Live Imaging Reveals the Cellular Events Downstream of SARM1 Activation

SARM1 is an inducible NAD+ hydrolase that triggers axon loss and neuronal cell death in the injured and diseased nervous system. While SARM1 activation and enzyme function are well defined, the cellular events downstream of SARM1 activity but prior to axonal demise are much less well understood. Defects in calcium, mitochondria, ATP, and membrane homeostasis occur in injured axons, but the relationships among these events have been difficult to disentangle because prior studies analyzed large collections of axons in which cellular events occur asynchronously. Here we used live imaging with single axon resolution to investigate the cellular events downstream of SARM1 activity. Our studies support a model in which SARM1 NADase activity leads to an ordered sequence of events from loss of cellular ATP, to defects in mitochondrial movement and depolarization, followed by calcium influx, externalization of phosphatidylserine, and loss of membrane permeability prior to catastrophic axonal self destruction.

Download Full-text

Live imaging reveals the cellular events downstream of SARM1 activation

eLife ◽

10.7554/elife.71148 ◽

2021 ◽

Vol 10 ◽

Author(s):

Kwang Woo Ko ◽

Laura Devault ◽

Yo Sasaki ◽

Jeffrey Milbrandt ◽

Aaron DiAntonio

Keyword(s):

Sensory Neurons ◽

Calcium Influx ◽

Neuronal Cell Death ◽

Neuronal Cell ◽

Live Imaging ◽

Mitochondrial Movement ◽

Cellular Events ◽

Sequence Of Events ◽

Single Axon ◽

Axon Loss

SARM1 is an inducible NAD+ hydrolase that triggers axon loss and neuronal cell death in the injured and diseased nervous system. While SARM1 activation and enzyme function are well defined, the cellular events downstream of SARM1 activity but prior to axonal demise are much less well understood. Defects in calcium, mitochondria, ATP, and membrane homeostasis occur in injured axons, but the relationships among these events have been difficult to disentangle because prior studies analyzed large collections of axons in which cellular events occur asynchronously. Here we used live imaging of mouse sensory neurons with single axon resolution to investigate the cellular events downstream of SARM1 activity. Our studies support a model in which SARM1 NADase activity leads to an ordered sequence of events from loss of cellular ATP, to defects in mitochondrial movement and depolarization, followed by calcium influx, externalization of phosphatidylserine, and loss of membrane permeability prior to catastrophic axonal self-destruction.

Download Full-text

Oxidative Stress: Major Threat in Traumatic Brain Injury

CNS & Neurological Disorders - Drug Targets ◽

10.2174/1871527317666180627120501 ◽

2018 ◽

Vol 17 (9) ◽

pp. 689-695 ◽

Cited By ~ 37

Author(s):

Nidhi Khatri ◽

Manisha Thakur ◽

Vikas Pareek ◽

Sandeep Kumar ◽

Sunil Sharma ◽

...

Keyword(s):

Oxidative Stress ◽

Traumatic Brain Injury ◽

Brain Injury ◽

Mitochondrial Dysfunction ◽

Calcium Influx ◽

Neuronal Cell Death ◽

Neuronal Cell ◽

Physical Assault ◽

Mortality And Morbidity ◽

Primary Injury

Background & Objective: Traumatic Brain Injury (TBI) is one of the major causes of mortality and morbidity worldwide. It represents mild, moderate and severe effects of physical assault to brain which may cause sequential, primary or secondary ramifications. Primary injury can be due to the first physical hit, blow or jolt to one of the brain compartments. The primary injury is then followed by secondary injury which leads to biochemical, cellular, and physiological changes like blood brain barrier disruption, inflammation, excitotoxicity, necrosis, apoptosis, mitochondrial dysfunction and generation of oxidative stress. Apart from this, there is also an immediate increase in glutamate at the synapses following severe TBI. Excessive glutamate at synapses in turn activates corresponding NMDA and AMPA receptors that facilitate excessive calcium influx into the neuronal cells. This leads to the generation of oxidative stress which further leads to mitochondrial dysfunction, lipid peroxidation and oxidation of proteins and DNA. As a consequence, neuronal cell death takes place and ultimately people start facing some serious disabilies. Conclusion: In the present review we provide extensive overview of the role of reactive oxygen species (ROS)-induced oxidative stress and its fatal effects on brain after TBI.

