α-突触核蛋白对MES23．5多巴胺能神经细胞的促增殖作用

目的：分析外源性野生型α-突触核蛋白对多巴胺能神经细胞增殖的影响及其分子机制。 方法：实验于2005—04／11在北京老年病研究所神经生物室完成。向MES23．5多巴胺能神经细胞的培养基中加入重组人野生型α-突触核蛋白，孵育48h后用细胞免疫荧光标记法和Western blot分析法检测α-突触核蛋白在细胞内的分布，用MTS法绘制生长曲线观察细胞增殖率，用基因芯片分技术观察α-突触核蛋白处理细胞的基因表达谱变化。 结果：重组人野生型α-突触核蛋白可以进入MES23．5多巴胺能神经细胞，并促进其增殖。在α-突触核蛋白处理的细胞。有22个基因的表达发生明显变化，有3个基因与内吞相关，5个与转录有关，3个与蛋白质合成有关，3个与细胞生长和增殖有关，4个与分化有关，1个与增殖及分化均有关，2个与小泡生成和神经递质释放有关，1个与生理周期有关。 结论：外源性α-突触核蛋白可能通过内吞作用进入MES23．5多巴胺能神经细胞。从而促进其增殖；α-突触核蛋白的促细胞增殖作用可能与其影响某些基因表达有关。     

重组α-突触核蛋白对 SD大鼠黑质多巴胺能神经元的作用

目的 研究重组人全长α-突触核蛋白对大鼠黑质多巴胺能神经元的毒性作用. 方法 原核表达、鉴定α-突触核蛋白;雄性 SD大鼠 30只,随机分为α-突触核蛋白注射组、六羟多巴注射组及α-突触核蛋白和六羟多巴联合注射组.用立体定位的方法分别右侧黑质注射α-突触核蛋白,六羟多巴及α-突触核蛋白+六羟多巴,左侧黑质注射等量的生理盐水,测定大鼠纹状体多巴胺含量和黑质酪氨酸羟化酶阳性神经元数目. 结果 六羟多巴和α-突触核蛋白+六羟多巴注射使注射侧多巴胺分别减少到对照侧的 36.98%和 21.79%,多巴胺能神经元数减少到 30.81%和 28.05%.而α-突触核蛋白注射对纹状体多巴胺和黑质多巴胺能神经元数目无显著影响. 结论 没有发现重组α-突触核蛋白对大鼠黑质多巴胺能神经元有明显的毒性作用.     

神经细胞凋亡机制的研究进展:α-突触核蛋白与线粒体

目的:在帕金森病的病理结构中常常存在反常聚集的α-突触核蛋白和线粒体功能失常,就神经退行性病变中α-突触核蛋白和线粒体功能失常的关系做一综述。资料来源:应用计算机检索Pubmed2000-01/2005-09的相关文章,检索词为“α-synuclein,mitochondriaandParkinson’sdisease”并限定语种为“English”。资料选择:对资料进行初审,查找全文的文献。纳入标准为:①与α-突触核蛋白的作用有关。②与线粒体和神经细胞凋亡有关。排除标准为较陈旧和重复研究的文章。资料提炼:共收集到349篇文章,其中30篇文献符合纳入标准。资料综合:在30篇文献中,15篇与α-突触核蛋白的作用有关;12篇与线粒体和神经细胞凋亡有关;3篇与α-突触核蛋白和线粒体的关系有关。以往的研究证明α-突触核蛋白是一种在神经退行性病变中起关键作用的毒性蛋白。但是近期研究表明,α-突触核蛋白可能具有双重作用。α-突触核蛋白与线粒体之间的相互作用可能是此种作用的关键。结论:α-突触核蛋白与线粒体之间存在复杂的相互作用。未来集中于α-突触核蛋白与线粒体之间的关系的研究可能对帕金森病的病因学研究提供一种新的探索。     

