Prevention of Amyloid-Beta Oligomer-Induced Neuronal Death by EGTA, Estradiol, and Endocytosis Inhibitor

Background and objective. Alzheimer’s disease is a progressive neurodegenerative disease that is biochemically characterized by the accumulation of amyloid beta (Aβ) peptides in the brain. The current hypothesis suggests that Aβ oligomers rather than fibrillar aggregates are the most toxic species of Aβ though the mechanisms of their neurotoxicity are unclear. The authors have previously shown that small Aβ1–42 oligomers at around 1 μM concentration caused rapid (in 24 h) neuronal death in cerebellar granule cell (CGC) cultures. In this study, we aimed to investigate whether protracted (up to 7 days) incubation of CGC cultures with lower submicromolar concentration of various aggregates of Aβ1–42 had an effect on viability of neurons. In order to get some insight into the mechanism of Aβ-induced cell death, we also sought to determine whether extracellular Ca2+ and process of endocytosis contributed to Aβ oligomer-induced neurotoxicity and whether pharmacological interventions into these processes would prevent Aβ oligomer-induced cell death. Material and Methods. Primary cultures of CGC were treated with various aggregate forms of Aβ1–42. Cell viability was assessed by fluorescent microscopy using propidium iodide and Hoechst 33342 staining. Results. Exposure of neurons to 500 nM Aβ1–42 oligomers for 72–168 h caused extensive neuronal necrosis. Lower concentrations (100–250 nM) were not toxic to cells during 7 days of incubation. Aβ1–42 monomers and fibrils had no effect on neuronal viability even after 7 days of incubation. Treatment of neurons with EGTA, steroid hormone 17β-estradiol, and methyl-β-cyclodextrin significantly reduced Aβ1-42 oligomers-induced neuronal death. Conclusions. The results show that submicromolar concentrations of Aβ1-42 oligomers were highly toxic to neurons during protracted incubation inducing neuronal necrosis that can be prevented by chelating extracellular Ca2+ with EGTA, inhibiting endocytosis with methyl-β-cyclodextrin, or by estradiol, which may protect against mitochondrial permeability transition pore opening.

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Role of Calcium Homeostasis in Ischemic Stroke: A Review

CNS & Neurological Disorders - Drug Targets ◽

10.2174/1871527320666210212141232 ◽

2021 ◽

Vol 20 ◽

Author(s):

Abhilash Ludhiadch ◽

Rashmi Sharma ◽

Aishwarya Muriki ◽

Anjana Munshi

Keyword(s):

Cell Death ◽

Ischemic Stroke ◽

Neuronal Death ◽

Complex Disease ◽

Mitochondrial Permeability Transition ◽

Permeability Transition ◽

Vital Role ◽

Calcium Accumulation ◽

Cell Death Pathway

: Stroke is the second most common cause of death worldwide. It occurs due to the insufficient supply of oxygen-rich blood to the brain. It is a complex disease with multiple associated risk factors including smoking, alcoholism, age, sex, ethnicity, etc. Calcium ions are known to play a vital role in cell death pathways, which is a ubiquitous intracellular messenger during and immediately after an ischemic period. Disruption in normal calcium hemostasis is known to be a major initiator and activator of the ischemic cell death pathway. Under Ischemic stroke conditions, glutamate is released from the neurons and glia which further activates the N-methyl-D-aspartate (NMDA) receptor and triggers the rapid translocation of Ca2+ from extracellular to intracellular spaces in cerebral tissues and vice versa. Various studies indicated that Ca2+ could have harmful effects on neurons under acute ischemic conditions. Mitochondrial dysfunction also contributes to delayed neuronal death, and it was established decades ago that massive calcium accumulation triggers mitochondrial damage. Elevated Ca2+ levels cause mitochondria to swell and release their contents. As a result oxidative stress and mitochondrial calcium accumulation activate mitochondrial permeability transition and lead to depolarization-coupled production of reactive oxygen species. This association between calcium levels and mitochondrial death suggests that elevated calcium levels might have a role in the neurological outcome in ischemic stroke. Previous studies have also reported that elevated Ca2+ levels play a role in the determination of infarct size, outcome, and recurrence of ischemic stroke. The current review has been compiled to understand the multidimensional role of altered Ca2+ levels in the initiation and alteration of neuronal death after ischemic attack. The underlying mechanisms understood to date have also been discussed.

