Background and Objectives: Protein kinase C (PKC) activation plays an important role in activation of T-lymphocytes in asthma. Airway hypersensitivity is one of the main characteristic features of asthma, the mechanis...Background and Objectives: Protein kinase C (PKC) activation plays an important role in activation of T-lymphocytes in asthma. Airway hypersensitivity is one of the main characteristic features of asthma, the mechanism of onset of which is not clearly understood. Therefore, the objective was to elucidate the role of PKC in etiopathogenesis of airway hypersensitivity in asthma. Methods: Male guinea pigs (n = 30) were sensitized with ovalbumin and day of initial allergen-specific immune response determined by intradermal test, airway hypersensitivity, BALF cytology and lung histopathology. Total PKC activity, PKC isoenzymes and phosphoinositides were assessed in airway smooth muscles (ASM) and peripheral blood lymphocytes. Results: Intradermal test revealed that day 9 was the earliest time of allergen-specific response and onset of airway hypersensitivity to ovalbumin. It was associated with significant increase in total and differential (lymphocytes and eosinophils) BALF counts and grade I peribronchiolar chronic lymphocytic inflammation in lung. On day 14, grade II infiltration of lymphocytes and eosinophils with onset ofstructural remodelingofproximal and distal airways was seen. Total PKC activity, expression of PKCα, PKCε and phosphoinositides increased significantly in ASM and lymphocytes on day 9 and were maximum on day 14. There was no change in PKC-τ expression. Conclusions: Activation of PKC, particularly PKCα and PKCε, mediated signal transduction pathway plays a critical role in lymphocyte infiltration and onset of airway hypersensitivity, airway remodeling and asthma pathophysiology. The present study is the first one on the mechanism of the etiopathogenesis of the disease, which shows a direct evidence of the role of PKC mediated pathway in the initiation and onset of airway hypersensitivity in ovalbumin sensitized guinea pig model.展开更多
Ischemic stroke is a major cause of morbidity and mortality,and currently there is no effective treatment.The family of protein kinase C(PKCs)could phosphorylate serine or threonine residues of its substrate proteins ...Ischemic stroke is a major cause of morbidity and mortality,and currently there is no effective treatment.The family of protein kinase C(PKCs)could phosphorylate serine or threonine residues of its substrate proteins and play a key role in the ischemia/reperfusion injury.Autophagy is essential for maintaining cell homeostasis under physiological condition and acts as a double-edged sword in the process of ischemic neuronal death.In this article,we reviewed the PKCs isoform-specific signaling pathways and PKC-modulated autophagy in ischemic stroke.展开更多
The effects of protein kinase C （PKC） on the tension and the activity of voltage-dependent delayed rectifier potassium channel （K,,） were examined in normal and passively sensitized human airway smooth muscle （H...The effects of protein kinase C （PKC） on the tension and the activity of voltage-dependent delayed rectifier potassium channel （K,,） were examined in normal and passively sensitized human airway smooth muscle （HASM）, by measuring tones and whole-cell patch clamp techniques, and the Kv activities and membrane potential （Em） were also detected. The results showed that phorbol 12-myristate 13-acetate （PMA）, a PKC activator, caused a concentration-dependent constriction in normal HASM rings. The constriction of the passively sensitized muscle in asthma serum group was significantly higher than that of the normal group （P〈0.05）, and the constrictions of both groups were completely abolished by PKC inhibitor Ro31-8220 and calcium channel inhibitor nifedipine. Kv activities of HASM cells were significantly inhibited by PMA, and the Em became more positive, as compared with the DMSO （a PMA menstruum）-treated group （P〈0.01）. This effect could be blocked by Ro31-8220 （P〈0.01 ）. It was concluded that activation of PKC could increase the tones of HASM, which might be related to the reduced Kv activity. In passively sensitized HASM rings, this effect was more notable.展开更多
Studies on structure-activity relationship of phenothiazines (PTZs) forinhibition of protein kinase C (PKC) and reversal of multidrug resistance (MDR) has been made invitro. The results showed that the order of potenc...Studies on structure-activity relationship of phenothiazines (PTZs) forinhibition of protein kinase C (PKC) and reversal of multidrug resistance (MDR) has been made invitro. The results showed that the order of potency of reversal effect of PTZs on MDR is as follows:2-COC_3 H_7 > 2-CF_3 > 2-COCH_3 > H. The type of piperazinyl substitution also significantlyaffected potency against MDR. The results show the order: CH_3 > COOC_2 H_5 > C_2 H_4 OH. Inaddition, PKC plays a marked role in diverse cellular process including MDR. Some derivatives of PTZwas tested for inhibition of PKC, of which PTZ11 showed the highest inhibitory effect of MDR andPKC, implying a potential reversal agent of MDR for tumor therapy in the future. We also tried toexplore the possible binding model of PTZs to PKC. Our molecular-modeling study preliminarilysuggests how these PTZs bind to PKC and provides a structural basis for the design of high affinityPKC-modulator. The infor-mation may be used in the rational design of more effective drugs.展开更多
