Transcriptional regulation of PEN-2, a key component of the γ-secretase complex, by CREB

Gamma-secretase, which is responsible for the intramembranous cleavage of Alzheimer's P-amyloid precursor protein (APP), the signaling receptor Notch, and many other substrates, is a multiprotein complex consisting of at least four components: presenilin (PS), nicastrin, APH-1, and PEN-2. Despite the fact that PEN-2 is known to mediate endoproteolytic cleavage of full-length PS and APH-1 and nicastrin are required for maintaining the stability of the complex, the detailed physiological function of each component remain elusive. Unlike that of PS, the transcriptional regulation of PEN-2, APH-1, and nicastrin has not been investigated. Here, we characterized the upstream regions of the human PEN-2 gene and identified a 238-bp fragment located 353 bp upstream of the translational start codon as the key region necessary for the promoter activity. Further analysis revealed a CREB binding site located in the 238-bp region that is essential for the transcriptional activity of the PEN-2 promoter. Mutation of the CREB site abolished the transcriptional activity of the PEN-2 promoter. Electrophoretic mobility shift assays and chromatin immunoprecipitation analysis showed the binding of CREB to the PEN-2 promoter region both in vitro and in vivo. Activation of the CREB transcriptional factor by forskolin dramatically promoted the expression of PEN-2 mRNA and protein, whereas the other components of the gamma-secretase complex remained unaffected. Forskolin treatment slightly increases the secretion of soluble APP alpha and A beta without affecting Notch cleavage. These results demonstrate that expression of PEN-2 is regulated by CREB and suggest that the specific control of PEN-2 expression may imply additional physiological functions uniquely assigned to PEN-2

Deficiency in LRP6-Mediated Wnt Signaling Contributes to Synaptic Abnormalities and Amyloid Pathology in Alzheimer’s Disease

该课题是卜国军教授课题组与美国梅奥医学中心、以及厦门大学神经科学研究所教授许华曦课题组等多位科学家合作完成的。由许华曦和卜国军领导的厦门大学神经科学研究所暨福建省神经退行性疾病及衰老研究重点实验室近年来在神经退行性疾病研究领域取得了一系列优秀的成果，先后在NatMed、NatStructMolBiol、NatRevNeurol、Neuron、ProcNatlAcadSciUSA等国际高水平杂志上以厦门大学为第一署名或通讯单位发表了30多篇SCI论文，总影响因子达250多。Alzheimer’s disease (AD) is an age-related neurological disorder characterized by synaptic loss and dementia. The low-density lipoprotein receptor-related protein 6 (LRP6) is an essential coreceptor for Wnt signaling, and its genetic variants have been linked to AD risk. Here we report that neuronal LRP6-mediated Wnt signaling is critical for synaptic function and cognition. Conditional deletion of Lrp6 gene in mouse forebrain neurons leads to age-dependent deficits in synaptic integrity and memory. Neuronal LRP6 deficiency in an amyloid mouse model also leads to exacerbated amyloid pathology due to increased APP processing to amyloid-β. In humans, LRP6 and Wnt signaling are significantly downregulated in AD brains, likely by a mechanism that depends on amyloid-β. Our results define a critical pathway in which decreased LRP6-mediated Wnt signaling, synaptic dysfunction, and elevated Aβ synergistically accelerate AD progression and suggest that restoring LRP6-mediated Wnt signaling can be explored as a viable strategy for AD therapy

Menin Deficiency Leads to Depressive-like Behaviors in Mice by Modulating Astrocyte-Mediated Neuroinflammation

