Role of Extracelluar Regulated Protein Kinases in FTY720-induced Apoptosis of Leukemia Cell Lines HL-60 and U937

The effects of a novel immunosuppressive agent FTY720 on proliferation inhibition and apoptosis of acute leukemia cell lines HL 60 and U937, and the role of extracelluar regulated protein kinase (ERK) in the course of proliferation inhibition and apoptosis induced by FTY720 were studied. The proliferation inhibition rate of HL 60 and U937 cells by various concentrations of FTY720 was detected by MTT assay. Cell apoptosis was detected by DNA fragment analysis and flow cytometry. The phosphorylated ERK1/2 protein expression was observed by Western blotting. The change of intracellular distribution of ERK1/2 protein was identified by SP immunohistochemical staining. The results showed that FTY720 could inhibit the growth of HL 60 and U937 cells effectively in a dose dependent manner. After incubation with FTY720 for 24 h, apoptosis was observed in HL 60 and U937 cells. The intracellular expression of phosphorylated ERK1/2 protein was also down regulated and the distribution of ERK1/2 protein in cell nuclear was reduced during FTY720 induced apoptosis. So, that FTY720 inhibited ERK1/2 phosphorylation might mediate the role of FTY720 induced apoptosis and proliferation inhibition of leukemia cells.

Regulative Function of Telomerase and Extracelluar Regulated Protein Kinases to Leukemic Cell Apoptosis

In order to investigate the regulative function of telom erase and phosphorylated (acti- vated) extracelluar regulated protein kinase (ERK) 1and 2 in the leukemic cell lines HL - 6 0 and K5 6 2 proliferation inhibition and apoptosis,three chemotherapeutic drugs Harringtonine(HRT) , Vincristine(VCR) and Etoposide(Vp16 ) were selected as inducers.The proliferation inhibition rate was detected by MTT m ethod,the cell cycle and cell apoptosis was analyzed by flow cytometry and the telom erase activity was detected by the telom eric repeat am plification protocol(TRAP) assay and bioluminescence analysis method.The phosphorylated ERK 1/ 2 protein expression was detected by western blot method.The results showed that HRT,VCR and Vp16 could inhibit cell proliferation,induce apoptosis,inhibit telomerase activity and down- regulate the protein expres- sion of phosphorylated ERK.Itwas suggested that ERK signal transduction pathway was involved in the down- regulation of telomerase activity and the onset of apoptosis in the leukem ic cells treat- ed by HRT,VCR and Vp16 .

Prostaglandin E1 protects hepatocytes against endoplasmic reticulum stress-induced apoptosis via protein kinase A-dependent induction of glucose-regulated protein 78 expression

AIM To investigate the protective effect of prostaglandin E1(PGE1) against endoplasmic reticulum(ER) stressinduced hepatocyte apoptosis, and to explore its underlying mechanisms.METHODS Thapsigargin(TG) was used to induce ER stress in the human hepatic cell line L02 and hepatocarcinomaderived cell line Hep G2. To evaluate the effects of PGE1 on TG-induced apoptosis, PGE1 was used an hour prior to TG treatment. Activation of unfolded protein response signaling pathways were detected by western blotting and quantitative real-time RTPCR. Apoptotic index and cell viability of L02 cells and Hep G2 cells were determined with flow cytometry and MTS [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2 H-tetrazolium] assay. RESULTS Pretreatment with 1 μmol/L PGE1 protected against TG-induced apoptosis in both L02 cells and Hep G2 cells. PGE1 enhanced the TG-induced expression of C/EBP homologous protein(CHOP), glucose-regulated protein(GRP) 78 and spliced X box-binding protein 1 at 6 h. However, it attenuated their expressions after 24 h. PGE1 alone induced protein and m RNA expressions of GRP78; PGE1 also induced protein expression of DNA damage-inducible gene 34 and inhibited the expressions of phospho-PKR-like ER kinase, phosphoeukaryotic initiation factor 2α and CHOP. Treatment with protein kinase A(PKA)-inhibitor H89 or KT5720 blocked PGE1-induced up-regulation of GRP78. Further, the cytoprotective effect of PGE1 on hepatocytes was not observed after blockade of GRP78 expression by H89 or small interfering RNA specifically targeted against human GRP78.CONCLUSION Our study demonstrates that PGE1 protects against ER stress-induced hepatocyte apoptosis via PKA pathwaydependent induction of GRP78 expression.