The major pathological changes in Alzheimer＇s disease are beta amyloid deposits and cognitive impairment. Calycosin is a typical phy- toestrogen derived from radix astragali that binds to estrogen receptors to produc...The major pathological changes in Alzheimer＇s disease are beta amyloid deposits and cognitive impairment. Calycosin is a typical phy- toestrogen derived from radix astragali that binds to estrogen receptors to produce estrogen-like effects. Radix astragali Calycosin has been shown to relieve cognitive impairment induced by diabetes mellitus, suggesting calycosin may improve the cognitive function of Alzhei- mer＇s disease patients. The protein kinase C pathway is upstream of the mitogen-activated protein kinase pathway and exerts a neuropro- tective effect by regulating Alzheimer＇s disease-related beta amyloid degradation. We hypothesized that calycosin improves the cognitive function of a transgenic mouse model of Alzheimer＇s disease by activating the protein kinase C pathway. Various doses of calycosin （10, 20 and 40 mg/kg） were intraperitoneally injected into APP/PS1 transgenic mice that model Alzheimer＇s disease. Calycosin diminished hippocampal beta amyloid, Tau protein, interleukin-lbeta, tumor necrosis factor-alpha, acetylcholinesterase and malondialdehyde levels in a dose-dependent manner, and increased acetylcholine and glutathione activities. The administration of a protein kinase C inhibitor, cal- phostin C, abolished the neuroprotective effects of calycosin including improving cognitive ability, and anti-oxidative and anti-inflammato- ry effects. Our data demonstrated that calycosin mitigated oxidative stress and inflammatory responses in the hippocampus of Alzheimer＇s disease model mice by activating the protein kinase C pathway, and thereby improving cognitive function.展开更多
INTRODUCTIONGastrin is atrophic gastrointestinal hormone whichis secreted by G cell.Gastrin has long beenconsidered a growth stimulatory hormone formucosa of the gastrointestinal tract.The growthresponses of certain c...INTRODUCTIONGastrin is atrophic gastrointestinal hormone whichis secreted by G cell.Gastrin has long beenconsidered a growth stimulatory hormone formucosa of the gastrointestinal tract.The growthresponses of certain colorectal cancer cells,andxenografts,can be stimulated by endogenousgastrin.Protein kinase C (PKC) is a family ofisozymes that plays a crucial role in transducingsignals of many hormones,growth peptides,展开更多
AIM： To investigate the effects of hyperlipidemia on acute pancreatitis （AP） and the possible mechanisms. METHODS： Rat models of hyperlipidemia and AP were established by Triton WR1339 and cerulein respectively. H...AIM： To investigate the effects of hyperlipidemia on acute pancreatitis （AP） and the possible mechanisms. METHODS： Rat models of hyperlipidemia and AP were established by Triton WR1339 and cerulein respectively. Human albumin was used to treat AP complicated by hyperlipidemia. In each group, we compared the histological score, volume of ascites, ratio of pancreatic wet/dry weight, serum amylase （AMY） and pancreatic acinar cell apoptosis. The level of protein kinase C （PKC） membrane translocation in pancreatic tissue was detected by Western blot.RESULTS： In the hyperlipidemia model established by Triton WR1339, triglyceride （TG） increased remarkably and reached its peak 6 h after injection, and most rats developed mild acute pancreatitis. Histological score, volume of ascites, ratio of wet/dry weight and serum AMY in AP animals with hyperlipidemia were obviously higher than those in AP animals （P 〈 0.05） and decreased after albumin therapy but not significantly （P 〉 0.05）. Apoptotic cells detected by terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling （TUNEL） increased in AP animals with hyperlipidemia and did not change distinctly after albumin therapy. PKC membrane translocation level increased in AP animals with hyperlipidemia and decreased remarkably after albumin therapy （P 〈 0.05）.CONCLUSION： Hyperlipidemia may induce AP or intensify pancreatic injury. Albumin therapy can not alleviate pancreatic lesion effectively. PKC activation may be one mechanism by which AP is intensified by hyperlipidemia.展开更多
The potential role of the protein kinase C (PKC) transduction systemin controlling proliferation of human pituitary somatotrophinomas was investigat-ed. Twenty somatotrophinomas were studied using PCR and diract seque...The potential role of the protein kinase C (PKC) transduction systemin controlling proliferation of human pituitary somatotrophinomas was investigat-ed. Twenty somatotrophinomas were studied using PCR and diract sequencing methods. No point mutation within the QPKC gene, previously thought to be as-sociated with invasive pituitary tumors, was found in any of the 20 somatotrophi-nomas. It is concluded that PKC trareduction system may play an important rolein controlling pituitary somatotrophinoma proliferation, but there is no correlation between invasiveness and the previously reported QPKC gene mutation.展开更多