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Neuronal Cell Death

Physiological Reviews ◽

10.1152/physrev.00011.2017 ◽

2018 ◽

Vol 98 (2) ◽

pp. 813-880 ◽

Cited By ~ 173

Author(s):

Michael Fricker ◽

Aviva M. Tolkovsky ◽

Vilmante Borutaite ◽

Michael Coleman ◽

Guy C. Brown

Keyword(s):

Cell Death ◽

Neuronal Death ◽

Mitochondrial Permeability Transition ◽

Neuronal Cell Death ◽

Neuronal Cell ◽

Permeability Transition ◽

Therapeutic Implications ◽

Unfolded Protein ◽

Cell Cycle Reentry ◽

The Unfolded Protein Response

Neuronal cell death occurs extensively during development and pathology, where it is especially important because of the limited capacity of adult neurons to proliferate or be replaced. The concept of cell death used to be simple as there were just two or three types, so we just had to work out which type was involved in our particular pathology and then block it. However, we now know that there are at least a dozen ways for neurons to die, that blocking a particular mechanism of cell death may not prevent the cell from dying, and that non-neuronal cells also contribute to neuronal death. We review here the mechanisms of neuronal death by intrinsic and extrinsic apoptosis, oncosis, necroptosis, parthanatos, ferroptosis, sarmoptosis, autophagic cell death, autosis, autolysis, paraptosis, pyroptosis, phagoptosis, and mitochondrial permeability transition. We next explore the mechanisms of neuronal death during development, and those induced by axotomy, aberrant cell-cycle reentry, glutamate (excitoxicity and oxytosis), loss of connected neurons, aggregated proteins and the unfolded protein response, oxidants, inflammation, and microglia. We then reassess which forms of cell death occur in stroke and Alzheimer’s disease, two of the most important pathologies involving neuronal cell death. We also discuss why it has been so difficult to pinpoint the type of neuronal death involved, if and why the mechanism of neuronal death matters, the molecular overlap and interplay between death subroutines, and the therapeutic implications of these multiple overlapping forms of neuronal death.

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Faculty Opinions recommendation of Loss of cyclophilin D reveals a critical role for mitochondrial permeability transition in cell death.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1025130.301711 ◽

2005 ◽

Author(s):

Atan Gross

Keyword(s):

Cell Death ◽

Mitochondrial Permeability Transition ◽

Critical Role ◽

Permeability Transition ◽

Cyclophilin D ◽

Mitochondrial Permeability

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Faculty Opinions recommendation of Loss of cyclophilin D reveals a critical role for mitochondrial permeability transition in cell death.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1025130.297852 ◽

2005 ◽

Author(s):

Robert Sapolsky

Keyword(s):

Cell Death ◽

Mitochondrial Permeability Transition ◽

Critical Role ◽

Permeability Transition ◽

Cyclophilin D ◽

Mitochondrial Permeability

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Inhibition of Autophagy Potentiated Hippocampal Cell Death Induced by Endoplasmic Reticulum Stress and its Activation by Trehalose Failed to be Neuroprotective

Current Neurovascular Research ◽

10.2174/1567202616666190131155834 ◽

2019 ◽

Vol 16 (1) ◽

pp. 3-11

Author(s):

Luisa Halbe ◽

Abdelhaq Rami

Keyword(s):

