Hesperidin ameliorates H_(2)O_(2)-induced bovine mammary epithelial cell oxidative stress via the Nrf2 signaling pathway

Background Hesperidin is a citrus flavonoid with anti-inflammatory and antioxidant potential. However, its protective effects on bovine mammary epithelial cells(b MECs) exposed to oxidative stress have not been elucidated.Results In this study, we investigated the effects of hesperidin on H_(2)O_(2)-induced oxidative stress in b MECs and the underlying molecular mechanism. We found that hesperidin attenuated H_(2)O_(2)-induced cell damage by reducing reactive oxygen species(ROS) and malondialdehyde(MDA) levels, increasing catalase(CAT) activity, and improving cell proliferation and mitochondrial membrane potential. Moreover, hesperidin activated the Keap1/Nrf2/ARE signaling pathway by inducing the nuclear translocation of Nrf2 and the expression of its downstream genes NQO1 and HO-1, which are antioxidant enzymes involved in ROS scavenging and cellular redox balance. The protective effects of hesperidin were blocked by the Nrf2 inhibitor ML385, indicating that they were Nrf2 dependent.Conclusions Our results suggest that hesperidin could protect b MECs from oxidative stress injury by activating the Nrf2 signaling pathway, suggesting that hesperidin as a natural antioxidant has positive potential as a feed additive or plant drug to promote the health benefits of bovine mammary.

Roles of TGF-β Signaling Pathway in Endoplasmic Reticulum Stress in Endothelial Cells Stimulated with Cigarette Smoke Extract

To investigate the role of signaling pathway in the effect of endoplasmic reticulum stress（ER stress） in endothelial cells stimulated with cigarette smoke extract（CSE）. Human umbilical vein endothelial cells（HUVECs） were cultured and divided into 3 groups： CSE-stimulated group, CSE-stimulated with 4-PBA group, and negative control group. HUVECs were cultured and stimulated with CSE at concentrations of 5%, 10% and 20%, respectively, mR NA of CXCL-8 and GRP78 was detected by real-time PCR. ELISA was performed to test the expression of CXCL-8 protein, and neutrophils migration was detected by Transwell board test. The NF-κB, ERK, p38 MAPK and transforming growth factor beta（TGF-β） were detected by flow cytometry. The mRNA of CXCL-8 and GRP78 increased in CSE-stimulated HUVECs（P〈0.05）. Furthermore, it was concentration-dependent. 4-PBA significantly reduced the expression of CXCL-8 protein（P〈0.05） and neutrophil migration（P〈0.05）. The TGF-β, rather than the NF-κB, ERK and P38 MAPK pathway might be involved in ER stress stimulated by CSE. CSE induced neutrophils migration by increasing the expression of CXCL-8 in endothelial cells. ER stress might play a role in the effect of neutrophils migration stimulated with CSE, and TGF-β pathway may contribute to the ER stress in HUVECs.

Angelica sinensis polysaccharides ameliorate 5-flourouracil-induced bone marrow stromal cell proliferation inhibition via regulating Wnt/β-catenin signaling