XAF1 mediates apoptosis through an extracellular signal-regulated kinase pathway in colon cancer

Background:XIAP-associated factor 1(XAF1)negatively regulates the function of the X-linked inhibitor of apoptosis protein(XIAP),a member of the IAP family that exerts antiapoptotic effects.The extracellular signal-regulated kinase(ERK)pathway is thought to increase cell proliferation and to protect cells from apoptosis.The aim of the study was to investigate the correlation between the ERK1/2 signaling pathway and XAF1 in colon cancer.Methods:Four human colon cancer cell lines,HCT1116 and Lovo(wildtype p53),DLD1 and SW1116(mutant p53),were used.Lovo stable transfectants with XAF1 sense and antisense were established.The effects of dominant-negative MEK1(DN-MEK1)and MEK-specific inhibitor U0126 on the ERK signaling pathway and expression of XAF1 and XIAP proteins were determined.The transcription activity of core XAF1 promoter was assessed by dual luciferase reporter assay.Cell proliferation was measured by MTT assay.Apoptosis was determined by Hoechst 33258 staining.Results:U0126 increased the expression of XAF1 in a time-and dose-dependent manner.A similar result was obtained in cells transfected with DN-MEK1 treatment.Conversely,the expression of XIAP was down-regulated.Activity of the putative promoter of the XAF1 gene was significantly increased by U0126 treatment and DN-MEK1 transient transfection.rhEGF-stimulated phosphorylation of ERK appeared to have little or no effect on XAF1 expression.Overexpression of XAF1 was more sensitive to U0126-induced apoptosis,whereas down-regulation of XAF1 by antisense reversed U0126-induced inhibition of cell proliferation.Conclusions:XAF1 expression was up-regulated by inhibition of the ERK1/2 pathway through transcriptional regulation,which required de novo protein synthesis.The results suggest that XAF1 mediates apoptosis induced by the ERK1/2 pathway in colon cancer.

Protective effect of apoptosis signal-regulating kinase1 inhibitor against mice liver injury

Objective:To explore the protective effect and its molecular mechanism of apoptosis signalregulating kinase 1(ASK1) inhibitor(GS-459679) on acetaminophen-induced liver injury in mice.Methods:The model of liver injury was established by administration of acetaminophen(APAP)(300 mg/kg,i.p.) on C57BL/6 mice.Forty-eight male C57BL/6 mice were randomly divided into four groups,consisting of control group,GS group(GS-459679,30 mg/kg,i.p.),APAPinduced group,and GS combined with APAP-induced group.For GS combined with APAPinduced group,mice were treated with GS 30 min prior to administration of APAP.After mice were euthanized at 6 h or 12 h.respectively,serum levels of alanine aminotransferase(ALT) and aspartate aminotransferase(AST) were analyzed,and mRNA levels of TNF- α,IL-6 and IL-1βwere tested.The activity of glutathione(GSH),oxidized GSH(GSSG) and malondialdehyde were quantified.In addition,ASK1,P-ASK1,JNK and P-JNK protein levels were tested in all groups.Results:The ASK1 and P-ASK1 levels were up-regulated in APAP-induced group.Compared to the control group,serum levels of ALT and AST.and mRNA levels of TNF- a,IL-6 and IL-1(3were increased in APAP-induced group.Meanwhile,the levels of MAD and GSSG.and the ratio of GSSG/GSH were higher and the JNK was activatedin APAP-induced group compared with that in control group.However,compared to APAP-induced group,GS combined with APAP-induced group displayed a decrease of protein expression levels of ASK 1,P-ASKI and P-JNK,a reduction of serum levels of ALT and AST,a decrease in TNF- a.IL-6 and IL-1(3 mRNA levels,and a low ration of GSSG/GSH.Conclusions:GS-459679 treatment effectively down-regulates ASK1 and P-ASK 1 expression.Addition of GS-459679 decreases the generation of liver metabolites and inflammatory factors,reduces oxidative stress reaction,inhibits JNK activation,and then protects the responsiveness to APAP-induced liver injury.

