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Rebecca L Williamson, Karine Laulagnier, André Miguel Miranda, Marty A Fernandez, Michael S Wolfe, Rémy Sadoul, Gilbert Di Paolo
Amyloid plaques, a neuropathological hallmark 1 of Alzheimer's disease (AD), are largely 2 composed of amyloid beta (Aβ) peptide, derived 3 from cleavage of amyloid precursor protein 4 (APP) by β- and γ-secretases. The endosome is 5 increasingly recognized as an important 6 crossroad for APP and these secretases, with 7 major implications for APP processing and 8 amyloidogenesis. Among various 9 posttranslational modifications affecting APP 10 accumulation, ubiquitination of cytodomain 11 lysines may represent a key signal controlling 12 APP endosomal sorting...
October 11, 2017: Journal of Biological Chemistry
Serena Stanga, Céline Vrancx, Bernadette Tasiaux, Claudia Marinangeli, Helena Karlström, Pascal Kienlen-Campard
The two presenilin-1 (PS1) and presenilin-2 (PS2) homologs are the catalytic core of the γ-secretase complex, which has a major role in cell fate decision and Alzheimer's disease (AD) progression. Understanding the precise contribution of PS1- and PS2-dependent γ-secretases to the production of β-amyloid peptide (Aβ) from amyloid precursor protein (APP) remains an important challenge to design molecules efficiently modulating Aβ release without affecting the processing of other γ-secretase substrates...
October 10, 2017: Journal of Cellular and Molecular Medicine
Li Juan Zheng, Yun Yan Su, Yun Fei Wang, Jianhui Zhong, Xue Liang, Gang Zheng, Guang Ming Lu, Long Jiang Zhang
OBJECTIVE: To explore genetic effects of amyloid precursor protein (APP), presenilin-1/2 and apolipoprotein E (APOE) ε4 on brain structural and functional alterations in cognitively normal young adults. MATERIALS AND METHODS: Eighty healthy adults (mean age 24.0±2.5years; n=18, APP/presenilin-1/2 group; n=31, APOE ε4 group; n=31, control group [without above-mentioned gene mutation]) underwent high-resolution T1-weighted 3D anatomical imaging, resting-state functional MR imaging and neuropsychological assessments...
October 2017: European Journal of Radiology
H R H Mohamed
Silver (Ag) nanoparticles (nano-Ag) are widely used because of their distinctive antimicrobial properties, but this widespread use increases Ag release into the environment along with many other pollutants such as heavy metals. Therefore, this study was undertaken to study the modulatory effect of cadmium chloride (CdCl2) on the genotoxicity and mutagenicity of nano-Ag in mice liver, kidney and brain tissues. Co-injections of CdCl2 (1.5 mg/kg) with nano-Ag (20, 41, or 82 mg/kg) resulted in significant elevations in both single and double DNA strand breaks that triggered higher apoptotic DNA damage, as revealed by the more fragmented appearance of genomic DNA and the significant increase in apoptotic fractions...
September 30, 2017: Cellular and Molecular Biology
Shinji Tagami, Kanta Yanagida, Takashi S Kodama, Mako Takami, Naoki Mizuta, Hiroshi Oyama, Kouhei Nishitomi, Yu-Wen Chiu, Toru Okamoto, Takeshi Ikeuchi, Gaku Sakaguchi, Takashi Kudo, Yoshiharu Matsuura, Akio Fukumori, Masatoshi Takeda, Yasuo Ihara, Masayasu Okochi
γ-secretase inhibitors (GSI) are drugs developed to decrease amyloid-β peptide (Aβ) production by inhibiting intramembranous cleavage of β-amyloid protein precursor (βAPP). However, a large phase 3 trial of semagacestat, a potential non-transition state analog (non-TSA) GSI, in patients with Alzheimer's disease (AD) was terminated due to unexpected aggravation of cognitive deficits and side effects. Here, we show that some semagacestat effects are clearly different from a phenotype caused by a loss of function of presenilins, core proteins in the γ-secretase complex...
