scholarly journals Increased Apoptosis Arising from Increased Expression of the Alzheimer's Disease–associated Presenilin-2 Mutation (N141I)

1997 ◽  
Vol 139 (2) ◽  
pp. 485-495 ◽  
Author(s):  
Susan Janicki ◽  
Mervyn J. Monteiro
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Cell Death ◽  
Hela Cells ◽  
Fluorescent Protein ◽  
Normal Function ◽  
Protein Accumulation ◽  
Protein Cleavage ◽  
Wild Type ◽  
Green Fluorescent

Mutations in the genes for presenilin 1 and 2 (PS-1 and PS-2) have been linked to development of early-onset Alzheimer's disease (AD). As neither the normal function of either presenilin is known nor why mutations cause disease, we examined the properties of wild-type, truncated, and mutant PS-2 upon expression in HeLa cells. Although HeLa cells are strongly predisposed to continued mitosis, expression of PS-2 induced programmed cell death (apoptosis). Direct evidence for apoptosis was obtained by double staining for terminal deoxynucleotide transferase nick end labeling (TUNEL) and PS-2 expression and by following green fluorescent protein–tagged PS-2 over time. Deletion analysis indicates that as little as 166 NH2-terminal residues of PS-2 are sufficient for endoplasmic reticulum (ER) localization and apoptosis. Moreover, the AD- associated PS-2 missense mutation (N141I) more efficiently induced cell death compared to wild-type PS-2 despite lower mutant protein accumulation. Expression of the presenilins in several other cell lines and transgenic mice has been accompanied by rapid protein cleavage without the induction of cell death. In contrast, PS-2 expressed in HeLa cells was not cleaved, and cell death occurred. We hypothesize that full-length but not cleaved PS-2 may be important in the regulation or induction of apoptosis.

scholarly journals A C-Terminal Domain Targets the Pseudomonas aeruginosa Cytotoxin ExoU to the Plasma Membrane of Host Cells

2006 ◽  
Vol 74 (5) ◽  
pp. 2552-2561 ◽  
Author(s):  
Shira D. P. Rabin ◽  
Jeffrey L. Veesenmeyer ◽  
Kathryn T. Bieging ◽  
Alan R. Hauser
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Cell Death ◽  
Plasma Membrane ◽  
Hela Cells ◽  
Type Iii Secretion ◽  
Fluorescent Protein ◽  
Host Cells ◽  
Type Iii ◽  
C Terminus ◽  
Green Fluorescent

ABSTRACT ExoU, a phospholipase injected into host cells by the type III secretion system of Pseudomonas aeruginosa, leads to rapid cytolytic cell death. Although the importance of ExoU in infection is well established, the mechanism by which this toxin kills host cells is less clear. To gain insight into how ExoU causes cell death, we examined its subcellular localization following transfection or type III secretion/translocation into HeLa cells. Although rapid cell lysis precluded visualization of wild-type ExoU by fluorescence microscopy, catalytically inactive toxin was readily detected at the periphery of HeLa cells. Biochemical analysis confirmed that ExoU was targeted to the membrane fraction of transfected cells. Visualization of ExoU peptides fused with green fluorescent protein indicated that the domain responsible for this targeting was in the C terminus of ExoU, between residues 550 and 687. Localization to the plasma membrane occurred within 1 h of expression, which is consistent with the kinetics of cytotoxicity. Together, these results indicate that a domain between residues 550 and 687 of ExoU targets this toxin to the plasma membrane, a process that may be important in cytotoxicity.

scholarly journals A Myristoylated Calcium-binding Protein that Preferentially Interacts with the Alzheimer's Disease Presenilin 2 Protein

1999 ◽  
Vol 145 (6) ◽  
pp. 1277-1292 ◽  
Author(s):  
Stacy M. Stabler ◽  
Lisa L. Ostrowski ◽  
Susan M. Janicki ◽  
Mervyn J. Monteiro
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Cell Death ◽  
Hela Cells ◽  
Calcium Binding ◽  
Binding Protein ◽  
Calcium Binding Protein ◽  
Cellular Functions ◽  
Disease States ◽  
Presenilin 2