神经细胞凋亡机制的研究进展：α-突触核蛋白与线粒体

目的：在帕金森病的病理结构中常常存在反常聚集的α-突触核蛋白和线粒体功能失常，就神经退行性病变中α-突触核蛋白和线粒体功能失常的关系做一综述。 资料来源：应用计算机检索Pubmed 2000-01／2005-09的相关文章。检索词为“α-synuclein，mitochondria and Parkinson＇s disease”并限定语种为“English”。 资料选择：对资料进行初审，查找全文的文献。纳入标准为：①与α-突触核蛋白的作用有关。②与线粒体和神经细胞凋亡有关。排除标准为较陈旧和重复研究的文章。 资料提炼：共收集到349篇文章，其中30篇文献符合纳入标准。 资料综合：在30篇文献中，15篇与α-突触核蛋白的作用有关；12篇与线粒体和神经细胞凋亡有关；3篇与α-突触核蛋白和线粒体的关系有关。以往的研究证明α-突触核蛋白是一种在神经退行性病变中起关键作用的毒性蛋白。但是近期研究表明，α-突触核蛋白可能具有双重作用。α-突触核蛋白与线粒体之间的相互作用可能是此种作用的关键。 结论：α-突触核蛋白与线粒体之间存在复杂的相互作用。未来集中于α-突触核蛋白与线粒体之间的关系的研究可能对帕金森病的病因学研究提供一种新的探索。     

制备与鉴定导致家族性帕金森病突变蛋白质的α-突触核蛋白聚合体

目的：制备和鉴定与家族性帕金森病发病有关的α-突触核蛋白突变体A53T与A30P的聚合体，为帕金森病患者的治疗乃至康复干预提供重要理论基础及靶点。方法：实验于2004—01／05在首都医科大学宣武医院北京老年医学研究所神经生物研究室完成。设计含适当酶切位点的聚合酶链反应引物，用聚合酶链反应法从质粒pBS-α-突触核蛋白(A53T)和pBS-α-突触核蛋白(A30P)合成α-突触核蛋白突变DNA，并将其亚克隆至谷胱甘肽巯基转移酶融合表达载体pGEX-4T-1。转化大肠杆菌B121，以异丙基-D-硫代半乳糖苷诱导，使其表达融合蛋白GST-α-突触核蛋白(A53T)和GST-α-突触核蛋白(A30P)。用凝血酶定点分解融合蛋白，并用亲和层析法纯化突变的基因重组型人α-突触核蛋白。将重组蛋白在37℃下孵育2h制备蛋白聚合体。所制备聚合体用Westem blot分析法和透射电镜鉴定。结果：DNA测序结果证明构建载体插入正确α-突触核蛋白突变体A53T与A30P基因。基因表达产物在十二烷基磺酸钠-聚丙烯酰胺凝胶电泳上表现为单一条带，分子量约为18ku，与所报道的该蛋白的分子量一致。Westem blot分析表明，所表达蛋白可被α-突触核蛋白特异性抗体识别，证明表达的重组蛋白为α-突触核蛋白，聚合后的α-突触核蛋白在108ku左右，相当于六聚体。聚合体在电镜下呈短的丝状结构。结论：制备出人重组α-突触核蛋白突变体A53T与A30P并建立其聚合体模型，这为帕金森病的病因研究提供重要的物质基础从而为帕金森病患者的康复提供新的靶点。     