October 3, 2017: Cell Reports
Patricia Martín-Maestro, Ricardo Gargini, Andrew A Sproul, Esther García, Luis C Antón, Scott Noggle, Ottavio Arancio, Jesús Avila, Vega García-Escudero
Familial Alzheimer's disease (FAD) is clearly related with the accumulation of amyloid-beta (Aβ) and its deleterious effect on mitochondrial function is well established. Anomalies in autophagy have also been described in these patients. In the present work, functional analyses have been performed to study mitochondrial recycling process in patient-derived fibroblasts and neurons from induced pluripotent stem cells harboring the presenilin 1 mutation A246E. Mitophagy impairment was observed due to a diminished autophagy degradation phase associated with lysosomal anomalies, thus causing the accumulation of dysfunctional mitochondria labeled by Parkin RBR E3 ubiquitin protein ligase (PARK2)...
2017: Frontiers in Molecular Neuroscience
Kati-Sisko Vellonen, Jouni Ihalainen, Marie-Christine Boucau, Fabien Gosselet, Théo Picardat, Mikko Gynther, Katja M Kanninen, Anthony R White, Tarja Malm, Jari Koistinaho, Markus M Forsberg, Marika Ruponen
PURPOSE: Alzheimer's disease (AD) may disturb functions of the blood-brain barrier and change the disposition of drugs to the brain. This study assessed the disease-induced changes in drug transporters in the brain capillaries of transgenic AD mice. METHODS: Eighteen drug transporters and four tight junction-associated proteins were analyzed by RT-qPCR in cortex, hippocampus and cerebellum tissue samples of 12-16-month-old APdE9, Tg2576 and APP/PS1 transgenic mice and their healthy age-matched controls...
September 26, 2017: Pharmaceutical Research
Ahmed A Moustafa, Mubashir Hassan, Doaa H Hewedi, Iman Hewedi, Julia K Garami, Hany Al Ashwal, Nazar Zaki, Sung-Yum Seo, Vassilis Cutsuridis, Sergio L Angulo, Joman Y Natesh, Mohammad M Herzallah, Dorota Frydecka, Błażej Misiak, Mohamed Salama, Wael Mohamed, Mohamad El Haj, Michael Hornberger
In this review, we discuss the genetic etiologies of Alzheimer's disease (AD). Furthermore, we review genetic links to protein signaling pathways as novel pharmacological targets to treat AD. Moreover, we also discuss the clumps of AD-m ediated genes according to their single nucleotide polymorphism mutations. Rigorous data mining approaches justified the significant role of genes in AD prevalence. Pedigree analysis and twin studies suggest that genetic components are part of the etiology, rather than only being risk factors for AD...
September 26, 2017: Reviews in the Neurosciences
Ziyan Li, Kaili Jia, Yale Duan, Dong Wang, Zongli Zhou, Suzhen Dong
Agonists of M1 muscarinic acetylcholine receptors are promising therapeutic agents for the treatment of Alzheimer's disease (AD). An example of one of these agents is xanomeline, which has been a leading candidate, however induces various unwanted adverse effects. 3‑[3‑(3‑florophenyl‑2‑propyn‑1‑ylthio)‑1,2,5‑thiadiazol-4-yl]-1,2,5,6-tetrahydro‑1‑methylpyridine oxalate (EUK1001), a fluorinated derivative of xanomeline, has been demonstrated to attenuate AD‑like neurodegenerative pathology in presenilin‑deficient mice, which has no β‑amyloid (Aβ) pathology...
September 18, 2017: Molecular Medicine Reports
Fumihiko Okumura, Akiko Joo-Okumura, Keisuke Obara, Alexander Petersen, Akihiko Nishikimi, Yoshinori Fukui, Kunio Nakatsukasa, Takumi Kamura
Eph receptor tyrosine kinases and their ephrin ligands are overexpressed in various human cancers, including colorectal malignancies, suggesting important roles in many aspects of cancer development and progression as well as in cellular repulsive responses. The ectodomain of EphB2 receptor is cleaved by metalloproteinases (MMPs) MMP-2/MMP-9 and released into the extracellular space after stimulation by its ligand. The remaining membrane-associated fragment is further cleaved by the presenilin-dependent γ-secretase and releases an intracellular peptide that has tyrosine kinase activity...