厦门大学医学院、神经科学研究所张杰教授团队发现了抑郁症新的致病基因MEN1，并阐明了MEN1调控星形胶质细胞炎症导致抑郁发生发展的新机制，为抑郁症的诊治提供了新靶点和方向。抑郁症是严重威胁人类健康的重大神经系统疾病，危及全球30%的人口。但对其发病机制并不清楚。张杰教授团队发现，在慢性不可预测以及LPS处理的模拟抑郁小鼠模型中，多发性内分泌肿瘤蛋白(menin)在大脑中的表达显著降低，并且在星形胶质细胞中降低最明显。为了研究menin是否参与了小鼠抑郁表型的产生，研究团队制作了多种神经系统menin条件性敲除小鼠。通过对这些小鼠行为学的检测，锁定了只有在星形胶质细胞中敲除menin后，小鼠才会表现出抑郁样表型。证实了menin可能是通过调控星形胶质细胞的功能促进了抑郁的发生。 MEN1基因的突变会导致多发性内分泌肿瘤，而内分泌的紊乱和抑郁等精神疾病有着密切的联系。下丘脑-垂体-肾上腺轴（HPA轴）的功能紊乱直接参与了抑郁的产生。基于此研究团队推测MEN1的基因突变是否也会导致抑郁的发生。通过和中国医学科学院基础所的许琪教授合作，研究团队对1000多例重度抑郁患者和800多例对照人群进行了MEN1基因的外显子测序。通过测序发现MEN1的一个SNP s375804228和抑郁的发生有着显著关联。该SNP导致menin第503位的氨基酸由G突变成D。通过功能研究进一步证实该突变可以阻断menin和p65的结合，从而过度激活NF-κB-IL-1β通路，导致神经炎症的发生。 张杰，厦门大学特聘教授、博士生导师。国家优秀青年科学基金；教育部新世纪优秀人才；福建省杰出青年科学基金；厦门市五四青年奖章等获得者。2011年8月加入厦门大学医学院神经科学研究所担任教授至今。张杰博士主要从事重大神经系统疾病（老年痴呆、帕金森、抑郁症、自闭症、术后认知障碍、胶质瘤）等的发病机制和药物开发研究。至今以第一作者或者通讯作者在国际知名期刊发表研究论文21篇。其中回国独立开展研究工作以后，作为通讯作者在 Neuron，Cell Reports, PNAS, The Journal of Neuroscience, Clinical Cancer Research，Cell Death and Disease, JBC, Chemistry，Chem. Biol. Drug Des.等杂志上发表多篇研究论文。【Abstract】Astrocyte dysfunction and inflammation are associated with the pathogenesis of major depressive disorder (MDD). However, the mechanisms underlying these effects remain largely unknown. Here, we found that multiple endocrine neoplasia type 1 (Men1; protein: menin) expression is attenuated in the brain of mice exposed to CUMS (chronic unpredictable mild stress) or lipopolysaccharide. Astrocyte-specific reduction of Men1 (GcKO) led to depressive-like behaviors in mice. We observed enhanced NF-κB activation and IL-1β production with menin deficiency in astrocytes, where depressive-like behaviors in GcKO mice were restored by NF-κB inhibitor or IL-1β receptor antagonist. Importantly, we identified a SNP, rs375804228, in human MEN1, where G503D substitution is associated with a higher risk of MDD onset. G503D substitution abolished menin-p65 interactions, thereby enhancing NF-κB activation and IL-1β production. Our results reveal a distinct astroglial role for menin in regulating neuroinflammation in depression, indicating that menin may be an attractive therapeutic target in MDD.We thank Prof. Guanghui Jin (Xiamen University) and Prof. Xianxin Hua (University of Pennsylvania) for providing the Men1-floxp mice. This work was supported by the National Natural Science Foundation of China (grants 81522016, 81271421, and 31571055 to J.Z.; 81625008 and 31430048 to Q.X.; 81630026 to Z.Y.; 81771163 and U1405222 to H.X.; U1505227 to G.B.; 81472725 to W.M.), the Natural Science Foundation of Fujian Province of China (grant 2013J01147 and 2014J06019 to J.Z.), the Fundamental Research Funds for the Central Universities (grants 20720150062 and 20720180049 to J.Z.), the National Key Research and Development Program of China (2016YFC1305903), and CAMS Innovation Fund for Medical Sciences (grant 2016I2M1004 to Q.X.).研究工作得到国家自然科学基金项目（81522016、81271421、31571055）以及厦门大学校长基金等资助

