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。     

自噬对TRAIL诱导的肿瘤细胞凋亡的影响

正肿瘤坏死因子相关凋亡诱导配体(tumornecrosis factor related apoptosis-induced ligand,TRAIL)是肿瘤坏死因子家族中的一员,能够诱导大多数人类肿瘤细胞凋亡,而对正常细胞没有明显的细胞毒性。因此,TRAIL被认为是一种很有希望有效的抗肿瘤药物~([1])。在临床前期试验中,TRAIL表现     

氯喹通过抑制自噬促进TRAIL诱导的胶质瘤细胞凋亡

目的探讨氯喹对肿瘤坏死因子相关凋亡诱导配体(TRAIL)诱导的胶质瘤细胞凋亡的影响。方法体外培养人脑胶质瘤细胞U251和Hela细胞,分为对照组、氯喹组、重组人TRAIL蛋白(rhTRAIL)组和联用组(氯喹与rhTRAIL联合应用);MTT法检测细胞活力,Annexin V-FITC/PI凋亡检测试剂盒检测细胞凋亡,共聚焦显微镜检测GFP-LC3的分布判断细胞自噬水平,Western Blot检测cleaved caspase-8的表达水平。结果氯喹和rhTRAIL均显著增加U251细胞和Hela细胞自噬水平,而且联用较单独应用自噬水平更高,Hela细胞自噬水平明显高于U251细胞。U251细胞和Hela细胞增殖抑制率和细胞凋亡率:氯喹组与对照组均无统计学差异(P0.05),rhTRAIL和联用组均明显高于氯喹组(P0.05),联用组明显高于rhTRAIL组(P0.05)。氯喹组和对照组Cleaved caspases-8水平无统计学差异(P0.05),rhTRAIL和联用组均明显增高(P0.05),联用组明显高于rhTRAIL组(P0.05)。结论氯喹能通过抑制细胞自噬,增强TRAIL诱导的U251细胞凋亡。     

自噬在ALA-PDT诱导C6胶质瘤细胞死亡中的作用机制

目的 探讨自噬在光敏剂5-氨基乙酰丙酸(aminolaevulinic acid,ALA)介导的光动力治疗(photodynamic therapy,PDT)C6胶质瘤细胞死亡中作用机制.方法 ALA-PDT处理后不同时间,用自噬特异染料MDC和免疫荧光法观察自噬水平变化,Western blotting检测自噬相关蛋白cathepsin B的表达水平.结果 MDC染色和免疫荧光观察可见ALA-PDT后C6胶质瘤细胞内有大量含点状荧光颗粒的自噬泡和自噬体标志物LC3绿色荧光蛋白,Western-blot示自噬相关蛋白cathepsin B表达水平明显升高,其白噬水平随AIA-PDT后时间而逐渐增强.结论 ALA-PDT可诱导C6胶质瘤细胞发生自噬,其诱导胶质瘤细胞发生自噬的机制可能与溶酶体酶cathepsin B大量释放有关.     

自噬和蛋白酶体降解途径在突变型α-突触核蛋白PC12细胞凋亡中的作用

目的 利用建立好的转染A53T突变型α-突触核蛋白的大鼠嗜铬细胞瘤(PC12)细胞株,探讨自噬和泛素-蛋白酶体通路在细胞凋亡途径中的具体作用.方法 选择特异性蛋白酶体抑制剂和大自噬抑制剂及诱导剂作用于稳定转染的A53T细胞株,四甲基偶氮唑盐法和流式细胞仪检测细胞活力和各组细胞凋亡率,电镜观察超微结构,并测定细胞培养液中NO的活力和热休克蛋白70(Hsp70)及Caspase-3蛋白表达.结果 蛋白酶体抑制剂环氧霉素(100 nmol/L)和(或)大自噬抑制剂3-MA(10 mmol/L)处理A53T细胞24 h后环氧霉素组、3-MA组和环氧霉素+3-MA组细胞活力(A值分别为0.23±0.01、0.19±0.01、0.17±0.01)较对照A53T细胞组(A值为0.32±0.06)明显下降(P<0.05);而大自噬诱导剂雷帕霉素(0.2 μg/ml)处理后细胞存活率(A值为0.44±0.08)显著高于其余用药组.与对照组(1.55%±1.15%)相比,3-MA、环氧霉素、环氧霉素+3-MA组作用24 h后A53T细胞的凋亡百分率(分别为4.74%±0.91%、4.59%±1.18%、5.40%±1.75%)显著增高(P<0.05),而大自噬诱导剂下调蛋白酶体抑制剂导致的凋亡;蛋白酶体抑制剂组NO和Hsp70蛋白含量也明显高于对照组.结论 大自噬和蛋白酶体途径障碍促进了凋亡发生,抑制或诱导自噬对Hsp70和NO的影响不如蛋白酶体途径对其影响大.     

