scholarly journals INF2-mediated actin filament reorganization confers intrinsic resilience to neuronal ischemic injury

2021 ◽  
Author(s):  
Barbara Calabrese ◽  
Steven Jones ◽  
Yoko Yamaguchi-Shiraishi ◽  
Michael J Lingelbach ◽  
Uri Manor ◽  
...  
Keyword(s):  
Actin Filament ◽  
Dendritic Spines ◽  
Glucose Deprivation ◽  
Receptor Activation ◽  
Cell Swelling ◽  
Filament Bundles ◽  
Activation Conditions ◽  
Neuronal Swelling

During early stages of ischemic brain injury, glutamate receptor hyperactivation mediates neuronal death via osmotic cell swelling. Here we show that ischemia and excess NMDA receptor activation, conditions that trigger neuronal swelling, cause actin filaments to undergo a rapid and extensive reorganization within the somatodendritic compartment. Normally, Factin is concentrated within dendritic spines, with relatively little Factin in the dendrite shaft. However, beginning <5 min after incubation of neurons with NMDA, Factin depolymerizes within dendritic spines and polymerizes into long, stable filament bundles within the dendrite shaft and soma. A similar actinification of the somatodendritic compartment occurs after oxygen/glucose deprivation in vitro, and in mouse brain after photothrombotic stroke in vivo. Following transient, sub-lethal NMDA exposure these actin changes spontaneously reverse within 1-2 hours. A combination of Na+, Cl-, water, and Ca2+ entry are all necessary, but not individually sufficient, for induction of actinification. Spine F-actin depolymerization is also required. Actinification is driven by activation of the Factin polymerization factor inverted formin2 (INF2). Silencing of INF2 renders neurons more vulnerable to NMDA induced membrane leakage and cell death, and formin inhibition markedly increases ischemic infarct severity in vivo. These results show that ischemia induced actin filament reorganization within the dendritic compartment is an intrinsic pro-survival response that protects neurons from death induced by swelling.

scholarly journals GABAA Receptor Activation Attenuates Excitotoxicity but Exacerbates Oxygen—Glucose Deprivation-Induced Neuronal Injury In Vitro

1996 ◽  
Vol 16 (6) ◽  
pp. 1211-1218 ◽  
Author(s):  
Judith K. Muir ◽  
Doug Lobner ◽  
Hannelore Monyer ◽  
Dennis W. Choi
Keyword(s):  
Neuronal Death ◽  
Receptor Agonist ◽  
Cortical Cell ◽  
Glucose Deprivation ◽  
Receptor Activation ◽  
Oxygen Glucose Deprivation ◽  
Receptor Stimulation ◽  
Bathing Medium

We examined the effects of GABA receptor stimulation on the neuronal death induced by exogenously added excitatory amino acids or combined oxygen–glucose deprivation in mouse cortical cell cultures. Death induced by exposure to NMDA, AMPA, or kainate was attenuated by addition of GABA or the GABAA receptor agonist, muscimol, but not by the GABAB receptor agonist, baclofen. The antiexcitotoxic effect of GABAA receptor agonists was blocked by bicuculline or Picrotoxin. In contrast, GABA or muscimol, but not baclofen, markedly increased the neuronal death induced by oxygen–glucose deprivation. Muscimol potentiation of neuronal death was associated with increased glutamate efflux to the bathing medium, and increased cellular 45Ca2+ accumulation; it was blocked by MK-801, but not NBQX, suggesting mediation by NMDA receptors. Bicuculline only weakly attenuated muscimol potentiation of oxygen–glucose deprivation-induced neuronal death, probably because it itself increased this death. Present results raise a note of caution in the proposed use of GABAA receptor stimulation to limit ischemic brain damage in vivo.

scholarly journals Palladin Is a Regulator of Actin Filament Bundles at the Ectoplasmic Specialization in Adult Rat Testes

