Rational Design and Synthesis of a Novel BODIPY-based Probe for Selective Imaging of Tau Tangles in Human iPSC-derived Cortical Neurons

2021 ◽  
Author(s):  
Alessandro Soloperto ◽  
Deborah Quaglio ◽  
Paola Baiocco ◽  
Isabella Romeo ◽  
Mattia Mori ◽  
...  
Keyword(s):  
Neurofibrillary Tangles ◽  
Fluorescent Probes ◽  
Tau Protein ◽  
Cortical Neurons ◽  
Rational Design ◽  
Amyloid Β ◽  
Neuronal Cell ◽  
Quantitative Detection ◽  
Core Electron

Abstract Numerous studies have shown a strong correlation between the number of neurofibrillary tangles of the tau protein and Alzheimer's disease progression, making the quantitative detection of tau very promising from a clinical point of view. However, the lack of highly reliable fluorescent probes for selective imaging of tau neurofibrillary tangles is a major challenge due to sharing similar β−sheet motifs with homologous Amyloid-β fibrils. In the current work, we describe the rational design and the in silico evaluation of a small-size focused library of fluorescent probes, consisting of a BODIPY core (electron acceptor) featuring highly conjugated systems (electron donor) with a length in the range 13-19 Å at C3. Among the most promising probes in terms of binding mode, theoretical affinity and polarity, BT1 has been synthesized and tested in vitro onto human induced pluripotent stem cells derived neuronal cell cultures. The probe showed excellent photophysical properties and high selectivity allowing in vitro imaging of hyperphosphorylated tau protein filaments with minimal background noise. Our findings offer new insight into the structure-activity relationship of this class of tau selective fluorophores, paving the way for boosting tau tangle detection in patients possibly through retinal spectral scans.

scholarly journals Extracellular vesicles from amyloid-β exposed cell cultures induce severe dysfunction in cortical neurons

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Chiara Beretta ◽  
Elisabeth Nikitidou ◽  
Linn Streubel-Gallasch ◽  
Martin Ingelsson ◽  
Dag Sehlin ◽  
...  
Keyword(s):  
Extracellular Vesicles ◽  
Cortical Neurons ◽  
Amyloid Β ◽  
Neuronal Cell ◽  
Time Lapse ◽  
Cellular Mechanisms ◽  
Axonal Swelling ◽  
Tem Analysis ◽  
Neuronal Cell Bodies ◽  
Time Lapse Imaging

AbstractAlzheimer’s disease (AD) is characterized by a substantial loss of neurons and synapses throughout the brain. The exact mechanism behind the neurodegeneration is still unclear, but recent data suggests that spreading of amyloid-β (Aβ) pathology via extracellular vesicles (EVs) may contribute to disease progression. We have previously shown that an incomplete degradation of Aβ42 protofibrils by astrocytes results in the release of EVs containing neurotoxic Aβ. Here, we describe the cellular mechanisms behind EV-associated neurotoxicity in detail. EVs were isolated from untreated and Aβ42 protofibril exposed neuroglial co-cultures, consisting mainly of astrocytes. The EVs were added to cortical neurons for 2 or 4 days and the neurodegenerative processes were followed with immunocytochemistry, time-lapse imaging and transmission electron microscopy (TEM). Addition of EVs from Aβ42 protofibril exposed co-cultures resulted in synaptic loss, severe mitochondrial impairment and apoptosis. TEM analysis demonstrated that the EVs induced axonal swelling and vacuolization of the neuronal cell bodies. Interestingly, EV exposed neurons also displayed pathological lamellar bodies of cholesterol deposits in lysosomal compartments. Taken together, our data show that the secretion of EVs from Aβ exposed cells induces neuronal dysfunction in several ways, indicating a central role for EVs in the progression of Aβ-induced pathology.

scholarly journals Overexpression of Mitochondrial Calcium Uniporter Causes Neuronal Death

2019 ◽  
Vol 2019 ◽  
pp. 1-15 ◽  
Author(s):  
Veronica Granatiero ◽  
Marco Pacifici ◽  
Anna Raffaello ◽  
Diego De Stefani ◽  
Rosario Rizzuto
Keyword(s):  
Cell Fate ◽  
Neuronal Death ◽  
Cortical Neurons ◽  
Neuronal Cell Death ◽  
Neuronal Cell ◽  
Neuronal Loss ◽  
Calcium Uniporter ◽  
Organelle Morphology