14-3-3和CLIC4蛋白在U251细胞自噬中的相互作用

目的通过饥饿诱导神经胶质瘤U251细胞发生自噬,探讨细胞CLIC4和14-3-3蛋白在饥饿条件下诱导自噬过程中的相互作用。方法通过Hoechst、14-3-3 epsilon、CLIC4染色于共聚焦显微镜下观察抑制CLIC4表达对于饥饿条件下,14-3-3 epsilon蛋白与CLIC4共定位的影响。通过Western Blot技术检测Beclin 1及14-3-3蛋白表达。免疫共沉淀技术检测14-3-3 epsilon蛋白与CLIC4蛋白的结合水平。结果共聚焦显微镜观察14-3-3 epsilon和CLIC4荧光染色结果显示,饥饿条件下,14-3-3 epsilon蛋白与CLIC4共定位显著增加,并广泛分布于胞浆及细胞核中。同时Western Blot结果表明抑制CLIC4表达能够引起14-3-3蛋白以及自噬相关蛋白Beclin1表达增加。饥饿条件下,14-3-3 epsilon蛋白与CLIC4共沉淀增强,而抑制CLIC4表达能够降低两者结合水平。结论 14-3-3epsilon蛋白与CLIC4的相互作用由于RNA干扰而减弱,促进了14-3-3蛋白水平上调,进而增强了14-3-3蛋白对Beclin1信号通路的调节,引起Beclin1表达增加,进一步激活饥饿条件下U251细胞自噬过程。     

阿尔茨海默病中β淀粉样前体蛋白羧基端短肽C31与自噬的相关性研究

目的 探讨β淀粉样前体蛋白羧基端短肽C31的毒性作用和自噬的关系,以及自噬是否介导C31的清除.方法 首先构建p3 xFLAG—CMV—10—mCherry-C31(C31)质粒和p3xFLAG-CMV-10-mCherry(Vector)质粒(对照),采用脂质体转染法转染入SH-SY5Y和APPsw稳转的HEK293(APPsw HEK293)细胞系中,并通过Western blot方法验证其表达;采用MTT法检测C31和Vector质粒瞬时转染48 h后的细胞存活率;分别予以不同的自噬调节药物,Western blot检测自噬相关蛋白(LC3)和C31水平.最后,通过免疫共沉淀法检测C31是否可以和LC3结合,并采用免疫荧光检测C31是否可以与LC3共定位,以进一步验证自噬是否为介导C31降解的关键途径.结果 在SH-SY5Y和APPsw HEK293细胞系中,C31质粒转染组细胞活力显著低于对照组(P＜0.05);转染C31组与对照组自噬水平无明显差异;促自噬情况下(雷帕霉素和饥饿处理),LC3—Ⅱ的水平比未加药处理组略增高,但未达到统计学意义,C31水平相对于空载水平差异无统计学意义;自噬抑制剂3-甲基腺嘌呤(3-MA)作用于APPsw HEK293细胞后,LC3—Ⅱ水平有轻度降低,但未达到统计学意义,C31水平改变也未达到统计学意义;加入自噬体和溶酶体融合抑制剂氯喹(CQ)和氯化铵(NH4Cl)后,细胞自噬水平有明显的增高,且CQ的作用最为明显,C31水平相对于空载水平明显增高(P＜0.05).在SH—SY5Y细胞中,结果类似,但CQ和NH4Cl作用后,C31水平相对于空载水平无统计学差异.免疫荧光显示C31通过与自噬相关蛋白LC3结合,从而锚定到自噬体上,而参与到自噬代谢过程.结论 C31在SH-SY5Y细胞和APPsw HEK293细胞中均能产生细胞毒性作用.过表达C31不改变细胞的自噬水平.自噬途径介导C31的清除,表明自噬可能在阿尔茨海默病中起到保护作用.     