This study examined the effect of GHRP-6, a known GHSs receptor agonist, on the phosphorylation of cAMP-responsive element-binding protein （CREB） and the tmderly mechanism. GH3 cells were cultured and subjected to d...This study examined the effect of GHRP-6, a known GHSs receptor agonist, on the phosphorylation of cAMP-responsive element-binding protein （CREB） and the tmderly mechanism. GH3 cells were cultured and subjected to different treatments as follows： GHRP-6, GHRP-6 plus GHRH, phorbol ester （PMA）, an activator of PKC, alone or in combination with GHRP-6, G66983, a general inhibitor of PKCs, in the presence or absence of GHRP-6, rottlerin, an inhibitor of PKCs, alone or plus GHRP-6. The cells were transiently transfected with PKCσ-specific siRNA and then treated with GHRP-6. GH level was measured by enzyme-linked immunosorbent assay （ELISA）. The expression of phosphor-CREB, PKCσ, PKC0 and phosphor-PKCo was determined by Western blotting. The results showed that GHRP-6 stimulated GH secretion in both time- and dose-dependent manners and enhanced the effect of GHRH on GH secretion. GHRP-6 was also found to induce CREB phosphorylation. Moreover, GH secretion was enhanced by the PKC activator PMA and reduced by the PKC inhibitors （G66983, rottlerin） and knockdown of PKCσ. PKCσ could be activated by GHRP-6. It is concluded that PKC, especialiy PKCσ, mediates CREB phosphorylation and GHRP-6-induced GH secretion.展开更多
Trail, a tumor necrosis factor-related apoptosis-inducing ligand, is a novel potent endogenous activator of the cell death pathway through the activation of cell surface death receptors Trail-R1 and Trail-R2. Its role...Trail, a tumor necrosis factor-related apoptosis-inducing ligand, is a novel potent endogenous activator of the cell death pathway through the activation of cell surface death receptors Trail-R1 and Trail-R2. Its role, like FasL in activation-induced cell death (AICD), has been demonstrated in immune system. However the mechanism of Trail induced apoptosis remains unclear. In this report, the recombinant Trail protein was expressed and purified. The apoptosis-inducing activity and the regulation mechanism of recombinant Trail on Jurkat T cells were explored in vitro. Trypan blue exclusion assay demonstrated that the recombinant Trail protein actively killed Jurkat T cells in a dose-dependent manner. Trail-induced apoptosis in Jurkat T cells were remarkably reduced by Bcl-2 over expression in Bcl-2 gene transfected cells. Treatment with PMA (phorbol 12-myristate 13-acetate), a PKC activator, suppressed Trail-induced apoptosis in Jurkat T cells. The inhibition of apoptosis by PMA was abolished by pretreatment with Bis, a PKC inhibitor. Taken together, it was suggested that Bcl-2 over-expression and PMA activated PKC actively down-regulated the Trail-mediated apoptosis in Jurkat T cell.展开更多
BACKGROUND: The molecular mechanism of hepaticmetastasis of colorectal cancer is not well understood. Theaim of this study was to assess the relations between phos-pholipid contents of cellular membrane and isoenzyme ...BACKGROUND: The molecular mechanism of hepaticmetastasis of colorectal cancer is not well understood. Theaim of this study was to assess the relations between phos-pholipid contents of cellular membrane and isoenzyme ex-pression of protein kinase C (PKC) and their effects on he-patic metastasis of colorectal cancer.METHODS: High performance liquid chromatography wasused to detect contents of cell membrane phospholipids:phosphatidylinosital (PI), phosphatidylserine (PS), phos-phatidylethanolamine (PE) and phosphatidylcholine (PC)in primary foci, paratumor mucosa and hepatic metastaticfoci in patients with colorectal carcinoma. The mRNA ex-pression levels of PKC-α, -δ, -ε, -λ, -ξ isoenzymeswere detected with the QRT-PCR technique.RESULTS: The levels of PI, PC and PE in primary foci andhepatic metastatic foci were higher than those in paratumormucosa. The level of PE in hepatic metastatic foci wasmuch higher than that in primary foci (t =98.88, P <0.01);but the levels of PI and PC were not significantly differentbetween primary foci and hepatic metastatic foci (t =1.73 ,1.36, P>0.05). The expression levels of -δ, -ε,-λ, -ξ were enhanced in primary foci and hepatic metasta-tic foci, but the level of PKC-α in primary foci was de-creased as compared with that in paratumor mucosa. Thelevels of PKC-δ, -ε, -λ, -ξ in hepatic metastatic foci werehigher than those in primary foci. A positive correlationwas observed between the expression levels of PI, PC andand also between those of PE and PKC-δ, -ε, -λ,-ξ. However, there was a close negative correlation be-tween PE and PKC-α.CONCLUSION: Increased levels of PI and PC and de-creased ratio of PKC-α to are related to colorectalcancer genesis. Increased levels of PE, increased expressionof PKC-δ, -ε, -λ, -ξ isoenzymes and decreased level ofPKC-α are related to hepatic metastasis in colorectal carci-noma.展开更多
