Activation of extracellular signal-related kinases 1 and 2 in Sertoli cells in experimentally cryptorchid rhesus monkeys

Aim： To assess the spatiotemporal changes in the expression of extracellular signal-regulated kinases 1 and 2 （ERK1/ 2）, c-Jun N-terminal kinases （JNK） and p38 mitogen-activated protein kinases （MAPK） in response to heat stress in the cryptorchid testis, and to investigate a possible relation to Sertoli cell dedifferentiation. Methods： Immunohistochemistry and western blot were used to examine the expression and activation of ERK1/2, p38 and JNK in the cryptorchid testis at various stages after experimental cryptorchidism. Results： The abdominal temperature did not obviously change the total ERK1/2 expression but significantly activated phospho-ERK1/2 in the Sertoli cells of the cryptorchid testis. Heat stress increased total JNK expression in the Sertoli cells of the cryptorchid testis but did not activate phospho-JNK. Neither total p38 nor phospho-p38 was induced by heat stress in the Sertoli cells of the cryptorchid testis. Changes in the spatiotemporal expression of cytokeratin 18 （CK18）, a marker of immature or undifferentiated Sertoli cells, were induced in the cryptorchid testis in a pattern similar to the activation of ERK1/2. Condusion： The activation of ERK1/2 in the testis may be related to dedifferentiation of Sertoli cells under heat stress induced by experimental cryptorchidism.

Activation of extracellular signal-related kinases 1 and 2 in Sertoli cells in experimentally cryptorchid rhesus monkeys

Aim:To assess the spatiotemporal changes in the expression of extracellular signal-regulated kinases 1 and 2(ERK1/ 2),c-Jun N-terminal kinases(JNK)and p38 mitogen-activated protein kinases(MAPK)in response to heat stress in the cryptorchid testis,and to investigate a possible relation to Sertoli cell dedifferentiation.Methods:Immunohis- tochemistry and western blot were used to examine the expression and activation of ERK1/2,p38 and JNK in the cryptorchid testis at various stages after experimental cryptorchidism.Results:The abdominal temperature did not obviously change the total ERK1/2 expression but significantly activated phospho-ERK1/2 in the Sertoli cells of the cryptorchid testis.Heat stress increased total JNK expression in the Sertoli cells of the cryptorchid testis but did not activate phospho-JNK.Neither total p38 nor phospho-p38 was induced by heat stress in the Sertoli cells of the cryptorchid testis.Changes in the spatiotemporal expression of cytokeratin 18(CK18),a marker of immature or undifferentiated Sertoli cells,were induced in the cryptorchid testis in a pattern similar to the activation of ERK1/2. Conclusion:The activation of ERK1/2 in the testis may be related to dedifferentiation of Sertoli cells under heat stress induced by experimental cryptorchidism.

Dexamethasone suppresses DU145 cell proliferation and cell cycle through inhibition of the extracellular signal-regulated kinase 1 /2 pathway and cyclin D1 expression

Aim： To determine the mechanisms of glucocorticoids in inhibiting advanced prostate cancer growth. Methods： The cell proliferation and cell cycle of prostate cancer DU145 cells following dexamethasone treatment were determined by proliferation assay and fluorescence-activated cell sorter. Western blot analysis was carried out to evaluate the effects of dexamethasone on phosphorylation of extracellular signal-regulated kinase （ERK）1/2 and expression of cyclin D1 in DU145 cells with or without glucocorticoid receptor （GR） antagonist RU486. Reverse transcription- polymerase chain reaction verified the expression of GR mRNA in DU145 cells. Results： Dexamethasone significantly inhibited DU 145 cell proliferation at the G0/G1 phase. Westem blot analysis showed a dramatic reduction of ERK1/2 activity and cyclin D1 expression in dexamethasone-treated cells. The decreased phosphorylation of ERK1/2 in dexamethasone-treated cells was attenuated by GR blockade. Additionally, the effects of dexamethasone in inhibiting cyclin D1 expression were altered by GR blockade. Conclusion： Dexamethasone suppresses DU145 cell proliferation and cell cycle, and the underlying mechanisms are through the inhibition of phosphorylation of ERK1/2 and cyclin D1 expression. The inhibition of ERK1/2 phosphorylation and cyclin D1 expression is attenuated by GR blockade, suggesting that GR regulates ERK1/2 and cyclin D1 pathways. These observations suggest that dexamethasone has a potential clinical application in prostate cancer therapy.