Download Full-text

Mesenchymal Stem Cells (MSCs) Coculture Protects [Ca2+]i Orchestrated Oxidant Mediated Damage in Differentiated Neurons In Vitro

Cells ◽

10.3390/cells7120250 ◽

2018 ◽

Vol 7 (12) ◽

pp. 250 ◽

Cited By ~ 9

Author(s):

Adel Alhazzani ◽

Prasanna Rajagopalan ◽

Zaher Albarqi ◽

Anantharam Devaraj ◽

Mohamed Hessian Mohamed ◽

...

Keyword(s):

Cell Death ◽

Transforming Growth Factor ◽

Neuronal Cells ◽

Neuronal Cell Death ◽

Neuronal Cell ◽

Apoptotic Cells ◽

Sequence Of Events ◽

Cox 2 ◽

Anti Inflammatory

Cell-therapy modalities using mesenchymal stem (MSCs) in experimental strokes are being investigated due to the role of MSCs in neuroprotection and regeneration. It is necessary to know the sequence of events that occur during stress and how MSCs complement the rescue of neuronal cell death mediated by [Ca2+]i and reactive oxygen species (ROS). In the current study, SH-SY5Y-differentiated neuronal cells were subjected to in vitro cerebral ischemia-like stress and were experimentally rescued from cell death using an MSCs/neuronal cell coculture model. Neuronal cell death was characterized by the induction of proinflammatory tumor necrosis factor (TNF)-α, interleukin (IL)-1β and -12, up to 35-fold with corresponding downregulation of anti-inflammatory cytokine transforming growth factor (TGF)-β, IL-6 and -10 by approximately 1 to 7 fold. Increased intracellular calcium [Ca2+]i and ROS clearly reaffirmed oxidative stress-mediated apoptosis, while upregulation of nuclear factor NF-B and cyclo-oxygenase (COX)-2 expressions, along with ~41% accumulation of early and late phase apoptotic cells, confirmed ischemic stress-mediated cell death. Stressed neuronal cells were rescued from death when cocultured with MSCs via increased expression of anti-inflammatory cytokines (TGF-β, 17%; IL-6, 4%; and IL-10, 13%), significantly downregulated NF-B and proinflammatory COX-2 expression. Further accumulation of early and late apoptotic cells was diminished to 23%, while corresponding cell death decreased from 40% to 17%. Low superoxide dismutase 1 (SOD1) expression at the mRNA level was rescued by MSCs coculture, while no significant changes were observed with catalase (CAT) and glutathione peroxidase (GPx). Interestingly, increased serotonin release into the culture supernatant was proportionate to the elevated [Ca2+]i and corresponding ROS, which were later rescued by the MSCs coculture to near normalcy. Taken together, all of these results primarily support MSCs-mediated modulation of stressed neuronal cell survival in vitro.

Download Full-text

Protective Effects of Active Compounds from Salviae miltiorrhizae Radix against Glutamate-Induced HT-22 Hippocampal Neuronal Cell Death

Processes ◽

10.3390/pr8080914 ◽

2020 ◽

Vol 8 (8) ◽

pp. 914

Author(s):

Hung Manh Phung ◽

Sullim Lee ◽

Ki Sung Kang

Keyword(s):