CDK5-dependent BAG3 degradation modulates synaptic protein turnover

阿尔茨海默病（AD）是严重威胁人类健康的重大神经系统疾病，AD的发生发展与衰老密切相关，目前临床治疗方法十分有限。因此迫切需要从AD致病早期入手，发现和鉴定导致AD神经功能紊乱的机制和靶点，为AD的早期防治提供基础。张杰教授及其团队从高通量磷酸化蛋白质组学入手，系统研究了CDK5在神经细胞中的磷酸化底物，鉴定出了在蛋白质量控制中发挥重要功能的BAG3蛋白是CDK5的全新底物。课题组从磷酸化蛋白质组学入手，发现和阐明了细胞周期蛋白激酶5（CDK5）通过调控BAG3在维持突触蛋白水平调控中的作用机制，及其在阿尔茨海默病（AD）发生发展中的机理。 该研究是多个团队历时8年合作完成的，香港中文大学的周熙文教授、美国匹兹堡大学的Karl Herrup教授、美国Sanford-Burnham研究所的许华曦教授、美国梅奥医学中心的卜国军教授，厦门大学医学院的文磊教授、张云武教授、赵颖俊教授、薛茂强教授，军事医学科学院的袁增强教授等都参与了该工作。 厦门大学医学院2012级博士生周杰超等为文章的第一作者，张杰教授为通讯作者。Background Synaptic protein dyshomeostasis and functional loss is an early invariant feature of Alzheimer’s disease (AD), yet the unifying etiological pathway remains largely unknown. Knowing that cyclin-dependent kinase 5 (CDK5) plays critical roles in synaptic formation and degeneration, its phosphorylation targets were re-examined in search for candidates with direct global impacts on synaptic protein dynamics, and the associated regulatory network was also analyzed. Methods Quantitative phospho-proteomics and bioinformatics analyses were performed to identify top-ranked candidates. A series of biochemical assays were used to investigate the associated regulatory signaling networks. Histological, electrochemical and behavioral assays were performed in conditional knockout, shRNA-mediated knockdown and AD-related mice models to evaluate its relevance to synaptic homeostasis and functions. Results Among candidates with known implications in synaptic modulations, BCL2-associated athanogene-3 (BAG3) ranked the highest. CDK5-mediated phosphorylation on Ser297/Ser291 (Mouse/Human) destabilized BAG3. Loss of BAG3 unleashed the selective protein degradative function of the HSP70 machinery. In neurons, this resulted in enhanced degradation of a number of glutamatergic synaptic proteins. Conditional neuronal knockout of Bag3 in vivo led to impairment of learning and memory functions. In human AD and related-mouse models, aberrant CDK5-mediated loss of BAG3 yielded similar effects on synaptic homeostasis. Detrimental effects of BAG3 loss on learning and memory functions were confirmed in these mice, and such were reversed by ectopic BAG3 re-expression. Conclusions Our results highlight that neuronal CDK5-BAG3-HSP70 signaling axis plays a critical role in modulating synaptic homeostasis. Dysregulation of the signaling pathway directly contributes to synaptic dysfunction and AD pathogenesis.This work was supported by the National Science Foundation in China (Grant: 31571055, 81522016, 81271421 to J.Z.; 81801337 to L.L; 81774377 and 81373999 to L.W.); Fundamental Research Funds for the Central Universities of China-Xiamen University (Grant: 20720150062, 20720180049 and 20720160075 to J.Z.); Fundamental Research Funds for Fujian Province University Leading Talents (Grant JAT170003 to L.L); Hong Kong Research Grants Council (HKUST12/CRF/13G, GRF660813, GRF16101315, AoE/M-05/12 to K.H.; GRF16103317, GRF16100718 and GRF16100219 to H.-M,C.); Offices of Provost, VPRG and Dean of Science, HKUST (VPRGO12SC02 to K.H.); Chinese University of Hong Kong (CUHK) Improvement on Competitiveness in Hiring New Faculty Funding Scheme (Ref. 133), CUHK Faculty Startup Fund and Alzheimer’s Association Research Fellowship (AARF-17-531566) to H.-M, C. 该研究受到了国家自然科学基金、厦门大学校长基金、福建省卫生教育联合攻关基金等的资助

Appoptosin-Mediated Caspase Cleavage of Tau Contributes to Progressive Supranuclear Palsy Pathogenesis