Endoplasmic Reticulum ◽

Cell Death ◽

Er Stress ◽

Cell Damage ◽

Protective Mechanism ◽

Unfolded Proteins ◽

Neuronal Viability ◽

Hippocampal Cell ◽

Trigger Cell Death ◽

Autophagy Inhibition

Introduction: Endoplasmic reticulum (ER) stress induced the mobilization of two protein breakdown routes, the proteasomal- and autophagy-associated degradation. During ERassociated degradation, unfolded ER proteins are translocated to the cytosol where they are cleaved by the proteasome. When the accumulation of misfolded or unfolded proteins excels the ER capacity, autophagy can be activated in order to undertake the degradative machinery and to attenuate the ER stress. Autophagy is a mechanism by which macromolecules and defective organelles are included in autophagosomes and delivered to lysosomes for degradation and recycling of bioenergetics substrate. Materials and Methods: Autophagy upon ER stress serves initially as a protective mechanism, however when the stress is more pronounced the autophagic response will trigger cell death. Because autophagy could function as a double edged sword in cell viability, we examined the effects autophagy modulation on ER stress-induced cell death in HT22 murine hippocampal neuronal cells. We investigated the effects of both autophagy-inhibition by 3-methyladenine (3-MA) and autophagy-activation by trehalose on ER-stress induced damage in hippocampal HT22 neurons. We evaluated the expression of ER stress- and autophagy-sensors as well as the neuronal viability. Results and Conclusion: Based on our findings, we conclude that under ER-stress conditions, inhibition of autophagy exacerbates cell damage and induction of autophagy by trehalose failed to be neuroprotective.

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

Current Alzheimer Research ◽

10.2174/1567205015666171227154016 ◽

2018 ◽

Vol 15 (6) ◽

pp. 504-510 ◽

Cited By ~ 9

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.

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Electrical characteristics of amyloid beta peptides in vertical junctions

NPG Asia Materials ◽

10.1038/s41427-021-00321-z ◽

2021 ◽

Vol 13 (1) ◽

Author(s):

Sohyeon Seo ◽

Jinju Lee ◽

Jungsue Choi ◽

G. Hwan Park ◽

Yeseul Hong ◽

...

Keyword(s):

Electron Transfer ◽

Electron Transport ◽

Amyloid Beta ◽

Field Effect Transistors ◽

Brain Diseases ◽

Electrical Characteristics ◽

Transport Pathway ◽

Sequence Dependence ◽

Aβ Oligomers ◽

Aβ Peptides

AbstractAssembled amyloid beta (Aβ) peptides have been considered pathological assemblies involved in human brain diseases, and the electron transfer or electron transport characteristics of Aβ are important for the formation of structured assemblies. Here, we report the electrical characteristics of surface-assembled Aβ peptides similar to those observed in Alzheimer’s patients. These characteristics correlate to their electron transfer characteristics. Electrical current–voltage plots of Aβ vertical junction devices show the Aβ sequence dependence of the current densities at both Aβ monomers (mono-Aβs) and Aβ oligomers (oli-Aβs), while Aβ sequence dependence is not clearly observed in the electrical characteristics of Aβ planar field effect transistors (FETs). In particular, surface oligomerization of Aβ peptides drastically decreases the activity of electron transfer, which presents a change in the electron transport pathway in the Aβ vertical junctions. Electron transport at oli-Aβ junctions is symmetric (tunneling/tunneling) due to the weak and voltage-independent coupling of the less redox-reactive oli-Aβ to the contacts, while that at mono-Aβ junctions is asymmetric (hopping/tunneling) due to redox levels of mono-Aβ voltage-dependently coupled with contact electrodes. Consequently, through vertical junctions, the sequence- and conformation-dependent electrical characteristics of Aβs can reveal their electron transfer activities.