Cell Death ◽

Rosmarinic Acid ◽

Calcium Influx ◽

Salvia Miltiorrhiza ◽

Neuroprotective Effect ◽

Neuronal Cell Death ◽

Neuronal Cell ◽

Salvianolic Acid B ◽

Tanshinone Iia ◽

Salvianolic Acid

Oxidative stress is considered one of the factors that cause dysfunction and damage of neurons, causing diseases such as amyotrophic lateral sclerosis (ALS), Alzheimer’s disease (AD), and Parkinson’s disease (PD).Recently, natural antioxidant sources have emerged as one of the main research areas for the discovery of potential neuroprotectants that can be used to treat neurological diseases. In this research, we assessed the neuroprotective effect of a 70% ethanol Salvia miltiorrhiza Radix (SMR) extract and five of its constituent compounds (tanshinone IIA, caffeic acid, salvianolic acid B, rosmarinic acid, and salvianic acid A) in HT-22 hippocampal cells. The experimental data showed that most samples were effective in attenuating the cytotoxicity caused by glutamate in HT-22 cells, except for rosmarinic acid and salvianolic acid B. Of the compounds tested, tanshinone IIA (TS-IIA) exerted the strongest effect in protecting HT-22 cells against glutamate neurotoxin. Treatment with 400 nM TS-IIA restored HT-22 cell viability almost completely. TS-IIA prevented glutamate-induced oxytosis by abating the accumulation of calcium influx, reactive oxygen species, and phosphorylation of mitogen-activated protein kinases. Moreover, TS-IIA inhibited glutamate-induced cytotoxicity by reducing the activation and phosphorylation of p53, as well as by stimulating Akt expression. This research suggested that TS-IIA is a potential neuroprotective component of SMR, with the ability to protect against neuronal cell death induced by excessive amounts of glutamate.

Download Full-text

From tau phosphorylation to tau aggregation: what about neuronal death?

Biochemical Society Transactions ◽

10.1042/bst0380967 ◽

2010 ◽

Vol 38 (4) ◽

pp. 967-972 ◽

Cited By ~ 50

Author(s):

Luc Buée ◽

Laëtitia Troquier ◽

Sylvie Burnouf ◽

Karim Belarbi ◽

Anneke Van der Jeugd ◽

...

Keyword(s):

Cell Death ◽

Cognitive Impairment ◽

Neurodegenerative Disorders ◽

Neuronal Death ◽

Neuronal Cell Death ◽

Neuronal Cell ◽

Tau Phosphorylation ◽

Tau Proteins ◽

Phosphorylated Tau ◽

Sequence Of Events

Tau pathology is characterized by intracellular aggregates of abnormally and hyperphosphorylated tau proteins. It is encountered in many neurodegenerative disorders, but also in aging. These neurodegenerative disorders are referred to as tauopathies. Comparative biochemistry of the tau aggregates shows that they differ in both tau isoform phosphorylation and content, which enables a molecular classification of tauopathies. In conditions of dementia, NFD (neurofibrillary degeneration) severity is correlated to cognitive impairment and is often considered as neuronal death. Using tau animal models, analysis of the kinetics of tau phosphorylation, aggregation and neuronal death in parallel to electrophysiological and behavioural parameters indicates a disconnection between cognition deficits and neuronal cell death. Tau phosphorylation and aggregation are early events followed by cognitive impairment. Neuronal death is not observed before the oldest ages. A sequence of events may be the formation of toxic phosphorylated tau species, their aggregation, the formation of neurofibrillary tangles (from pre-tangles to ghost tangles) and finally neuronal cell death. This sequence will last from 15 to 25 years and one can ask whether the aggregation of toxic phosphorylated tau species is a protection against cell death. Apoptosis takes 24 h, but NFD lasts for 24 years to finally kill the neuron or rather to protect it for more than 20 years. Altogether, these data suggest that NFD is a transient state before neuronal death and that therapeutic interventions are possible at that stage.

Download Full-text

Temporospatial sequence of cellular events associated with etoposide-induced neuronal cell death: Role of antiapoptotic protein Bcl-XL

Journal of Neuroscience Research ◽

10.1002/jnr.10028 ◽

2001 ◽

Vol 66 (6) ◽

pp. 1074-1082 ◽

Cited By ~ 2

Author(s):

Ji-Eun Kim ◽

Baek S. Han ◽

Won-Seok Choi ◽

Dae-Seok Eom ◽

Eun-Hee Lee ◽

...

Keyword(s):

Cell Death ◽

Neuronal Cell Death ◽

Neuronal Cell ◽

Antiapoptotic Protein ◽

Cellular Events

Download Full-text

Pre-clinical to Clinical Translational Failures and Current Status of Clinical Trials in Stroke Therapy: A Brief Review

Current Neuropharmacology ◽

10.2174/1570159x18666200114160844 ◽

2020 ◽

Vol 18 (7) ◽

pp. 596-612 ◽

Cited By ~ 2

Author(s):

Neha Dhir ◽

Bikash Medhi ◽

Ajay Prakash ◽

Manoj Kumar Goyal ◽

Manish Modi ◽

...