Chemotherapy may cause cellular oxidative stress to bone marrow.Oxidative damage of bone marrow hematopoietic microenvironment is closely related to chronic myelosuppression after chemotherapeutic treatment.Angelica sinensis polysaccharides(ASP)are major effective ingredients of traditional Chinese medicine Angelica with multi-target anti-oxidative stress features.In the current study,we investigated the protective roles and mechanisms of ASP on chemotherapy-induced bone marrow stromal cell(BMSC)damage.The human bone marrow stromal cell line HS-5 cells were divided into control group,5-FU group,5-FU+ASP group,and 5-FU+LiCl group to investigate the mechanism of ASP to alleviate 5-FU-induced BMSC proliferation inhibition.The results showed that 5-FU inhibits the growth of HS-5 cells in a time and dose-dependent manner;however,ASP partially counteracted the 5-FU-induced decrease in cell viability,whereas Wnt signaling inhibitor Dkk1 antagonized the effect of ASP on HS-5 cells.ASP reversed the decrease in total cytoplasmicβ-catenin,p-GSK-3β,and CyclinD1 following 5-FU treatment and modulated nuclear expression ofβ-catenin,Lef-1,and C-myc proteins.Furthermore,ASP also enhanced the antioxidant capacity of cells and reduced 5-FU-induced oxidative stress,attenuated FoxO1 expression,thus weakened its downstream apoptosis-related proteins and G0/G1 checkpoint-associated p27^(Kip1) expression to alleviate 5-FU-induced apoptosis and to promote cell cycle progression.All the results above suggest that the protective role of ASP in 5-FU-treated BMSCs proliferation for the chemotherapy may be related to its activating Wnt/β-catenin signaling and keeping homeostasis betweenβ-catenin and FoxO1 under oxidative stress.The study provides a potential therapeutic strategy for alleviating chemotherapeutic damage on BMSCs.

Mitochondrial oxidative damage and apoptosis induced by high glucose through Rho kinase signal pathway in renal tubular epithelial cells

Objective:To investigate the role of oxidative stress in human renal tubular epithelial cells(HK-2)induced by high glucose and the underlying signal pathway in vitro.Methods:MYPT1,pro-caspase-3,PGC-1α,and Drpl protein expressions were measured by Western blot.MnSOD2,Drp1 and PGC-1αmRNA expressions were detected by real time PCR.Results:Results showed that high glucose significantly up-regulated the protein expressions of MYPT1,pro-caspase-3 and the mRNA expression of MnSOD2 in HK-2 cells;while Rho kinase inhibitor fasudil and ROCK1 siRNA inhibited protein expressions of pro-caspase-3 and the mRNA expression of MnSOD2 in HK-2 cells induced by high glucose.Importantly,fasudil and ROCK1 siRNA markedly inhibited the expressions of mitochondrial motor proteins Drp1 and mitochondrial gene PGC-la in HK-2 cell=s induced by high glucose.Conclusions:Our findings suggest that Rho kinase signal pathway is involved in mitochondrial oxidative damage and apoptosis in high glucose-induced renal tubular epithelial cells by regulating mitochondrial motor proteins Drp1 and mitochondrial gene PGC-1α.Targeting Rho kinase signal pathway might be a potential strategy for the treatment of diabetic nephropathy.

HIV protease inhibitors sensitize human head and neck carcinoma cells to radiation by activating endoplasmic reticulum stress

Aim Head and neck cancers are the eighth most common cancer worldwide. Despite significant ad- vances in the delivery of treatment and surgical reconstruction, the mortality rates for this disease have not improved in the past 4 decades. Our previous study has shown that HIV protease inhibitors （HIV PIs） induce cell apoptosis via activating endoplasmic reticulum （ER） stress. It also has been reported that a few HIV PIs are able to radio- sensitize tumor cells. However, the underlying cellular mechanisms remain to be identified. The aim of this study was to examine whether HIV PIs activate the ER stress response and sensitize human head and neck carcinoma cells to radiation. Methods Human SQ20B and Fadu cells and the most commonly used HIV PIs, lopinavir and ritona- vir, were used in this study. The mRNA and protein levels of ER stress-related genes （ CHOP, ATF4, XBP-1, and GRP78 ） were detected by real time RT-PCR and Western blot, respectively. Cell viability and apoptosis were ana- lyzed using Cellometer Vision CBA. After treatment with HIV PIs, cells were irradiated at a dose of 2G or 4G. Col- onies were stained and counted 10 days after irradiation. Results HIV PIs significantly induced activation of ER stress and apoptosis. Treatment of HIV PIs inhibited Akt phosphorylation, induced cell cycle arrest in G1 phase and increased tumor cell sensitivity to irradiation-induced cell death. Conclusion HIV PIs sensitize human head and neck carcinoma cells to radiation by activating ER stress.