Bcl-2 over-expression and activation of protein kinase C suppress the Trail-induced apoptosis in Jurkat T cells

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.

Regulating effect of glycyrrhetinic acid on bronchial asthma smooth muscle proliferation and apoptosis as well as inflammatory factor expression through ERK1/2 signaling pathway

Objective: To study the influence of glycyrrhetinic acid(GA) on bronchial asthma(BA)smooth muscle proliferation and apoptosis as well as inflammatory factor expression and its molecular mechanism.Methods: Male SD guinea pigs were selected and made into asthma models, bronchial asthma smooth muscle cells were cultured and divided into BA group, GA group and GA + LM group that were treated with serum-free RPMI1640 culture medium, serumfree RPMI1640 culture medium containing 50 ng/mL glycyrrhetinic acid, serum-free RPMI1640 culture medium containing 50 ng/mL glycyrrhetinic acid and 100 ng/mL LM22B-10 respectively; normal guinea pigs were collected and bronchial smooth muscle cells were cultured as control group. The cell proliferation activity as well as the expression of proliferation and apoptosis genes, inflammatory factors and p-ERK1/2 was determined.Results: Proliferation activity value and m RNA expression of Bcl-2, TNF-α, IL-4, IL-6,YKL-40, protein expression of p-ERK1/2 of airway smooth muscle cell in BA group were significantly higher than those of control group while m RNA expression levels of Bax,caspase-9 as well as caspase-3 were significantly lower than that of control group(P < 0.05); proliferation activity value and m RNA expression of Bcl-2, TNF-α, IL-4, IL-6, YKL-40, protein expression of p-ERK1/2 of airway smooth muscle cell in GA group were significantly lower than those of BA group(P < 0.05) while the m RNA expression levels of Bax, caspase-9 as well as caspase-3 were significantly higher than those of BA group(P < 0.05); proliferation activity value and m RNA expression of Bcl-2, TNF-α, IL-4, IL-6, YKL-40 of airway smooth muscle cell in GA + LM group were significantly higher than those of GA group(P < 0.05) while m RNA expression levels of Bax, caspase-9 as well as caspase-3 were significantly lower that of GA group(P < 0.05).Conclusion: GA can inhibit the proliferation of bronchial smooth muscle cells and reduce the expression of inflammatory factors by inhibiting the phosphorylation of ERK1/2.

Serine-threonine protein kinase activation may be an effective target for reducing neuronal apoptosis after spinal cord injury

The signaling mechanisms underlying ischemia-induced nerve cell apoptosis are poorly understood. We investigated the effects of apoptosis-related signal transduction pathways following ischemic spinal cord injury, including extracellular signal-regulated kinase（ERK）, serine-threonine protein kinase（Akt） and c-Jun N-terminal kinase（JNK） signaling pathways. We established a rat model of acute spinal cord injury by inserting a catheter balloon in the left subclavian artery for 25 minutes. Rat models exhibited notable hindlimb dysfunction. Apoptotic cells were abundant in the anterior horn and central canal of the spinal cord. The number of apoptotic neurons was highest 48 hours post injury. The expression of phosphorylated Akt（pAkt） and phosphorylated ERK（p-ERK） increased immediately after reperfusion, peaked at 4 hours（p-Akt） or 2 hours（p-ERK）, decreased at 12 hours, and then increased at 24 hours. Phosphorylated JNK expression reduced after reperfusion, increased at 12 hours to near normal levels, and then showed a downward trend at 24 hours. Pearson linear correlation analysis also demonstrated that the number of apoptotic cells negatively correlated with p-Akt expression. These findings suggest that activation of Akt may be a key contributing factor in the delay of neuronal apoptosis after spinal cord ischemia, particularly at the stage of reperfusion, and thus may be a target for neuronal protection and reduction of neuronal apoptosis after spinal cord injury.