It is well established that mutations in the presenilin 1 and 2 genes cause the majority of early onset Alzheimer's disease (AD). However, our understanding of the cellular functions of the proteins they encode remains rudimentary. Knowledge of proteins with which the presenilins interact should lead to a better understanding of presenilin function in normal and disease states. We report here the identification of a calcium-binding protein, calmyrin, that interacts preferentially with presenilin 2 (PS2). Calmyrin is myristoylated, membrane-associated, and colocalizes with PS2 when the two proteins are overexpressed in HeLa cells. Yeast two-hybrid liquid assays, affinity chromatography, and coimmunoprecipitation experiments confirm binding between PS2 and calmyrin. Functionally, calmyrin and PS2 increase cell death when cotransfected into HeLa cells. These results allude to several provocative possibilities for a dynamic role of calmyrin in signaling, cell death, and AD.

Antioxidant as Talented Drug Applicants for the Treatment of Alzheimer’s Disease and their Molecular Mechanism Insights

2020 ◽  
Vol 26 ◽  
Author(s):  
Rokeya Akter ◽  
Md. Arifur Rahman Chowdhury ◽  
Md. Habib ur Rahman
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Cell Death ◽  
Programmed Cell Death ◽  
Conventional Medicine ◽  
Antioxidant Properties ◽  
Extensive Study ◽  
Protein Accumulation ◽  
Neuroprotective Effects ◽  
Cellular Changes

: Alzheimer's disease (AD), with no preventive or curative therapy, is the most prevalent neurodegenerative condition to date. Histopathological features of AD include β-amyloid plate deposition and neurofibrillary tangles development. Extensive pathology studies have provided significant results concerning disease processes and therapeutic objectives. Some cellular changes, including oxidative stress, Ca2 + homeostasis, flame retardation, metabolic disorders, and protein accumulation, that lead to programmed cell death. AD is a cause of cellular changes. Despite extensive study, only five licensed medicines for AD management are available. Alternative therapies must also be considered. Over the last years, it has gained interest through the use of natural ingredients and culinary herbs. Many natural substances have been extensively researched with neuroprotective effects. Some of these compound products have amazing antioxidant properties and are primarily used by free radical species. Others enhance cell survival and cognition by influencing amyloidogenesis and programmed cell death. Further research on these natural products and their modes of action, along with the application of new drug design and methods of delivery; allow us to add conventional medicine. In this report, many natural antioxidant products with possible neuroprotective characteristics against Aβ were discussed in their mechanism of action.

scholarly journals The ROCO Kinase QkgA Is Necessary for Proliferation Inhibition by Autocrine Signals in Dictyostelium discoideum

2010 ◽  
Vol 9 (10) ◽  
pp. 1557-1565 ◽  
Author(s):  
Jonathan E. Phillips ◽  
Richard H. Gomer
Keyword(s):  
Cell Proliferation ◽  
Dictyostelium Discoideum ◽  
Fluorescent Protein ◽  
Signal Transduction Pathway ◽  
Protein Accumulation ◽  
Proliferation Inhibition ◽  
Wild Type ◽  
Content Type ◽  
Multicellular Development ◽  
Green Fluorescent