制备与鉴定导致家族性帕金森病突变蛋白质的α-突触核蛋白聚合体

目的:制备和鉴定与家族性帕金森病发病有关的α-突触核蛋白突变体A53T与A30P的聚合体,为帕金森病患者的治疗乃至康复干预提供重要理论基础及靶点。方法:实验于2004-01/05在首都医科大学宣武医院北京老年医学研究所神经生物研究室完成。设计含适当酶切位点的聚合酶链反应引物,用聚合酶链反应法从质粒pBS-α-突触核蛋白(A53T)和pBS-α-突触核蛋白(A30P)合成α-突触核蛋白突变DNA,并将其亚克隆至谷胱甘肽巯基转移酶融合表达载体pGEX-4T-1。转化大肠杆菌BL21,以异丙基-D-硫代半乳糖苷诱导,使其表达融合蛋白GST-α-突触核蛋白(A53T)和GST-α-突触核蛋白(A30P)。用凝血酶定点分解融合蛋白,并用亲和层析法纯化突变的基因重组型人α-突触核蛋白。将重组蛋白在37℃下孵育2h制备蛋白聚合体。所制备聚合体用Westernblot分析法和透射电镜鉴定。结果:DNA测序结果证明构建载体插入正确α-突触核蛋白突变体A53T与A30P基因。基因表达产物在十二烷基磺酸钠-聚丙烯酰胺凝胶电泳上表现为单一条带,分子量约为18ku,与所报道的该蛋白的分子量一致。Westernblot分析表明,所表达蛋白可被α-突触核蛋白特异性抗体识别,证明表达的重组蛋白为α-突触核蛋白,聚合后的α-突触核蛋白在108ku左右,相当于六聚体。聚合体在电镜下呈短的丝     

老年神经变性疾病蛋白基因研究:3种α-突触核蛋白提取纯化方法的比较

目的:用经济、简便、快捷的方法得到大量、高纯度的α-突触核蛋白。方法:将重组的proEXNACP,pGEXNACPH和pTYBNACP质粒分别转入大肠杆菌DH5α,BL21和ER2566细胞进行培养增菌,IPTG诱导产生α-突触核蛋白;超声破碎、离心粗提取得到融合的α-突触核蛋白;分别经Ni-NTAresin,GlutathioneSepharose4B和ChitinBeads纯化,得到α-突触核蛋白。用SDS-PAGE电泳观察纯度、Western杂交检测正确性、用BCA蛋白定量法测定蛋白含量。结果:3种方法均能得到较高纯度的α-突触核蛋白,其中用Ni-NTAresin提取纯化的α-突触核蛋白的纯度最高;蛋白收获量分别是10mg/L,5mg/L和5mg/L;经济耗费和实验的繁简程度没有较大差异。结论:3种方法均可作为α-突触核蛋白的提取方法。     

重组α-突触核蛋白对SD大鼠黑质多巴胺能神经元的作用

目的：研究重组人全长α-突触核蛋白对大鼠黑质多巴胺能神经元的霉性作用。方法：原核表达、鉴定α-突触核蛋白；雄性SD大鼠30只，随机分为α-突触核蛋白注射组、六羟多巴注射组及α-突触核蛋白和六羟多巴联合注射组。用立体定位的方法分别右侧黑质注射α-突触核蛋白，六羟多巴及α-突触核蛋白 六羟多巴，左侧黑质注射等量的生理盐水，测定大鼠纹状体多巴胺含量和黑质酪氨酸羟化酶阳性神经元数目。结果：六羟多巴和α-突触核蛋白 六羟多巴注射使注射侧多巴胺分别减少到对照侧的36．98％和21．79％，多巴胺能神经元数减少到30．81％和28．05％。而α-突触核蛋白注射对纹状体多巴胺和黑质多巴胺能神经元数目无显著影响。结论：没有发现重组α-突触核蛋白对大鼠黑质多巴胺能神经元有明显的毒性作用。     

揭示α-突触核蛋白与帕金森病的关系：α-突触核蛋白单克隆抗体的研究

目的：α-突触核蛋白(α-Synuclein，α-Syn)是与帕金森病的发病密切相关的蛋白质。关于这种蛋白质在脑内神经元的亚细胞分布迄今尚无定论。制备α-Syn抗体探讨α-Syn在亚细胞的定位。方法：实验于2004—01／05在北京老年医学研究所神经生物研究室完成。采用重组的人α-Syn免疫小鼠，并将其脾细胞与骨髓瘤融合制备出杂交瘤，利用免疫组化和Western blot法筛选阳性克隆，获得一特异性抗α-Syn单克隆抗体。结果：噬菌体多肽展示分析表明，该抗体识别人α-Syn C-末端的一段特异序列，但该序列与大鼠和小鼠的相应序列差一个氨基酸。免疫印记分析表明，该抗体能够检测人、大鼠与小鼠脑组织中的α-Syn。用该抗体进行免疫组化染色结果显示，α-Syn免疫阳性物质主要存在于神经元末梢与核中。结论：所制备的单克隆抗体对α-Syn具有特异性，可用于人、大鼠和小鼠的α-Syn研究。     