TRAIL-induced apoptosis of hepatocellular carcinoma cells is augmented by targeted therapies

AIM:To analyze the effect of chemotherapeutic drugs and specific kinase inhibitors,in combination with the death receptor ligand tumor necrosis factor-related apoptosis inducing ligand(TRAIL),on overcoming TRAIL resistance in hepatocellular carcinoma(HCC)and to study the efficacy of agonistic TRAIL antibodies,as well as the commitment of antiapoptotic BCL-2 proteins, in TRAIL-induced apoptosis. METHODS:Surface expression of TRAIL receptors (TRAIL-R1-4)and expression levels of the antiapoptotic BCL-2 proteins MCL-1 and BCL-xL were analyzed by flow cytometry and Western blotting,respectively. Knock-down of MCL-1 and BCL-xL was performed by transfecting specific small interfering RNAs.HCC cellswere treated with kinase inhibitors and chemotherapeutic drugs.Apoptosis induction and cell viability were analyzed via flow cytometry and 3-(4,5-Dimethyl-thiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. RESULTS:TRAIL-R1 and-R2 were profoundly expressed on the HCC cell lines Huh7 and Hep-G2. However,treatment of Huh7 and Hep-G2 with TRAIL and agonistic antibodies only induced minor apoptosis rates.Apoptosis resistance towards TRAIL could be considerably reduced by adding the chemotherapeutic drugs 5-fluorouracil and doxorubicin as well as the kinase inhibitors LY294002[inhibition of phosphoinositol- 3-kinase(PI3K)],AG1478(epidermal growth factor receptor kinase),PD98059(MEK1),rapamycin(mam- malian target of rapamycin)and the multi-kinase inhibitor Sorafenib.Furthermore,the antiapoptotic BCL-2 proteins MCL-1 and BCL-xL play a major role in TRAIL resistance:knock-down by RNA interference increased TRAIL-induced apoptosis of HCC cells.Additionally, knock-down of MCL-1 and BCL-xL led to a significant sensitization of HCC cells towards inhibition of both c-Jun N-terminal kinase and PI3K.CONCLUSION:Our data identify the blockage of survival kinases,combination with chemotherapeutic drugs and targeting of antiapoptotic BCL-2 proteins as promising ways to overcome TRAIL resistance in HCC.

The involvement of p38 MAPK in transforming growth factor β1-induced apoptosis in murine hepatocytes

We reported in this manuscript that TGF-beta1 induces apoptosis in AML12 murine hepatocytes, which is associated with the activation of p38 MAPK signaling pathway. SB202190, a specific inhibitor of p38 MAPK, strongly inhibited the TGF-beta1-induced apoptosis and PAI-1 promoter activity. Treatment of cells with TGF-beta1 activates p38. Furthermore, over-expression of dominant negative mutant p38 also reduced the TGF-beta1-induced apoptosis. The data indicate that the activation of p38 is involved in TGF-beta1-mediated gene expression and apoptosis.

Effects of Oxymatrine on the Apoptosis of Human Esophageal Carcinoma Eca109 Cell Line and Its Mechanism

The effects of Oxymatrine （Oxy） on the proliferation and apoptosis of human esophageal carcinoma Ecal09 cell line and the mechanism were investigated. The human esophageal carcinoma Eca 109 celis were cultured in vitro. The Oxy-induced apoptosis of Eca 109 cells was assayed by using flow cytometry. The expressions of p-ERKII2, Cyclin D1, p21^waf/cipl, Bax and Bcl-2 were detected by Western blot. Flow cytometry revealed that Oxy could induce the apoptosis of Eca l09 cells. Western blot showed that Oxy of different concentrations suppressed the expressions of p-ERK1/2, Cyclin D1 and Bcl-2, but up-regulated the expression of p21waf/cip1 and Bax, and the ratio of Bax/Bcl-2 was increased. It was suggested the Oxy could induce the apoptosis of Eca l09 cells, which might be related to the upregulation of p21waf/cip1 and the downregulation of p-ERK1/2, Cyclin D1 and p21^waf/cip1. The possible pathway may be related to Bcl-2/Bax.

