Abstract P800: Liposomal Delivery of PICK1 Inhibitor, FSC231, Prevents Ischemic/Reperfusion-Induced Degradation of GluA2 AMPA Receptor Subunit

Stroke ◽  
2021 ◽  
Vol 52 (Suppl_1) ◽  
Author(s):  
Lindsay Achzet ◽  
Darrell A Jackson
Keyword(s):  
Ischemic Stroke ◽  
Intracellular Calcium ◽  
Ampa Receptor ◽  
Neuronal Death ◽  
Research Effort ◽  
Ischemia Reperfusion ◽  
Hippocampal Slices ◽  
The United States ◽  
Delayed Neuronal Death ◽  
Ischemic Reperfusion

Stroke remains to be a leading cause of disability within the United States. Despite an enormous amount of research effort within the scientific community, very few therapeutics are available for stroke patients. Cytotoxic accumulation of intracellular calcium is a well-studied phenomenon that occurs following ischemic stroke. This intracellular calcium overload results from excessive release of the excitatory neurotransmitter glutamate, a process known as excitotoxicity, eventually leading to delayed neuronal death. The hippocampus is particularly susceptible to AMPA receptor-mediated delayed neuronal death. AMPA receptors (AMPARs) are homo- or hetero-tetramers composed of GluA1-4 subunits. The majority of AMPARs are impermeable to calcium due to a post-transcriptional modification in the channel pore of the GluA2 AMPAR subunit. Calcium-permeable AMPARs lacking the GluA2 subunit, contribute to calcium cytotoxicity and subsequent neuronal death. The internalization and subsequent degradation of GluA2 AMPAR subunits following oxygen-glucose deprivation/reperfusion (OGD/R) is, at least in part, mediated by protein-interacting with C Kinase-1 (PICK1). We hypothesize that disrupting the PICK1—GluA2 interaction will prevent the degradation of GluA2, thereby protecting neurons within the hippocampus from AMPAR-mediated delayed neuronal death. Pretreatment with liposome-encapsulated FSC231, an inhibitor of PICK1, in acute rodent hippocampal slices prevents the OGD/R-induced association of PICK1—GluA2. FSC231 treatment during OGD/R rescues total GluA2 AMPAR subunit protein levels. This work is the first to utilize a liposomal drug delivery system for the delivery of a small molecule in ex vivo acute rodent hippocampal slices exposed to ischemia/reperfusion injury. These results suggest that the interaction between GluA2 and PICK1 serves as an important step in the ischemic/reperfusion-induced reduction in total GluA2 levels and is a potential therapeutic target for the treatment of ischemic stroke.

scholarly journals Oxidative Stress Underlies the Ischemia/Reperfusion-Induced Internalization and Degradation of AMPA Receptors

2021 ◽  
Vol 22 (2) ◽  
pp. 717
Author(s):  
Lindsay M. Achzet ◽  
Clara J. Davison ◽  
Moira Shea ◽  
Isabella Sturgeon ◽  
Darrell A. Jackson
Keyword(s):  
Oxidative Stress ◽  
Reperfusion Injury ◽  
Ampa Receptors ◽  
Neuronal Death ◽  
Ischemia Reperfusion ◽  
The United States ◽  
Delayed Neuronal Death ◽  
Rab Proteins ◽  
Ischemic Reperfusion Injury ◽  
Ischemic Reperfusion

Stroke is the fifth leading cause of death annually in the United States. Ischemic stroke occurs when a blood vessel supplying the brain is occluded. The hippocampus is particularly susceptible to AMPA receptor-mediated delayed neuronal death as a result of ischemic/reperfusion injury. AMPA receptors composed of a GluA2 subunit are impermeable to calcium due to a post-transcriptional modification in the channel pore of the GluA2 subunit. GluA2 undergoes internalization and is subsequently degraded following ischemia/reperfusion. The subsequent increase in the expression of GluA2-lacking, Ca2+-permeable AMPARs results in excitotoxicity and eventually delayed neuronal death. Following ischemia/reperfusion, there is increased production of superoxide radicals. This study describes how the internalization and degradation of GluA1 and GluA2 AMPAR subunits following ischemia/reperfusion is mediated through an oxidative stress signaling cascade. U251-MG cells were transiently transfected with fluorescently tagged GluA1 and GluA2, and different Rab proteins to observe AMPAR endocytic trafficking following oxygen glucose-deprivation/reperfusion (OGD/R), an in vitro model for ischemia/reperfusion. Pretreatment with Mn(III)tetrakis(1-methyl-4-pyridyl)porphyrin (MnTMPyP), a superoxide dismutase mimetic, ameliorated the OGD/R-induced, but not agonist-induced, internalization and degradation of GluA1 and GluA2 AMPAR subunits. Specifically, MnTMPyP prevented the increased colocalization of GluA1 and GluA2 with Rab5, an early endosomal marker, and with Rab7, a late endosomal marker, but did not affect the colocalization of GluA1 with Rab11, a marker for recycling endosomes. These data indicate that oxidative stress may play a vital role in AMPAR-mediated cell death following ischemic/reperfusion injury.