Neurodegenerative diseases are a large and heterogeneous group of disorders characterized by selective and progressive death of specific neuronal subtypes. In most of the cases, the pathophysiology is still poorly understood, although a number of hypotheses have been proposed. Among these, dysregulation of Ca2+ homeostasis and mitochondrial dysfunction represent two broadly recognized early events associated with neurodegeneration. However, a direct link between these two hypotheses can be drawn. Mitochondria actively participate to global Ca2+ signaling, and increases of [Ca2+] inside organelle matrix are known to sustain energy production to modulate apoptosis and remodel cytosolic Ca2+ waves. Most importantly, while mitochondrial Ca2+ overload has been proposed as the no-return signal, triggering apoptotic or necrotic neuronal death, until now direct evidences supporting this hypothesis, especially in vivo, are limited. Here, we took advantage of the identification of the mitochondrial Ca2+ uniporter (MCU) and tested whether mitochondrial Ca2+ signaling controls neuronal cell fate. We overexpressed MCU both in vitro, in mouse primary cortical neurons, and in vivo, through stereotaxic injection of MCU-coding adenoviral particles in the brain cortex. We first measured mitochondrial Ca2+ uptake using quantitative genetically encoded Ca2+ probes, and we observed that the overexpression of MCU causes a dramatic increase of mitochondrial Ca2+ uptake both at resting and after membrane depolarization. MCU-mediated mitochondrial Ca2+ overload causes alteration of organelle morphology and dysregulation of global Ca2+ homeostasis. Most importantly, MCU overexpression in vivo is sufficient to trigger gliosis and neuronal loss. Overall, we demonstrated that mitochondrial Ca2+ overload is per se sufficient to cause neuronal cell death both in vitro and in vivo, thus highlighting a potential key step in neurodegeneration.

Amyloid-β Deposits Target Efficient Near-Infrared Fluorescent Probes: Synthesis, in Vitro Evaluation, and in Vivo Imaging

2016 ◽  
Vol 88 (3) ◽  
pp. 1944-1950 ◽  
Author(s):  
Hualong Fu ◽  
Peiyu Tu ◽  
Liu Zhao ◽  
Jiapei Dai ◽  
Boli Liu ◽  
...  
Keyword(s):  
Fluorescent Probes ◽  
In Vivo Imaging ◽  
Near Infrared ◽  
Amyloid Β ◽  
In Vitro Evaluation

scholarly journals Loss of function of the mitochondrial peptidase PITRM1 induces proteotoxic stress and Alzheimer’s disease-like pathology in human cerebral organoids

2020 ◽  
Author(s):  
Dina Ivanyuk ◽  
María José Pérez ◽  
Vasiliki Panagiotakopoulou ◽  
Gabriele Di Napoli ◽  
Dario Brunetti ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Cell Death ◽  
Cortical Neurons ◽  
Amyloid Β ◽  
Neuronal Cell ◽  
Protein Aggregates ◽  
Neuronal Cultures ◽  
Loss Of Function ◽  
Proteotoxic Stress

AbstractMutations in pitrilysin metallopeptidase 1 (PITRM1), a mitochondrial protease involved in mitochondrial precursor processing and degradation, result in a slow-progressive syndrome, characterized by cerebellar ataxia, psychotic episodes and obsessive behavior as well as cognitive decline. To investigate the pathogenetic mechanisms of mitochondrial presequence processing, we employed cortical neurons and cerebral organoids generated from PITRM1 knockout human induced pluripotent stem cells (iPSCs). PITRM1 deficiency strongly induced mitochondrial unfolded protein response (UPRmt) and enhanced mitochondrial clearance in iPSC-derived neurons. Furthermore, we observed increased levels of amyloid precursor protein and amyloid β in PITRM1 knockout neurons. However, neither cell death nor protein aggregates were observed in 2D iPSC-derived cortical neuronal cultures. On the contrary, cerebral organoids generated from PITRM1 knockout iPSCs spontaneously developed over time pathological features of Alzheimer’s disease (AD), including accumulation of protein aggregates, tau pathology, and neuronal cell death. Importantly, we provide evidence for a protective role of UPRmt and mitochondrial clearance against impaired mitochondrial presequence processing and proteotoxic stress. In summary, we propose a novel concept of PITRM1-linked neurological syndrome whereby defects of mitochondrial presequence processing induce an early activation of UPRmt that, in turn, modulates cytosolic quality control pathways. Thus our work supports a mechanistic link between mitochondrial function and common neurodegenerative proteinopathies.