AIM: To identify whether Aspergillus fumigatus(A.fumigatus) hyphae antigens induced the release of interleukin-8(IL-8) in anti-fungal innate immunity of cultured human corneal epithelial cells(HCECs) and determine the...AIM: To identify whether Aspergillus fumigatus(A.fumigatus) hyphae antigens induced the release of interleukin-8(IL-8) in anti-fungal innate immunity of cultured human corneal epithelial cells(HCECs) and determine the involvement of intracellular signalling pathways. METHODS: HCECs were treated with A. fumigatus hyphae antigens with different concentrations and time.The cytoplasmic calcium of HCECs were assessed by fluorescence imaging. Western blot was used to detect the expression of Ca2 +-dependent protein kinase C(PKC). The IL-8 levels were determined by specific human IL-8 enzyme-linked immunosorbent assay(ELISA) and reverse transcriptase polymerase chain reaction(RT-PCR). Using a series of pharmacological inhibitors, we examined the upstream signalling pathway responsible for IL-8 expression in response to A.fumigatus hyphae antigens. RESULTS: Cells exposed to A. fumigatus hyphae antigens showed higher level of IL-8 m RNA expression and protein production. We demonstrated here that stimulation of HCECs with A. fumigatus hyphae triggers an intracellular Ca2 +flux and results in the activation of Ca2 +-dependent PKC(α, βⅠ and βⅡ) which can be attenuated by pre-treatment of cells with laminarin,suggesting that Dectin-1 signals pathway induced cytoplasmic calcium and influence the activation of PKC in HCECs. Inhibitors of Ca2 +-dependent PKC(Ro-31-8220 and Go6976) significantly abolished hyphae-induced expression of IL-8.CONCLUSION: Our findings suggest that A. fumigatushyphae-induced IL-8 expression was regulated by the activation of Dectin-1-mediated Ca2 +-dependent PKC in HCECs.展开更多
BACKGROUND: Fructose is cytoprotective during bile salt-induced apoptosis of hepatocytes by regulating protein kinase C (PKC). This study was undertaken to explore the regulating mechanism of hepatic injury in rats wi...BACKGROUND: Fructose is cytoprotective during bile salt-induced apoptosis of hepatocytes by regulating protein kinase C (PKC). This study was undertaken to explore the regulating mechanism of hepatic injury in rats with obstructive jaundice, and to detect the PKC signal pathway. METHODS: Rat hepatocytes were isolated by in situ colla-genase perfusion and primary culture, and pretreated with various concentrations of PKC agonist phorbol myristate acetale (PMA) and inhibitor chelerythrine for 20 minutes. After pretreatment, 50 μmol/L glycochenodeoxycholate (GCDC) was added for additional 24 hours. Subsequently, the cells were detected by FCM and TUNEL. After adding with different concentrations of fructose and 100 μmol GCDC , the hepatocytes were evaluated by FCM and TUNEL. Experimental obstructive jaundice was induced with fructose and without fructose via double ligation of the bile duct for 3, 7, 14, and 21 days. Apoptotic status in the liver of all rats was detected with TUNEL, and PKC protein in the liver of obstructive jaundice ( OJ) with the immunohisto-chemistry method. RESULTS: PMA increased GCDC-induced apoptosis and chelerythrine decreased GCDC-induced apoptosis in a concentration-dependent manner. Adding with different concentration of fructose and 100 μmol GCDC, the decreased apoptotic rate was related to the concentration of fructose. The apoptotic rate of the liver was related to times of OJ. PKC and apoptosis index (AI) were the highest after a 14-day ligation of the bile duct without use of fructose. AI and PKC were decreasing from a 14-day ligation of the bile duct with fructose. CONCLUSIONS: PKC takes part in the regulation, occurrence , and progression of hepatic injury in OJ. Fructose is cytoprotective during bile salt-induced apoptosis of hepato-cytes by regulating PKC.展开更多
The effects of ATP-sensitive mitochondrial K + channel(mitoK ATP) on mitochondrial membrane potential(Δψm),cell proliferation and protein kinase C alpha(PKCα) expression in airway smooth muscle cells(ASMCs) were in...The effects of ATP-sensitive mitochondrial K + channel(mitoK ATP) on mitochondrial membrane potential(Δψm),cell proliferation and protein kinase C alpha(PKCα) expression in airway smooth muscle cells(ASMCs) were investigated.Thirty-six Sprague-Dawley(SD) rats were immunized with saline(controls) or ovalbumin(OVA) with alum(asthma models).ASMCs were cultured from the lung of control and asthma rats.ASMCs were treated with diazoxide(the potent activator of mitoK ATP) or 5-hydroxydencanote(5-HD,the inhibitor of mitoK ATP).Rhodamine-123(R-123) was used to detect Δψm.The expression of PKCα protein was examined by using Western blotting,while PKCα mRNA expression was detected by using real-time PCR.The proliferation of ASMCs was measured by MTT assay and cell cycle analysis.In diazoxide-treated normal ASMCs,the R-123 fluorescence intensity,protein and mRNA levels of PKCα,MTT A values and percentage of cells in S phase were markedly increased as compared with untreated controls.The ratio of G 0 /G 1 cells was decreased(P<0.05) in diazoxide-treated ASMCs from normal rats.However,there were no significant differences between the ASMCs from healthy rats treated with 5-HD and the normal control group.In untreated and diazoxide-treated ASMCs of asthmatic rats,the R-123 fluorescence intensity,protein and mRNA levels of PKCα,MTT A values and the percentage of cells in S phase were increased in comparison to the normal control group.Furthermore,in comparison to ASMCs from asthmatic rats,these values were considerably increased in asthmatic group treated with diazoxide(P<0.05).After exposure to 5-HD for 24 h,these values were decreased as compared with asthma control group(P<0.05).In ASMCs of asthma,the signal transduction pathway of PKCα may be involved in cell proliferation,which is induced by the opening of mitoK ATP and the depolarization of Δψm.展开更多
