IFN-γ增强细胞毒类药物对神经母细胞瘤的诱导凋亡作用

目的探讨细胞毒类药物对神经母细胞瘤细胞株SH-SY5Y（SY5Y）细胞的作用及γ-干扰素（IFN-γ）对其抗瘤活性的影响。方法应用逆转录酶-聚合酶链反应（RT-PCR）方法检测IFN-γ作用前后半胱-天冬氨酸蛋白酶8（Caspase8）mRNA的表达;应用流式细胞仪检测细胞毒类药物[阿霉素、肿瘤坏死因子-α（TNF-α）、肿瘤坏死因子相关凋亡诱导配体（TRAIL）]及IFN-γ联合细胞毒类药物对SY5Y细胞的诱导凋亡作用;应用比色法测定Caspase8相对活性。结果SY5Y细胞不表达Caspase8,经IFN-γ作用后Caspase8mRNA表达明显增加。SY5Y细胞对阿霉素相对敏感,对TNF-α和TRAIL不敏感;经IFN-γ预处理后,表达Caspase8的SY5Y细胞对三种细胞毒类药物的诱导凋亡作用敏感并伴随Caspase8活性增高,此作用可被Caspase8抑制剂所阻断。结论IFN-γ通过上调Caspase8表达而增强细胞毒类药物对神经母细胞瘤细胞的诱导凋亡作用。     

胶质瘤细胞GDNF基因启动子Ⅰ区甲基化水平对其基因转录的影响

目的 探讨胶质瘤细胞胶质细胞原性神经营养因子（GDNF）基因启动子Ⅰ区甲基化水平对其基因转录的影响。方法 体外培养胶质瘤U251细胞,加入不同浓度5-氮杂胞苷（浓度分别为1、5、10和20 μmol/L）干预,以加入PBS为对照。采用重亚硫酸盐测序法测定GDNF基因启动子Ⅰ区甲基化水平,RT-PCR检测GDNF mRNA的表达。结果 与PBS组相比,1 μmol/L 5-氮杂胞苷对GDNF基因启动子Ⅰ区甲基化水平无显著影响（P>0.05）,5、10和20 μmol/L 5-氮杂胞苷均显著降低其甲基化水平（P<0.05）。与PBS组相比,1 μmol/L 5-氮杂胞苷对GDNF mRNA表达水平无显著影响（P>0.05）,5 μmol/L 5-氮杂胞苷显著增加其表达水平（P<0.05）,但随着浓度进一步增加（10、20 μmol/L）,其表达水平逐渐降低。结论 5-氮杂胞苷对GDNF基因具有去甲基化作用;GDNF启动子Ⅰ区去甲基化能够增加GDNF基因的转录水平。     

嘌呤霉素敏感的氨肽酶对β-淀粉样蛋白诱导的细胞凋亡的影响

目的 探讨嘌呤霉素敏感的氨肽酶(PSA)对β-淀粉样蛋白(Aβ25-35)诱导的SH-SY5Y细胞、PC12细胞凋亡的影响. 方法 采用MTT法检测Aβ25-35对SH-SY5Y、PC12细胞生长的影响;Hoechst染色检测Aβ25-35对SH-SY5Y、PC12细胞核形态的影响;进一步采用脂质体转染法在SH-SY5Y细胞中瞬时转染PSA-siRNA,在PC12细胞中瞬时转染PSA重组质粒,加入Aβ25-35作用24h后收集细胞,进行流式细胞术检测细胞凋亡率;Western blotting检测PSA、caspase-3蛋白的表达变化;酶标仪检测caspase-3活性. 结果 Aβ25-35抑制SH-SY5Y、PC12细胞增殖,细胞核发生凋亡的形态学改变,流式检测细胞凋亡率增加;在SH-SY5Y细胞中,沉默PSA表达能使Aβ25-35诱导的细胞凋亡率升高,促进caspase-3酶原激活,caspase-3活性升高.反之,PC12细胞中过表达的PSA能使Aβ25-35诱导的细胞凋亡率下降,抑制caspase-3酶原激活,caspase-3活性降低. 结论 Aβ25-35能抑制神经细胞生长,引起神经细胞凋亡;PSA能抑制Aβ25-35诱导的神经细胞凋亡,对神经元具有保护作用,其机制可能与抑制caspase-3通路的激活有关.     