在该研究中，许教授课题组鉴定了一个在Tau疾病中起关键致病作用的新蛋白Appoptosin。Tau疾病是一类具有共同病理特征：即随着疾病的进程，在脑中会产生Tau蛋白异常聚集和缠结的神经退行性疾病，包括阿尔茨海默症（老年性痴呆）、额颞痴呆、以及进行性核上麻痹（PSP）等。虽然人们推测Tau蛋白异常很可能是导致这些疾病中神经元和脑功能受损的关键因素，但是并不清楚它究竟是如何诱发疾病的。尤其是PSP患者在平衡、眼球运动以及思维上都存在严重的障碍，但迄今为止，人们对该疾病的致病机制几乎一无所知。许教授的研究团队通过对PSP患者的检测，发现一个与该疾病相关的DNA单核苷酸突变（SNP）可以引起Appoptosin蛋白水平的增高，并增加Tau蛋白的过度磷酸化以及caspase-3酶介导的Tau蛋白切割，从而导致Tau蛋白的异常聚集和突触功能障碍。更为重要的是，在阿尔茨海默症和额颞痴呆患者的脑组织中，同样发现了致病蛋白Appoptosin和Tau蛋白异常切割的增加，进一步证明了Appoptosin介导的途径在Tau疾病的发病机制中起到了关键性作用。该研究为进一步阐明神经退行性疾病的病理机制指引了新的研究方向，为痴呆和运动功能障碍的临床治疗提供了全新的治疗靶点和思路，具有重要的临床意义。Progressive supranuclear palsy (PSP) is a movement disorder characterized by tau neuropathology where the underlying mechanism is unknown. An SNP (rs1768208 C/T) has been identified as a strong risk factor for PSP. Here, we identified a much higher T-allele occurrence and increased levels of the pro-apoptotic protein appoptosin in PSP patients. Elevations in appoptosin correlate with activated caspase-3 and caspase-cleaved tau levels. Appoptosin overexpression increased caspase-mediated tau cleavage, tau aggregation, and synaptic dysfunction, whereas appoptosin deficiency reduced tau cleavage and aggregation. Appoptosin transduction impaired multiple motor functions and exacerbated neuropathology in tau-transgenic mice in a manner dependent on caspase-3 and tau. Increased appoptosin and caspase-3-cleaved tau were also observed in brain samples of patients with Alzheimer’s disease and frontotemporal dementia with tau inclusions. Our findings reveal a novel role for appoptosin in neurological disorders with tau neuropathology, linking caspase-3-mediated tau cleavage to synaptic dysfunction and behavioral/motor defects

ApoE and A beta in Alzheimer's Disease: Accidental Encounters or Partners?

NIH [R01AG035355, R01AG027924, R01AG046205, P01AG030128, P01NS074969]; Alzheimer's Association IIRG; Cure Alzheimer's Fund; Mayo Clinic CRM Career Developmental Award; Alzheimer's Association NIRGAmong the three human apolipoprotein E (apoE) isoforms, apoE4 increases the risk of Alzheimer's disease (AD). While transporting cholesterol is a primary function, apoE also regulates amyloid-beta (A beta) metabolism, aggregation, and deposition. Although earlier work suggests that different affinities of apoE isoforms to A beta might account for their effects on A beta clearance, recent studies indicate that apoE also competes with A beta for cellular uptake through apoE receptors. Thus, several factors probably determine the variable effects apoE has on A beta. In this Review, we examine biochemical, structural, and functional studies and propose testable models that address the complex mechanisms underlying apoE-A beta interaction and how apoE4 may increase AD risk and also serve as a target pathway for therapy

Morphology and ultrastructure of compound eye in horseshoe crab,Tachypleus tridentatus

应用光镜及电镜技术研究中国鲎(Tachypleus tridentatus(Leach))复眼的形态和超微结构。结果表明,中国鲎复眼表面覆盖角膜层,外形呈半球形,由800~1 200个小眼组成,组成复眼的小眼面均为椭圆形。每个小眼包括透光和感光两部分。透光部分由透光锥体和透光孔径组成;感光部分包括小网膜细胞及色素细胞。小网膜细胞分R-区和A-区,R-区是有感杆束分布的区域,A-区是没有感杆束分布的区域,但A-区的表面覆盖着色素细胞,色素颗粒主要分布于A-区和R-区的交界处。8个小网膜细胞排列成的桔瓣状结构组成1个小眼的感光部分。[中国水产科学,2006,13(4):517-524]The morphology and fine structure of the compound eye in horseshoe crab,Tachypleus tridentatus was investigated by using light and electron microscopy.The results indicated that the compound eye of Tachypleus tridentatus consists of 800-1?200 ommatidia;the facet of the compound eye is oval.An ommatidium is composed of transparency area and photonasty area;the transparency area is made up of cuticular cone and aperture,but photonasty area includes retinular cells and a lot of pigment cells.Retinular cell divides into rhabdomeral-segment and arhabdomeral-segment.Rhabdom distributs in rhabdomeral-segment but not in arhabdomeral-segment,moreover pigment cells are covered with arhabdomeral-segment and the majority pigment cells distribute in the join point of rhabdomeral-segment and arhabdomeral-segment.Eight wedge-shaped retinula cells rank radially about the optical axis of the ommatidium like the segment of an orange,which are the morphological and functional units of a compound eye.[Journal of Fishery Sciences of China,2006,13(4):517-524]国家自然科学基金项目(30572077);; 2005年厦门市海洋与渔业局基金项目(k53008