内质网应激PERK通路在肿瘤中的研究进展

肿瘤细胞在生长、浸润和转移过程中经历的缺氧、低糖等多种环境压力会对肿瘤细胞造成内质网应激,为应对内质网应激,肿瘤细胞会诱发未折叠蛋白反应(Unfolded protein response,UPR)。PERK通路作为激活UPR的一条关键通路可通过提高肿瘤对不良微环境的耐受程度、诱导新生血管生成、诱导自噬体形成、激活凋亡信号分子等促进肿瘤细胞生长、增殖、侵袭及保护性自噬,并且在UPR达到一定程度时诱导肿瘤细胞凋亡及自噬性死亡。

Fucoxanthin suppresses OxLDL-induced inflammation via activation of Nrf2 and inhibition of NF-κB signaling

Objective:To explore the impact of fucoxanthin on oxidized low-density lipoprotein(OxLDL)-induced stress and inflammation in human endothelial cells and its underlying mechanisms.Methods:HUVECs were treated with OxLDL and/or fucoxanthin for a range of time points and concentrations.We evaluated the effects of fucoxanthin on OxLDL-induced HUVECs using the MTT assay,reactive oxygen species accumulation assay,ELISA,RT-PCR,immunofluorescence,and Western blotting.Results:Fucoxanthin enhanced the cell viability in a dose dependent manner after OxLDL exposure.Furthermore,fucoxanthin pretreatment significantly decreased OxLDL-induced reactive oxygen species production and prevented the activation of the nuclear factor kappa-B pathway,which led to substantial suppression of pro-inflammatory gene expressions.OxLDL-induced upregulation of interleukin-6,intercellular adhesion molecule-1,vascular cell adhesion molecule-1,interleukin-1β,monocyte chemotactic protein-1,cyclooxygenase-1,and tumor necrosis factor-αwas significantly reduced by fucoxanthin.Conclusions:Fucoxanthin can inhibit OxLDL-induced vascular inflammation and oxidative stress in HUVECs by targeting Nrf2 signaling pathways.

Novel nervous and multi-system regenerative therapeutic strategies for diabetes mellitus with mTOR

Throughout the globe,diabetes mellitus（DM） is increasing in incidence with limited therapies presently available to prevent or resolve the significant complications of this disorder.DM impacts multiple organs and affects all components of the central and peripheral nervous systems that can range from dementia to diabetic neuropathy.The mechanistic target of rapamycin（m TOR） is a promising agent for the development of novel regenerative strategies for the treatment of DM.m TOR and its related signaling pathways impact multiple metabolic parameters that include cellular metabolic homeostasis,insulin resistance,insulin secretion,stem cell proliferation and differentiation,pancreatic β-cell function,and programmed cell death with apoptosis and autophagy.m TOR is central element for the protein complexes m TOR Complex 1（m TORC1） and m TOR Complex 2（m TORC2） and is a critical component for a number of signaling pathways that involve phosphoinositide 3-kinase（PI 3-K）,protein kinase B（Akt）,AMP activated protein kinase（AMPK）,silent mating type information regulation 2 homolog 1（Saccharomyces cerevisiae）（SIRT1）,Wnt1 inducible signaling pathway protein 1（WISP1）,and growth factors.As a result,m TOR represents an exciting target to offer new clinical avenues for the treatment of DM and the complications of this disease.Future studies directed to elucidate the delicate balance m TOR holds over cellular metabolism and the impact of its broad signaling pathways should foster the translation of these targets into effective clinical regimens for DM.

c-Abl-MST1 Signaling Pathway Mediates Oxidative Stress Induced Neuronal Cell Death

Oxidative stress influences cell survival and homeostasis, but the mechanisms underlying the biological effects of oxidative stress remain to be elucidated. We have defined that the

Glucose-regulated protein 78 inhibits scavenger receptor A-mediated internalization of acetylated low density lipoprotein