Differential activation of mitogen-activated protein kinases by γ-irradi-ation in IEC-6 cells: Role of intracellular Ca^(2+)

Objective: To explore the effects of γ-irradiation on mitogen-activated protein kinases (MAPKs) and role of intracellular calcium in this event in intestinal epithelial cell line 6 (IEC-6 cells). Methods: After cultured rat IIEC-6 cells with or without the pretreatment of intracellular Ca2+ chelator were exposed to Y-ir-radiation of 6 Gy, the total and phosphorylated MAPKs in the cells were determined with Western blotting and apoptosis was examined with flow cytometry. Activities of Extracellular signal-regulated protein kinase (ERK) and p38 MAPK were determined by using immuoprecipitation followed by Western blotting. Results: In response to γ-irradiation, phosphorylation of ERK was not significantly observed, while the levels of phosphorylated c-Jun NH2-terminal kinase (JNK) and p38 MAPK were increased in 30 min and reached the peak 2 h after exposure to 6 Gy γ-irradiation, though the cell viability was significantly lowered 12 h. On the other hand, no obvious changes were seen in the total protein levels of ERK, JNK and p38 MAPK. Chelation of intracellular Ca2+ almost completely suppressed the JNK and p38 MAPK phosphorylation induced by γ-irradia-tion, but removal of external Ca2+ had no such effect. Activation of p38 MAPK, but not of ERK, was seen to have a correlation with γ-irradiation induced apoptosis. Conclusion: The results suggest that γ-irradiation is a potent activator for JNK and p38 MAPK, and Ca2+ mobilized from intracellular stores plays an important role in the activation of MAPKs and the induction of apoptosis in IEC-6 cells.

Physiological roles of mitogen-activated-protein-kinase-activated p38-regulated/activated protein kinase

Mitogen-activated protein kinases(MAPKs)are a family of proteins that constitute signaling pathways involved in processes that control gene expression,cell division, cell survival,apoptosis,metabolism,differentiation and motility.The MAPK pathways can be divided into conventional and atypical MAPK pathways.The first group converts a signal into a cellular response through a relay of three consecutive phosphorylation events exerted by MAPK kinase kinases,MAPK kinase,and MAPK.Atypical MAPK pathways are not organized into this three-tiered cascade.MAPK that belongs to both conventional and atypical MAPK pathways can phosphorylate both non-protein kinase substrates and other protein kinases.The latter are referred to as MAPK-activated protein kinases.This review focuses on one such MAPK-activated protein kinase,MAPK-activated protein kinase 5(MK5)or p38-regulated/activated protein kinase(PRAK).This protein is highly conserved throughout the animal kingdom and seems to be the target of both conventional and atypical MAPK pathways.Recent findings on the regulation of the activity and subcellular localization,bona fide interaction partners and physiological roles of MK5/PRAK are discussed.

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.

Human ciliary muscle cell responses to kinins:Activation of ERK1/2 and pro-matrix metalloproteinases secretion

AIM To study activation of extracellular signal-regulated kinase-1/2(ERK1/2) and pro-matrix metalloproteinases(pro-MMPs) secretion from isolated primary human ciliary muscle(h-CM) cells in response to bradykinin(BK) and other agonists. METHODS Serum-starved h-CM cells were challenged with vehicle, BK agonists or antagonists. Cell lysates were evaluated for phosphorylated ERK1/2 using homogeneous timeresolved fluorescence technology based on a sandwich immunoassay. Rabbit polyclonal anti-pro-MMP antibodies were used to measure pro-MMPs using immunoblot analysis.RESULTS A 10 min incubation time using 5 × 104 h-CM cells/well was optimum condition for studying stimulation of ERK1/2 phosphorylation. BK(100 nmol/L) caused a 1.86 ± 0.26 fold(n = 3) increase in ERK1/2 phosphorylation above baseline. BK analogs, Met-Lys-BK and RMP-7(100 nmol/L), also stimulated ERK1/2 phosphorylation by 1.57 ± 0.04 and 1.55 ± 0.09 fold, respectively. However, DesArg9-Bradykinin, a B1 receptor-selective agonist(0.1-1 μmol/L), was essentially inactive. HOE-140 or WIN-64338(B2-antagonists) appreciably blocked phosphorylation of ERK1/2 induced by various BK agonists. Pre-treatmentof cells with a prostaglandin(PG) synthase inhibitor(bromfenac; 1 μmol/L) failed to alter kinin-induced ERK1/2 activation. BK and a non-peptide BK agonist(FR-190997)(10 nmol/L-1 μmol/L) also enhanced pro-MMPs secretion(pro-MMP-1 > pro-MMP-3 > pro-MMP-2; 1.45-1.75-fold over baseline) from h-CM cells. CONCLUSION These collective data suggest that B2 kinin receptors initiate signaling in h-CM cells by a relatively rapid mechanism(within minutes) involving ERK1/2 activation which in turn regulates MMPs production(within hours). The latter process does not involve PGs.