Endocrinology ◽  
2013 ◽  
Vol 154 (5) ◽  
pp. 1907-1920 ◽  
Author(s):  
Xiaojing Qian ◽  
Dolores D. Mruk ◽  
Elissa W. P. Wong ◽  
Pearl P. Y. Lie ◽  
C. Yan Cheng
Keyword(s):  
Actin Filament ◽  
Actin Filaments ◽  
Plasma Membranes ◽  
Permeability Barrier ◽  
Protein Distribution ◽  
Filament Bundles ◽  
Ectoplasmic Specialization ◽  
Blood Testis Barrier

Abstract In rat testes, the ectoplasmic specialization (ES) at the Sertoli-Sertoli and Sertoli-spermatid interface known as the basal ES at the blood-testis barrier and the apical ES in the adluminal compartment, respectively, is a testis-specific adherens junction. The remarkable ultrastructural feature of the ES is the actin filament bundles that sandwiched in between the cisternae of endoplasmic reticulum and apposing plasma membranes. Although these actin filament bundles undergo extensive reorganization to switch between their bundled and debundled state to facilitate blood-testis barrier restructuring and spermatid adhesion/transport, the regulatory molecules underlying these events remain unknown. Herein we report findings of an actin filament cross-linking/bundling protein palladin, which displayed restrictive spatiotemporal expression at the apical and the basal ES during the epithelial cycle. Palladin structurally interacted and colocalized with Eps8 (epidermal growth factor receptor pathway substrate 8, an actin barbed end capping and bundling protein) and Arp3 (actin related protein 3, which together with Arp2 form the Arp2/3 complex to induce branched actin nucleation, converting bundled actin filaments to an unbundled/branched network), illustrating its role in regulating actin filament bundle dynamics at the ES. A knockdown of palladin in Sertoli cells in vitro with an established tight junction (TJ)-permeability barrier was found to disrupt the TJ function, which was associated with a disorganization of actin filaments that affected protein distribution at the TJ. Its knockdown in vivo also perturbed F-actin organization that led to a loss of spermatid polarity and adhesion, causing defects in spermatid transport and spermiation. In summary, palladin is an actin filament regulator at the ES.

Mu-opioid receptor activation promotes in vitro and in vivo tumor growth in head and neck squamous cell carcinoma

Life Sciences ◽  
2021 ◽  
Vol 278 ◽  
pp. 119541
Author(s):  
Aysegul Gorur ◽  
Miguel Patiño ◽  
Hideaki Takahashi ◽  
German Corrales ◽  
Curtis R. Pickering ◽  
...  
Keyword(s):  
Squamous Cell Carcinoma ◽  
Tumor Growth ◽  
Cell Carcinoma ◽  
Head And Neck ◽  
Opioid Receptor ◽  
Receptor Activation ◽  
Mu Opioid Receptor ◽  
Mu Opioid

scholarly journals LINGO-1 shRNA protects the brain against ischemia/reperfusion injury by inhibiting the activation of NF-κB and JAK2/STAT3

Human Cell ◽  
2021 ◽  
Author(s):  
Jiaying Zhu ◽  
Zhu Zhu ◽  
Yipin Ren ◽  
Yukang Dong ◽  
Yaqi Li ◽  
...  
Keyword(s):  
Cerebral Ischemia ◽  
Nuclear Translocation ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Glucose Deprivation ◽  
Artery Occlusion ◽  
Mice Model ◽  
Down Regulation

AbstractLINGO-1 may be involved in the pathogenesis of cerebral ischemia. However, its biological function and underlying molecular mechanism in cerebral ischemia remain to be further defined. In our study, middle cerebral artery occlusion/reperfusion (MACO/R) mice model and HT22 cell oxygen–glucose deprivation/reperfusion (OGD/R) were established to simulate the pathological process of cerebral ischemia in vivo and in vitro and to detect the relevant mechanism. We found that LINGO-1 mRNA and protein were upregulated in mice and cell models. Down-regulation LINGO-1 improved the neurological symptoms and reduced pathological changes and the infarct size of the mice after MACO/R. In addition, LINGO-1 interference alleviated apoptosis and promoted cell proliferation in HT22 of OGD/R. Moreover, down-regulation of LINGO-1 proved to inhibit nuclear translocation of p-NF-κB and reduce the expression level of p-JAK2 and p-STAT3. In conclusion, our data suggest that shLINGO-1 attenuated ischemic injury by negatively regulating NF-KB and JAK2/STAT3 pathways, highlighting a novel therapeutic target for ischemic stroke.