揭示α-突触核蛋白与帕金森病的关系:α-突触核蛋白单克隆抗体的研究

目的:α-突触核蛋白(α-Synuclein,α-Syn)是与帕金森病的发病密切相关的蛋白质。关于这种蛋白质在脑内神经元的亚细胞分布迄今尚无定论。制备α-Syn抗体探讨α-Syn在亚细胞的定位。方法:实验于2004-01/05在北京老年医学研究所神经生物研究室完成。采用重组的人α-Syn免疫小鼠,并将其脾细胞与骨髓瘤融合制备出杂交瘤,利用免疫组化和Westernblot法筛选阳性克隆,获得一特异性抗α-Syn单克隆抗体。结果:噬菌体多肽展示分析表明,该抗体识别人α-SynC-末端的一段特异序列,但该序列与大鼠和小鼠的相应序列差一个氨基酸。免疫印记分析表明,该抗体能够检测人、大鼠与小鼠脑组织中的α-Syn。用该抗体进行免疫组化染色结果显示,α-Syn免疫阳性物质主要存在于神经元末梢与核中。结论:所制备的单克隆抗体对α-Syn具有特异性,可用于人、大鼠和小鼠的α-Syn研究。     

Dieldrin induces ubiquitin-proteasome dysfunction in alpha-synuclein overexpressing dopaminergic neuronal cells and enhances susceptibility to apoptotic cell death

Exposure to pesticides is implicated in the etiopathogenesis of Parkinson's disease (PD). The organochlorine pesticide dieldrin is one of the environmental chemicals potentially linked to PD. Because recent evidence indicates that abnormal accumulation and aggregation of alpha-synuclein and ubiquitin-proteasome system dysfunction can contribute to the degenerative processes of PD, in the present study we examined whether the environmental pesticide dieldrin impairs proteasomal function and subsequently promotes apoptotic cell death in rat mesencephalic dopaminergic neuronal cells overexpressing human alpha-synuclein. Overexpression of wild-type alpha-synuclein significantly reduced the proteasomal activity. Dieldrin exposure dose-dependently (0-70 microM) decreased proteasomal activity, and 30 microM dieldrin inhibited activity by more than 60% in alpha-synuclein cells. Confocal microscopic analysis of dieldrin-treated alpha-synuclein cells revealed that alpha-synuclein-positive protein aggregates colocalized with ubiquitin protein. Further characterization of the aggregates with the autophagosomal marker mondansyl cadaverine and the lysosomal marker and dot-blot analysis revealed that these protein oligomeric aggregates were distinct from autophagosomes and lysosomes. The dieldrin-induced proteasomal dysfunction in alpha-synuclein cells was also confirmed by significant accumulation of ubiquitin protein conjugates in the detergent-insoluble fraction. We found that proteasomal inhibition preceded cell death after dieldrin treatment and that alpha-synuclein cells were more sensitive than vector cells to the toxicity. Furthermore, measurement of caspase-3 and DNA fragmentation confirmed the enhanced sensitivity of alpha-synuclein cells to dieldrin-induced apoptosis. Together, our results suggest that increased expression of alpha-synuclein predisposes dopaminergic cells to proteasomal dysfunction, which can be further exacerbated by environmental exposure to certain neurotoxic compounds, such as dieldrin.     