scholarly journals Liposomal Encapsulated FSC231, a PICK1 Inhibitor, Prevents the Ischemia/Reperfusion-Induced Degradation of GluA2-Containing AMPA Receptors

Pharmaceutics ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 636
Author(s):  
Lindsay M. Achzet ◽  
Fanny Astruc-Diaz ◽  
Phillip H. Beske ◽  
Nicholas R. Natale ◽  
Travis T. Denton ◽  
...  
Keyword(s):  
Intracellular Calcium ◽  
Ampa Receptors ◽  
Research Effort ◽  
Ischemia Reperfusion ◽  
Glucose Deprivation ◽  
The United States ◽  
Excitatory Neurotransmitter ◽  
Protein Levels ◽  
Neurotransmitter Glutamate ◽  
Subsequent Degradation

Strokes remain one of the leading causes of disability within the United States. Despite an enormous amount of research effort within the scientific community, very few therapeutics are available for stroke patients. Cytotoxic accumulation of intracellular calcium is a well-studied phenomenon that occurs following ischemic stroke. This intracellular calcium overload results from excessive release of the excitatory neurotransmitter glutamate, a process known as excitotoxicity. Calcium-permeable AMPA receptors (AMPARs), lacking the GluA2 subunit, contribute to calcium cytotoxicity and subsequent neuronal death. The internalization and subsequent degradation of GluA2 AMPAR subunits following oxygen–glucose deprivation/reperfusion (OGD/R) is, at least in part, mediated by protein-interacting with C kinase-1 (PICK1). The purpose of the present study is to evaluate whether treatment with a PICK1 inhibitor, FSC231, prevents the OGD/R-induced degradation of the GluA2 AMPAR subunit. Utilizing an acute rodent hippocampal slice model system, we determined that pretreatment with FSC231 prevented the OGD/R-induced association of PICK1–GluA2. FSC231 treatment during OGD/R rescues total GluA2 AMPAR subunit protein levels. This suggests that the interaction between GluA2 and PICK1 serves as an important step in the ischemic/reperfusion-induced reduction in total GluA2 levels.

Delayed Neuronal Death in Experimental Ischemic Stroke

1999 ◽  
pp. 267-273
Author(s):  
J. H. Garcia ◽  
Z.-R. Ye ◽  
K.-F. Liu ◽  
J. A. Gutierrez
Keyword(s):  
Ischemic Stroke ◽  
Neuronal Death ◽  
Delayed Neuronal Death

Abstract 1944: Atorvastatin Reduces Intracerebral Hemorrhage after Experimental Stroke

Circulation ◽  
2007 ◽  
Vol 116 (suppl_16) ◽  
Author(s):  
Hazem F Elewa ◽  
Anna Kozak ◽  
David Rychly ◽  
Adviye Ergul ◽  
Reginald Frye ◽  
...  
Keyword(s):  
Ischemic Stroke ◽  
Intracerebral Hemorrhage ◽  
Infarct Volume ◽  
Ischemia Reperfusion ◽  
Methyl Cellulose ◽  
The United States ◽  
Experimental Stroke ◽  
High Risk Population ◽  
Protective Agent ◽  
Oral Gavage

Ischemic stroke is a leading cause of death and disability in the United States and diabetes mellitus is the fastest growing risk factor for stroke. In addition, hyperglycemia, which is usually associated with diabetes, tends to worsen ischemia/reperfusion injury and to induce more oxidative stress damage. Preliminary data from our laboratory showed that diabetic animals (Goto-Kakizaki rats (GKs) are more susceptible to vascular damage leading to intracerebral hemorrhage. Many studies have indicated that statins possess neuroprotective properties even when administered after the onset of ischemia. However, the acute vascular effects of statins after ischemic stroke have not been studied to date. Objective: to evaluate the efficacy and magnitude of vascular protection of acute statin therapy in both GKs and their normoglycemic controls after experimental ischemic stroke. Methods: Male Wistar (W) and GK rats (270–305 g) underwent 3 hours of middle cerebral artery occlusion (MCAO) followed by reperfusion for 21 hours. Animals were randomized to receive either atorvastatin (15mg/Kg) or methyl cellulose (0.5%), administered by oral gavage, the first dose 5 minutes after reperfusion and the second dose after 12 hours. Brain tissue was analyzed for infarct volume and hemoglobin content. In another set of Wistar rats (n=3), atorvastatin (15mg/Kg) was administered by oral gavage to compare its pharmacokinetic profile with that of humans Results: Atorvastatin-treated groups had significantly lower hemoglobin (p=0.0156) and infarct volume (p=0.0132) compared to their controls. Atorvastatin peak concentration (27–77 ng/ml) in rats’ plasma was found to be similar to that seen after 80mg/day of atorvastatin in humans. Conclusion: Atorvastatin can be a novel vascular protective agent after acute ischemic stroke especially in a high risk population like diabetics. The mechanisms through which these effects are mediated are currently being investigated.