文摘Background and Objectives: Protein kinase C (PKC) activation plays an important role in activation of T-lymphocytes in asthma. Airway hypersensitivity is one of the main characteristic features of asthma, the mechanism of onset of which is not clearly understood. Therefore, the objective was to elucidate the role of PKC in etiopathogenesis of airway hypersensitivity in asthma. Methods: Male guinea pigs (n = 30) were sensitized with ovalbumin and day of initial allergen-specific immune response determined by intradermal test, airway hypersensitivity, BALF cytology and lung histopathology. Total PKC activity, PKC isoenzymes and phosphoinositides were assessed in airway smooth muscles (ASM) and peripheral blood lymphocytes. Results: Intradermal test revealed that day 9 was the earliest time of allergen-specific response and onset of airway hypersensitivity to ovalbumin. It was associated with significant increase in total and differential (lymphocytes and eosinophils) BALF counts and grade I peribronchiolar chronic lymphocytic inflammation in lung. On day 14, grade II infiltration of lymphocytes and eosinophils with onset ofstructural remodelingofproximal and distal airways was seen. Total PKC activity, expression of PKCα, PKCε and phosphoinositides increased significantly in ASM and lymphocytes on day 9 and were maximum on day 14. There was no change in PKC-τ expression. Conclusions: Activation of PKC, particularly PKCα and PKCε, mediated signal transduction pathway plays a critical role in lymphocyte infiltration and onset of airway hypersensitivity, airway remodeling and asthma pathophysiology. The present study is the first one on the mechanism of the etiopathogenesis of the disease, which shows a direct evidence of the role of PKC mediated pathway in the initiation and onset of airway hypersensitivity in ovalbumin sensitized guinea pig model.
文摘Ischemic stroke is a major cause of morbidity and mortality,and currently there is no effective treatment.The family of protein kinase C(PKCs)could phosphorylate serine or threonine residues of its substrate proteins and play a key role in the ischemia/reperfusion injury.Autophagy is essential for maintaining cell homeostasis under physiological condition and acts as a double-edged sword in the process of ischemic neuronal death.In this article,we reviewed the PKCs isoform-specific signaling pathways and PKC-modulated autophagy in ischemic stroke.
基金This project was supported by a grant from the National Natural Sciences Foundation of China (No. 30270583)
文摘The effects of protein kinase C （PKC） on the tension and the activity of voltage-dependent delayed rectifier potassium channel （K,,） were examined in normal and passively sensitized human airway smooth muscle （HASM）, by measuring tones and whole-cell patch clamp techniques, and the Kv activities and membrane potential （Em） were also detected. The results showed that phorbol 12-myristate 13-acetate （PMA）, a PKC activator, caused a concentration-dependent constriction in normal HASM rings. The constriction of the passively sensitized muscle in asthma serum group was significantly higher than that of the normal group （P〈0.05）, and the constrictions of both groups were completely abolished by PKC inhibitor Ro31-8220 and calcium channel inhibitor nifedipine. Kv activities of HASM cells were significantly inhibited by PMA, and the Em became more positive, as compared with the DMSO （a PMA menstruum）-treated group （P〈0.01）. This effect could be blocked by Ro31-8220 （P〈0.01 ）. It was concluded that activation of PKC could increase the tones of HASM, which might be related to the reduced Kv activity. In passively sensitized HASM rings, this effect was more notable.
文摘Studies on structure-activity relationship of phenothiazines (PTZs) forinhibition of protein kinase C (PKC) and reversal of multidrug resistance (MDR) has been made invitro. The results showed that the order of potency of reversal effect of PTZs on MDR is as follows:2-COC_3 H_7 > 2-CF_3 > 2-COCH_3 > H. The type of piperazinyl substitution also significantlyaffected potency against MDR. The results show the order: CH_3 > COOC_2 H_5 > C_2 H_4 OH. Inaddition, PKC plays a marked role in diverse cellular process including MDR. Some derivatives of PTZwas tested for inhibition of PKC, of which PTZ11 showed the highest inhibitory effect of MDR andPKC, implying a potential reversal agent of MDR for tumor therapy in the future. We also tried toexplore the possible binding model of PTZs to PKC. Our molecular-modeling study preliminarilysuggests how these PTZs bind to PKC and provides a structural basis for the design of high affinityPKC-modulator. The infor-mation may be used in the rational design of more effective drugs.