Overexpression of mitogen-activated protein kinase phosphatase-1 in endothelial cells reduces blood-brain barrier injury in a mouse model of ischemic stroke

Ischemic stroke can cause blood-brain barrier(BBB)injury,which worsens brain damage induced by stroke.Abnormal expression of tight junction proteins in endothelial cells(ECs)can increase intracellular space and BBB leakage.Selective inhibition of mitogen-activated protein kinase,the negative regulatory substrate of mitogen-activated protein kinase phosphatase(MKP)-1,improves tight junction protein function in ECs,and genetic deletion of MKP-1 aggravates ischemic brain injury.However,whether the latter affects BBB integrity,and the cell type-specific mechanism underlying this process,remain unclear.In this study,we established an adult male mouse model of ischemic stroke by occluding the middle cerebral artery for 60 minutes and overexpressed MKP-1 in ECs on the injured side via lentiviral transfection before stroke.We found that overexpression of MKP-1 in ECs reduced infarct volume,reduced the level of inflammatory factors interleukin-1β,interleukin-6,and chemokine C-C motif ligand-2,inhibited vascular injury,and promoted the recovery of sensorimotor and memory/cognitive function.Overexpression of MKP-1 in ECs also inhibited the activation of cerebral ischemia-induced extracellular signal-regulated kinase(ERK)1/2 and the downregulation of occludin expression.Finally,to investigate the mechanism by which MKP-1 exerted these functions in ECs,we established an ischemic stroke model in vitro by depriving the primary endothelial cell of oxygen and glucose,and pharmacologically inhibited the activity of MKP-1 and ERK1/2.Our findings suggest that MKP-1 inhibition aggravates oxygen and glucose deprivation-induced cell death,cell monolayer leakage,and downregulation of occludin expression,and that inhibiting ERK1/2 can reverse these effects.In addition,co-inhibition of MKP-1 and ERK1/2 exhibited similar effects to inhibition of ERK1/2.These findings suggest that overexpression of MKP-1 in ECs can prevent ischemia-induced occludin downregulation and cell death via deactivating ERK1/2,thereby protecting the integrity of BBB,alleviating brain injury,and improving post-stroke prognosis.

6-OHDA Induces Cycle Reentry and Apoptosis of PC12 Cells through Activation of ERK1/2 Signaling Pathway

This study investigated the effect and mechanism of cell cycle reentry induced by 6-hydrodopamine （6-OHDA） in PC12 cells. By using neural differentiated PC12 cells treated with 6-OHDA, the apoptosis model of dopaminergic neurons was established. Cell viability was measured by MTT. Cell apoptosis and the distribution of cell cycle were assessed by flow cytometry. Western blot was used to detect the activation of extracellular regulator kinasel/2 （ERK1/2） pathway and the phosphorylation of retinoblastoma protein （RB）. Our results showed that after PC12 cells were treated wtih 6-OHDA, the viability of PC12 cells was declined in a concentration-dependent manner. Flow cytornetry revealed that 6-OHDA could increase the apoptosis ratio of PC12 cells in a time-dependent manner. The percentage of ceils in G0/G1 phase of cell cycle was decreased and that in S phase and G2/M phase increased. Simultaneously, ERK1/2 pathway was activated and phosphorylated RB increased. It was concluded that 6-OHDA could induce cell cycle reentry of dopaminergic neurons through the activation of ERK1/2 pathway and RB phosphorylation. The aberrant cell cycle reentry contributes to the apoptosis of dopaminergic neurons.