Post-insult activity is a major cause of delayed neuronal death in organotypic hippocampal slices exposed to glutamate

Neuroscience ◽  
2001 ◽  
Vol 105 (1) ◽  
pp. 131-137 ◽  
Author(s):  
H Lahtinen ◽  
A.-M Autere ◽  
P Paalasmaa ◽  
S.E Lauri ◽  
K Kaila
Keyword(s):  
Neuronal Death ◽  
Hippocampal Slices ◽  
Delayed Neuronal Death

Delayed neuronal death in ischemic hippocampus involves stimulation of protein tyrosine phosphorylation

1996 ◽  
Vol 271 (4) ◽  
pp. C1085-C1097 ◽  
Author(s):  
T. Ohtsuki ◽  
M. Matsumoto ◽  
K. Kitagawa ◽  
T. Mabuchi ◽  
K. Mandai ◽  
...  
Keyword(s):  
Tyrosine Phosphorylation ◽  
Kainic Acid ◽  
Neuronal Death ◽  
Tyrosine Kinases ◽  
Ischemia Reperfusion ◽  
Delayed Neuronal Death ◽  
Mongolian Gerbils ◽  
Protein Tyrosine Phosphorylation ◽  
Protein Tyrosine ◽  
Stimulation Of

Glutamate triggers neuronal degeneration after ischemia-reperfusion in the brain. However, the details of intracellular signal transduction that propagates cell death remain unknown. The present work investigated whether protein tyrosine phosphorylation mediates neuronal death in the ischemic brain. Transient forebrain ischemia for 5-10 min in Mongolian gerbils or intoxication with the glutamate analogue kainic acid (12 mg/kg) in Sprague-Dawley rats caused neuronal death selectively in the hippocampus 2-4 days or 1 day later, respectively. Under these conditions, 160-, 115-, 105-, 92-, and 85-kDa proteins showed a significant increase in tyrosyl residue phosphorylation selectively in the hippocampus 3-12 h after ischemia or 4-8 h after kainic acid-induced seizures. Tyrosine kinases, including pp60c-src, were activated without a change of tyrosine phosphatases. Administration of radicicol, a selective inhibitor of tyrosine kinases, attenuated stimulation of tyrosine phosphorylation and hippocampal degeneration after ischemia or kainic acid injection. The results suggest that protein tyrosine phosphorylation might propagate delayed neuronal death in the mature hippocampus through glutamate overload after ischemia-reperfusion.

Cytochrome C Is Released from Mitochondria Into the Cytosol after Cerebral Anoxia or Ischemia

1999 ◽  
Vol 19 (1) ◽  
pp. 39-43 ◽  
Author(s):  
Miguel A. Pérez-Pinzón ◽  
Guang Ping Xu ◽  
James Born ◽  
José Lorenzo ◽  
Raul Busto ◽  
...  
Keyword(s):  
Cerebral Ischemia ◽  
Cytochrome C ◽  
Mitochondrial Dysfunction ◽  
Neuronal Death ◽  
Hippocampal Slices ◽  
Neuronal Cell Death ◽  
Brain Slices ◽  
Neuronal Cell ◽  
Severe Hypoxia ◽  
Delayed Neuronal Death

Mitochondrial dysfunction may underlie both acute and delayed neuronal cell death resulting from cerebral ischemia. Specifically, postischemic release of mitochondrial constituents such as the pro-apoptotic respiratory chain component cytochrome c could contribute acutely to further mitochondrial dysfunction and to promote delayed neuronal death. Experiments reported here tested the hypothesis that ischemia or severe hypoxia results in release of cytochrome c from mitochondria. Cytochrome c was measured spectrophotometrically from either the cytosolic fraction of cortical brain homogenates after global ischemia plus reperfusion, or from brain slices subjected to severe hypoxia plus reoxygenation. Cytochrome c content in cytosol derived from cerebral cortex was increased after ischemia and reperfusion. In intact hippocampal slices, there was a loss of reducible cytochrome c after hypoxia/reoxygenation, which is consistent with a decrease of this redox carrier in the mitochondrial pool. These results suggest that cytochrome c is lost to the cytosol after cerebral ischemia in a manner that may contribute to postischemic mitochondrial dysfunction and to delayed neuronal death.

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