Phosphorylated extracellular signal-regulated kinase up-regulated p53 expression in shikonin-induced HeLa cell apoptosis

Background The role of extracellular signal-regulated kinase 1/2 (ERK1/2) in shikonin-induced HeLa cells apoptosis remains vague. This study was to investigate the activation of caspase pathways and the role of ERK1/2 in human cervical cancer cells, HeLa, by shikonin. Methods The inhibitory effect of shikonin on the growth of HeLa cells was measured by MTT assay. Fluorescent microscopic analysis of apoptotic cells stained with 4’,6’-oliiamiclino-2-phenylindole C (DAPI) and Hoechst 33258 was carried out. Caspase-3 and -8 activities were detected using caspase-3 substrate and caspase-8 substrate as substrates, respectively. The protein levels of ERK, p53 and p-ERK were determined by Western blot analysis.Results Shikonin inhibited cell growth in a time- and dose-dependent manner. Caspase-3 and caspase-8 were activated in the apoptotic process and caspase inhibitors effectively reversed shikonin-induced apoptosis. Phosphorylation of ERK resulted in up-regulation of p53 expression, which was blocked by mitogen-activated protein kinase (MEK), inhibitor PD 98059.Conclusion Shikonin induces HeLa cell apoptosis through the ERK, p53 and caspase pathways.

Regulation of extracellular signal-regulated kinase 1/2 influences hippocampal neuronal survival in a rat model of diabetic cerebral ischemia

Activation of extracellular signal-regulated kinase 1/2 has been demonstrated in acute brain ischemia. We hypothesized that activated extracellular signal-regulated kinase 1/2 can protect hippocampal neurons from injury in a diabetic model after cerebral ischemia/reperfusion. In this study, transient whole-brain ischemia was induced by four-vessel occlusion in normal and diabetic rats, and extracellular signal-regulated kinase 1/2 inhibitor （U0126） was administered into diabetic rats 30 minutes before ischemia as a pretreatment. Results showed that the number of surviving neurons in the hippocampal CA1 region was reduced, extracellular signal-regulated kinase 1/2 phosphorylation and KuT0 activity were decreased, and pro-apoptotic Bax expression was upregulated after intervention using U0126. These findings demonstrate that inhibition of extracellular signal-regulated kinase 1/2 activity aggravated neuronal loss in the hippocampus in a diabetic rat after cerebral ischemia/reperfusion, further decreased DNA repairing ability and ac- celerated apoptosis in hippocampal neurons. Extracellular signal-regulated kinase 1/2 activation plays a neuroprotective role in hippocampal neurons in a diabetic rat after cerebral ischemia/ reperfusion.

Neurotransmitter regulation of extracellular signal-regulated kinase expression following subarachnoid hemorrhage