Class A scavenger receptor(SR-A) plays an important role in foam cell formation.However, the mechanism underlying the internalization of the receptor-ligand complexes remains unclear.The aim of the present study was to investigate the molecular mechanism to regulate SR-A-mediated intracellular lipid accumulation in macrophages A pull-clown assay was performed and glucoseregulated protein 78(GRP78) was identified to bind with the cytoplasmic domain of SR-A(CSR-A).Immunoprecipitation and artificially expressed protein binding assay demonstrated the direct specific binding of GRP78 with SR-A in cells.Indirect immunofluorescence assay and western blot analysis showed their co-localization in membrane and cytoplasm.Over-expression of GRP78 specifically inhibited SR-A-mediated uptake of fluorescent acetylated low-density lipoprotein, a specific ligand for SR-A, without altering cellular SR-A expression and binding ability, and significantly inhibited cholesterol ester accumulation in cells, which can be partly attributed to the suppression of c-Jun-NH2-terminal kinase signaling pathway.These results suggest that GRP78 may act as an inhibitor of SR-A-mediated internalization of modified low-density lipoprotein into macrophages(C) 2009 Elsevier Inc.All rights reserved.

非折叠蛋白反应——一条综合的细胞内信号通路

内质网(endoplasmic reticulum,ER)作为细胞中蛋白成熟的场所,可以很敏感的感受细胞内外环境的变化。当ER内环境改变,细胞就会激活信号应对这些改变,并且重新恢复折叠蛋白的环境。内质网的这种改变就是内质网应激(endoplasmic reticulum stress,ERS),而对这种应激作出的反应就是非折叠蛋白反应[1(]Unfolded Protein Response,UPR)。UPR至少引起了3种不同的信号通路,这些通路不仅调控分泌途径中大部分基因的表达,而且还广泛影响细胞的各个方面包括蛋白质、氨基酸和脂类的代谢。同时,这3条通路可以综合的调控细胞分泌器官的重塑并根据ERS重新调节细胞的生理活性。就UPR相关的感受器及其信号通路作简要的介绍。

丹参酮ⅡA减轻棕榈酸诱导的心肌细胞凋亡及内质网应激

【目的】探讨丹参酮ⅡA对棕榈酸诱导心肌细胞脂毒性损伤模型内质网应激凋亡的影响。【方法】将对数期H9c2细胞分6组,即对照组,棕榈酸(400μmol/L)组,丹参酮ⅡA 20μmol/L组和棕榈酸+丹参酮ⅡA(5、10、20μmol/L)组,另外引入棕榈酸+CCT020312组与棕榈酸+CCT020312+丹参酮ⅡA 20μmol/L组考察通路激活状态。细胞计数试剂盒8(CCK-8)法测定H9c2细胞活力;流式细胞术测定细胞凋亡情况;实时定量聚合酶链反应(RT-qPCR)法检测细胞内质网应激相关分子葡萄糖调控蛋白78(GRP78)、转录激活因子4(ATF4)和CCAAT/增强子结合蛋白同源蛋白(CHOP)的mRNA表达水平;蛋白免疫印迹(Western Blot)法检测细胞GRP78、ATF4、CHOP、Caspase-3、Caspase-9、Caspase-12、蛋白激酶RNA样内质网激酶(PERK)、磷酸化PERK(p-PERK)、真核生物翻译起始因子2α(eIF2α)、磷酸化eIF2α(p-eIF2α)的蛋白表达水平。【结果】与对照组比较,棕榈酸组细胞存活率显著降低(P <0.01),GRP78、ATF4、CHOP m RNA和蛋白表达水平均显著升高(P <0.01),H9c2细胞的凋亡率升高,p-PERK/PERK和p-eIF2α/eIF2α比例也显著增大(P <0.01),凋亡相关分子Caspase-3、Caspase-9和Caspase-12蛋白表达水平均显著升高(P <0.01)。不同浓度丹参酮ⅡA作用后,与棕榈酸组比较,棕榈酸+丹参酮ⅡA(5、10、20μmol/L)组细胞存活率显著升高(P <0.01),GRP78、ATF4、CHOP mRNA和蛋白表达水平均显著降低(P <0.01),H9c2细胞的凋亡率降低,p-PERK/PERK和p-eIF2α/eIF2α比例也显著减小(P <0.01),Caspase-3、Caspase-9和Caspase-12蛋白表达水平显著降低(P <0.01),均具有剂量依赖性,且棕榈酸+丹参酮ⅡA 10μmol/L组(P <0.05)和棕榈酸+丹参酮ⅡA 20μmol/L组(P <0.05)变化显著。加入PERK通路激活剂CCT020312作用后,与棕榈酸组比较,棕榈酸+CCT020312组的p-PERK/PERK和p-eIF2α/eIF2α比例,细胞凋亡率,GRP78、ATF4、CHOP的mRNA和蛋白表达水平均显著升高(P <0.05);再经过丹参酮ⅡA处理,与棕榈酸+CCT020312组比较,棕榈酸+CCT020312+丹参酮ⅡA组的p-PERK/PERK和p-eIF2α/eIF2α比例,细胞凋亡率,GRP78、ATF4、CHOP的m RNA和蛋白表达水平均显著回降(P <0.05)。【结论】丹参酮ⅡA可减轻心肌细胞脂毒性损伤,其机制与其通过抑制PERK信号通路活化来减轻棕榈酸诱导的心肌H9c2细胞凋亡,并且控制内质网应激反应有关。