铁离子促进过量多巴胺引起SH-SY5Y细胞儿茶酚异喹啉物质生成和氧化损伤

目的帕金森氏病（Pakinson’s disease,PD）中多巴胺能神经元选择性缺失与胞内铁水平升高有密切关系,提示铁可能通过参与氧化应激在PD发病机制中起重要作用。本研究使用一定浓度的Fe^2＋和多巴胺诱导人多巴胺能成神经细胞瘤SH—SY5Y细胞产生氧化应激状态,并且检测胞内是否有多巴胺衍生类的神经内毒素物质产生。方法多巴胺添加不同浓度的Fe^2＋诱导SH—SY5Y细胞,24h后用乳酸脱氢酶法、水杨酸捕获法、硫代巴比妥酸法、Hoechst33258染色法和带有电化学检测器的高效液相色谱仪分别检测细胞存活率、羟自由基生成量、丙二醛含量、细胞凋亡和儿茶酚异喹啉物质的生成情况。结果（1）150μmol／L多巴胺添加40或80μmol／LFe^2＋后,胞内羟自由基和丙二醛含量较对照组显著增加：（2）单独多巴胺以及多巴胺加40或80μmol／LFe^2＋诱导后细胞发生凋亡：（3）在诱导后的胞内检测到Salsolinol和N-methylsalsolinol的含量高于对照组。结论一定浓度的Fe^2＋和多巴胺诱导SH—SY5Y细胞可模拟帕金森氏病人黑质区多巴胺能神经元所受到的氧化应激状态,胞内检测到的儿茶酚异喹啉物质,如去甲猪毛菜碱和N-methyl—salsolinol,可能作为一类潜在的神经毒性物质与帕金森氏病的发病有关。     

5-氮杂胞苷诱导人脐带间充质干细胞向心肌样细胞的分化☆

背景：5-氮杂胞苷能诱导人脐带间充质干细胞分化为心肌细胞。 目的：以5-氮杂胞苷诱导人脐带间充质干细胞分化为心肌细胞。 方法：采用贴壁培养法分离、纯化人脐带间充质干细胞,以5-氮杂胞苷诱导第3代人脐带间充质干细胞分化为心肌样细胞。 结果与结论：诱导前人脐带间充质干细胞呈典型的梭形;诱导后一二周细胞体积变大,三四周后相邻细胞间胞膜有接触,逐渐相连呈肌管状,细胞胞质内可见细丝样结构。诱导4周后免疫组织化学鉴定人脐带间充质干细胞cTnI表达阳性,未诱导细胞cTnI表达阴性;诱导组Nkx2.5、GATA 4 mRNA表达水平较未诱导组显著增加(P < 0.05)。提示5-氮杂胞苷可能通过调控GATA4、Nkx2.5基因的表达促进人脐带间充质干细胞分化为心肌样细胞,并促进其成熟。     

促红细胞生成素对1-甲基-4-苯基吡啶损伤的PC12细胞的保护作用

目的探讨促红细胞生成素（erythropoietin,EPO）对1-甲基-4-苯基吡啶离子（MPP^＋）诱导的PC12细胞,变性损伤的保护作用及机制。方法用MPP^＋处理PC12细胞制作帕金森病细胞模型,采用四甲基偶氮哗监泫检测暴露于不同浓度EPO后细胞的活性;流式细胞术与DNA断端原位标记法（terminal deoxynucleotidyl transferase dUTP nick end labeling,TUNEL）检测各组的细胞凋亡率;免疫印迹法检测不同处理组PC12细胞Bcl-2和Bax的表达,并采用荧光法观察不同处理组PC12细胞活性氧（reactive oxygen species,ROS）与线粒体膜电位水平以及caspase-3活性的变化。结果MPP^＋可以使PC12细胞存活率下降,凋亡率增高;同时PC12细胞内ROS增多,线粒体膜电位下降。MPP^＋还可以明显地提高Bax／Bcl-2比值并激活caspase-3。而EPO可以抑制这些由MPP^＋引发的改变,并在1U／mL时发挥最大保护作用。结论EPO可抑制MPP^＋诱导的PC12绌胞死亡,其作用机制可能其自身抗氧化和抗凋亡的特性有关。     