IL-1β通过激活ERK1/2信号通路抑制人脐带间充质干细胞CD200表达抑制巨噬细胞M2极化

目的探究白细胞介素1β(IL-1β)调控人脐带间充质干细胞CD200表达及其对巨噬细胞极化的影响及作用机制。方法无血清培养基分离培养获得人脐带间充质干细胞(hUC-MSC),形态学观察及流式细胞术检测CD73、CD90、CD105、CD14、CD34、CD45、人类白细胞抗原DR(HLA-DR)的表达,确定间充质干细胞属性;20 ng/mL IL-1β处理hUC-MSC 24 h,流式细胞术检测CD200阳性细胞率,实时定量PCR和Western blot法检测CD200 mRNA和蛋白表达水平;佛波酯(PMA)诱导THP-1巨噬细胞活化,并与IL-1β处理感染CD200过表达慢病毒的hUC-MSC共培养,流式细胞术检测CD11c和CD206阳性细胞比例;IL-1β联合细胞外信号调节激酶1/2(ERK1/2)特异性抑制剂PD98059处理hUC-MSC,Western blot法检测细胞丝裂原激活蛋白激酶(MAPK)信号分子与CD200的表达。结果IL-1β显著下调hUC-MSC CD200蛋白表达与CD200阳性细胞率;过表达CD200显著上调hUC-MSC CD200表达,且CD200过表达hUC-MSC提高巨噬细胞CD206阳性细胞比率;IL-1β激活hUC-MSC的ERK1/2信号通路,PD98059上调IL-1β处理后hUC-MSC中CD200的蛋白表达。结论IL-1β通过激活ERK1/2信号通路抑制CD200的表达,进而抑制hUC-MSC对巨噬细胞向M2型极化的促进作用。

金合欢素调节Sirt1/AMPK/Nrf2信号通路对糖尿病白内障大鼠氧化应激损伤的影响

目的探讨金合欢素对糖尿病白内障(DC)大鼠氧化应激损伤的影响及其对沉默调节蛋白1(Sirt1)/腺苷酸活化蛋白激酶(AMPK)/核因子E2相关因子2(Nrf2)信号通路的调控作用。方法60只SD大鼠随机分为对照组、模型组、金合欢素低剂量组、金合欢素高剂量组、金合欢素+Sirt1抑制剂(EX527)组,除对照组以外均构建DC大鼠模型,其中,金合欢素低剂量组、金合欢素高剂量组大鼠分别经颈部皮下注射10 mg·kg^(-1)、20 mg·kg^(-1)的金合欢素,金合欢素+EX527组大鼠经颈部皮下注射20 mg·kg^(-1)金合欢素,均为每天2次,同时金合欢素+EX527组大鼠经皮下埋入渗透微型泵每天泵入3.5 mg·kg^(-1)EX527,其余组别均泵入等量生理盐水,给药持续4周。给药结束后,测量血压和空腹血糖(FBG),裂隙灯照射法观察大鼠晶状体混浊状况,HE染色观察晶状体组织病理学变化,ELISA测定血清丙二醛(MDA)、超氧化物歧化酶(SOD)、谷胱甘肽过氧化物酶(GSH-Px)、白细胞介素(IL)-6、IL-1β的含量,Western blot检测Sirt1、p-AMPK、AMPK、Nrf2蛋白表达水平。结果与对照组相比,模型组大鼠晶状体上皮细胞呈片状、条索状,发生迁移性聚集,收缩压、FBG、晶状体混浊评分、MDA、IL-6、IL-1β水平均升高,SOD、GSH-Px含量及Sirt1、p-AMPK/AMPK、Nrf2蛋白表达水平均降低(均为P<0.05);与模型组比较,金合欢素低、高剂量组大鼠晶状体上皮细胞迁移性聚集现象改善,收缩压、FBG、晶状体混浊评分、MDA、IL-6、IL-1β水平均降低,SOD、GSH-Px含量及Sirt1、p-AMPK/AMPK、Nrf2蛋白表达水平均升高(均为P<0.05);与金合欢素高剂量组比较,金合欢素+EX527组晶状体上皮细胞形态改变和聚集现象加重,收缩压、FBG、晶状体混浊评分、MDA、IL-6、IL-1β水平均升高,SOD、GSH-Px含量及Sirt1、p-AMPK/AMPK、Nrf2蛋白表达水平均降低(均为P<0.05)。结论金合欢素可能通过激活Sirt1/AMPK/Nrf2通路保护DC大鼠免受氧化应激损伤。