基金supported by the a grant from China Postdoctoral Science Project,No.801161020425the Natural Science Foundation of China,No.8160010172
文摘The major pathological changes in Alzheimer＇s disease are beta amyloid deposits and cognitive impairment. Calycosin is a typical phy- toestrogen derived from radix astragali that binds to estrogen receptors to produce estrogen-like effects. Radix astragali Calycosin has been shown to relieve cognitive impairment induced by diabetes mellitus, suggesting calycosin may improve the cognitive function of Alzhei- mer＇s disease patients. The protein kinase C pathway is upstream of the mitogen-activated protein kinase pathway and exerts a neuropro- tective effect by regulating Alzheimer＇s disease-related beta amyloid degradation. We hypothesized that calycosin improves the cognitive function of a transgenic mouse model of Alzheimer＇s disease by activating the protein kinase C pathway. Various doses of calycosin （10, 20 and 40 mg/kg） were intraperitoneally injected into APP/PS1 transgenic mice that model Alzheimer＇s disease. Calycosin diminished hippocampal beta amyloid, Tau protein, interleukin-lbeta, tumor necrosis factor-alpha, acetylcholinesterase and malondialdehyde levels in a dose-dependent manner, and increased acetylcholine and glutathione activities. The administration of a protein kinase C inhibitor, cal- phostin C, abolished the neuroprotective effects of calycosin including improving cognitive ability, and anti-oxidative and anti-inflammato- ry effects. Our data demonstrated that calycosin mitigated oxidative stress and inflammatory responses in the hippocampus of Alzheimer＇s disease model mice by activating the protein kinase C pathway, and thereby improving cognitive function.
文摘INTRODUCTIONGastrin is atrophic gastrointestinal hormone whichis secreted by G cell.Gastrin has long beenconsidered a growth stimulatory hormone formucosa of the gastrointestinal tract.The growthresponses of certain colorectal cancer cells,andxenografts,can be stimulated by endogenousgastrin.Protein kinase C (PKC) is a family ofisozymes that plays a crucial role in transducingsignals of many hormones,growth peptides,
基金Supported by the Key Program of Beijing Academy of Health, No. 1998-11-2001-09
文摘AIM： To investigate the effects of hyperlipidemia on acute pancreatitis （AP） and the possible mechanisms. METHODS： Rat models of hyperlipidemia and AP were established by Triton WR1339 and cerulein respectively. Human albumin was used to treat AP complicated by hyperlipidemia. In each group, we compared the histological score, volume of ascites, ratio of pancreatic wet/dry weight, serum amylase （AMY） and pancreatic acinar cell apoptosis. The level of protein kinase C （PKC） membrane translocation in pancreatic tissue was detected by Western blot.RESULTS： In the hyperlipidemia model established by Triton WR1339, triglyceride （TG） increased remarkably and reached its peak 6 h after injection, and most rats developed mild acute pancreatitis. Histological score, volume of ascites, ratio of wet/dry weight and serum AMY in AP animals with hyperlipidemia were obviously higher than those in AP animals （P 〈 0.05） and decreased after albumin therapy but not significantly （P 〉 0.05）. Apoptotic cells detected by terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling （TUNEL） increased in AP animals with hyperlipidemia and did not change distinctly after albumin therapy. PKC membrane translocation level increased in AP animals with hyperlipidemia and decreased remarkably after albumin therapy （P 〈 0.05）.CONCLUSION： Hyperlipidemia may induce AP or intensify pancreatic injury. Albumin therapy can not alleviate pancreatic lesion effectively. PKC activation may be one mechanism by which AP is intensified by hyperlipidemia.
文摘The potential role of the protein kinase C (PKC) transduction systemin controlling proliferation of human pituitary somatotrophinomas was investigat-ed. Twenty somatotrophinomas were studied using PCR and diract sequencing methods. No point mutation within the QPKC gene, previously thought to be as-sociated with invasive pituitary tumors, was found in any of the 20 somatotrophi-nomas. It is concluded that PKC trareduction system may play an important rolein controlling pituitary somatotrophinoma proliferation, but there is no correlation between invasiveness and the previously reported QPKC gene mutation.