ABSTRACT AprA and CfaD are secreted proteins that function as autocrine signals to inhibit cell proliferation in Dictyostelium discoideum. Cells lacking AprA or CfaD proliferate rapidly, and adding AprA or CfaD to cells slows proliferation. Cells lacking the ROCO kinase QkgA proliferate rapidly, with a doubling time 83% of that of the wild type, and overexpression of a QkgA-green fluorescent protein (GFP) fusion protein slows cell proliferation. We found that qkgA − cells accumulate normal levels of extracellular AprA and CfaD. Exogenous AprA or CfaD does not slow the proliferation of cells lacking qkgA, and expression of QkgA-GFP in qkgA − cells rescues this insensitivity. Like cells lacking AprA or CfaD, cells lacking QkgA tend to be multinucleate, accumulate nuclei rapidly, and show a mass and protein accumulation per nucleus like those of the wild type, suggesting that QkgA negatively regulates proliferation but not growth. Despite their rapid proliferation, cells lacking AprA, CfaD, or QkgA expand as a colony on bacteria less rapidly than the wild type. Unlike AprA and CfaD, QkgA does not affect spore viability following multicellular development. Together, these results indicate that QkgA is necessary for proliferation inhibition by AprA and CfaD, that QkgA mediates some but not all of the effects of AprA and CfaD, and that QkgA may function downstream of these proteins in a signal transduction pathway regulating proliferation.

scholarly journals Model Identifies Genetic Predisposition of Alzheimer’s Disease as Key Decider in Cell Susceptibility to Stress

2021 ◽  
Vol 22 (21) ◽  
pp. 12001
Author(s):  
Ioanna C. Stefani ◽  
François-Xavier Blaudin de Thé ◽  
Cleo Kontoravdi ◽  
Karen M. Polizzi
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Cell Lines ◽  
Transcriptional Activation ◽  
Mutant Cell ◽  
Human Neuroblastoma Cell ◽  
Protein Accumulation ◽  
Wild Type ◽  
Human Neuroblastoma ◽  
Unfolded Protein

Accumulation of unfolded/misfolded proteins in neuronal cells perturbs endoplasmic reticulum homeostasis, triggering a stress cascade called unfolded protein response (UPR), markers of which are upregulated in Alzheimer’s disease (AD) brain specimens. We measured the UPR dynamic response in three human neuroblastoma cell lines overexpressing the wild-type and two familial AD (FAD)-associated mutant forms of amyloid precursor protein (APP), the Swedish and Swedish-Indiana mutations, using gene expression analysis. The results reveal a differential response to subsequent environmental stress depending on the genetic background, with cells overexpressing the Swedish variant of APP exhibiting the highest global response. We further developed a dynamic mathematical model of the UPR that describes the activation of the three branches of this stress response in response to unfolded protein accumulation. Model-based analysis of the experimental data suggests that the mutant cell lines experienced a higher protein load and subsequent magnitude of transcriptional activation compared to the cells overexpressing wild-type APP, pointing to higher susceptibility of mutation-carrying cells to stress. The model was then used to understand the effect of therapeutic agents salubrinal, lithium, and valproate on signalling through different UPR branches. This study proposes a novel integrated platform to support the development of therapeutics for AD.

[18F]-florbetaben PET/CT Imaging in the Alzheimer’s Disease Mouse Model APPswe/PS1dE9

2018 ◽  
Vol 16 (1) ◽  
pp. 49-55 ◽  
Author(s):  
J. Stenzel ◽  
C. Rühlmann ◽  
T. Lindner ◽  
S. Polei ◽  
S. Teipel ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Mouse Model ◽  
New Drugs ◽  
Imaging Data ◽  
Wild Type ◽  
Preclinical Research ◽  
Standardized Uptake Values ◽  
Pet Ct