Protein kinase Cdelta is a key downstream mediator of manganese-induced apoptosis in dopaminergic neuronal cells

Manganese (Mn) exposure causes manganism, a neurological disorder similar to Parkinson's disease. However, the cellular mechanism by which Mn induces dopaminergic neuronal cell death remains unclear. In the present study, we sought to investigate the key downstream apoptotic cell signaling events that contribute to Mn-induced cell death in mesencephalic dopaminergic neuronal (N27) cells. Mn exposure induced a dose-dependent increase in neuronal cell death in N27 cells. The cell death was accompanied by sequential activation of mitochondrial-dependent proapoptotic events, including cytochrome c release, caspase-3 activation, and DNA fragmentation, but not caspase-8 activation, indicating that the mitochondrial-dependent apoptotic cascade primarily triggers Mn-induced apoptosis. Notably, Mn treatment proteolytically activated protein kinase Cdelta (PKCdelta), a member of a novel class of protein kinase C. The caspase-3 specific inhibitor benzyloxycarbonyl-Asp-Glu-Val-Asp-fluoromethylketone (Z-DEVD-FMK) significantly blocked PKCdelta cleavage and its kinase activity, indicating that caspase-3 mediates the proteolytic activation. Cotreatment with the PKCdelta inhibitor rottlerin or the caspase-3 inhibitor Z-DEVD-FMK almost completely blocked Mn-induced DNA fragmentation. Additionally, N27 cells expressing a catalytically inactive PKCdelta(K376R) protein (PKCdelta dominant negative mutant) or a caspase cleavage resistant PKCdelta(D327A) protein (PKCdelta cleavage resistant mutant) were found to be resistant to Mn-induced apoptosis. To further establish the proapoptotic role of PKCdelta, RNA interference-mediated gene knockdown was performed. Small interfering RNA suppression of PKCdelta expression protected N27 cells from Mn-induced apoptotic cell death. Collectively, these results suggest that caspase-3-dependent proteolytic activation of PKCdelta plays a key role in Mn-induced apoptotic cell death.     

Mechanism of specific dopaminergic neuronal death in Parkinson's disease

Parkinson's disease (PD) is characterized by progressive degeneration of dopaminergic (DAergic) neurons of the nigrostriatal system, with resulting reduction in striatal dopamine (DA) concentration. Various mechanisms have been implicated in the pathogenesis and progression of PD. Among them, mitochondrial dysfunction, inflammation and oxidative stress had been accepted as the most plausible mechanism of disease progression. The free radicals/oxidative stress produced by MPTP, 6-hydroxydopamine, rotenone, activated microglias, and disturbances in mitochondrial respiratory enzymes provide a common pathway for the progression of all kinds of neurons. On the other hand, numerous studies on DA-induced neurotoxicity have been reported recently, and DA itself exerts cytotoxicity in DAergic neurons mainly due to the generation of highly reactive DA -quinones which are DAergic neuron-specific cytotoxic molecules. DA quinones may irreversibly alter protein function through the formation 5-cysteinyl-dopamine on the protein. For example, the formation of DA quinone-alpha-synuclein complex consequently increases cytotoxic protofibrils and covalent modification of functional enzymes. Thus, DA quinones play an important role in 'specific' DAergic neuro-degeneration of PD.     

