Enhanced expression of 14-3-3 proteins in reactive astrocytes in Creutzfeldt-Jakob disease brains

14-3-3 proteins have been reported to be detected specifically in the cerebrospinal fluid (CSF) from patients with Creutzfeldt-Jakob disease (CJD). To elucidate the role of 14-3-3 proteins in patients with CJD, we performed immunohistochemical studies on 14-3-3 proteins in autopsied brains from five patients with sporadic CJD (sCJD), three patients with Alzheimers disease (AD), and seven normal control subjects. Formalin-fixed, paraffin-embedded sections from all cases were immunostained with several types of specific anti-14-3-3 antibodies. In the normal control brains, 14-3-3 immunoreactivity was localized mainly in the neuronal somata and processes; in contrast, glial cells showed no or faint immunoreactivity. In the brains from the patients with AD, 14-3-3 immunoreactivity was observed in the surviving neurons as well as some neurofibrillary tangles. In the brains from the patients with sCJD, 14-3-3 immunoreactivity was well preserved in the remaining neurons. Furthermore, the glial cells, especially the reactive astrocytes, were intensely immunostained in the brains affected by sCJD. Our findings suggest that 14-3-3 proteins may be up-regulated in the glial cells, particularly in reactive astrocytes, and that the enhanced expression of 14-3-3 proteins in these glial elements may be associated with the pathogenesis of sCJD.     

Intranuclear localization and isoform-dependent translocation of 14-3-3 proteins in human brain with infarction

Immunolocalization of 14-3-3 proteins in human brains with infarction was investigated using isoform-specific antibodies. Neurons around acute or subacute ischemic foci exhibited an enhanced immunoreactivity for 14-3-3 proteins either in the cytoplasm (especially for its sigma isoform) or in the nucleus (especially for its beta isoform), and sometimes in both. 14-3-3-like immunoreactivity was evaluated in each neuron, which enabled us to identify into three patterns: intense cytoplasmic staining with or without nuclear staining; a predominant nuclear staining with weak cytoplasmic staining; and an exclusive nuclear staining without cytoplamic staining. Quantification of 1500 neurons in relation to the severity of ischemia estimated by the relative distance from ischemic foci clarified that nuclear immunoreactivity for 14-3-3 proteins was more frequent in neurons near the ischemic core. Although the cytoplasm of astrocytes was similarly positive for the sigma and the epsilon isoform, their nuclei were only immunopositive for the gamma isoform. In the cerebral white matter with ischemia, axonal swelling and some nuclei of oligodendrocytes were positive for the zeta isoform. Isoform-specific translocation of 14-3-3 proteins into nuclei is a cellular reaction to ischemic stress that may be related to survival of neurons and their protection against cell death.     

14—3—3蛋白在细胞凋亡中的作用

14—3—3蛋白是存在于所有真核细胞中的蛋白家族分子，参与蛋白激酶信号通路。通过磷酸化丝氨酸或磷酸化苏氨酸的方式，14—3—3蛋白与磷酸化依赖的蛋白间相互作用，调控细胞周期的进展，启动并维持了DNA损害的枪金点，激活促分裂素原活化蛋白激酶（mitogen—activated protein kinases，MAPK），调节生存信号及细胞骨架，对细胞凋亡发挥重要作用。本文对近年来关于14—3—3蛋白与细胞凋亡的研究进展作一综述。     

14-3-3蛋白在PC12细胞的分布及MPP+对其表达的影响

目的探讨14-3-3蛋白在PC12细胞中的分布及其与MPP 诱导PC12细胞死亡的关系。方法用免疫荧光染色检测14-3-3蛋白的分布,并分别用免疫印迹技术与MTT法检测MPP ,对14-3-3蛋白表达及细胞活力的影响。结果PC12细胞中β、γ、ε、ζ、η和θ亚型免疫反应阳性。14-3-3蛋白表达随着MPP 处理的时间延长呈下降趋势,在6h变化不明显,12h显著下降(P<0.05),到48h后14-3-3蛋白的减少极其显著(P<0.01)。PC12细胞的存活率也呈现同样的变化趋势。结论MPP 引起PC12细胞的死亡可能与细胞内14-3-3蛋白含量的下降有关。     