缺氧后胚鼠神经元自噬及凋亡相关蛋白的表达

目的观察缺氧致胚鼠神经元损伤后,凋亡和自噬的发生及变化情况,并探讨其在脑细胞缺血缺氧中的意义。方法取大鼠的胚鼠皮质神经元进行体外原代培养,建立缺氧(oxygen deprivation,OD)损伤模型,通过Western blot方法检测不同缺氧时间点自噬微管相关蛋白轻链3抗体(microtubule-associated protein 1 light chain 3,LC3)以及半胱天冬蛋白酶3(caspase-3)的表达情况。结果神经元于缺氧后可观察到自噬的发生,同时凋亡也随之出现,两者的标志蛋白于OD 0.5h开始表达,并且表达逐渐增加,于OD 4h时间点到达高峰,OD 6h时后凋亡标志蛋白caspase-3继续上调,自噬的标志蛋白LC3表达不再增强。结论 (1)除凋亡外,单纯缺氧能诱导胚鼠神经元发生自噬现象;(2)缺氧所致神经元的损伤过程中,凋亡与自噬同时发生,且表达趋势在OD 4h内一致,OD 4h后细胞凋亡增强。     

姜黄素通过PI3K/AKT信号通路激活细胞自噬对大鼠颅脑损伤的神经保护作用

目的 探讨姜黄素对颅脑损伤（TBI大鼠）的神经保护作用及其机制。方法 48只成年雄性SD大鼠随机分成假手术组、TBI组、溶媒组、姜黄素组,每组12只。采用重物撞击法制作控制皮质冲击伤模型。造模后,姜黄素组腹腔注射姜黄素（60 mg/kg）,溶媒组腹腔注射姜黄素溶媒磷酸缓冲盐溶液;姜黄素干预72 h采用改良神经功能损伤量表（mNSS）评分评估神经功能;每组取6只大鼠采用Nissl染色评估损伤面积,采用TUNEL染色评估细胞凋亡率;另取6只大鼠免疫印迹法检测PI3K/AKT信号通路以及细胞自噬相关蛋白（LC3、Beclin-1、P62蛋白）表达水平。结果 与假手术组比较,TBI组和溶媒组mNSS评分显著增加（P<0.05）,损伤面积和神经元凋亡率均明显增加（P<0.05）,LC3、Beclin-1表达水平明显增高（P<0.05）,P62表达水平明显降低（P<0.05）,而PI3K和AKT蛋白表达水平无明显变化（P>0.05）;TBI组和溶媒组均无统计学差异（P>0.05）。与溶媒组相比,姜黄素组mNSS评分明显下降（P<0.05）,损伤面积和神经元凋亡率显著降低（P<0.05）,磷酸化PI3K/AKT水平明显增高（P<0.05）,LC3、Beclin-1表达水平明显增高（P<0.05）,P62表达水平明显降低（P<0.05）。结论 姜黄素对TBI大鼠具有显著神经保护作用,机制可能是通过PI3K/AKT信号通路激活自噬     

低氧和(或)高糖对小鼠神经母细胞瘤细胞Neuro-2a活性的影响及自噬机制研究

目的观察低氧和(或)高糖对小鼠神经母细胞瘤细胞Neuro-2a活性的影响,并探讨其自噬相关机制。方法 Neuro-2a细胞分为4组:正常对照组、高糖组、低氧组和高糖低氧组。使用MTS方法检测细胞活性;透射电镜、免疫印记、免疫荧光染色检测各组细胞自噬水平。结果相较于正常对照组,低氧组、高糖低氧组的Neuro-2a细胞活性明显下降(P0.01),胞质内LC3B蛋白明显聚集;细胞内自噬囊泡样物质增加;自噬相关蛋白LC3B-Ⅱ、P62蛋白水平均升高(P0.05)。自噬抑制剂(bafilomycin A1)处理后,正常对照组、高糖组Neuro-2a细胞LC3B-Ⅱ、P62蛋白水平升高(P0.05),活性显著下降(P0.01)。结论低氧可以降低Neuro-2a细胞活性,可能是通过抑制自噬降解途径发挥作用。     

CADASIL syndrome in a large Turkish kindred caused by the R90C mutation in the Notch3 receptor

Mutations in the Notch3 gene are the cause of the autosomal dominant disorder CADASIL (cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy). The CADASIL is an adult-onset neurologic disorder (average age of onset is 45 years) characterized by recurrent strokes and dementia. Clinical features combined with cerebral magnetic resonance imaging (MRI), showing a diffuse leukoencephalopathy with subcortical infarcts in the basal ganglia and white matter, are highly contributive to the diagnosis. We present a Turkish family with CADASIL, in which 12 individuals in four generations were affected showing the typical clinical features of recurrent strokes. Mutation analysis of the Notch3 receptor gene identified the recently described R90C mutation in the N-terminal part of the gene in affected individuals. Interestingly, migraine without aura was found as an initial symptom of the disease in two young mutation carriers (22 and 25 years, respectively), who did not show any additional clinical features or any MRI abnormalities. This indicates that migraine without aura in the absence of MRI abnormalities may represent an early initial symptom of CADASIL, which is difficult to diagnose in the absence of molecular diagnosis. Therefore, the used molecular screening method for Notch3 mutations provides a rapid and accurate diagnostic tool in addition to the standard diagnostic procedures.     