BACKGROUND： Very few studies have addressed neuronal injury in cerebral vasospasm and subarachnoid hemorrhage （SAH）, and the role of neurotransmitters in the regulation of extracellular signal-regulated kinase 1/2 （ERK1/2） expression following SAH. OBJECTIVE： To analyze neurotransmitter regulation of ERK1/2 expression through the use of signal transduction, and to investigate cerebral injury mechanisms following SAH. DESIGN, TIME AND SETTING： A completely randomized grouping and controlled animal experiment was performed at the Experimental Center of Medical College of Xi＇an Jiaotong University from March to December 2008. MATERIALS： Extraceliular signal-regulated ERK1/2 polyclonal antibody and streptavidin-peroxidase method kits were purchased from Beijing Biosynthesis Biotechnology, China; DAB kit was purchased from Zhongshan Golden Bridge Biotechnology, China; TUNEL kit was purchased from Promega, USA. METHODS： A total of 114 male, Sprague Dawley rats, aged 55-63 days old, were randomly assigned to five groups： SAH （n = 30）, saline control （n = 30）, puncture control （n = 30）, normal control （n = 6）, and neurotransmitter-treated （n = 18）. The SAH model was established by twice injecting blood through the cisterna magna. The neurotransmitters-treated group was subdivided into three groups according to drugs injected into the lateral cerebral ventricle： acetylcholine chloride, norepinephrine, and saline, with six animals in each group. MAIN OUTCOME MEASURES： Rats from the SAH, saline control, and puncture control groups were respectively sacrificed at 6, 12, and 24 hours, as well as 3 and 5 days, with six rats at each time point. The normal control group rats were sacrificed at 6 hours, and the neurotransmitter group rats were sacrificed 3 days following neurotransmitter injection. Morphological cellular changes were observed by hematoxylin and eosin staining. Immunohistochemical SP method was used to detect expression of ERK1/2 in the cortex, and cortical apoptosis was detected using the TUNEL method. RESULTS： Neural tissue edema, apoptosis, and necrosis occurred in the cortex of the SAH group. ERK1/2-positive cells were first observed at 6 hours, peaked at 12 hours following SAH in the cortex, and gradually decreased thereafter. Cellular apoptosis was observed in the cortex at 6 hours and peaked at 24 hours following SAH. ERK1/2 distribution in the brain overlapped apoptotic cells to a great degree. The number of ERK1/2-positive and apoptotic cells was significantly greater in the SAH group compared with the three control groups （P 〈 0.05）. Compared to the number of ERK1/2-positive cells in the saline-treated group, acetylcholine chloride treatment resulted in decreased ERK1/2 expression and apoptosis （P 〈 0.05）. Norepinephrine resulted in increased ERK1/2 expression, but there was no significance in apoptosis compared to the saline-treated group （P 〉 0.05）. CONCLUSION： Apoptosis was observed early in the rat cortex following SAH. In addition, ERK1/2 was expressed earlier than apoptosis. Acetylcholine chloride treatment resulted in decreased numbers of apoptotic cells following SAH, possibly by down-regulating ERK1/2 expression.

Shenfu injection attenuates lipopolysaccharide-induced myocardial inflammation and apoptosis in rats

Shenfu injection(SFI), a Chinese medicinal product, shows potent efficacy in treating sepsis. The aim of the present study was to clarify the protective effects of SFI against lipopolysaccharide(LPS)-induced myocardial inflammation and apoptosis.Experiments were carried out in Sprague-Dawley(SD) rats treated with LPS or LPS + SFI, and in H9 C2 cardiomyocytes. The sepsisassociated myocardial inflammation and apoptosis was induced by the intraperitoneal injection of LPS(20 mg·kg–1). SFI attenuated the increased expression of tumor necrosis factor(TNF)-α and interleukin(IL)-1β induced by LPS both in serum and heart. In LPS group,cell viability was reduced, and reversed after SFI administration. LPS treatment increased the expression levels of cleaved-caspase 3 and Bax, and those of Bcl2 and Bcl2/Bax. These two trends were reversed by SFI administration. The expression levels of phosphorylated mitogen-activated protein kinase kinase(p-MEK) and phosphorylated extracellular regulated protein kinases(p-ERK) were increased by LPS, and reversed by SFI. MEK inhibitor U0126 attenuated the apoptosis induced by LPS. These results indicate that SFI could treat LPS-induced cardiac dysfunction. In conclusion, SFI attenuates the inflammation and apoptosis induced by LPS via downregulating the MEK and ERK signaling pathways.