scholarly journals Hippo-YAP/MCP-1 mediated tubular maladaptive repair promote inflammation in renal failed recovery after ischemic AKI

2021 ◽  
Vol 12 (8) ◽  
Author(s):  
Zhihuang Zheng ◽  
Chuanlei Li ◽  
Guangze Shao ◽  
Jinqing Li ◽  
Kexin Xu ◽  
...  
Keyword(s):  
Chronic Inflammation ◽  
Ischemia Reperfusion ◽  
Hippo Pathway ◽  
Glucose Deprivation ◽  
Macrophage Infiltration ◽  
Renal Inflammation ◽  
Monocyte Chemoattractant Protein 1 ◽  
The Hippo Pathway

AbstractAcute kidney injury (AKI) is associated with significant morbidity and its chronic inflammation contributes to subsequent chronic kidney disease (CKD) development. Yes-associated protein (YAP), the major transcriptional coactivator of the Hippo pathway, has been shown associated with chronic inflammation, but its role and mechanism in AKI-CKD transition remain unclear. Here we aimed to investigate the role of YAP in AKI-induced chronic inflammation. Renal ischemia/reperfusion (I/R) was used to induce a mouse model of AKI-CKD transition. We used verteporfin (VP), a pharmacological inhibitor of YAP, to treat post-IRI mice for a period, and evaluated the influence of YAP inhibition on long-term outcomes of AKI. In our results, severe IRI led to maladaptive tubular repair, macrophages infiltration, and progressive fibrosis. Following AKI, the Hippo pathway was found significantly altered with YAP persistent activation. Besides, tubular YAP activation was associated with the maladaptive repair, also correlated with interstitial macrophage infiltration. Monocyte chemoattractant protein 1 (MCP-1) was found notably upregulated with YAP activation. Of note, pharmacological inhibition of YAP in vivo attenuated renal inflammation, including macrophage infiltration and MCP-1 overexpression. Consistently, in vitro oxygen-glucose deprivation and reoxygenation (OGD/R) induced YAP activation and MCP-1 overproduction whereas these could be inhibited by VP. In addition, we modulated YAP activity by RNA interference, which further confirmed YAP activation enhances MCP-1 expression. Together, we concluded tubular YAP activation with maladaptive repair exacerbates renal inflammation probably via promoting MCP-1 production, which contributes to AKI-CKD transition.

Physiology, Pharmacology, and Topography of Cholinergic Neocortical Oscillations In Vitro

1997 ◽  
Vol 77 (5) ◽  
pp. 2427-2445 ◽  
Author(s):  
Heath S. Lukatch ◽  
M. Bruce Maciver
Keyword(s):  
Current Source ◽  
Brain Slices ◽  
Receptor Activation ◽  
Brain Regions ◽  
Oscillatory Activity ◽  
Cortical Layers ◽  
Eeg Activity ◽  
Layer 2