黄芩苷对AB25-35诱导人神经原母细胞瘤SH-SY5Y凋亡的保护作用

目的：探讨黄芩苷对Aβ诱导的神经细胞凋亡的保护作用,同时通过对诱导凋亡的关键因素综合分析阐明其作用机制。 方法：①实验方法及分组：正常对照组,神经元母细胞瘤SH-SY5Y无血清培养;模型组,模型组加终浓度为25μmol/L 的Aβ25-35处理24h;黄芩苷治疗组,黄芩苷预处理1h,再加终浓度为25μmol/L的 Aβ25-35处理24h,大剂量组采用100μM,小剂量组采用50μM。②实验评估：各实验组作用24小时后,收集细胞上清ELISA测定细胞NO、LDH分泌;MTT实验测定各组细胞存活率;流式细胞仪测定细胞凋亡及线粒体膜电位的改变;RT-PCR检测caspase-3的mRNA水平。 结果：MTT实验显示,Aβ25-35处理后SH-SY5Y细胞的存活率明显下降（p<0.01）,而黄芩苷各治疗组则显示出明显的保护作用（p＜0.05,p＜0.01）;细胞上清LDH活性测试显示,Aβ25-35组上清中的LDH明显升高（p＜0.01）;黄芩苷组各治疗组与模型组比差异显著（p＜0.05,p＜0.01）;比色法测定细胞上清中NO分泌显示,Aβ25-35处理后细胞NO分泌明显上升（31.64±1.96μM）,而黄芩苷各治疗组均能有效抑制NO的产生,黄芩苷100μM（9.43±0.63μM）,黄芩苷50μM（23.41±0.94μM）p＜0.01;流式细胞仪分别测定细胞凋亡率及线粒体膜电位,结果显示与正常对照组比较Aβ25-35明显诱导了细胞凋亡,同时线粒体膜电位也明显下降（p＜0.01）,而黄芩苷各治疗通过保护线粒体膜电位有效抑制了凋亡的发生发生;进一步的caspase-3mRNA表达测定中也显示黄芩苷各组均能明显抑制caspase-3的表达。 结论：本研究结果明确了黄芩苷能有效抑制Aβ25-35诱导的神经元细胞的调亡,在进一步机制研究中显示了黄芩苷同过抑制自由基损伤、调亡分子caspase-3的表达以及保护线粒体正常功能等凋亡发生的关键环节保护了神经元细胞。     

突变型 TDP-43（A315T）蛋白诱导S H-SY5Y 细胞凋亡的机制研究

目的：探讨TDP‐43（A315T ）突变蛋白诱导SH‐SY5Y细胞凋亡的机制。方法采用真核细胞转染技术将Flag‐TDP‐43（w t）及Flag‐TDP‐43（A315T ）质粒转入SH‐SY5Y细胞,通过Western blot检测 TDP‐43截短型表达及自噬水平的变化;PI／Annexin‐V‐FITC检测细胞凋亡率;单丹磺酰尸胺（monodansylcadaverin ,MDC）染色检测细胞自噬空泡的变化。结果与转染Flag‐TDP‐43（wt）组相比,过表达Flag‐TDP‐43（A315T）细胞截短型片段Flag‐TDP‐35及Flag‐TDP‐25表达明显上调,下调细胞内源性Beclin 1水平及LC3Ⅱ／LC3Ⅰ的比值降低。与转染Flag‐TDP‐43（wt）组相比,过表达Flag‐TDP‐43（A315T）诱导SH‐SY5Y细胞自噬性小泡聚集明显减少。与转染Flag‐TDP‐43（wt）组相比,过表达Flag‐TDP‐43（A315T）后SH‐SY5Y细胞凋亡率增加。结论 TDP‐43（A315T ）突变蛋白可通过增加其截短型表达及抑制细胞巨自噬水平诱导SH‐SY5Y细胞凋亡。     

