In addition, taxol rapidly (< 1 hr) primed RAW264.7 cells to enhance O2- release stimulated with PMA. Taxol also enhanced stimulation of O2- production by FMLP, but not by Con A. This effect was abolished by prior treatment with both superoxide dismutase (SOD) and N-acetyl-L-cystein, a free radical scavenger. To investigate the mechanism of taxol-induced macrophage stimulation, we evaluated the ability of colchicine, a drug that inhibit tubulin polymerization, and cAMP analogues, which is known to depolymerize microtubule. Taxol-induced O2- production was inhibited by the treatment with both colchicine and DB-cAMP. Taken together, these results demonstrated that taxol provides two signals, "priming" and "enhancing", to generate superoxide anion via the stabilization of microtubules in murine RAW264.7 cells

Cyclic adenosine monophosphate inhibits nitric oxide-induced apoptosis in human leukemic HL-60 cells

Previously we reported that phorbol ester, a protein kinase C (PKC) activator, exhibits a unique pattern of potentiation of nitric oxide (NO)-related apoptosis in HL-60 human promyelocytic leukemia cells. Here we show that elevation of intracellular cAMP could protect HL-60 cells from NO- or NO plus PMA-induced DNA damage. Exposure of cells to sodium nitroprusside (SNP; 0.5 to 4 mM), a NO-generating agent, induced apoptotic cell death as monitored by morphological means, gel electrophoresis, and in situ TdT-apoptosis assay. However, concomitant incubation of the cells with DB-cAMP markedly inhibited SNP-induced apoptotic cell death in a dose-dependent manner. Similar results were obtained with other commonly used cAMP analogs such as CPT-cAMP and 8-C1-cAMP and the intracellular cAMP-elevating agent such as forskolin. In contrast, pretreatment of HL-60 cells with H89 or KT5720, which are known to inhibit cAMP-dependent protein kinase (PKA), abolished the protective effect of cAMP analogs and forskolin on SNP-induced apoptosis. Synergism between SNP and phorbol ester to induce apoptosis was also inhibited by prior treatment of HL-60 cells with DB-cAMP or forskolin. The effect of DB-cAMP in maintaining cell viability was not associated with the onset of G0/G1 cell cycle arrest. In addition, neither dimethyl sulfoxide nor retinoic acid (which produce granulocyte differentiation) could produce cAMP effect. Under the same conditions, DB-cAMP also inhibited NO- or NO plus phorbol ester-induced apoptosis in another transformed cell line, U-937 cells. Taken together, these findings suggest that exposure of HL-60 cells to cAMP analogs renders them more resistant to NO-induced DNA damage and further suggest the existence of specific down-modulatory mechanisms related to NO-induced apoptotic DNA fragmentation.

Nitric oxide is a regulator of bone remodelling

Nitric oxide (NO) is known to be implicated in the metabolism of bone, especially as a mediator of cytokine effects on the remodelling of bone tissue. In this study we examine whether NO affects the osteoblast activation or the osteoclast differentiation of primary mouse osteoblast-like and osteosarcoma ROS 17/2.8 cell lines. Primary osteoblast and ROS 17/2.8 cells released NO upon stimulation of interleukin-1 beta, tumour necrosis factor-alpha, and interferon-gamma. Sodium nitroprusside, a donor of nitric oxide, increased the activity of alkaline phosphatase in ROS 17/2.8 cells as well as the number of calcified nodule formations in primary mouse osteoblast-like cells. Sodium nitroprusside also completely inhibited 1 alpha, 25-(OH)2D3-induced osteoclast generation in a high concentration (100 microM). However, a low concentration of sodium nitroprusside (3-30 microM) significantly increased the generation of osteoclasts. These results indicated that NO appears to be an important regulatory molecule in the processes of bone formation and resorption. Hence, NO may be involved in the pathogenesis of bone loss in diseases associated with cytokine activation, such as periodontal disease and rheumatoid arthritis.