Reduced WWOX protein expression in human astrocytoma

The WW domain‐containing oxidoreductase (WWOX) functions as a tumor suppressor by interacting with various proteins in numerous important signaling pathways. WWOX silencing via homozygous deletion of its locus and/or promoter hypermethylation has been observed in various human cancers. However, the relationship between WWOX and tumors in the central nervous system has not been fully explored. In this study, the expression levels of WWOX protein in astrocytomas from 38 patients with different tumor grades were retrospectively analyzed by immunohistochemical staining. The results showed that 19 (50.0%) samples had highly reduced WWOX protein expression when compared with normal controls, while 14 (36.8%) and five (13.2%) cases exhibited moderate and mild decreases in WWOX expression, respectively. Reduction of the expression of WWOX protein correlated with patient age, supra‐tentorial localization of the tumor and severity of the symptoms. Furthermore, loss of WWOX expression inversely correlated with survival time. No significant correlation was observed between the loss of WWOX expression and the gender of patients or the difference in pre‐operative and post‐operative karnofsky performance status scores. Surprisingly, there was no significant correlation between the loss of WWOX protein expression and overall tumor grades. Nevertheless, it was found that 63.6% (7/11) of the grade II astrocytomas had highly reduced WWOX expression and 36.4% (4/11) showed moderately reduced WWOX expression, while none of the samples exhibited mild reductions. Similar results were also found in grade III astrocytomas. The results from this small‐size sample pilot study suggest that the loss of WWOX expression may be an early event in the pathogenesis of human astrocytoma.     

Accumulation of 14-3-3 proteins in glial cytoplasmic inclusions in multiple system atrophy

Glial cytoplasmic inclusions are the pathological hallmark of multiple system atrophy. However, the molecular mechanisms underlying the formation of glial cytoplasmic inclusions remain unclear. Alpha-synuclein, a major component of glial cytoplasmic inclusions, has the ability to interact with 14-3-3 proteins, which mediate several types of signal transduction pathways. To elucidate the role of these 14-3-3 proteins in patients with multiple system atrophy, we performed immunohistochemical studies on 14-3-3 in brain tissue specimens from 7 control subjects and from 15 patients with multiple system atrophy. In both control and multiple system atrophy cases, 14-3-3 immunoreactivity was observed mainly in the neuronal somata and proximal processes, as well as the nerve fibers. Even in the severely affected regions of patients with multiple system atrophy, 14-3-3 immunoreactivity generally was spared in the surviving neurons, some of which were strongly immunolabeled. In addition, numerous glial cytoplasmic inclusions were intensely immunostained, and neuronal cytoplasmic inclusions and dystrophic neurites were also immunoreactive for 14-3-3. Our results suggest that an aberrant accumulation of 14-3-3 proteins may occur in brains affected by multiple system atrophy, and that 14-3-3 proteins may be associated with the pathogenesis of multiple system atrophy.     

Quantitation of 14-3-3 and neuron-specific enolase proteins in CSF in Creutzfeldt-Jakob disease

CSF 14-3-3 and neuron-specific enolase (NSE) proteins were quantitated from patients who had Creutzfeldt-Jakob disease (CJD) or other rapidly dementing disorders initially considered to be CJD. Thirty-one patients were diagnosed as having CJD among 152 studied. CSF 14-3-3 values more than 8 ng/mL correlated with CJD. CSF NSE values less than 30 ng/mL and 14-3-3 values less than 8 ng/mL made a diagnosis of CJD unlikely, but did not exclude it.     

Rapid identification of 14-3-3-binding proteins by protein microarray analysis

The 14-3-3 protein family consists of acidic 30-kDa proteins composed of seven isoforms in mammalian cells, expressed abundantly in neurons and glial cells of the central nervous system (CNS). The 14-3-3 isoforms form a dimer that acts as a molecular adaptor interacting with key signaling components involved in cell proliferation, transformation, and apoptosis. Until present, more than 300 proteins have been identified as 14-3-3-binding partners, although most of previous studies focused on a limited range of 14-3-3-interacting proteins. Here, we studied a comprehensive profile of 14-3-3-binding proteins by analyzing a high-density protein microarray using recombinant human 14-3-3 epsilon protein as a probe. Among 1752 proteins immobilized on the microarray, 20 were identified as 14-3-3 interactors, most of which were previously unreported 14-3-3-binding partners. However, 11 known 14-3-3-binding proteins, including keratin 18 (KRT18) and mitogen-activated protein kinase-activated protein kinase 2 (MAPKAPK2), were not identified as a 14-3-3-binding protein. The specific binding to 14-3-3 of EAP30 subunit of ELL complex (EAP30), dead box polypeptide 54 (DDX54), and src homology three (SH3) and cysteine rich domain (STAC) was verified by immunoprecipitation analysis of the recombinant proteins expressed in HEK293 cells. These results suggest that protein microarray is a powerful tool for rapid and comprehensive profiling of 14-3-3-binding proteins.     