Lukatch, Heath S. and M. Bruce MacIver. Physiology, pharmacology, and topography of cholinergic neocortical oscillations in vitro. J. Neurophysiol. 77: 2427–2445, 1997. Rat neocortical brain slices generated rhythmic extracellular field [microelectroencephalogram (micro-EEG)] oscillations at theta frequencies (3–12 Hz) when exposed to pharmacological conditions that mimicked endogenous ascending cholinergic and GABAergic inputs. Use of the specific receptor agonist and antagonist carbachol and bicuculline revealed that simultaneous muscarinic receptor activation and γ-aminobutyric acid-A (GABAA)-mediated disinhibition werenecessary to elicit neocortical oscillations. Rhythmic activity was independent of GABAB receptor activation, but required intact glutamatergic transmission, evidenced by blockade or disruption of oscillations by 6-cyano-7-nitroquinoxaline-2,3-dione and (±)-2-amino-5-phosphonovaleric acid, respectively. Multisite mapping studies showed that oscillations were localized to areas 29d and 18b (Oc2MM) and parts of areas 18a and 17. Peak oscillation amplitudes occurred in layer 2/3, and phase reversals were observed in layers 1 and 5. Current source density analysis revealed large-amplitude current sinks and sources in layers 2/3 and 5, respectively. An initial shift in peak inward current density from layer 1 to layer 2/3 indicated that two processes underlie an initial depolarization followed by oscillatory activity. Laminar transections localized oscillation-generating circuitry to superficial cortical layers and sharp-spike-generating circuitry to deep cortical layers. Whole cell recordings identified three distinct cell types based on response properties during rhythmic micro-EEG activity: oscillation-on (theta-on) and -off (theta-off) neurons, and transiently depolarizing glial cells. Theta-on neurons displayed membrane potential oscillations that increased in amplitude with hyperpolarization (from −30 to −90 mV). This, taken together with a glutamate antagonist-induced depression of rhythmic micro-EEG activity, indicated that cholinergically driven neocortical oscillations require excitatory synaptic transmission. We conclude that under the appropriate pharmacological conditions, neocortical brain slices were capable of producing localized theta frequency oscillations. Experiments examining oscillation physiology, pharmacology, and topography demonstrated that neocortical brain slice oscillations share many similarities with the in vivo and in vitro theta EEG activity recorded in other brain regions.

scholarly journals Protein kinase D promotes plasticity-induced F-actin stabilization in dendritic spines and regulates memory formation

2015 ◽  
Vol 210 (5) ◽  
pp. 771-783 ◽  
Author(s):  
Norbert Bencsik ◽  
Zsófia Szíber ◽  
Hanna Liliom ◽  
Krisztián Tárnok ◽  
Sándor Borbély ◽  
...  
Keyword(s):  
Synaptic Plasticity ◽  
Protein Kinase ◽  
Dendritic Spines ◽  
Morphological Changes ◽  
Long Term Potentiation ◽  
Memory Formation ◽  
Protein Kinase D

Actin turnover in dendritic spines influences spine development, morphology, and plasticity, with functional consequences on learning and memory formation. In nonneuronal cells, protein kinase D (PKD) has an important role in stabilizing F-actin via multiple molecular pathways. Using in vitro models of neuronal plasticity, such as glycine-induced chemical long-term potentiation (LTP), known to evoke synaptic plasticity, or long-term depolarization block by KCl, leading to homeostatic morphological changes, we show that actin stabilization needed for the enlargement of dendritic spines is dependent on PKD activity. Consequently, impaired PKD functions attenuate activity-dependent changes in hippocampal dendritic spines, including LTP formation, cause morphological alterations in vivo, and have deleterious consequences on spatial memory formation. We thus provide compelling evidence that PKD controls synaptic plasticity and learning by regulating actin stability in dendritic spines.

scholarly journals NIK promotes metabolic adaptation of glioblastoma cells to bioenergetic stress

2021 ◽  
Vol 12 (3) ◽  
Author(s):  
Michael L. Kamradt ◽  
Ji-Ung Jung ◽  
Kathryn M. Pflug ◽  
Dong W. Lee ◽  
Victor Fanniel ◽  
...  
Keyword(s):  
Stress Responses ◽  
Glucose Deprivation ◽  
Metabolic Adaptation ◽  
Mitochondrial Morphology ◽  
Atp Production ◽  
Tumor Microenvironments ◽  
Iκb Kinase ◽  
Critical Measure