IGF-1介导MAPKs通路在C3H10T1/2细胞成骨分化中的作用

目的探究胰岛素样生长因子1(IGF-1)介导丝裂原活化蛋白激酶(MAPKs)信号通路在C3H10T1/2细胞成骨分化中的调控作用及机制。方法不同浓度IGF-1(0、5、10、20 ng/mL)培养C3H10T1/2细胞,碱性磷酸酶(ALP)与茜素红(ARS)染色检测ALP活性、钙盐沉积情况,qRT-PCR法检测成骨特性因子核心结合因子α-1(RUNX2)、成骨分化特异性因子骨桥蛋白(OPN)、骨钙蛋白(OCN)mRNA表达水平,Western Blot法检测MAPK通路蛋白磷酸化表达水平。对数期细胞分为空白组、IGF-1组、ERK通路抑制剂(PD98059)组、PD+IGF-1组、p38通路抑制剂(SB202192)组、SB+IGF-1组,qRT-PCR法检测成骨特性因子RUNX2、成骨分化特异性因子骨桥蛋白(OPN)、骨钙蛋白(OCN)mRNA表达水平。结果不同浓度IGF-1组ALP显色加深,ALP活性升高,钙盐结节形成增多,RUNX2、OPN、OCN mRNA表达水平升高,磷酸化ERK、p38、JNK蛋白表达增加,具有剂量效应(P<0.05)。与空白组比较,PD组、SB组C3H10T1/2细胞RUNX2、OPN、OCN mRNA表达水平明显降低(P<0.05),PD+IGF-1组、SB+IGF-1组C3H10T1/2细胞RUNX2、OPN、OCN mRNA表达水平明显升高(P<0.05);但与IGF-1组比较,PD+IGF-1组、SB+IGF-1组C3H10T1/2细胞RUNX2、OPN、OCN mRNA表达水平明显降低(P<0.05)。结论IGF-1促进C3H10T1/2细胞成骨分化,其作用机制可能与激活ERK信号通路和p38 MAPK信号通路有关。

SOX7靶向ERK1/2/PD-L1通路抑制结直肠癌血管生成

目的探讨性别决定区Y框蛋白7(SOX7)对结直肠癌血管生成的影响及潜在作用机制。方法应用免疫荧光检测结直肠癌患者组织样本中SOX7表达水平,之后通过裸鼠、转染SOX7 mimic的人结直肠癌细胞系SW480细胞和人脐静脉内皮细胞(HUVEC)共培养进一步研究。用Western-blot验证SOX7与ERK1/2/PD-L1对结直肠癌细胞的相关蛋白表达的影响。用CCK8检测SOX7与ERK1/2/PD-L1对HUVEC增殖的影响。通过体外内皮细胞成管实验测定SOX7与ERK1/2/PD-L1对肿瘤血管生成的影响。结果SOX7在人结直肠癌组织中表达被抑制(P<0.01),同时SOX7的过表达抑制了小鼠体内肿瘤生长(P<0.01)。SW480细胞中SOX7的过表达抑制了ERK1/2、c-Jun的表达,并在ERK1/2的激动剂Senkyunolide I的作用下上调了SW480细胞的ERK1/2、c-Jun蛋白表达(P<0.01),逆转了SOX7对SW480细胞中ERK1/2、c-Jun蛋白表达的影响(P<0.01)。HUVEC中SOX7抑制了PD-L1、V-EGFR2、p-PI3K、HIF-1α的蛋白表达,Senkyunolide I上调了HUVEC的PD-L1、V-EGFR2、p-PI3K、HIF-1α的蛋白表达,并逆转了SOX7对HUVEC中上述相关蛋白表达的影响(P<0.01)。PD-1/PD-L1 Inhibitor 3抑制了PD-L1、V-EGFR2、p-PI3K、HIF-1α的蛋白表达,SOX7过表达在PD-1/PD-L1 Inhibitor 3的影响下并没有表现出抑制作用。CCK8实验结果显示SOX7过表达显著抑制了HUVEC的增殖能力,Senkyunolide I作用下的两组HUVEC增殖能力较SOX7 NC组与SOX7 mimic组明显上升,PD-1/PD-L1 Inhibitor 3作用下的两组HUVEC增殖能力较SOX7 NC组与SOX7 mimic组明显下降,以上均有明显统计学差异(P<0.01)。成管实验结果显示SOX7过表达抑制了HUVEC的血管生成,Senkyunolide I强烈加速了血管生成,而PD-1/PD-L1 Inhibitor 3血管生成则被显著抑制,以上均有明显统计学差异(P<0.01)。结论SOX7通过ERK1/2/PD-L1通路抑制结直肠肿瘤的增殖和血管生成,SOX7可能是晚期CRC患者临床治疗中潜在的抗血管生成靶点。