scholarly journals Upregulation of Peroxiredoxin 3 Protects Afg3l2-KO Cortical Neurons In Vitro from Oxidative Stress: A Paradigm for Neuronal Cell Survival under Neurodegenerative Conditions

2019 ◽  
Vol 2019 ◽  
pp. 1-13
Author(s):  
Barbara Bettegazzi ◽  
Ilaria Pelizzoni ◽  
Floramarida Salerno Scarzella ◽  
Lisa Michelle Restelli ◽  
Daniele Zacchetti ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Cortical Neurons ◽  
Mitochondrial Dynamics ◽  
Neuronal Cell ◽  
The Other ◽  
Antioxidant Defenses ◽  
Glutathione Depletion ◽  
Other Hand ◽  
Peroxiredoxin 3

Several neurodegenerative disorders exhibit selective vulnerability, with subsets of neurons more affected than others, possibly because of the high expression of an altered gene or the presence of particular features that make them more susceptible to insults. On the other hand, resilient neurons may display the ability to develop antioxidant defenses, particularly in diseases of mitochondrial origin, where oxidative stress might contribute to the neurodegenerative process. In this work, we investigated the oxidative stress response of embryonic fibroblasts and cortical neurons obtained from Afg3l2-KO mice. AFG3L2 encodes a subunit of a protease complex that is expressed in mitochondria and acts as both quality control and regulatory enzyme affecting respiration and mitochondrial dynamics. When cells were subjected to an acute oxidative stress protocol, the survival of AFG3L2-KO MEFs was not significantly influenced and was comparable to that of WT; however, the basal level of the antioxidant molecule glutathione was higher. Indeed, glutathione depletion strongly affected the viability of KO, but not of WT MEF, thereby indicating that oxidative stress is more elevated in KO MEF even though well controlled by glutathione. On the other hand, when cortical KO neurons were put in culture, they immediately appeared more vulnerable than WT to the acute oxidative stress condition, but after few days in vitro, the situation was reversed with KO neurons being more resistant than WT to acute stress. This compensatory, protective competence was not due to the upregulation of glutathione, rather of two mitochondrial antioxidant proteins: superoxide dismutase 2 and, at an even higher level, peroxiredoxin 3. This body of evidence sheds light on the capability of neurons to activate neuroprotective pathways and points the attention to peroxiredoxin 3, an antioxidant enzyme that might be critical for neuronal survival also in other disorders affecting mitochondria.

scholarly journals Transforming Growth Factor β2 Is a Neuronal Death-Inducing Ligand for Amyloid-β Precursor Protein

2005 ◽  
Vol 25 (21) ◽  
pp. 9304-9317 ◽  
Author(s):  
Yuichi Hashimoto ◽  
Tomohiro Chiba ◽  
Marina Yamada ◽  
Mikiro Nawa ◽  
Kohsuke Kanekura ◽  
...  
Keyword(s):  
Growth Factor ◽  
Binding Affinity ◽  
Neuronal Death ◽  
Cortical Neurons ◽  
Transforming Growth Factor ◽  
Neuronal Cell Death ◽  
Amyloid Β ◽  
Neuronal Cell ◽  
Precursor Protein ◽  
Transforming Growth Factor Β2

ABSTRACT APP, amyloid β precursor protein, is linked to the onset of Alzheimer's disease (AD). We have here found that transforming growth factor β2 (TGFβ2), but not TGFβ1, binds to APP. The binding affinity of TGFβ2 to APP is lower than the binding affinity of TGFβ2 to the TGFβ receptor. On binding to APP, TGFβ2 activates an APP-mediated death pathway via heterotrimeric G protein Go, c-Jun N-terminal kinase, NADPH oxidase, and caspase 3 and/or related caspases. Overall degrees of TGFβ2-induced death are larger in cells expressing a familial AD-related mutant APP than in those expressing wild-type APP. Consequently, superphysiological concentrations of TGFβ2 induce neuronal death in primary cortical neurons, whose one allele of the APP gene is knocked in with the V642I mutation. Combined with the finding indicated by several earlier reports that both neural and glial expression of TGFβ2 was upregulated in AD brains, it is speculated that TGFβ2 may contribute to the development of AD-related neuronal cell death.