体外模拟心肌环境诱导骨髓间充质干细胞向心肌细胞的分化★

目的：以往研究将长有一层心肌细胞的半透膜放于骨髓间充质干细胞培养皿中，或用培养过心肌细胞的培养基来培养骨髓间充质干细胞，均未发现心肌细胞特异蛋白表达。为此体外模拟心肌微环境诱导骨髓间充质干细胞向心肌细胞分化，并与常规诱导剂5-氮杂胞苷的诱导效果进行比较。 方法：实验于2007-03/09在山西医科大学中心实验室完成。①动物：Wistar大鼠20只，新生1 d龄Wistar乳鼠10只，均由山西医科大学动物房提供，清洁级，实验过程中对动物的处置符合动物伦理学标准。诱导剂5-氮杂胞苷为美国Sigma公司产品。②实验方法：自新生Wistar乳鼠心脏分离培养心肌细胞，取第1、2代制成1×109 L-1细胞悬液，-70 ℃放置4~5 h后融化，吸管吹打，反复3次，离心取上清，过滤后即为心肌细胞冻融液，以此作为培养基体外模拟心肌微环境。自成年Wistar大鼠骨髓分离骨髓间充质干细胞，取生长良好的第2代制成1×108 L-1细胞悬液，分为4组：血清对照组加入含15％胎牛血清的DMEM/F12培养基；5-氮杂胞苷组加入10μmol/L 5-氮杂胞苷37 ℃避光孵育24 h后，换DMEM/F12培养基继续培养；5-氮杂胞苷+心肌细胞冻融液组加入10μmol/L 5-氮杂胞苷诱导24 h后，在培养体系中加入相当于4倍骨髓间充质干细胞数量的心肌细胞冻融液；心肌细胞冻融液组加入相当于4倍骨髓间充质干细胞数量的心肌细胞冻融液。③实验评估：诱导1周后观察骨髓间充质干细胞的形态变化，利用免疫细胞化学技术鉴定心肌特异性肌钙蛋白T、连接蛋白43、α-横纹肌肌动蛋白、CD31的表达情况。 结果：①体外模拟心肌微环境情况：培养7 d时心肌细胞形成细胞簇或细胞单层，呈放射状排列的同心圆状或峰谷样生长，细胞簇搏动呈明显同步性。传代后的心肌细胞仍具有自主收缩的特性。②骨髓间充质干细胞的体外诱导结果：诱导处理1周后，5-氮杂胞苷组多数细胞呈杆状，紧密平行排列生长，细胞体积变大，可见肌丝样结构形成；心肌细胞冻融液组细胞有聚集生长趋势，形成大量的子细胞，可见大量的肌丝样的结构；5-氮杂胞苷+心肌细胞冻融液组脱落或降解的细胞数明显少于5-氮杂胞苷组，也形成肌丝样结构，但部分细胞内有脂肪空泡形成。③免疫细胞化学鉴定结果：诱导培养1周后，血清对照组仅表达α-横纹肌肌动蛋白；5-氮杂胞苷组表达心肌特异性蛋白T、α-横纹肌肌动蛋白、连接蛋白43，其阳性率分别为20%，28%，25%，抗CD31染色呈阴性；心肌细胞冻融液组上述蛋白阳性表达率分别为23%，32%，28%，明显高于5-氮杂胞苷组（P < 0.05），同时抗CD31染色呈阳性；5-氮杂胞苷+心肌细胞冻融液组上述蛋白阳性表达率略低于心肌细胞冻融液组，抗CD31染色呈阳性。 结论：①以心肌细胞冻融液体外模拟心肌微环境，可高效诱导骨髓间充质干细胞分化为心肌细胞。②部分骨髓间充质干细胞表达CD31，即可向血管内皮细胞分化，提示与5-氮杂胞苷单一的肌细胞诱导作用相比，心肌细胞冻融液更能提供一个心肌再生所需的自然条件。     