Background: Positron-emission-tomography (PET) using 18F labeled florbetaben allows noninvasive in vivo-assessment of amyloid-beta (Aβ), a pathological hallmark of Alzheimer’s disease (AD). In preclinical research, [<sup>18</sup>F]-florbetaben-PET has already been used to test the amyloid-lowering potential of new drugs, both in humans and in transgenic models of cerebral amyloidosis. The aim of this study was to characterize the spatial pattern of cerebral uptake of [<sup>18</sup>F]-florbetaben in the APPswe/ PS1dE9 mouse model of AD in comparison to histologically determined number and size of cerebral Aβ plaques. Methods: Both, APPswe/PS1dE9 and wild type mice at an age of 12 months were investigated by smallanimal PET/CT after intravenous injection of [<sup>18</sup>F]-florbetaben. High-resolution magnetic resonance imaging data were used for quantification of the PET data by volume of interest analysis. The standardized uptake values (SUVs) of [<sup>18</sup>F]-florbetaben in vivo as well as post mortem cerebral Aβ plaque load in cortex, hippocampus and cerebellum were analyzed. Results: Visual inspection and SUVs revealed an increased cerebral uptake of [<sup>18</sup>F]-florbetaben in APPswe/ PS1dE9 mice compared with wild type mice especially in the cortex, the hippocampus and the cerebellum. However, SUV ratios (SUVRs) relative to cerebellum revealed only significant differences in the hippocampus between the APPswe/PS1dE9 and wild type mice but not in cortex; this differential effect may reflect the lower plaque area in the cortex than in the hippocampus as found in the histological analysis. Conclusion: The findings suggest that histopathological characteristics of Aβ plaque size and spatial distribution can be depicted in vivo using [<sup>18</sup>F]-florbetaben in the APPswe/PS1dE9 mouse model.

Is it All Said for NSAIDs in Alzheimer’s Disease? Role of Mitochondrial Calcium Uptake

2018 ◽  
Vol 15 (6) ◽  
pp. 504-510 ◽  
Author(s):  
Sara Sanz-Blasco ◽  
Maria Calvo-Rodríguez ◽  
Erica Caballero ◽  
Monica Garcia-Durillo ◽  
Lucia Nunez ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Cell Death ◽  
Amyloid Β ◽  
Epidemiological Data ◽  
Amyloid Β Peptide ◽  
Aβ Oligomers ◽  
Mitochondrial Potential ◽  
Disease Modifying Drugs ◽  
Definitive Evidence

Objectives: Epidemiological data suggest that non-steroidal anti-inflammatory drugs (NSAIDs) may protect against Alzheimer's disease (AD). Unfortunately, recent trials have failed in providing compelling evidence of neuroprotection. Discussion as to why NSAIDs effectivity is uncertain is ongoing. Possible explanations include the view that NSAIDs and other possible disease-modifying drugs should be provided before the patients develop symptoms of AD or cognitive decline. In addition, NSAID targets for neuroprotection are unclear. Both COX-dependent and independent mechanisms have been proposed, including γ-secretase that cleaves the amyloid precursor protein (APP) and yields amyloid β peptide (Aβ). Methods: We have proposed a neuroprotection mechanism for NSAIDs based on inhibition of mitochondrial Ca2+ overload. Aβ oligomers promote Ca2+ influx and mitochondrial Ca2+ overload leading to neuron cell death. Several non-specific NSAIDs including ibuprofen, sulindac, indomethacin and Rflurbiprofen depolarize mitochondria in the low µM range and prevent mitochondrial Ca2+ overload induced by Aβ oligomers and/or N-methyl-D-aspartate (NMDA). However, at larger concentrations, NSAIDs may collapse mitochondrial potential (ΔΨ) leading to cell death. Results: Accordingly, this mechanism may explain neuroprotection at low concentrations and damage at larger doses, thus providing clues on the failure of promising trials. Perhaps lower NSAID concentrations and/or alternative compounds with larger dynamic ranges should be considered for future trials to provide definitive evidence of neuroprotection against AD.