September 20, 2017: Molecular Biology of the Cell
M Pavlovsky, O Sarig, M Eskin-Schwartz, N Malchin, R Bochner, J Mohamad, A Gat, A Peled, A Hafner, E Sprecher
Dowling-Degos disease, featuring reticulate pigmentation, and familial hidradenitis suppurativa share many clinical features including autosomal dominant inheritance, flexural location and follicular defects. The co-existence of the two disorders was recently found to result from mutations in PSENEN, encoding protein presenilin enhancer gamma-secretase subunit. Here we report 4 additional families of Jewish Ashkenazi origin who presented with clinical features characteristic of both disorders. All patients were found to carry the same, heterozygous mutation in PSENEN (c...
September 18, 2017: British Journal of Dermatology
Frank Raven, Joseph F Ward, Katarzyna M Zoltowska, Yu Wan, Enjana Bylykbashi, Sean J Miller, Xunuo Shen, Se Hoon Choi, Kevin D Rynearson, Oksana Berezovska, Steven L Wagner, Rudolph E Tanzi, Can Zhang
A central pathogenic event of Alzheimer's disease (AD) is the accumulation of the Aβ42 peptide, which is generated from amyloid-β precursor protein (APP) via cleavages by β- and γ-secretase. We have developed a class of soluble 2-aminothiazole γ-secretase modulators (SGSMs) that preferentially decreases Aβ42 levels. However, the effects of SGSMs in AD animals and cells expressing familial AD mutations, as well as the mechanism of γ-secretase modulation remain largely unknown. Here, a representative of this SGSM scaffold, SGSM-36, was investigated using animals and cells expressing FAD mutations...
September 4, 2017: EBioMedicine
Frédéric Checler, Thomas Goiran, Cristine Alves da Costa
Autophagic and mitophagic defects are consistently observed in Alzheimer's disease-affected brains. However, the mechanistic defects underlying these anatomical lesions remained unexplained. We have delineated a molecular cascade by which PSEN1 and PSEN2 (presenilins 1 and 2) control PINK1 transcription and function by an AICD-mediated FOXO3a-dependent mechanism. Further, we establish that PARK2 (parkin) acts upstream to PINK1 and regulates its function by a PSEN-dependent mechanism. Our study thus demonstrates a functional interplay between PSEN and PINK1 and establishes a feedback process by which PARK2 and PINK1 could control mitochondrial dysfunction and autophagic processes in various neurodegenerative pathologies including Alzheimer's and Parkinson's diseases...
September 15, 2017: Autophagy
Johannes A M Merilahti, Veera K Ojala, Anna M Knittle, Arto T Pulliainen, Klaus Elenius
Receptor tyrosine kinases (RTK) have been demonstrated to signal via regulated intramembrane proteolysis (RIP), in which ectodomain shedding and subsequent intramembrane cleavage by gamma-secretase leads to release of a soluble intracellular receptor fragment with functional activity. For most RTKs, however, it is not known whether they can exploit this new signaling mechanism or not. Here we used a system-wide screen to address the frequency of susceptibility to gamma-secretase cleavage among human RTKs. The screen covering 45 of the 55 human RTKs identified 12 new as well as all 9 previously published gamma-secretase substrates...
September 13, 2017: Molecular Biology of the Cell
Dimitry Ofengeim, Sonia Mazzitelli, Yasushi Ito, Judy Park DeWitt, Lauren Mifflin, Chengyu Zou, Sudeshna Das, Xian Adiconis, Hongbo Chen, Hong Zhu, Michelle A Kelliher, Joshua Z Levin, Junying Yuan
Dysfunction of microglia is known to play an important role in Alzheimer's disease (AD). Here, we investigated the role of RIPK1 in microglia mediating the pathogenesis of AD. RIPK1 is highly expressed by microglial cells in human AD brains. Using the amyloid precursor protein (APP)/presenilin 1 (PS1) transgenic mouse model, we found that inhibition of RIPK1, using both pharmacological and genetic means, reduced amyloid burden, the levels of inflammatory cytokines, and memory deficits. Furthermore, inhibition of RIPK1 promoted microglial degradation of Aβ in vitro...