TRAIL及其在脑胶质瘤中的研究应用进展

TNF相关的凋亡诱导配体（TNF-related　apoptosis　inducing　ligand,TRAIL）为TNF超家族成员之一,能够与死亡受体结合,激活Caspase级联反应,选择性地诱导多种肿瘤细胞的凋亡,正常组织则对其不敏感,其调节机制与多种因素有关。TRAIL及其受体在脑胶质瘤表达与否存有异议,胶质瘤级胞系对TRAIL诱导凋亡敏感程度因其种类而不同,在体研究证明TRAIL对体内胶质瘤有显著的杀瘤效果,而没有其系统应用的肝脏毒性及局部应用的周围正常组织毒性。     

肿瘤坏死因子相关凋亡诱导配体诱导胶质瘤细胞凋亡机制研究

目的 探讨肿瘤坏死因子相关凋亡诱导配体(TRAIL)诱导胶质瘤细胞凋亡的机制.方法 以人重组可溶性TRAIL蛋白(rsTRAIL)处理人胶质瘤细胞U87;AnnexinV-FITC/PI双染色流式细胞术检测细胞凋亡;DiOC6荧光染色流式细胞术检测细胞线粒体跨膜电位(△ψm);比色法测定细胞caspase-3、8、9活性的变化;ELISA法检测胞浆cytC浓度;观察caspase-8阻断剂(Z-IETD-fmk)对U87细胞凋亡、△ψm和caspase-3、8、9活性变化的影响. 结果 rsTRAIL以时间依赖方式诱导U87细胞凋亡.同时导致U87细胞△ψm进行性下降,caspase-3、8、9活性及胞浆内cyt C浓度升高:caspase-8阻断剂可明显减弱rsTRAIL对U87细胞的上述生物学效应. 结论 TRAU通过激活caspase-8间接启动线粒体凋亡途径诱导恶性胶质瘤细胞U87凋亡.     

TRAIL诱发人脑H4神经胶质瘤细胞凋亡的研究

目的研究TRAIL对H4神经胶质瘤细胞的凋亡诱导作用，并探讨其可能机制。方法利用显微镜、透射电镜、流式细胞仪，观察和检测TRAIL对传代培养的肿瘤细胞的凋亡诱导作用，用MTT法检测easpase-8抑制剂zIETD—fmk对TRAIL凋亡诱导作用的抑制情况。结果TRAIL作用后镜下可见到H4细胞凋亡的典型表现；在流式细胞仪检测PI荧光直方图上，出现典型的亚二倍体峰，随着作用时间的延长，H4细胞凋亡率明显增加；zIETD—fmk能显著抑制TRAIL对H4细胞的凋亡诱导作用。结论TRAIL可有效的诱导H4神经胶质瘤细胞凋亡；easpase-8在H4瘤细胞的凋亡过程发挥着重要作用，TRAIL可能是通过激活caspase系统而诱发H4瘤细胞凋亡的。     

Staurosporine- and H-7-induced cell death in SH-SY5Y neuroblastoma cells is associated with caspase-2 and caspase-3 activation, but not with activation of the FAS/FAS-L-caspase-8 signaling pathway

Apoptotic cell death is induced in SH-SY5Y neuroblastoma cells following exposure to the protein kinase inhibitors staurosporine (100 nM) and 1-(5-Isoquinolinesulfonyl)-2-methylpiperazine: H-7 (100 microM). This is associated with reduced levels of PARP 117 kDa and with the concomitant formation of PARP-cleaved products of 89 kDa that result from caspase-3 activation. The process is inhibited with DEVD-fmk, a potent caspase-3 (and caspase-8) inhibitor, thus indicating that staurosporine- and H-7-induced cell death in SH-SY5Y is mediated by caspase activation. Increased caspase-2- and caspase-3-like activities, but not caspase-9-like activity, were demonstrated by monitoring proteolysis of the corresponding colorimetric substrates. Caspase-2 activity peaked at 6 h, whereas caspase-3 peaked at 12 h in parallel with the maximal loss of cell viability. No modifications in the expression levels of Fas and Fas-L were observed by Western blotting. Furthermore, no activation of caspase-8 was elicited by colorimetric assays through the process of apoptosis of neuroblastoma cells. These findings indicate that the Fas/Fas-L-caspase-8 pathway of cell death signaling is not involved in staurosporine- and H-7-induced apoptosis in SH-SY5Y neuroblastoma cells.     