The Involvement of Post-Translational Modifications in Alzheimer's Disease

2018 ◽  
Vol 15 (4) ◽  
pp. 313-335 ◽  
Author(s):  
Serena Marcelli ◽  
Massimo Corbo ◽  
Filomena Iannuzzi ◽  
Lucia Negri ◽  
Fabio Blandini ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Protein Modification ◽  
Neurodegenerative Disorder ◽  
Amyloid Β ◽  
Normal Function ◽  
Ageing Population ◽  
Covalent Bonds ◽  
Post Translational Modifications ◽  
Related Proteins

Background: Alzheimer's disease (AD) is a neurodegenerative disorder recognized as the most common cause of chronic dementia among the ageing population. AD is histopathologically characterized by progressive loss of neurons and deposits of insoluble proteins, primarily composed of amyloid-β pelaques and neurofibrillary tangles (NFTs). Methods: Several molecular processes contribute to the formation of AD cellular hallmarks. Among them, post-translational modifications (PTMs) represent an attractive mechanism underlying the formation of covalent bonds between chemical groups/peptides to target proteins, which ultimately result modified in their function. Most of the proteins related to AD undergo PTMs. Several recent studies show that AD-related proteins like APP, Aβ, tau, BACE1 undergo post-translational modifications. The effect of PTMs contributes to the normal function of cells, although aberrant protein modification, which may depend on many factors, can drive the onset or support the development of AD. Results: Here we will discuss the effect of several PTMs on the functionality of AD-related proteins potentially contributing to the development of AD pathology. Conclusion: We will consider the role of Ubiquitination, Phosphorylation, SUMOylation, Acetylation and Nitrosylation on specific AD-related proteins and, more interestingly, the possible interactions that may occur between such different PTMs.

scholarly journals Transcriptome analyses of 7-day-old zebrafish larvae possessing a familial Alzheimer’s disease-like mutation in psen1 indicate effects on oxidative phosphorylation, ECM and MCM functions, and iron homeostasis

BMC Genomics ◽  
2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Yang Dong ◽  
Morgan Newman ◽  
Stephen M. Pederson ◽  
Karissa Barthelson ◽  
Nhi Hin ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Oxidative Phosphorylation ◽  
Transcriptome Analysis ◽  
Iron Homeostasis ◽  
Late Onset ◽  
Wild Type ◽  
Familial Alzheimer’S Disease ◽  
Zebrafish Larvae ◽  
Familial Alzheimer's Disease

Abstract Background Early-onset familial Alzheimer’s disease (EOfAD) is promoted by dominant mutations, enabling the study of Alzheimer’s disease (AD) pathogenic mechanisms through generation of EOfAD-like mutations in animal models. In a previous study, we generated an EOfAD-like mutation, psen1Q96_K97del, in zebrafish and performed transcriptome analysis comparing entire brains from 6-month-old wild type and heterozygous mutant fish. We identified predicted effects on mitochondrial function and endolysosomal acidification. Here we aimed to determine whether similar effects occur in 7 day post fertilization (dpf) zebrafish larvae that might be exploited in screening of chemical libraries to find ameliorative drugs. Results We generated clutches of wild type and heterozygous psen1Q96_K97del 7 dpf larvae using a paired-mating strategy to reduce extraneous genetic variation before performing a comparative transcriptome analysis. We identified 228 differentially expressed genes and performed various bioinformatics analyses to predict cellular functions. Conclusions Our analyses predicted a significant effect on oxidative phosphorylation, consistent with our earlier observations of predicted effects on ATP synthesis in adult heterozygous psen1Q96_K97del brains. The dysregulation of minichromosome maintenance protein complex (MCM) genes strongly contributed to predicted effects on DNA replication and the cell cycle and may explain earlier observations of genome instability due to PSEN1 mutation. The upregulation of crystallin gene expression may be a response to defective activity of mutant Psen1 protein in endolysosomal acidification. Genes related to extracellular matrix (ECM) were downregulated, consistent with previous studies of EOfAD mutant iPSC neurons and postmortem late onset AD brains. Also, changes in expression of genes controlling iron ion transport were observed without identifiable changes in the prevalence of transcripts containing iron responsive elements (IREs) in their 3′ untranslated regions (UTRs). These changes may, therefore, predispose to the apparent iron dyshomeostasis previously observed in 6-month-old heterozygous psen1Q96_K97del EOfAD-like mutant brains.

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