scholarly journals Rational Design and Identification of Harmine-Inspired, N-Heterocyclic DYRK1A Inhibitors Employing a Functional Genomic in vivo Drosophila Model System

2021 ◽  
Author(s):  
Brandon Ashfeld ◽  
Francisco Huizar ◽  
Harrison Hill ◽  
Jeremiah Zartman ◽  
Emily Bacher ◽  
...  
Keyword(s):  
Small Molecule ◽  
Rational Design ◽  
Kinase Inhibitors ◽  
Low Cost ◽  
Neuronal Cell ◽  
Model System ◽  
In Vivo Model ◽  
Functional Genomic

Deregulation of dual-specificity tyrosine phosphorylation-regulated kinase 1A (DYRK1A) plays a significant role in developmental brain defects, early-onset neurodegeneration, neuronal cell loss, and dementia. Herein, we report the discovery of three new classes of <i>N</i>-heterocyclic DYRK1A inhibitors based on the potent, yet toxic kinase inhibitors, harmine and harmol. An initial in vitro evaluation of the small molecule collection assembled revealed that the core heterocyclic motifs benzofuranones, oxindoles, and pyrrolones, showed statistically significant DYRK1A inhibition. Further, the utilization of a low cost, high-throughput functional genomic in vivo model system to identify small molecule inhibitors that normalize DYRK1A overexpression phenotypes is described. This in vivo assay confirmed the in vitro results, and the resulting correspondence validates generated classes as architectural motifs that serve as potential DYRK1A inhibitors. Further expansion and analysis of these core compound structures will allow discovery of safe, more effective chemical inhibitors of DYRK1A to ameliorate phenotypes caused by DYRK1A overexpression.

scholarly journals Minocycline Increases in-vitro Cortical Neuronal Cell Survival after Laser Induced Axotomy

2020 ◽  
Vol 15 (2) ◽  
pp. 105-109 ◽  
Author(s):  
Burak Yulug ◽  
Mehmet Ozansoy ◽  
Merve Alokten ◽  
Muzaffer B.C. Ozansoy ◽  
Seyda Cankaya ◽  
...  
Keyword(s):  
Cell Survival ◽  
Cortical Neurons ◽  
Neuroprotective Effect ◽  
Neuronal Cell ◽  
Neuroprotective Effects ◽  
Therapeutic Trials ◽  
Trauma Model ◽  
Injury Models ◽  
Translational Block

Background: Antibiotic therapies targeting multiple regenerative mechanisms have the potential for neuroprotective effects, but the diversity of experimental strategies and analyses of non-standardised therapeutic trials are challenging. In this respect, there are no cases of successful clinical application of such candidate molecules when it comes to human patients. Methods: After 24 hours of culturing, three different minocycline (Sigma-Aldrich, M9511, Germany) concentrations (1 μM, 10 μM and 100 μM) were added to the primary cortical neurons 15 minutes before laser axotomy procedure in order to observe protective effect of minocycline in these dosages. Results: Here, we have shown that minocycline exerted a significant neuroprotective effect at 1 and 100μM doses. Beyond confirming the neuroprotective effect of minocycline in a more standardised and advanced in-vitro trauma model, our findings could have important implications for future studies that concentrate on the translational block between animal and human studies. Conclusion: Such sophisticated approaches might also help to conquer the influence of humanmade variabilities in critical experimental injury models. To the best of our knowledge, this is the first study showing that minocycline increases in-vitro neuronal cell survival after laser-axotomy.

scholarly journals A Systematic Review of Glucose Transport Alterations in Alzheimer's Disease

2021 ◽  
Vol 15 ◽  
Author(s):  
Natalia Kyrtata ◽  
Hedley C. A. Emsley ◽  
Oli Sparasci ◽  
Laura M. Parkes ◽  
Ben R. Dickie
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Glucose Transport ◽  
Clinical Symptoms ◽  
Amyloid Β ◽  
Neuronal Cell ◽  
Glucose Transporters ◽  
Rodent Models ◽  
The Brain