TRAIL-induced apoptosis in U-1242 MG glioma cells

ABSTRACT: Tumor necrosis factor related apoptosis-inducing ligand (TRAIL) induces apoptosis in U-1242 MG cells. To investigate the molecular events involved in this process, we studied the effects of TRAIL on the localization within membrane fractions of molecules critical to the extrinsic apoptotic pathway. We report here that death receptor-5 (DR5), tumor necrosis factor receptor-1 (TNF-R1), and Fas receptor (FasR) are all located in the caveolin-1-enriched membrane fractions, and TRAIL caused the translocation of DR5, FasR, and TNF-R1 to the caveolar fractions. Caspase-8 is mainly located outside of caveolae, but TRAIL caused it to redistribute to the caveolin-1-enriched fractions where it was cleaved. Within 6 hours, the cleaved caspase-8 appeared in the high-density, noncaveolin fractions. Using confocal microscopy, we found that DR5, caspase-8, and caveolin-1 became progressively concentrated in blebs of plasmalemma as they formed in response to TRAIL. Our results provide the first evidence for the caveolar localization of TNF-R1 and DR5 and the coordinated redistribution among membrane fractions of several death receptors in response to TRAIL. We propose that the coordinated movement of these molecules among membrane compartments is probably an important component of the mechanisms regulating and initiating the extrinsic apoptotic pathway in human glioma cells.     

Stem-cell-like glioma cells are resistant to TRAIL/Apo2L and exhibit down-regulation of caspase-8 by promoter methylation

Tumour necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL/Apo2L) is a promising cancer drug. However, many tumours are resistant to TRAIL-based therapies. Glioma cells with stem cell features (SCG), such as CD133 expression and neurosphere formation, have been recently identified to be more resistant to cytotoxic drugs than glioma cells lacking stem-cell-like features (NSCGs). Here we report that SCGs are completely resistant to 100–2,000 ng/ml TRAIL, whereas NSCGs revealed a moderate sensitivity to TRAIL. We found that SCGs exhibited only low levels of caspase-8 mRNA and protein, known to be indispensable for TRAIL-induced apoptosis. In addition, we detected hypermethylation of CASP8 promoter in SCGs, whereas NSCGs exhibited a non-methylated CASP8 promoter. Reexpression of caspase-8 by 5-Aza-2′-deoxycytidine was not sufficient to restore TRAIL sensitivity in SCGs cells, suggesting that additional factors cause TRAIL resistance in SCGs. Our data suggest that therapy with TRAIL, either as monotherapy or in combination with demethylating agents, is not effective in treating glioblastoma because SCGs are not targeted by such treatment.     

过表达Mfn2基因通过PI3K/AKT通路抑制鱼藤酮诱导的帕金森病细胞模型的细胞凋亡

目的 探讨过表达线粒体融合蛋白2(Mfn2)基因通过PI3K/AKT通路抑制鱼藤酮诱导的帕金森病细胞模型的细胞凋亡。方法 培养SH-SY5Y细胞并分组,对照组用不含药物及质粒的DMEM干预; 鱼藤酮组用含有20 μmol/L鱼藤酮的DMEM干预; 鱼藤酮+空白质粒组用含有20 μmol/L鱼藤酮的DMEM干预并转染空白的pcDNA 3.1质粒; 鱼藤酮+Mfn2质粒组用含有20 μmol/L鱼藤酮的DMEM干预并转染表达Mfn2的pcDNA3.1质粒; 鱼藤酮+Mfn2质粒+LY组用含有20 μmol/L鱼藤酮、10 μmol/L LY294002的DMEM干预并转染表达Mfn2的pcDNA3.1质粒; 检测细胞活力、凋亡率及线粒体凋亡基因、p-PI3K、p-AKT的表达水平。结果 鱼藤酮组的细胞活力及细胞中p-PI3K、p-AKT的表达水平均低于对照组,凋亡率及细胞中caspase-9、cleaved caspase-3的表达水平均高于对照组; 鱼藤酮+Mfn2质粒组的细胞活力及细胞中p-PI3K、p-AKT的表达水平均高于鱼藤酮组,凋亡率及细胞中caspase-9、cleaved caspase-3的表达水平均低于鱼藤酮组; 鱼藤酮+Mfn2质粒+LY组的细胞活力及细胞中p-PI3K、p-AKT的表达水平均低于鱼藤酮+Mfn2质粒组,凋亡率及细胞中caspase-9、cleaved caspase-3的表达水平均高于鱼藤酮+Mfn2质粒组。结论 过表达Mfn2基因对鱼藤酮诱导的帕金森病细胞模型的细胞凋亡具有抑制作用,且该作用可能与抑制PI3K/AKT通路有关     