Keyword(s):

Functional Disability ◽

Calcium Influx ◽

Glutamate Release ◽

Clinical Stage ◽

Neuronal Cell Death ◽

Neuronal Cell ◽

Current Status ◽

Stroke Therapy ◽

Pump Failure ◽

Stroke Treatment

In stroke (cerebral ischemia), despite continuous efforts both at the experimental and clinical level, the only approved pharmacological treatment has been restricted to tissue plasminogen activator (tPA). Stroke is the leading cause of functional disability and mortality throughout worldwide. Its pathophysiology starts with energy pump failure, followed by complex signaling cascade that ultimately ends in neuronal cell death. Ischemic cascade involves excessive glutamate release followed by raised intracellular sodium and calcium influx along with free radicals’ generation, activation of inflammatory cytokines, NO synthases, lipases, endonucleases and other apoptotic pathways leading to cell edema and death. At the pre-clinical stage, several agents have been tried and proven as an effective neuroprotectant in animal models of ischemia. However, these agents failed to show convincing results in terms of efficacy and safety when the trials were conducted in humans following stroke. This article highlights the various agents which have been tried in the past but failed to translate into stroke therapy along with key points that are responsible for the lagging of experimental success to translational failure in stroke treatment.

Download Full-text

A novel neuroprotectant PAN-811 protects neurons from oxidative stress

Open Life Sciences ◽

10.2478/s11535-008-0062-1 ◽

2009 ◽

Vol 4 (1) ◽

pp. 34-40 ◽

Cited By ~ 3

Author(s):

Weiying Pan ◽

Chanteé Dancik ◽

Valery Nelson ◽

Zhi-Gang Jiang ◽

Michael Lebowitz ◽

...

Keyword(s):

Oxidative Stress ◽

Cell Death ◽

Nmda Receptor ◽

Calcium Influx ◽

Neuronal Cell Death ◽

Neuronal Cell ◽

Nmda Receptor Antagonist ◽

Free Calcium ◽

Oxygen Species ◽

Efficient Protection

AbstractHydrogen peroxide (H2O2), a major non-radical reactive oxygen species (ROS) could elicit intracellular oxidative damage and/or cause extracellular free calcium influx by activating the NMDA receptor or through calcium channels. In the present study, NMDA receptor antagonist MK-801 fully blocked H2O2-induced neuronal cell death, whereas green tea (GT) extract containing-antioxidants only partially suppressed the neurotoxicity of H2O2. These suggest that majority of ROS overproduction is downstream of H2O2-induced calcium influx. A novel neuroprotectant PAN-811 was previously demonstrated to efficiently attenuate ischemic neurotoxicity. PAN-811 hereby fully blocks H2O2-elicited neuronal cell death with a more advanced neuroprotective profile than that of GT extract. PAN-811 was also shown to protect against CaCl2-elicited neurotoxicity. Efficient protection against oxidative stress-induced neurotoxicity by PAN-811 indicates its potential application in treatment of ROS-mediated neurodegenerative diseases.

Download Full-text

Modes of Neuronal Calcium Entry and Homeostasis following Cerebral Ischemia

Stroke Research and Treatment ◽

10.4061/2010/316862 ◽

2010 ◽

Vol 2010 ◽

pp. 1-9 ◽

Cited By ~ 15

Author(s):

J. L. Cross ◽

B. P. Meloni ◽

A. J. Bakker ◽

S. Lee ◽

N. W. Knuckey

Keyword(s):

Cerebral Ischemia ◽

Calcium Influx ◽

Neuronal Cell Death ◽

Neuronal Cell ◽

Neuronal Loss ◽

Calcium Dysregulation ◽

Ischemic Brain ◽

Biochemical Mechanisms ◽

Influx Pathways ◽

New Treatments

One of the major instigators leading to neuronal cell death and brain damage following cerebral ischemia is calcium dysregulation. The neuron's inability to maintain calcium homeostasis is believed to be a result of increased calcium influx and impaired calcium extrusion across the plasma membrane. The need to better understand the cellular and biochemical mechanisms of calcium dysregulation contributing to neuronal loss following stroke/cerebral ischemia is essential for the development of new treatments in order to reduce ischemic brain injury. The aim of this paper is to provide a concise overview of the various calcium influx pathways in response to ischemia and how neuronal cells attempts to overcome this calcium overload.

Download Full-text