Ceramide from sphingomyelin hydrolysis differentially mediates mitogen-activated protein kinases (MAPKs) activation following cerebral ischemia in rat hippocampal CA1 subregion

Objective： To explore the role that ceramide plays in the activation of mitogen-activated protein kinases （MAPKs） during cerebral ischemia and reperfusion. Methods： Rats were subjected to ischemia by the fourvessel occlusion （4-VO） method. The sphingomyelinase inhibitor TPCK was administered to the CA1 subregion of the rat hippocampus before inducing ischemia. Western blot was used to examine the activity of extracellular- signal regulated kinase （ERK） and c-Jun N-terminal protein kinase （JNK） using antibodies against ERK, JNK and diphosphorylated ERK and JNK. Results： At lh reperfusion post-ischemia, JNK reached its peak activity while ERK was undergoing a sharp inactivation （P 〈 0.05）. The level of diphosphorylated JNK was significantly reduced but the sharp inactivation of ERK was visibly reversed （P 〈 0.05） by the sphingomyelinase inhibitor. Conclusion： The ceramide signaling pathway is up-regulated through sphingomyelin hydrolysis in brain ischemia, promoting JNK activation and suppressing ERK activation, culminating in the ischemic lesion.

MARK4在甲基苯丙胺诱导急性肾损伤中的作用

目的:甲基苯丙胺(methamphetamine,METH)是一种非法的精神活性物质,可以损害身体的各个器官,其中泌尿系统是其毒性作用的重要靶标之一。本研究旨在探讨微管亲和调控激酶4(microtubule affinity regulating kinase 4,MARK4)在METH诱导急性肾损伤(acute kidney injury,AKI)中的作用。方法:选取10只健康成年雄性C57BL/6小鼠,随机分为对照组和METH组,每组5只。METH组腹腔注射METH(20 mg/kg,每天1次,连续3 d),对照组腹腔注射同等体积的生理盐水。末次注射24 h后处死小鼠,通过血清肌酐、血尿素氮和肾脏HE染色检测AKI模型是否建立成功;蛋白质组学技术筛选METH诱导AKI的肾脏组织与正常肾脏组织之间差异表达的蛋白质,并进行基因本体(gene ontology,GO)分析、京都基因与基因组百科全书(Kyoto Encyclopedia of Genes and Genomes,KEGG)分析和生物信息学分析;蛋白质印迹法验证蛋白质组学数据的准确性,选择目标分子,检测小鼠肾脏中MARK4和cleaved caspase-3表达情况。进一步探讨MARK4在METH诱导AKI中的作用。首先在BUMPT细胞中建立METH毒性模型,筛选出合适的METH处理浓度和时间;使用抑制剂抑制MARK4的表达,检测METH处理后BUMPT细胞的活力以及cleaved caspase-3表达情况。结果:蛋白质组学分析共筛选出差异表达蛋白质17个,其中上调11个,下调6个(均P<0.05)。METH处理后小鼠肾脏中MARK4和cleaved caspase-3的表达水平升高(均P<0.05)。BUMPT细胞的活性随METH处理浓度升高而逐渐降低(均P<0.05),其中4 mmol/L的METH处理后BUMPT细胞活力下降至60%。与对照组相比,MARK4和cleaved caspase-3的表达水平随着METH处理浓度的升高和处理时间的延长而升高(均P<0.05),呈浓度和时间依赖性。抑制MARK4表达可以改善METH引起的BUMPT细胞活性下降情况,降低cleaved caspase-3表达,减少BUMPT细胞的细胞凋亡。结论:MARK4在METH诱导AKI小鼠模型中高表达,MARK4通过调控细胞凋亡来介导METH中毒所致AKI。