基金supported by a grant from the National Natural Sciences Foundation of China (No. 30672161)
文摘This study examined the effect of GHRP-6, a known GHSs receptor agonist, on the phosphorylation of cAMP-responsive element-binding protein （CREB） and the tmderly mechanism. GH3 cells were cultured and subjected to different treatments as follows： GHRP-6, GHRP-6 plus GHRH, phorbol ester （PMA）, an activator of PKC, alone or in combination with GHRP-6, G66983, a general inhibitor of PKCs, in the presence or absence of GHRP-6, rottlerin, an inhibitor of PKCs, alone or plus GHRP-6. The cells were transiently transfected with PKCσ-specific siRNA and then treated with GHRP-6. GH level was measured by enzyme-linked immunosorbent assay （ELISA）. The expression of phosphor-CREB, PKCσ, PKC0 and phosphor-PKCo was determined by Western blotting. The results showed that GHRP-6 stimulated GH secretion in both time- and dose-dependent manners and enhanced the effect of GHRH on GH secretion. GHRP-6 was also found to induce CREB phosphorylation. Moreover, GH secretion was enhanced by the PKC activator PMA and reduced by the PKC inhibitors （G66983, rottlerin） and knockdown of PKCσ. PKCσ could be activated by GHRP-6. It is concluded that PKC, especialiy PKCσ, mediates CREB phosphorylation and GHRP-6-induced GH secretion.
基金Major State BasicResearch (973) Program of China, (G1999053905).
文摘Trail, a tumor necrosis factor-related apoptosis-inducing ligand, is a novel potent endogenous activator of the cell death pathway through the activation of cell surface death receptors Trail-R1 and Trail-R2. Its role, like FasL in activation-induced cell death (AICD), has been demonstrated in immune system. However the mechanism of Trail induced apoptosis remains unclear. In this report, the recombinant Trail protein was expressed and purified. The apoptosis-inducing activity and the regulation mechanism of recombinant Trail on Jurkat T cells were explored in vitro. Trypan blue exclusion assay demonstrated that the recombinant Trail protein actively killed Jurkat T cells in a dose-dependent manner. Trail-induced apoptosis in Jurkat T cells were remarkably reduced by Bcl-2 over expression in Bcl-2 gene transfected cells. Treatment with PMA (phorbol 12-myristate 13-acetate), a PKC activator, suppressed Trail-induced apoptosis in Jurkat T cells. The inhibition of apoptosis by PMA was abolished by pretreatment with Bis, a PKC inhibitor. Taken together, it was suggested that Bcl-2 over-expression and PMA activated PKC actively down-regulated the Trail-mediated apoptosis in Jurkat T cell.
基金This study was supported by a grant from the National Nature Science Foun-dation of China (No. 30070747)
文摘BACKGROUND: The molecular mechanism of hepaticmetastasis of colorectal cancer is not well understood. Theaim of this study was to assess the relations between phos-pholipid contents of cellular membrane and isoenzyme ex-pression of protein kinase C (PKC) and their effects on he-patic metastasis of colorectal cancer.METHODS: High performance liquid chromatography wasused to detect contents of cell membrane phospholipids:phosphatidylinosital (PI), phosphatidylserine (PS), phos-phatidylethanolamine (PE) and phosphatidylcholine (PC)in primary foci, paratumor mucosa and hepatic metastaticfoci in patients with colorectal carcinoma. The mRNA ex-pression levels of PKC-α, -δ, -ε, -λ, -ξ isoenzymeswere detected with the QRT-PCR technique.RESULTS: The levels of PI, PC and PE in primary foci andhepatic metastatic foci were higher than those in paratumormucosa. The level of PE in hepatic metastatic foci wasmuch higher than that in primary foci (t =98.88, P <0.01);but the levels of PI and PC were not significantly differentbetween primary foci and hepatic metastatic foci (t =1.73 ,1.36, P>0.05). The expression levels of -δ, -ε,-λ, -ξ were enhanced in primary foci and hepatic metasta-tic foci, but the level of PKC-α in primary foci was de-creased as compared with that in paratumor mucosa. Thelevels of PKC-δ, -ε, -λ, -ξ in hepatic metastatic foci werehigher than those in primary foci. A positive correlationwas observed between the expression levels of PI, PC andand also between those of PE and PKC-δ, -ε, -λ,-ξ. However, there was a close negative correlation be-tween PE and PKC-α.CONCLUSION: Increased levels of PI and PC and de-creased ratio of PKC-α to are related to colorectalcancer genesis. Increased levels of PE, increased expressionof PKC-δ, -ε, -λ, -ξ isoenzymes and decreased level ofPKC-α are related to hepatic metastasis in colorectal carci-noma.