AbstractCancers, including glioblastoma multiforme (GBM), undergo coordinated reprogramming of metabolic pathways that control glycolysis and oxidative phosphorylation (OXPHOS) to promote tumor growth in diverse tumor microenvironments. Adaptation to limited nutrient availability in the microenvironment is associated with remodeling of mitochondrial morphology and bioenergetic capacity. We recently demonstrated that NF-κB-inducing kinase (NIK) regulates mitochondrial morphology to promote GBM cell invasion. Here, we show that NIK is recruited to the outer membrane of dividing mitochondria with the master fission regulator, Dynamin-related protein1 (DRP1). Moreover, glucose deprivation-mediated metabolic shift to OXPHOS increases fission and mitochondrial localization of both NIK and DRP1. NIK deficiency results in decreased mitochondrial respiration, ATP production, and spare respiratory capacity (SRC), a critical measure of mitochondrial fitness. Although IκB kinase α and β (IKKα/β) and NIK are required for OXPHOS in high glucose media, only NIK is required to increase SRC under glucose deprivation. Consistent with an IKK-independent role for NIK in regulating metabolism, we show that NIK phosphorylates DRP1-S616 in vitro and in vivo. Notably, a constitutively active DRP1-S616E mutant rescues oxidative metabolism, invasiveness, and tumorigenic potential in NIK−/− cells without inducing IKK. Thus, we establish that NIK is critical for bioenergetic stress responses to promote GBM cell pathogenesis independently of IKK. Our data suggest that targeting NIK may be used to exploit metabolic vulnerabilities and improve therapeutic strategies for GBM.

scholarly journals Simulated diabetic ketoacidosis therapy in vitro elicits brain cell swelling via sodium-hydrogen exchange and anion transport

2015 ◽  
Vol 309 (4) ◽  
pp. E370-E379 ◽  
Author(s):  
Keeley L. Rose ◽  
Andrew J. Watson ◽  
Thomas A. Drysdale ◽  
Gediminas Cepinskas ◽  
Melissa Chan ◽  
...  
Keyword(s):  
Diabetic Ketoacidosis ◽  
Hydrogen Exchange ◽  
Brain Slices ◽  
Anion Transport ◽  
Brain Cell ◽  
Cell Swelling ◽  
Sodium Hydrogen ◽  
Disulphonic Acid

A common complication of type 1 diabetes mellitus is diabetic ketoacidosis (DKA), a state of severe insulin deficiency. A potentially harmful consequence of DKA therapy in children is cerebral edema (DKA-CE); however, the mechanisms of therapy-induced DKA-CE are unknown. Our aims were to identify the DKA treatment factors and membrane mechanisms that might contribute specifically to brain cell swelling. To this end, DKA was induced in juvenile mice with the administration of the pancreatic toxins streptozocin and alloxan. Brain slices were prepared and exposed to DKA-like conditions in vitro. Cell volume changes were imaged in response to simulated DKA therapy. Our experiments showed that cell swelling was elicited with isolated DKA treatment components, including alkalinization, insulin/alkalinization, and rapid reductions in osmolality. Methyl-isobutyl-amiloride, a nonselective inhibitor of sodium-hydrogen exchangers (NHEs), reduced cell swelling in brain slices elicited with simulated DKA therapy (in vitro) and decreased brain water content in juvenile DKA mice administered insulin and rehydration therapy (in vivo). Specific pharmacological inhibition of the NHE1 isoform with cariporide also inhibited cell swelling, but only in the presence of the anion transport (AT) inhibitor 4,4′-diisothiocyanatostilbene-2,2′-disulphonic acid. DKA did not alter brain NHE1 isoform expression, suggesting that the cell swelling attributed to the NHE1 was activity dependent. In conclusion, our data raise the possibility that brain cell swelling can be elicited by DKA treatment factors and that it is mediated by NHEs and/or coactivation of NHE1 and AT.

Sign in / Sign up

Export Citation Format

Share Document