Involvement of MAPK/ERK kinase-ERK pathway in exogenous bFGF-induced Egr-1 binding activity enhancement in anoxia-reoxygenation injured astrocytes

Objective Intravenous administration of basic fibroblast growth factor （bFGF） is effective to reduce the volume of cerebral infract due to ischemia. This study was designed to investigate the molecular mechanism, especially the signal transduction pathways, involved in this protective role of bFGF. Methods Anoxia-reoxygenation treated atrocytes were used to study the role of mitogen-activated protein kinase/extracellular signal-regulated kinase kinase （MAPK/ERK kinase, MEK）-ERK signaling pathway after exogenous bFGF administration by Western blot. Electrophoretic mobile shift assay was used to detect the binding activity of early growth response factor-1 （Egr-1）, an important transcription factor for endogenous bFGF. Results bFGF could protect some signal transduction proteins from the oxygen-derived free radicals induced degradation. ERK1/2 was activated and involved in Egr-1 binding activity enhancement induced by exogenous bFGF. Conclusion MEK-ERK MAPK cascade may be an important signal transduction pathway contributed to bFGF induced enhancement of Egr-1 binding activity in anoxia-reoxygenation injured astrocytes.

Slit引导配体2通过调控AMPK/SIRT1-FoxO1信号通路影响糖尿病小鼠视网膜血管损伤的机制研究

目的 探讨Slit引导配体2(SLIT2)是否通过调控腺苷单磷酸活化蛋白激酶(AMPK)/转录沉默信息调节因子1(SIRT1)-叉头盒蛋白O1(FoxO1)信号通路通过对糖尿病小鼠视网膜血管损伤的影响。方法 30只db/db小鼠随机分为DR组(db/db小鼠)、DR+阴性对照载体组(DR+sh-NC组)和DR+sh-SLIT2组,每组10只。另选10只db/m小鼠为对照组。DR+sh-NC组和DR+sh-SLIT2组麻醉后分别在双眼玻璃体腔内注射sh-SLIT2的腺相关病毒(AAV)载体。眼底荧光血管造影(FFA)和苏木精伊红染色观察视网膜血管病变;酶联免疫吸附测定检测血清白细胞介素-6(IL-6),肿瘤坏死因子α(TNF-α)和血管内皮生长因子(VEGF)的水平,荧光定量PCR检测SLIT2 mRNA表达;Western blot检测视网膜组织SLIT2、AMPK、SIRT1、FoxO1蛋白水平。结果 与对照组相比,DR组、DR+sh-NC组、DR+sh-SLIT2组血糖、每日饮水量、每日排尿量、食物摄入量及体质量均明显升高(P<0.05);与对照组相比,DR组视网膜存在血管病变及病理损伤,SLIT2 mRNA及蛋白表达、IL-6、TNF-α和VEGF水平,FoxO1蛋白水平均明显升高(P<0.05),AMPK、SIRT1蛋白水平均明显降低(P<0.05);与DR+sh-NC组相比,DR+sh-SLIT2组的视网膜血管病变及病理损伤明显减轻,SLIT2 mRNA及蛋白表达、IL-6、TNF-α和VEGF水平,FoxO1蛋白水平均明显降低(P<0.05),AMPK、SIRT1蛋白水平均明显升高(P<0.05)。结论 沉默SLIT2表达显著改善糖尿病小鼠视网膜血管损伤及炎症水平,这可能是通过调控AMPK/SIRT1-FoxO1信号通路发挥作用的。