14-3-3 proteins and protein phosphatases are not reduced in tau-deficient mice

Tau is an axonal microtubule-associated protein, whose dysfunction causes neurodegenerative diseases such as Alzheimer's disease and other tauopathies. Earlier studies have shown the interactions of tau with glycogen synthase kinase-3beta, 14-3-3zeta, protein phosphatase 1 and protein phosphatase 2A. In this study, we compared the amounts of these tau-interacting proteins in brain microtubule-enriched fractions from wild-type and tau-deficient mice. Contrary to our expectation, we detected no difference in the amount of these proteins between wild-type and tau-deficient mice. Our findings indicate that only a small portion of tau-interacting proteins are bound to tau in vivo, and suggest the existence of other scaffolding proteins. We propose that tau-deficient mice are an ideal system for confirming the function of tau-interacting proteins.     

Immunoexpression of 14-3-3 proteins in glial cytoplasmic inclusions of multiple system atrophy

Glial cytoplasmic inclusions (GCIs) are the histological hallmark of multiple system atrophy (MSA). In six postmortem brains of patients with MSA, 14-3-3-protein immunoreactivity was identified in GCIs predominately in the white matter tissue of the basal forebrain and cerebellum. Using double immunohistochemistry, co-localization of 14-3-3-protein and alpha-synuclein immunoreactivities in the GCIs was confirmed. The immunolabeling rate of GCIs with 14-3-3 proteins varied regionally from approximately 40% to 90%. Semiquantitative analysis yielded a significant negative correlation between degree of tissue degeneration and density of 14-3-3-protein-immunoreactive GCIs. The 14-3-3 proteins are active cofactors involved in cellular regulation through binding to phosphorylated motifs in target proteins and alpha-synuclein is a known target of 14-3-3. Our study suggests that 14-3-3 proteins are closely associated with alpha-synuclein in GCIs and 14-3-3 proteins may be candidate cofactors of alpha-synuclein in GCI formation.     

14-3-3蛋白与阿尔茨海默病tau蛋白异常磷酸化的关系

目的研究阿尔茨海默病(Alzheimerdisease,AD)患者海马组织1433蛋白家族与神经原纤维缠结(NFT)形成及tau蛋白异常磷酸化之间的关系。方法以4例临床及病理确诊的AD患者及4名对照者海马组织为材料,用免疫组织化学、免疫印迹及免疫共沉淀技术来研究1433蛋白在AD患者海马的表达情况及其与异常磷酸化tau蛋白之间的关系。结果1433蛋白ζ及γ亚型能使AD患者海马的NFT显色,β亚型主要使海马的颗粒神经元着色,同时也使少许NFT染色。免疫印迹显示β和ζ亚型在AD中明显上调,其像素值(分别为4570±92和5630±40)比对照组(分别为1849±65和956±140)高2～3倍(P<0.01,t检验)。免疫共沉淀分析发现单抗双螺旋细丝(PHF1)从AD患者脑中沉淀的1433蛋白像素值(3859±78)显著多于对照组(1540±138,AD组像素值比对照组高1倍,P<0.05,t检验),这3种亚型均与异常磷酸化tau蛋白在AD患者脑部形成复合物。σ亚型在AD患者和对照组脑中均无表达。上述发现在4名对照者脑组织中并未观察到。结论β、ζ及γ亚型1433蛋白参与NFT形成,它们均可能参与tau蛋白的磷酸化调节,具体机制有待阐明。     

14-3-3β在人脑星形细胞瘤中的表达及意义

目的探讨14-3-3β在人脑星形细胞瘤中表达与肿瘤病理分级的关系。方法采用免疫组化法检测14-3-3β亚型在80例人脑星形细胞瘤和10例正常脑组织标本中的表达水平。结果在正常脑组织中，14-3-3蛋白6亚型只表达于神经元胞体和突起，在胶质细胞中未见表达。母亚型在人脑星形细胞瘤的表达阳性率及免疫反应评分（IRS）分别为60％、1．86±1．83。Ⅰ～Ⅳ级脑星形细胞瘤中β亚型表达阳性率分别为40％（8／20）、50％（10／20）、70％（14／20）和80％（16／20）。Ⅰ～Ⅳ级脑星形细胞瘤中β亚型IRS分别为0．88．4±0．27、1．15±0．28、2．19±0．37和3．23±0．47。不同恶性级别的脑星形细胞瘤中，14．3-3蛋白β亚型的阳性表达率无显著差异，但其IRS有显著差异（P〈0．05）。结论14-3-3β在人脑星形细胞瘤中高表达，且随着星形细胞瘤病理级别的增高而表达增强，14-3-3蛋白β亚型在脑星形细胞瘤的发生过程中具有重要作用。     