Japanese CADASIL case with limited dementia who had the Notch 3 R141C mutation]

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a rare hereditary disease characterized by recurrent transient ischemic attacks (TIA) and strokes, and vascular dementia caused by point mutations of the Notch 3 gene. Here, we report a Japanese CADASIL case who displayed limited dementia and had the Notch 3 R141C mutation. The relationship between pathogenesis and the mutation site in Notch 3 is discussed based on the case presented here.     

卡莫司汀对C6胶质瘤细胞凋亡作用机制的研究

目的研究卡莫司汀(BCNU)对胶质瘤凋亡的作用机制。方法取生长状态良好的C6胶质瘤细胞悬液,按1×107个细胞/25μl的密度接种于20只SD大鼠腹股沟区皮下,观察其生长情况。将16只成瘤大鼠随机等分为治疗组与非治疗组,前者按相同剂量隔日腹腔内注射BCNU。治疗2周后处死全部大鼠,取大鼠右侧腹股沟区皮下肿瘤行苏木精-伊红染色和免疫组织化学染色,检测胶质瘤的病理学特征及胶质纤维酸性蛋白(GFAP)、bax和bcl-2蛋白的表达情况,观察瘤细胞凋亡情况。结果C6胶质瘤细胞皮下接种4～5d后,大鼠腹股沟区皮下形成实体瘤;治疗2周,非治疗组和治疗组SD大鼠平均肿瘤质量差异有统计学意义(P<0.01),治疗组肿瘤抑制率为29.6%。肿瘤GFAP表达为阳性;BCNU治疗后bax基本无改变,bcl-2下调明显(P<0.01),bax/bcl-2比值明显增加。结论BCNU腹腔注射治疗大鼠神经胶质瘤导致胶质瘤细胞凋亡,其主要机制可能与下调凋亡蛋白bcl-2的表达和升高bax/bcl-2的比值有关。     

Functional analysis of human CNGA3 mutations associated with colour blindness suggests impaired surface expression of channel mutants A3(R427C) and A3(R563C)

Mutations in the CNGA3 gene have been associated with complete and incomplete forms of total colour blindness (achromatopsia), a disorder characterized by reduced visual acuity, lack of colour discrimination, photophobia and nystagmus. CNGA3 encodes the A-subunit of the cone photoreceptor cyclic nucleotide-gated (CNG) channel, an essential component of the phototransduction cascade. Here we report the identification of three new CNGA3 mutations in patients with achromatopsia. To assess the pathogenicity of these newly identified and four previously reported mutations, mutant CNGA3 channels were heterologously expressed in a human embryonic kidney cell line (HEK293 cells) and functionally analysed using calcium imaging. Channels with the mutations R427C and R563C showed a response in imaging experiments and were subsequently characterized in-depth with the patch-clamp technique. The mutant channels were analysed as homooligomers and also as heterooligomers with the wild-type B-subunit present in native channels. Overall, cyclic guanosine monophosphate (cGMP) maximum currents of mutant channels were profoundly reduced in homo- and heteromers. Treatment with the chemical chaperone glycerol effectively increased macroscopic currents, presumably by enhancing surface expression of mutant channels as confirmed by immunocytochemistry. These results suggest decreased channel density in the cell membrane due to impaired folding or trafficking of the channel protein as the main pathogenic effect of the mutations R427C and R563C. Moreover, A3(R427C) homomers showed distinctly increased cGMP and cyclic adenosine monophosphate (cAMP) sensitivities as well as cAMP fractional currents that were raised to over 90% of cGMP maximum currents. Co-expression of A3(R427C) with the B3 subunit compensated for most of these aberrant properties, apart from the reduced cGMP maximum currents.     