Introduction: Alzheimer's disease (AD) is characterized by cerebral glucose hypometabolism. Hypometabolism may be partly due to reduced glucose transport at the blood-brain barrier (BBB) and across astrocytic and neuronal cell membranes. Glucose transporters (GLUTs) are integral membrane proteins responsible for moving glucose from the bloodstream to parenchymal cells where it is metabolized, and evidence indicates vascular and non-vascular GLUTs are altered in AD brains, a process which could starve the brain of glucose and accelerate cognitive decline. Here we review the literature on glucose transport alterations in AD from human and rodent studies.Methods: Literature published between 1st January 1946 and 1st November 2020 within EMBASE and MEDLINE databases was searched for the terms “glucose transporters” AND “Alzheimer's disease”. Human and rodent studies were included while reviews, letters, and in-vitro studies were excluded.Results: Forty-three studies fitting the inclusion criteria were identified, covering human (23 studies) and rodent (20 studies). Post-mortem studies showed consistent reductions in GLUT1 and GLUT3 in the hippocampus and cortex of AD brains, areas of the brain closely associated with AD pathology. Tracer studies in rodent models of AD and human AD also exhibit reduced uptake of glucose and glucose-analogs into the brain, supporting these findings. Longitudinal rodent studies clearly indicate that changes in GLUT1 and GLUT3 only occur after amyloid-β pathology is present, and several studies indicate amyloid-β itself may be responsible for GLUT changes. Furthermore, evidence from human and rodent studies suggest GLUT depletion has severe effects on brain function. A small number of studies show GLUT2 and GLUT12 are increased in AD. Anti-diabetic medications improved glucose transport capacity in AD subjects.Conclusions: GLUT1 and GLUT3 are reduced in hippocampal and cortical regions in patients and rodent models of AD, and may be caused by high levels of amyloid-β in these regions. GLUT3 reductions appear to precede the onset of clinical symptoms. GLUT2 and GLUT12 appear to increase and may have a compensatory role. Repurposing anti-diabetic drugs to modify glucose transport shows promising results in human studies of AD.

An Aβ42 variant that inhibits intra- and extracellular amyloid aggregation and enhances cell viability

2018 ◽  
Vol 475 (19) ◽  
pp. 3087-3103 ◽  
Author(s):  
Ofek Oren ◽  
Victor Banerjee ◽  
Ran Taube ◽  
Niv Papo
Keyword(s):  
Amyloid Fibrils ◽  
Neuronal Cells ◽  
Amyloid Β ◽  
Neuronal Cell ◽  
Amyloid Β Peptide ◽  
Cell Cytotoxicity ◽  
Amyloid Aggregation ◽  
Molar Ratios

Aggregation and accumulation of the 42-residue amyloid β peptide (Aβ42) in the extracellular matrix and within neuronal cells is considered a major cause of neuronal cell cytotoxicity and death in Alzheimer's disease (AD) patients. Therefore, molecules that bind to Aβ42 and prevent its aggregation are therapeutically promising as AD treatment. Here, we show that a non-self-aggregating Aβ42 variant carrying two surface mutations, F19S and L34P (Aβ42DM), inhibits wild-type Aβ42 aggregation and significantly reduces Aβ42-mediated cell cytotoxicity. In addition, Aβ42DM inhibits the uptake and internalization of extracellularly added pre-formed Aβ42 aggregates into cells. This was the case in both neuronal and non-neuronal cells co-expressing Aβ42 and Aβ42DM or following pre-treatment of cells with extracellular soluble forms of the two peptides, even at high Aβ42 to Aβ42DM molar ratios. In cells, Aβ42DM associates with Aβ42, while in vitro, the two soluble recombinant peptides exhibit nano-molar binding affinity. Importantly, Aβ42DM potently suppresses Aβ42 amyloid aggregation in vitro, as demonstrated by thioflavin T fluorescence and transmission electron microscopy for detecting amyloid fibrils. Overall, we present a new approach for inhibiting Aβ42 fibril formation both within and outside cells. Accordingly, Aβ42DM should be evaluated in vivo for potential use as a therapeutic lead for treating AD.

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