nitiation of ER Body Formation and Indole Glucosinolate Metabolism by the Plastidia Retrograde Signaling Metabolite, MEcPP

Plants have evolved tightly regulated signaling networks to respond and adapt to environmental perturbations, but the nature of the signaling hub（s） involved have remained an enigma. We have previously established that methylerythritol cyclodiphosphate （MEcPP）, a precursor of plastidial isoprenoids and a stress- specific retrograde signaling metabolite, enables cellular readjustments for high-order adaptive functions. Here, we specifically show that MEcPP promotes two Brassicaceae-specific traits, namely endoplasmic reticulum （ER） body formation and induction of indole glucosinolate （IGs） metabolism selectively, via tran- scriptional regulation of key regulators NAIl for ER body formation and MYB51/122 for IGs biosynthesis）. The specificity of MEcPP is further confirmed by the lack of induction of wound-inducible ER body genes as well as IGs by other altered methylerythritol phosphate pathway enzymes. Genetic analyses revealed MEcPP-mediated COil-dependent induction of these traits. Moreover, MEcPP signaling integrates the biosynthesis and hydrolysis of IGs through induction of nitrile-specifier protein1 and reduction of the sup- pressor, ESM1, and production of simple nitriles as the bioactive end product. The findings position the plastidial metabolite, MEcPP, as the initiation hub, transducing signals to adjust the activity of hard- wired gene circuitry to expand phytochemical diversity and alter the associated subcellular structure required for functionality of the secondary metabolites, thereby tailoring plant stress responses.

艾塞那肽对高糖诱导INS-1细胞内质网应激及JNK信号通路的影响

目的探讨艾塞那肽对高糖诱导INS-1细胞的内质网应激(ERS)及对JNK信号通路的影响。方法小鼠INS-1细胞按不同的处理方式分为4组:对照组(A组,完全培养基)、高糖组(B组,30mmol/L糖培养基)、高糖+100nmol/L艾塞那肽组(C组)、高糖+100nmol/L艾塞那肽+JNK激动剂组(D组)。每天换液前观察各组细胞生存状态,培养7天后,MTT法检测细胞活性;提取细胞总蛋白,Western blot法检测Bip、CHOP、P-SAPK/JNK、caspase-3蛋白的表达水平。结果培养至第4天B组细胞出现死亡,培养至第6、7天B组及D组细胞出现大量死亡;与A组比较,B组和D组的活性(A值)下降(P <0. 05);与A组比较,B组高糖刺激后导致内质网应激上调Bip、CHOP、P-SAPK/JNK、caspase-3的表达量(P <0. 05);与B组比较,C组艾塞那肽可通过抑制内质网应激下调Bip、CHOP、P-SAPK/JNK、caspase-3表达量(P <0. 05);与C组比较,D组JNK激动剂促进JNK信号通路上调P-SAPK/JNK、caspase-3表达量(P <0. 05)。结论艾塞那肽可以缓解或阻断高糖刺激诱发的INS-1细胞内质网应激(ERS),抑制JNK信号通路,减少细胞凋亡。