Galectin-3在人脑星形胶质瘤细胞中的表达

目的探讨半乳糖凝集素Galectin-3(G3)在脑星形胶质细胞瘤中的表达.以及与星形胶质细胞瘤WHO分级之间的关系.方法应用免疫组化SP法检测60例脑星形胶质细胞瘤标本中Galectin-3的表达,并检测不同的分级之间是否具有差异性.结果Galectin-3的阳性率为85%,随着肿瘤恶性程度增加,阳性细胞数目增加,不同WHO分级之间阳性表达率差异具有显著性.结论Galectin-3在星形胶质细胞瘤中的阳性表达率与WHO分级有关,并可作为星形胶质细胞瘤恶性程度的重要分级指标.     

14-3-3蛋白在BV-2细胞中的表达及LPS对其表达的影响

目的 研究14-3-3蛋白在中枢神经系统小神经胶质细胞中的表达分布情况及LPS刺激后其表达变化；探讨14-3-3蛋白与小神经胶质细胞释放炎症因子的关系。方法应用小鼠小神经胶质细胞株BV-2作为体外小神经胶质细胞的模型，以LPS刺激其活化，应用免疫荧光检测14-3-3蛋白亚型在Bv-2细胞中的表达、免疫印迹技术检测14-3-3蛋白在LPS刺激后的表达变化，ELISA检测IL-1β的表达。结果14-3-3ξεθγ蛋白亚型在BV-2细胞中均有表达，主要分布在细胞浆；LPS刺激BV-2细胞活化后释放Ⅱ-1β,同时14-3-3蛋白表达下降。结论BV-2细胞高表达14-3-3蛋白，LPS刺激后表达下降，提示14-3-3蛋白参与了中枢神经系统免疫应答的调节。     

14-3-3 proteins in Lewy bodies in Parkinson disease and diffuse Lewy body disease brains

Several components of Lewy bodies have been identified, but the precise mechanism responsible for the formation of Lewy bodies remains undetermined. The 14-3-3 protein family is involved in numerous signal transduction pathways and interacts with alpha-synuclein, which is a major constituent of Lewy bodies. To elucidate the role of 14-3-3 proteins in neuro-degenerative disorders associated with Lewy bodies, we performed immunohistochemical studies on 14-3-3 in brains from 5 elderly control subjects and from 10 patients with Parkinson disease (PD) or diffuse Lewy body disease (DLBD). In the normal controls, 14-3-3-like immunoreactivity was mainly observed in the neuronal somata and processes in various cortical and subcortical regions. In the PD and DLBD cases, a similar immunostaining pattern was found and immunoreactivity was generally spared in the surviving neurons from the severely affected regions. In addition, both classical and cortical Lewy bodies were intensely immunolabeled and some dystrophic neurites were also immunoreactive for 14-3-3. Our results suggest that 14-3-3 proteins may be associated with Lewy body formation and may play an important role in the pathogenesis of PD and DLBD.     

14-3-3 proteins in Lewy body-like hyaline inclusions in patients with sporadic amyotrophic lateral sclerosis

14-3-3 proteins are highly conserved eukaryotic proteins that regulate various types of signal transduction pathways through phosphorylation-dependent protein-protein interactions. 14-3-3 mRNAs have been shown to be up-regulated in the injured rat motor neurons and in the spinal cords of patients with amyotrophic lateral sclerosis (ALS). To investigate the role of 14-3-3 proteins in ALS, we performed immunohistochemical studies on 14-3-3 using autopsied spinal cords from patients with sporadic ALS (sALS) and non-ALS subjects without spinal cord involvement. In the anterior horn of both groups, strong 14-3-3 immunoreactivity was observed in the somata and proximal processes of motor neurons. Many spheroids from all of the sALS cases were also immunopositive for 14-3-3. In addition, Lewy body-like hyaline inclusions (LBHIs), which were present in some sALS cases, were intensely immunostained. Our findings suggest that even in the severely affected anterior horn of patients with sALS, remaining motor neurons may contain abundant 14-3-3 proteins, and that 14-3-3 proteins may be partly associated with the pathogenesis of sALS, in particular with the formation of LBHIs.