诱导时间对体外培养大鼠神经干细胞向多巴胺能神经元分化的影响

背景:近年来通过筛选不同细胞因子的诱导分化作用发现,某些特定的细胞因子配伍可明显诱导中脑神经干细胞体外定向分化成多巴胺能神经元,研究还发现神经干细胞体外诱导分化的多巴胺能神经元可以有效应用于移植治疗帕金森病,为提高其体内移植的疗效,目前迫切需要深入研究神经干细胞诱导分化的生物学特性.目的:探讨大鼠神经干细胞在分化液中诱导不同时间后,其体外分化成多巴胺能神经元的效应.设计:单一样本观察.单位:中山大学附属第一医院神经外科.材料:实验于2007-05/10在中山大学附属第一医院完成,选择清洁级孕14 d的健康SD大鼠6只,体质量350-400 g,由中山大学动物实验中心提供(许可证号码SCXK(粤)2007-0034).实验过程中对动物处置符合动物伦理学标准.方法:①在含表皮生长因子及碱性成纤维细胞生长因子的无血清培养液中培养胚胎大鼠中脑神经干细胞.②经传代扩增后,在含白细胞介素1α、白细胞介素11、白血病抑制因子、胶质细胞源性神经营养因子的诱导分化液中向多巴胺能神经元分化.③诱导分化2,4,6,8,10 d后,流式细胞仪检测分化细胞中酪氨酸羟化酶阳性细胞的比值.主要观察指标:①大鼠神经干细胞诱导分化后细胞形态的变化.②诱导不同时间的大鼠神经干细胞分化成酪氨酸羟化酶阳性细胞的比值.结果:在诱导分化液中大鼠中脑神经干细胞球呈贴壁生长,球形结构开始塌陷,球内细胞从球体中央逐渐向四周分化扩展出较多形态各异的细胞,分化6 d后,多数细胞已生长出一两个长突起及多个短突起.免疫细胞化学显示分化的细胞中含有酪氨酸羟化酶染色阳性细胞,流式细胞仪检测诱导分化2,4,6,8,10 d的分化细胞中酪氨酸羟化酶染色阳性细胞的比例分别为(3.2±0,9)%,(6.8±1.6)%,(16.7±2.6)%.(14.8±1.8)%,(12.2±2.5)%,各组间差异有显著性意义(F=26.449.P＜0.05).结论:诱导时间对大鼠中脑神经干细胞体外分化成多巴胺能神经元的能力存在影响,诱导6 d的神经干细胞分化成多巴胺能神经元的比例最高.     

Effect of phenylalanine and its metabolites on the proliferation and viability of neuronal and astroglial cells: possible relevance in maternal phenylketonuria

Phenylketonuria is a genetic defect that, without strict dietary control, results in the accumulation of phenylalanine (Phe) in body fluids. If a low-Phe diet is not maintained during pregnancy, the offspring of phenylketonuric women are born with mental retardation and microcephaly. Primary cultures of rat cerebellar granule cells, rat cortical astrocytes, human fetal astrocytes, and human neuroblastoma (SY5Y) cells and human astrocytoma (1321N1) cells were used to test the hypothesis that the microencephaly may be a result of neuronal cell death and reduced astrocyte proliferation. Exposure to Phe or to six Phe metabolites [phenylacetic acid (PAA), phenyllactic acid, hydroxyphenylacetic acid, phenylpyruvic acid, phenylethylamine (PEA), and mandelic acid] did not result in astroglial or neuronal cell cytotoxicity. Treatment of 1321N1 cells, human fetal astrocytes, or rat astrocytes with 5 mM Phe for 24 h decreased DNA synthesis 19 +/- 4, 30 +/- 4, and 60 +/- 6%, respectively. This effect was concentration dependent, and flow cytometry revealed that Phe treatment resulted in the accumulation of cells in the G(0)/G(1) phase of the cell cycle. In addition, in 1321N1 cells, exposure to 5 mM PAA, and in rat astrocytes, exposure to 0.5 mM PEA inhibited cell proliferation 42 +/- 4 and 55 +/- 4%, respectively. These metabolites also resulted in the accumulation of cells in the G(0)/G(1) phase of the cell cycle. In human fetal astrocytes, 0.5 mM PEA and 0.5 mM PAA resulted in a 41 +/- 12 and 52 +/- 11% reduction proliferation, respectively.     