基金Supported by National Natural Science Foundation of China (No. 81470609 No. 81170825)+2 种基金the Specialized Research Fund for the Doctoral Program of Higher Education (No. 20123706110003)the Key Project of Natural Science Foundation of Shandong Province (No. ZR2012FZ001) the Youth Project of Natural Science Foundation of Shandong Province (No. ZR2013HQ007)
文摘AIM: To identify whether Aspergillus fumigatus(A.fumigatus) hyphae antigens induced the release of interleukin-8(IL-8) in anti-fungal innate immunity of cultured human corneal epithelial cells(HCECs) and determine the involvement of intracellular signalling pathways. METHODS: HCECs were treated with A. fumigatus hyphae antigens with different concentrations and time.The cytoplasmic calcium of HCECs were assessed by fluorescence imaging. Western blot was used to detect the expression of Ca2 +-dependent protein kinase C(PKC). The IL-8 levels were determined by specific human IL-8 enzyme-linked immunosorbent assay(ELISA) and reverse transcriptase polymerase chain reaction(RT-PCR). Using a series of pharmacological inhibitors, we examined the upstream signalling pathway responsible for IL-8 expression in response to A.fumigatus hyphae antigens. RESULTS: Cells exposed to A. fumigatus hyphae antigens showed higher level of IL-8 m RNA expression and protein production. We demonstrated here that stimulation of HCECs with A. fumigatus hyphae triggers an intracellular Ca2 +flux and results in the activation of Ca2 +-dependent PKC(α, βⅠ and βⅡ) which can be attenuated by pre-treatment of cells with laminarin,suggesting that Dectin-1 signals pathway induced cytoplasmic calcium and influence the activation of PKC in HCECs. Inhibitors of Ca2 +-dependent PKC(Ro-31-8220 and Go6976) significantly abolished hyphae-induced expression of IL-8.CONCLUSION: Our findings suggest that A. fumigatushyphae-induced IL-8 expression was regulated by the activation of Dectin-1-mediated Ca2 +-dependent PKC in HCECs.
文摘BACKGROUND: Fructose is cytoprotective during bile salt-induced apoptosis of hepatocytes by regulating protein kinase C (PKC). This study was undertaken to explore the regulating mechanism of hepatic injury in rats with obstructive jaundice, and to detect the PKC signal pathway. METHODS: Rat hepatocytes were isolated by in situ colla-genase perfusion and primary culture, and pretreated with various concentrations of PKC agonist phorbol myristate acetale (PMA) and inhibitor chelerythrine for 20 minutes. After pretreatment, 50 μmol/L glycochenodeoxycholate (GCDC) was added for additional 24 hours. Subsequently, the cells were detected by FCM and TUNEL. After adding with different concentrations of fructose and 100 μmol GCDC , the hepatocytes were evaluated by FCM and TUNEL. Experimental obstructive jaundice was induced with fructose and without fructose via double ligation of the bile duct for 3, 7, 14, and 21 days. Apoptotic status in the liver of all rats was detected with TUNEL, and PKC protein in the liver of obstructive jaundice ( OJ) with the immunohisto-chemistry method. RESULTS: PMA increased GCDC-induced apoptosis and chelerythrine decreased GCDC-induced apoptosis in a concentration-dependent manner. Adding with different concentration of fructose and 100 μmol GCDC, the decreased apoptotic rate was related to the concentration of fructose. The apoptotic rate of the liver was related to times of OJ. PKC and apoptosis index (AI) were the highest after a 14-day ligation of the bile duct without use of fructose. AI and PKC were decreasing from a 14-day ligation of the bile duct with fructose. CONCLUSIONS: PKC takes part in the regulation, occurrence , and progression of hepatic injury in OJ. Fructose is cytoprotective during bile salt-induced apoptosis of hepato-cytes by regulating PKC.
基金supported by grants from Natural Science Foundation of Hubei Province,China (No. 2010CDB096)the National Key Technology R&D Program of the 12th National Five-year Development Plan of China (No. 2012BAI05B01)
文摘The effects of ATP-sensitive mitochondrial K + channel(mitoK ATP) on mitochondrial membrane potential(Δψm),cell proliferation and protein kinase C alpha(PKCα) expression in airway smooth muscle cells(ASMCs) were investigated.Thirty-six Sprague-Dawley(SD) rats were immunized with saline(controls) or ovalbumin(OVA) with alum(asthma models).ASMCs were cultured from the lung of control and asthma rats.ASMCs were treated with diazoxide(the potent activator of mitoK ATP) or 5-hydroxydencanote(5-HD,the inhibitor of mitoK ATP).Rhodamine-123(R-123) was used to detect Δψm.The expression of PKCα protein was examined by using Western blotting,while PKCα mRNA expression was detected by using real-time PCR.The proliferation of ASMCs was measured by MTT assay and cell cycle analysis.In diazoxide-treated normal ASMCs,the R-123 fluorescence intensity,protein and mRNA levels of PKCα,MTT A values and percentage of cells in S phase were markedly increased as compared with untreated controls.The ratio of G 0 /G 1 cells was decreased(P<0.05) in diazoxide-treated ASMCs from normal rats.However,there were no significant differences between the ASMCs from healthy rats treated with 5-HD and the normal control group.In untreated and diazoxide-treated ASMCs of asthmatic rats,the R-123 fluorescence intensity,protein and mRNA levels of PKCα,MTT A values and the percentage of cells in S phase were increased in comparison to the normal control group.Furthermore,in comparison to ASMCs from asthmatic rats,these values were considerably increased in asthmatic group treated with diazoxide(P<0.05).After exposure to 5-HD for 24 h,these values were decreased as compared with asthma control group(P<0.05).In ASMCs of asthma,the signal transduction pathway of PKCα may be involved in cell proliferation,which is induced by the opening of mitoK ATP and the depolarization of Δψm.