GRP94 (94 kDa glucose-regulated protein) suppresses ischemic neuronal cell death against ischemia/reperfusion injury

The 94 kDa glucose-regulated protein (GRP94), the endoplasmic reticulum (ER) resident molecular chaperone, has a role in cell death due to endoplasmic reticulum stress (ER stress). Here, we report that expression of GRP94 was increased in human neuroblastoma cells (SH-SY5Y (SY5Y) cells) exposed to hypoxia/reoxygenation (H/R). H/R mediated death of SY5Y cells was associated with the activation of major cysteine proteases, caspase-3 and calpain, along with an elevated intracellular calcium concentration. Pretreatment with adenovirus-mediated antisense GRP94 (AdGRP94AS) led to reduced viability of SY5Y cells after being subjected to H/R compared with wild-type cells or cells with adenovirus-mediated overexpression of GRP94 (AdGRP94S). These results indicate that suppression of GRP94 is associated with accelerated apoptosis and that expression of GRP94 (as a stress protein) suppresses oxidative stress-mediated neuronal death and stabilizes calcium homeostasis in the ER. We also used gerbils with transient forebrain ischemia to study the role of GRP94 in vivo. Neurons with adenovirus-mediated overexpression of GRP94 were resistant to ischemic damage. These results confirmed that GRP94 could suppress ischemic injury to neurons, suggesting that gene transfer of GRP94 into the brain may have therapeutic potential in the treatment of cerebrovascular disease.     

Dysregulated expression of secretogranin III is involved in neurotoxin‐induced dopaminergic neuron apoptosis

The neurotoxins paraquat (PQ) and dopamine (DA or 6‐OHDA) cause apoptosis of dopaminergic neurons in the substantia nigra pars compacta (SNpc), reproducing an important pathological feature of Parkinson's disease (PD). Secretogranin III (SCG3), a member of the multifunctional granin family, plays a key role in neurotransmitter storage and transport and in secretory granule biogenesis, which involves the uptake of exogenous toxins and endogenous “toxins” in neuroendocrine cells. However, the molecular mechanisms of neurotoxin‐induced apoptosis in dopaminergic neurons and the role of SCG3‐associated signaling pathways in neuroendocrine regulation are unclear. To address this, we used PQ‐ and DA‐induced apoptosis in SH‐SY5Y human dopaminergic cells as an in vitro model to investigate the association between SCG3 expression level and apoptosis. SCG3 was highly expressed in SH‐SY5Y cells, and SCG3 mRNA and protein levels were dramatically decreased after PQ treatment. Apoptosis induced by PQ is associated with caspase activation and decreased SCG3 expression, and restoration of SCG3 expression is observed after treatment with caspase inhibitors. Overexpressed SCG3 in nonneuronal cells and endogenous SCG3 in SH‐SY5Y cells are cleaved into specific fragments by recombinant caspase‐3 and ‐7, but the fragments were not detected in PQ‐treated SH‐SY5Y cells. Therefore, SCG3 may be involved in apoptosis signal transduction as a caspase substrate, leading to loss of its original biological functions. In addition, SCG3 may be a pivotal component of the neuroendocrine pathway and play an important role in neuronal communication and neurotransmitter release, possibly representing a new potential target in the course of PD pathogenesis. © 2012 Wiley Periodicals, Inc.