许旺细胞对周围神经再生的促进效应

学术背景:许旺细胞是周围神经纤维的鞘细胞,是周围神经不可缺少的一部分.在周围神经损伤修复过程中,如何运用和调控许旺细胞的活性成为周围神经领域内的研究热点.目的:深入认识许旺细胞的作用及其促周围神经再生的研究进展.检索策略:由该论文的研究人员应用计算机检索Science Direct及PUBMED数据库1990-01/2007-10的相关文献,检索词"schwann cells,peripheral nerve injury,proliferation,macrophage,activation,neurotrophic factors,extracellular matrix,adhesionmolecule,axon,interaction,myelination,transplantation,gap,transgene,over-expressing,isolation,purification,stem cells",并限定文章语言种类为English.同时计算机检索中国期刊全文数据库1990-01/2007-10的相关文献,检索词"雪旺氏细胞,周围神经再生,人工神经移植物",并限定文章语言种类为中文.共检索到285篇文献,对资料进行初审,纳入标准:①文章所述内容应与许旺细胞促周围神经再生密切相关.②同一领域选择近期发表或在权威杂志上发表的文章.排除标准:①重复性研究.②Meta分析.文献评价:文献的来源主要是通过对许旺细胞促周围神经再生的作用机制与应用及其相关研究进展进行汇总分析,所选用的48篇文献中,2篇为综述,其余均为临床或基础实验研究.＃资料综合:①周围神经损伤后,其远侧段轴突及髓鞘崩解,同时许旺细胞大量增殖,增殖的许旺细胞在基底膜管内形成Bungner带,引导再生轴突的生长并最终形成新的髓鞘;增殖的许旺细胞还通过激活单核/巨噬细胞清除组织碎片、分泌神经营养因子以及维持受损神经元的活力、抑制其凋产,进一步促进周围神经的再生;并且通过许旺细胞与再生轴突之间的缝隙连接和紧密连接,使得再生过程中物质交换和信息交换更为便捷和有效的进行.②目前大量研究尝试利用许旺细胞促进周围神经再生,许旺细胞与人工神经移植物共间运用在动物实验中已经取得了显著功效.随着转基因技术的发展,遗传修饰的许旺细胞成为研究热点.③许旺细胞的分离纯化技术从最早的反复植块法、消化法,到以heregulin/forskolin处理细胞然后用神经切断造模法,再到最近的抗体磁珠分选法,体外培养许旺细胞的纯度得到不断提升.④实验证明间充质干细胞诱导后可以分化为表达p75、S100、GFAP等胶质细胞的标志性分子,并能显著促进轴突生长和髓鞘形成.结论:许旺细胞促进周围神经再生的作用已受到广泛肯定,但其作用的信号通路仍不确定.正确诱导许旺细胞分化为成熟的成髓鞘许旺细胞、保证其在损伤局部的存活是修复周围神经损伤的关键.     

Hsp104 antagonizes alpha-synuclein aggregation and reduces dopaminergic degeneration in a rat model of Parkinson disease

Parkinson disease (PD) is characterized by dopaminergic neurodegeneration and intracellular inclusions of alpha-synuclein amyloid fibers, which are stable and difficult to dissolve. Whether inclusions are neuroprotective or pathological remains controversial, because prefibrillar oligomers may be more toxic than amyloid inclusions. Thus, whether therapies should target inclusions, preamyloid oligomers, or both is a critically important issue. In yeast, the protein-remodeling factor Hsp104 cooperates with Hsp70 and Hsp40 to dissolve and reactivate aggregated proteins. Metazoans, however, have no Hsp104 ortholog. Here we introduced Hsp104 into a rat PD model. Remarkably, Hsp104 reduced formation of phosphorylated alpha-synuclein inclusions and prevented nigrostriatal dopaminergic neurodegeneration induced by PD-linked alpha-synuclein (A30P). An in vitro assay employing pure proteins revealed that Hsp104 prevented fibrillization of alpha-synuclein and PD-linked variants (A30P, A53T, E46K). Hsp104 coupled ATP hydrolysis to the disassembly of preamyloid oligomers and amyloid fibers composed of alpha-synuclein. Furthermore, the mammalian Hsp70 and Hsp40 chaperones, Hsc70 and Hdj2, enhanced alpha-synuclein fiber disassembly by Hsp104. Hsp104 likely protects dopaminergic neurons by antagonizing toxic alpha-synuclein assemblies and might have therapeutic potential for PD and other neurodegenerative amyloidoses.