September 13, 2017: Proceedings of the National Academy of Sciences of the United States of America
Norsharina Ismail, Maznah Ismail, Nur Hanisah Azmi, Muhammad Firdaus Abu Bakar, Zhang Yida, Maizaton Atmadini Abdullah, Hamidon Basri
Though the causes of Alzheimer's disease (AD) are yet to be understood, much evidence has suggested that excessive amyloid-β (Aβ) accumulation due to abnormal amyloid-β precursor protein (APP) processing and Aβ metabolism are crucial processes towards AD pathogenesis. Hence, approaches aiming at APP processing and Aβ metabolism are currently being actively pursued for the management of AD. Studies suggest that high cholesterol and a high fat diet have harmful effects on cognitive function and may instigate the commencement of AD pathogenesis...
September 8, 2017: Biomedicine & Pharmacotherapy, Biomédecine & Pharmacothérapie
Katarina Willén, Agnieszka Sroka, Reisuke H Takahashi, Gunnar K Gouras
Alzheimer's disease (AD) is increasingly viewed as a disease of synapses. Loss of synapses correlates better with cognitive decline than amyloid plaques and neurofibrillary tangles, the hallmark neuropathological lesions of AD. Soluble forms of amyloid-β (Aβ) have emerged as mediators of synapse dysfunction. Aβ binds to, accumulates, and aggregates in synapses. However, the anatomical and neurotransmitter specificity of Aβ and the amyloid-β protein precursor (AβPP) in AD remain poorly understood. In addition, the relative roles of Aβ and AβPP in the development of AD, at pre- versus post-synaptic compartments and axons versus dendrites, respectively, remain unclear...
2017: Journal of Alzheimer's Disease: JAD
Qian Huang, Georgios Voloudakis, Yimin Ren, Yonejung Yoon, Emily Zhang, Yuji Kajiwara, Zhiping Shao, Zhao Xuan, Denis Lebedev, Anastasios Georgakopoulos, Nikolaos K Robakis
Reduced cerebral glucose utilization is found in aged individuals and often is an early sign of neurodegeneration. Here, we show that under glucose deprivation (GD) conditions, decreased expression of presenilin 1 (PS1) results in decreased neuronal survival, whereas increased PS1 increases neuronal survival. Inhibition of γ-secretase also decreases neuronal survival under GD conditions, which suggests the PS1/γ-secretase system protects neurons from GD-induced death. We also show that neuronal levels of the survival protein, phosphoprotein enriched in astrocytes at ∼15 kDa (PEA15), and its mRNA are regulated by PS1/γ-secretase...
August 30, 2017: FASEB Journal: Official Publication of the Federation of American Societies for Experimental Biology
Arun Kumar Somavarapu, Kasper P Kepp
γ-Secretase produces β-amyloid (Aβ) within its presenilin (PS1) subunit, mutations in which cause Alzheimer's disease, and current therapies thus seek to modulate its activity. While the general structure is known from recent electron microscopy studies, direct loop and membrane interactions and explicit dynamics relevant to substrate processing remain unknown. We report a modeled structure utilizing the optimal multitemplate information available, including loops and missing side chains, account of maturation cleavage, and explicit all-atom molecular dynamics in the membrane...
August 25, 2017: ACS Chemical Neuroscience
Zhiyou Cai, Zhou Liu, Ming Xiao, Chuanling Wang, Fuming Tian
Chronic cerebral hypoperfusion (CCH) contributes to the Alzheimer's-like pathogenesis, but the relationship between CCH and the occurrence of Alzheimer's disease (AD) remains obscure. The aim is to elucidate the potential pathophysiological mechanism in the field of amyloid-beta (Aβ) pathology induced by CCH. A rat model of CCH has been developed with permanent bilateral occlusion of common carotid arteries (BCCAO). The cognitive function of rats was tested by the Morris water maze. The levels of Aβ (Aβ40 and Aβ42) and soluble amyloid precursor protein (sAPP: sAPPα and sAPPβ) were determined by enzyme linked immunosorbent assay...
August 24, 2017: Neurochemical Research
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