冠心宁通过TNFAIP3-ASK1/JNK通路对动脉粥样硬化血管平滑肌细胞表型转换的调控作用

目的探讨冠心宁(GXN)调控动脉粥样硬化(AS)斑块稳定性的分子机制。方法制备含有GXN药物的血清,利用氧化低密度脂蛋白(ox-LDL)诱导血管平滑肌细胞(VSMC)构建AS体外模型,Western blot和qPCR检测VSMC表型转换情况。通过沉默肿瘤坏死因子α诱导蛋白3(TNFAIP3),检测GXN对VSMC表型转换的影响。构建凋亡信号调节激酶1(ASK1)过表达载体,并利用Lip3000转染进细胞,检测GXN是否通过凋亡信号调节激酶1/c-Jun氨基末端激酶(ASK1/JNK)通路发挥作用。结果与对照组比较,ox-LDL组的细胞表型转换,表现为I型胶原蛋白(COLIA1和COLIA2)、TNFAIP3和α-平滑肌肌动蛋白(α-SMA)的表达水平降低(均P<0.01),基质金属蛋白酶(MMP)2、MMP9、MMP13、骨桥蛋白(OPN)、ASK1磷酸化与ASK1比值(p-ASK1/ASK1)、JNK磷酸化与JNK比值(p-JNK/JNK)升高(均P<0.01);GXN处理后VSMC表型转换为收缩型,表现为与ox-LDL组相比COLIA1、COLIA2和α-SMA水平增高(均P<0.01),MMP2、MMP9、MMP13、OPN、TNFAIP3的表达水平、p-ASK1/ASK1以及p-JNK/JNK都降低(均P<0.01)。沉默TNFAIP3后,与ox-LDL+10%GXN+sh-NC组相比,COLIA1、COLIA2、TNFAIP3和α-SMA水平降低(均P<0.01),MMP2、MMP9、MMP13、OPN、p-ASK1/ASK1以及p-JNK/JNK都升高(均P<0.01)。过表达ASK1后,与ox-LDL+10%GXN+oe-NC组相比,COLIA1、COLIA2和α-SMA的表达水平降低(均P<0.01),MMP2、MMP9、MMP13、OPN、p-ASK1/ASK1以及p-JNK/JNK都升高(均P<0.01)。结论GXN可能通过TNFAIP3调控ASK1/JNK通路介导VSMC表型转换,从而起到稳定动脉硬化斑块的作用。

基于ERK5信号通路探讨薯蓣健脾益智合剂对血管性痴呆大鼠海马神经元凋亡的影响

目的:探讨薯蓣健脾益智合剂对血管性痴呆(VaD)大鼠海马神经元凋亡的影响以及相关作用机制。方法:采用改良双侧颈总动脉结扎(2-VO)法建立VaD大鼠模型,将120只大鼠随机分为正常组、假手术组、模型组和治疗组,每组30只。治疗组予以10 mL/(kg·d)薯蓣健脾益智合剂灌胃,正常组、假手术组、模型组给予等量生理盐水灌胃,持续8周。观察大鼠一般状态,并于造模后第7天及造模后治疗4、8周分别进行行为学检测,苏木精-伊红(HE)染色观察海马神经元组织学改变,脱氧核糖核苷酸末端转移酶介导的缺口末端标记(TUNEL)染色观察海马神经元凋亡情况,免疫组织化学法检测丝分裂原活化蛋白激酶K2(MEKK2)、丝分裂原活化蛋白激酶K3(MEKK3)和丝裂原激活蛋白激酶5(MEK5)、细胞外信号调节激酶5(ERK5)表达的变化,蛋白免疫印迹法检测MEKK2、MEKK3和MEK5、ERK5的蛋白表达。结果:与正常组及假手术组比较,模型组行为学表现差异显著,变性神经元增加,神经元凋亡率增加(P<0.01),MEKK2、MEKK3和MEK5、ERK5的表达减少;与模型组比较,治疗组行为学表现改善,变性神经元减少,神经元凋亡率降低(P<0.05或P<0.01),MEKK2、MEKK3和MEK5、ERK5表达增加。结论:薯蓣健脾益智合剂可能通过上调ERK5信号通路,抑制海马神经元凋亡,促进海马神经元的修复进而治疗VaD。