澳洲茄碱对肺癌A549细胞生物活性、瘤体抑制及MAPK/ERK1/2的影响

目的澳洲茄碱对肺癌A549细胞生物活性、瘤体抑制及MAPK/ERK1/2信号的影响。方法将人肺癌细胞株A549分为空白组、低剂量澳洲茄碱组、中剂量澳洲茄碱组、高剂量澳洲茄碱组及顺铂组,分别加入浓度为0、15、20、25μmol/L的澳洲茄碱及2μg/mL顺铂培养。MTT检测活性;流式细胞仪检测凋亡率;Transwell法检测侵袭;划痕试验检测划痕愈合率。25只裸鼠分为空白组、低剂量澳洲茄碱组、中剂量澳洲茄碱组、高剂量澳洲茄碱组及顺铂组,皮下注射0.3 mL的0、15、20、25μmol/L的澳洲茄碱及2μg/mL顺铂共培养A549细胞,观察瘤体质量及抑瘤率。结果澳洲茄碱组降低A549细胞活性,凋亡率升高,侵袭、划痕愈合率、MAPK、p-MAPK、ERK1/2及p-ERK1/2蛋白水平降低(P<0.05)。结论澳洲茄碱可抑制肺癌细胞增殖、侵袭及转移,并加快凋亡,作用呈现剂量依赖性且高剂量效果最佳,研究机制可能与抑制MAPK/ERK1/2信号表达相关。

草鱼TAB2与TAK1蛋白互作鉴定及其对两种抗菌肽基因表达的影响

为了探究草鱼TAB2(Ci TAB2)与Ci TAK1能否互作及其对2种草鱼抗菌肽基因(Cihepcidin与Ciβ-defensin1)表达的影响,实验首先采用实时荧光定量PCR(qPCR)方法分析拟态弧菌感染后Citab2和Citak1在草鱼免疫相关组织中的时空表达模式。然后利用荧光共定位、免疫共沉淀及Western blot技术鉴定Ci TAB2与Ci TAK1在细胞内共定位及相互作用情况。最后将过表达质粒pEGFP-N1-Citak1与pEGFP-N1-Citab2共同转染草鱼肾细胞(CIK细胞),检测Cihepcidin与Ciβ-defensin1的相对mRNA表达水平。结果显示,拟态弧菌感染能够显著改变Citab2和Citak1的相对表达水平,前者于感染后不同时间在各检测组织中表现出不同的时空表达模式,而后者均呈现先上调后下调的表达模式;荧光显微镜下观察到Ci TAB2与Ci TAK1共定位于转染后的HEK293T和CIK细胞的胞质中,且在HEK293T细胞内能够形成Ci TAB2-Ci TAK1蛋白复合物;共同过表达Ci TAB2与Ci TAK1后,CIK细胞内Cihepcidin与Ciβ-defensin1的相对mRNA表达水平在各检测时间点均显著上调。结果表明,Ci TAB2与Ci TAK1存在互作关系且二者互作能够促进上述两种抗菌肽的转录表达。本研究从蛋白互作调控抗菌肽表达的角度为防治鱼类弧菌病提供了新策略。