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Metformin induces apoptosis via uterus mitochondrial permeability transition pore opening and protects against estradiol benzoate-induced uterine defect and associated pathophysiological disorder in female Wistar rats

Bulletin of the National Research Centre ◽

10.1186/s42269-021-00562-6 ◽

2021 ◽

Vol 45 (1) ◽

Author(s):

Adeola Oluwakemi Olowofolahan ◽

Obinna Matthew Paulinus ◽

Heritage Mojisola Dare ◽

Olufunso Olabode Olorunsogo

Keyword(s):

Cell Death ◽

Cytochrome C ◽

Mitochondrial Permeability Transition ◽

Permeability Transition ◽

Estradiol Benzoate ◽

Histological Evaluation ◽

Mitochondrial Atpase ◽

Rat Uterus ◽

Mitochondrial Permeability ◽

Pore Opening

Abstract Background Some antitumor or anticancer agents have been shown to execute cell death by induction of mitochondrial permeability transition (mPT) pore opening in order to elicit their chemotherapeutic effect. Therefore, this study investigated the effect of metformin on cell death via rat uterus mPT pore and estradiol benzoate-induced uterine defect and associated pathophysiological disorder in female rat. Mitochondria were isolated using differential centrifugation. The mPT pore opening, cytochrome c release and mitochondrial ATPase activity were determined spectrophotometrically. Caspases 9 and 3 activities, MDA and estradiol levels and SOD, GSH activities, were determined using ELISA technique. Histological and histochemical assessments of the uterine section were carried out using standard methods. Results Metformin at concentrations 10–90 μg/mL, showed no significant effect on mPT pore opening, mATPase activity and release of cytochrome c. However, oral administration of metformin caused mPT pore opening, enhancement of mATPase activity and activation of caspases 9 and 3 significantly at 300 and 400 mg/kg. Metformin protected against estradiol benzoate (EB)-induced uterine defect and other associated pathophysiological disorder. It also improved the antioxidant defense system. The histological evaluation revealed the protective effect of metformin on the cellular architecture of the uterus while the histochemical examination showed severe hyperplasia in the uterine section of EB-treated rats, remarkably reversed by metformin co-treatment. Conclusion This study suggests that metformin at high doses induces apoptosis via rat uterus mPT pore opening and protects against EB-induced uterine defect (hyperplasia) and associated pathophysiological disorder.

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Mitochondria and Pharmacologic Cardiac Conditioning—At the Heart of Ischemic Injury

International Journal of Molecular Sciences ◽

10.3390/ijms22063224 ◽

2021 ◽

Vol 22 (6) ◽

pp. 3224

Author(s):

Christopher Lotz ◽

Johannes Herrmann ◽

Quirin Notz ◽

Patrick Meybohm ◽

Franz Kehl

Keyword(s):

Cell Death ◽

Mitochondrial Permeability Transition ◽

Permeability Transition ◽

Research Field ◽

Calcium Handling ◽

Control Mechanisms ◽

Intrinsic Resistance ◽

Atp Production ◽

Cardiac Conditioning ◽

A Cell

Pharmacologic cardiac conditioning increases the intrinsic resistance against ischemia and reperfusion (I/R) injury. The cardiac conditioning response is mediated via complex signaling networks. These networks have been an intriguing research field for decades, largely advancing our knowledge on cardiac signaling beyond the conditioning response. The centerpieces of this system are the mitochondria, a dynamic organelle, almost acting as a cell within the cell. Mitochondria comprise a plethora of functions at the crossroads of cell death or survival. These include the maintenance of aerobic ATP production and redox signaling, closely entwined with mitochondrial calcium handling and mitochondrial permeability transition. Moreover, mitochondria host pathways of programmed cell death impact the inflammatory response and contain their own mechanisms of fusion and fission (division). These act as quality control mechanisms in cellular ageing, release of pro-apoptotic factors and mitophagy. Furthermore, recently identified mechanisms of mitochondrial regeneration can increase the capacity for oxidative phosphorylation, decrease oxidative stress and might help to beneficially impact myocardial remodeling, as well as invigorate the heart against subsequent ischemic insults. The current review highlights different pathways and unresolved questions surrounding mitochondria in myocardial I/R injury and pharmacological cardiac conditioning.

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