脑损伤触发细胞类型特异性和时间依赖性内质网应激反应

未折叠蛋白反应(UPR)是一种通过协调蛋白质稳态以响应内质网(ER)应激来维持细胞活力的信号转导网络。当适应性反应未能改善蛋白质稳态时,UPR也会引发细胞死亡。尽管越来越多的证据表明UPR在神经退行性疾病和脑损伤中发挥作用,但我们对在神经病理学条件下如何诱导ER应激的理解是有限的。我们使用ER应激激活指示剂(ERAI)小鼠研究了脑损伤后ER应激反应的细胞和时间特异性模式,这让我们能够通过剪接的XBP-1与绿色荧光蛋白(GFP)Venus变体融合蛋白增强的荧光来监测体内的UPR。在ERAI小鼠皮质刺伤后的整个观察期间(受伤后6 h~7 d),同侧皮质的GFP信号和GFP+细胞数量增加,证实了UPR的发生。脑损伤后早期(从6 h起)在受损神经元中即观察到了GFP信号。然而,非神经元细胞(主要是内皮细胞,其次是星形胶质细胞)在脑损伤后占GFP+细胞的大部分。在局灶性脑缺血的小鼠模型中观察到了类似的结果。这些发现表明,UPR在神经元和非神经元细胞中的激活,尤其是内皮细胞和星形胶质细胞,可能在急性脑损伤中发挥重要作用,并可能成为其潜在的治疗靶点。

A small molecule UPR modulator for diabetes identified by high throughput screening

Unfolded protein response(UPR) is a stress response that is specific to the endoplasmic reticulum(ER).UPR is activated upon accumulation of unfolded(or misfolded) proteins in the ER's lumen to restore protein folding capacity by increasing the synthesis of chaperones.In addition,UPR also enhances degradation of unfolded proteins and reduces global protein synthesis to alleviate additional accumulation of unfolded proteins in the ER.Herein,we describe a cell-based ultra-high throughput screening(uHTS) campaign that identifies a small molecule that can modulate UPR and ER stress in cellular and in vivo disease models.Using asialoglycoprotein receptor 1(ASGR) fused with Cypridina luciferase(CLuc) as reporter assay for folding capacity,we have screened a million small molecule library and identified APC655 as a potent activator of protein folding,that appears to act by promoting chaperone expression.Furthermore,APC655 improved pancreatic β cell viability and insulin secretion under ER stress conditions induced by thapsigargin or cytokines.APC655 was also effective in preserving β cell function and decreasing lipid accumulation in the liver of the leptin-deficient(ob/ob) mouse model.These results demonstrate a successful uHTS campaign that identified a modulator of UPR,which can provide a novel candidate for potential therapeutic development for a host of metabolic diseases.

内质网应激与疾病

内质网是蛋白质合成与折叠、维持Ca^(2+)动态平衡及合成脂类和固醇的场所。遗传或环境损伤引起内质网功能紊乱导致内质网应激,激活未折叠蛋白反应。未折叠蛋白反应是一种细胞自我保护性措施,但是内质网应激过强或持续时间过久可引起细胞凋亡。因此,内质网应激与众多人类疾病的发生发展密切相关。最近研究证明,癌症、炎症性疾病、代谢性疾病、骨质疏松症及神经退行性疾病等有内质网应激信号传递参与。然而内质网应激作为一个有效靶点参与各种疾病发挥作用的功能和机制仍然有待进一步研究。在近年来发表的文献基础上对内质网应激与疾病的关系,以及其可能的作用机制进行综述。