丁酸钠经AMPK/Nrf2/HO-1信号通路调节脂多糖诱导肺泡巨噬细胞极化的作用机制

目的探讨丁酸钠(sodium butyrate,SB)对脂多糖(lipopolysaccharide,LPS)诱导肺泡巨噬细胞极化的影响及其作用机制。方法小鼠肺泡巨噬细胞(MH-S细胞)随机分为对照(Control)组、LPS组、SB组、LPS+SB(LB)组、LPS+SB+腺苷酸活化蛋白激酶(AMPK)抑制剂(Compound C)(LC)组、LPS+SB+核因子E2相关因子2(Nrf2)抑制剂(ML385)(LM)组。通过CCK8检测MH-S细胞活力,筛选出最佳的1000 ng/mL LPS、1 mmol/L SB、10μmol/L Compound C、5μmol/L ML385药物浓度进行后续实验;实时荧光定量(qRT-PCR)检测MH-S细胞白细胞介素-6(IL-6)、肿瘤坏死因子-α(TNF-α)、白细胞介素-1β(IL-1β)、白细胞介素-10(IL-10)、白细胞分化抗原86(CD86)、巨噬细胞甘露糖受体(CD206)、AMPK、Nrf2和血红素加氧酶1(HO-1)的mRNA表达水平;酶联免疫吸附试验(ELISA)检测培养基上清IL-6、TNF-α、IL-1β和IL-10蛋白含量;流式细胞术测定M1和M2型巨噬细胞相关标记物CD86和CD206的表达。各组数据通过单因素方差分析和Tukey法进行检验。结果通过CCK8选取了1000 ng/mL LPS、1 mmol/L SB、10μmol/L Compound C和5μmol/L ML385进行造模和干预。qRT-PCR和ELISA结果一致显示,与LPS组比较,LB组M1型巨噬细胞相关促炎细胞因子IL-6、TNF-α、IL-1β显著降低(均P<0.01),但M2型巨噬细胞相关抑炎细胞因子IL-10显著升高(均P<0.01)。qRT-PCR和流式细胞术结果一致显示,与Control组比较,LPS组CD86水平显著升高(均P<0.01),SB组差异无统计学意义;与LPS组比较,LB组CD86表达水平显著降低(均P<0.01),但M2型巨噬细胞标记物CD206的变化趋势与CD86相反。qRT-PCR结果显示,与LPS组比较,LB组促进AMPK/Nrf2/HO-1的表达(均P<0.05);与LB组比较,LC组降低了AMPK/Nrf2/HO-1的表达(均P<0.05),LM组降低了Nrf2/HO-1的表达(均P<0.05)。流式细胞术结果显示,与LB组比较,LC组和LM组逆转了SB对CD86水平的抑制作用(均P<0.01);M2型巨噬细胞标记物CD206的表达趋势与M1型巨噬细胞标记物CD86相反。结论SB通过激活AMPK/Nrf2/HO-1信号通路,抑制LPS诱导的M1型、促进M2型肺泡巨噬细胞极化,改善了炎症反应。

SIRT6过表达激活AMPK/Nrf2/HO-1通路抑制AngⅡ诱导的心肌细胞凋亡

[目的]探讨沉默调节蛋白6(SIRT6)过表达抑制血管紧张素Ⅱ(AngⅡ)诱导的心肌细胞凋亡是否涉及腺苷酸活化蛋白激酶/核因子E2相关因子2/血红素加氧酶1(AMPK/Nrf2/HO-1)信号通路的激活。[方法]将实验分为4组:对照组、AngⅡ组、AngⅡ+SIRT6组和AngⅡ+空载体(EV)组,通过RT-PCR检测SIRT6的mRNA水平,MTT法检测细胞活性,流式细胞术检测细胞凋亡率,Western blot检测SIRT6、心肌细胞凋亡相关蛋白(Bax、cleaved Caspase-3、Bcl-2)、DNA损伤相关蛋白(γ-H2AX、p-ATM)及AMPK/Nrf2/HO-1信号通路相关蛋白(p-AMPK、Nrf2、HO-1)的表达水平,DCFH-DA染色法测定活性氧(ROS)含量,比较各组间上述指标的变化情况。[结果]与对照组相比,AngⅡ组SIRT6的mRNA、蛋白表达水平及细胞活性明显降低,细胞凋亡率增高,Bax、cleaved Caspase-3表达升高,Bcl-2表达降低,γ-H2AX、p-ATM蛋白表达升高,p-AMPK、Nrf2、HO-1蛋白表达降低,ROS活性增高(均P<0.01)。与AngⅡ+EV组相比,AngⅡ+SIRT6组SIRT6水平及细胞活性增高,细胞凋亡及Bax、cleaved Caspase-3表达降低,Bcl-2表达升高,γ-H2AX、p-ATM蛋白表达降低,p-AMPK、Nrf2、HO-1蛋白表达升高,ROS的活性降低(均P<0.01)。[结论]SIRT6过表达抑制AngⅡ诱导的心肌细胞凋亡与AMPK/Nrf2/HO-1信号通路的激活有关。