Cyclic AMP analogue as a triggering signal for the induction of nitric oxide synthesis in murine peritoneal macrophages

To understand the role of cAMP during macrophage activation, we investigated the effects of various cAMP analogues in the induction of nitric oxide (NO) synthesis in murine peritoneal macrophages. Intracellular cAMP modulators such as N6,O2'-dibutyryl cyclic AMP (DB-cAMP), 8-bromo-cAMP, or 8-chloro-cAMP had no effect on NO synthesis by themselves, whereas cAMP analogues in combination with interferon-gamma (IFN-gamma) had a marked cooperative induction of NO synthesis in a dose-dependent manner. This increase in NO synthesis was reflected as an increased amount of inducible NO synthase mRNA, as determined by Northern blotting. To find the point in the signaling pathways of macrophage activation at which cAMP is involved, we carried out several of the following experiments. Although DB-cAMP showed synergistic action with rIFN-gamma to induce NO synthesis when the cells were treated with DB-cAMP after or with simultaneous treatment with rIFN-gamma, there is no synergistic induction of NO synthesis when the cells were treated with DB-cAMP 6 hr before treatment with rIFN-gamma. In addition, when phorbol 12-myristate 13-acetate (PMA), which is known to provide a triggering signal in the induction of NO synthesis in murine macrophages, was added to the cells 6 hr after the treatment with DB-cAMP, PMA showed no synergistic cooperation with DB-cAMP. On the other hand, DB-cAMP alone induced the release of NO to the incubation medium from bacillus Calmette-Guerin-infected peritoneal macrophages just as lipopolysaccharide (LPS) did. However, DB-cAMP, unlike LPS, decreased the secretion of tumor necrosis factor-alpha from IFN-gamma-treated macrophages. Based on the results obtained in this study, we suggest that cAMP analogue could give a "triggering" signal which might be different from one given by LPS in the production of NO by primed macrophages.

Potentiation of the activity of nitric oxide by the protein kinase C activator phorbol ester in human myeloid leukemic HL-60 cells: association with enhanced fragmentation of mature genomic DNA

Nitric oxide (NO) has been known to induce programmed cell death or apoptosis in murine macrophages, mouse splenocytes, and thymocytes. We demonstrate here that phorbol ester, a protein kinase C (PKC) activator, synergistically augments the antileukemic actions of the NO in HL-60 human promyelocytic leukemia cells. Exposure of cells to sodium nitro-prusside (SNP; 0.5 to 2 mM), a NO-generating agent, induced time- and concentration-related increases in morphological changes, including condensation of nuclear chromatin, nuclear fragmentation, and the apoptotic peak of propidium iodide-stained nuclei by flow cytometry. Phorbol ester alone had a small effect on inducing DNA damage, whereas SNP in combination with phorbol ester at all concentrations tested markedly increased the extent of fragmentation. Maximal potentiation of fragmentation (e.g., four- to fivefold greater than that obtained with 0.5 mM SNP alone) was observed with simultaneous treatment of phorbol ester. Similar results were obtained with another commonly used NO donor agents such as SNAP (0.5 mM) and GSNO (0.5 mM). DNA fragmentation of HL-60 cells was also augmented by 100 U/ml human recombinant interferon-gamma but not by 1.5% (v/v) DMSO or 1 microM retinoic acid. The stage-2 tumor promotor mezerein also mimicked the effect of phorbol ester to induce NO-induced apoptosis. In contrast, PKC inhibitors such as staurosporine and 1-(5-isoquinolinesulfonyl)-2-methyl-piperazine partially blocked high concentration of SNP (2-3 mM)-induced apoptosis, suggesting that activation of PKC closely relates to the potentiation of the activity of NO on HL-60 cell apoptosis. Under the same conditions, SNP in combination with phorbol ester caused apoptosis in another transformed cell line, U-937 cells, but was ineffective at inducing apoptosis in normal peripheral blood mononuclear cells. Taken together, these findings suggest that exposure of HL-60 cells to phorbol ester renders them more susceptible to NO-induced DNA damage and that this phenomenon contributes to the cytotoxic effects of the NO-PKC combination in myeloid leukemia cells.