三氧化二砷诱导C6胶质瘤细胞凋亡实验研究

目的：研究三氧化二砷（As2O3）在体外是否具有抗鼠胶质瘤作用,并对其作用机制进行初步探讨。方法：应用不同浓度As2O3,且在不同时间点分别处理C6胶质瘤细胞株及原代培养的正常鼠神经胶质细胞,采用甲基噻唑基四唑（MTT）法,观察As2O3对C6胶质瘤细胞株及正常鼠神经胶质细胞生长的影响,以透射电镜、Hoechst33342和碘化丙啶（PI）双重荧光染色检测两种细胞凋亡的形态变化,并用异硫氰酸荧光素（FITC）标记的Annexin-V和PI双标记法通过流式细胞仪检测细胞凋亡率。结果：MTT法发现,As2O30.5～8.0μmol/L的浓度均可显著抑制C6胶质瘤细胞株的生长,而对正常原代神经胶质细胞株的抑制作用较弱。经As2O3作用后,透射电镜、Hoechst33342/PI双染荧光均观察到C6胶质瘤细胞发生了显著的凋亡形态改变;运用Annexin-V-FITC/PI双标记法在流式细胞仪检测显示,随As2O3浓度的增大和时间的延长,C6胶质瘤细胞株的凋亡率明显上升,而正常神经胶质细胞的凋亡率要明显小于C6胶质瘤细胞株。结论：As2O3在体外可显著抑制C6胶质瘤细胞株生长,其机制与诱导肿瘤细胞凋亡有关,且凋亡率随As2O3作用的时间和剂量的增加而增加。但As2O3对正常神经胶质细胞生长的抑制作用较弱,提示As2O3抑制细胞生长的作用具有一定的选择性。     

海葵毒素对神经胶质瘤细胞的凋亡诱导作用

目的 研究从海葵组织中提取的海葵毒素(Phyllodiscus semonii toxin,PsTX)对人神经胶质瘤细胞(U251)凋亡的诱导作用及其可能机制.方法 MTT法检测PsTX对肿瘤细胞的增殖抑制率;原位末端脱氧核糖苷肽转移酶分析法(TUNEL)及DNA Ladder法检测PsTX对肿瘤细胞的凋亡诱导作用;免疫组织化学染色显示Fas蛋白在U251细胞中的表达.结果 PsTX对人神经胶质瘤细胞具有明显的生长抑制及促凋亡作用,PsTX诱导Fas在人神经胶质瘤细胞膜上表达增高.结论 PsTX可能通过Fas途径诱导人神经胶质瘤细胞凋亡.     

The R110C mutation in Notch3 causes variable clinical features in two Turkish families with CADASIL syndrome

Mutations in Notch3 gene are responsible for the cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL). It is a late onset neurological disorder recognized by recurrent strokes and dementia. We describe here the clinical and molecular findings of three unrelated Turkish families with CADASIL syndrome. Two of the families were identified to have the same mutation, p.R110C (c.C328T), located in exon 3 of the Notch3 gene. Interestingly, the phenotypic expression of the disease in these two families was markedly different in severity and age of onset implicating additional genetic and/or non-genetic modulating factors involved in the pathogenesis. In addition, we identified the novel p.C201R (c.T601C) mutation in exon 4 of the Notch3 gene in a proband of the third family with two consecutive stroke-like episodes and typical MRI findings. Mutations described here cause an odd number of cysteines in the N-terminal of the EGF domain of Notch3 protein, which seems to have an important functional effect in the pathophysiology of CADASIL. The phenotypic variability in families carrying the same molecular defect as presented here makes the prediction of prognosis inconceivable. Although DNA analysis is effective and valuable in diagnosing approximately 90% of the CADASIL patients, lack of genotype-phenotype correlation and prognostic parameters makes the presymptomatic genetic counseling very difficult.     

Protein kinase C iota protects neural cells against apoptosis induced by amyloid beta-peptide

Protein kinase C (PKC) isoforms are increasingly recognized as playing important roles in the regulation of neuronal plasticity and survival. Recent findings from studies of non-neuronal cells suggest that atypical isoforms of PKC can modulate apoptosis in various paradigms. Because increasing data support a role for neuronal apoptosis in the pathogenesis of Alzheimer's disease (AD), we tested the hypothesis that PKCiota (PKCiota) can modify vulnerability of neural cells to apoptosis induced by amyloid beta-peptide (ABP), a cytotoxic peptide linked to neuronal degeneration in AD. Overexpression of PKCiota increased the resistance of PC12 cells to apoptosis induced by ABP. Associated with the increased resistance to apoptosis were improved mitochondrial function and reduced activity of caspases. In addition, ABP-induced increases in levels of oxidative stress and intracellular calcium levels were attenuated in cells overexpressing PKCiota. These findings suggest that PKCiota prevents apoptosis induced by ABP by interrupting the cell death process at a very early step, thereby allowing the cells to maintain ion homeostasis and mitochondrial function.