scholarly journals ERK1/2-p90RSK-mediated Phosphorylation of Na+/H+ Exchanger Isoform 1

2007 ◽  
Vol 282 (38) ◽  
pp. 28274-28284 ◽  
Author(s):  
Jing Luo ◽  
Douglas B. Kintner ◽  
Gary E. Shull ◽  
Dandan Sun
Keyword(s):  
Nuclear Translocation ◽  
Neuronal Damage ◽  
Glucose Deprivation ◽  
Mek Inhibitor ◽  
Oxygen And Glucose Deprivation ◽  
Genetic Ablation ◽  
Extracellular Signal ◽  
Nhe1 Activity ◽  
Ribosomal S6 Kinase

The function and regulation of Na+/H+ exchanger isoform 1 (NHE1) following cerebral ischemia are not well understood. In this study, we demonstrate that extracellular signal-related kinases (ERK1/2) play a role in stimulation of neuronal NHE1 following in vitro ischemia. NHE1 activity was significantly increased during 10-60 min reoxygenation (REOX) after 2-h oxygen and glucose deprivation (OGD). OGD/REOX not only increased the Vmax for NHE1 but also shifted the Km toward decreased [H+]i. These changes in NHE1 kinetics were absent when MAPK/ERK kinase (MEK) was inhibited by the MEK inhibitor U0126. There were no changes in the levels of phosphorylated ERK1/2 (p-ERK1/2) after 2 h OGD. The p-ERK1/2 level was significantly increased during 10-60 min REOX, which was accompanied by nuclear translocation. U0126 abolished REOX-induced elevation and translocation of p-ERK1/2. We further examined the ERK/90-kDa ribosomal S6 kinase (p90RSK) signaling pathways. At 10 min REOX, phosphorylated NHE1 was increased with a concurrent elevation of phosphorylation of p90RSK, a known NHE1 kinase. Inhibition of MEK activity with U0126 abolished phosphorylation of both NHE1 and p90RSK. Moreover, neuroprotection was observed with U0126 or genetic ablation or pharmacological inhibition of NHE1 following OGD/REOX. Taken together, these results suggest that activation of ERK1/2-p90RSK pathways following in vitro ischemia phosphorylates NHE1 and increases its activity, which subsequently contributes to neuronal damage.

Increased tolerance to oxygen and glucose deprivation in astrocytes from Na+/H+ exchanger isoform 1 null mice

2004 ◽  
Vol 287 (1) ◽  
pp. C12-C21 ◽  
Author(s):  
Douglas B. Kintner ◽  
Gui Su ◽  
Brett Lenart ◽  
Andy J. Ballard ◽  
Jamie W. Meyer ◽  
...  
Keyword(s):  
Regulatory Mechanism ◽  
Ischemic Injury ◽  
Glucose Deprivation ◽  
Cell Types ◽  
Oxygen And Glucose Deprivation ◽  
Genetic Ablation ◽  
Cortical Astrocyte ◽  
Nhe1 Activity ◽  
Acid Load

The ubiquitously expressed Na+/H+ exchanger isoform 1 (NHE1) functions as a major intracellular pH (pHi) regulatory mechanism in many cell types, and in some tissues its activity may contribute to ischemic injury. In the present study, cortical astrocyte cultures from wild-type (NHE1+/+) and NHE1-deficient (NHE1−/−) mice were used to investigate the role of NHE1 in pHi recovery and ischemic injury in astrocytes. In the absence of HCO3−, the mean resting pHi levels were 6.86 ± 0.03 in NHE1+/+ astrocytes and 6.53 ± 0.04 in NHE1−/− astrocytes. Removal of extracellular Na+ or blocking of NHE1 activity by the potent NHE1 inhibitor HOE-642 significantly reduced the resting level of pHi in NHE1+/+ astrocytes. NHE1+/+ astrocytes exhibited a rapid pHi recovery (0.33 ± 0.08 pH unit/min) after NH4Cl prepulse acid load. The pHi recovery in NHE1+/+ astrocytes was reversibly inhibited by HOE-642 or removal of extracellular Na+. In NHE1−/− astrocytes, the pHi recovery after acidification was impaired and not affected by either Na+-free conditions or HOE-642. Furthermore, 2 h of oxygen and glucose deprivation (OGD) led to an ∼80% increase in pHi recovery rate in NHE1+/+ astrocytes. OGD induced a 5-fold rise in intracellular [Na+] and 26% swelling in NHE1+/+ astrocytes. HOE-642 or genetic ablation of NHE1 significantly reduced the Na+ rise and swelling after OGD. These results suggest that NHE1 is the major pHi regulatory mechanism in cortical astrocytes and that ablation of NHE1 in astrocytes attenuates ischemia-induced disruption of ionic regulation and swelling.

scholarly journals Stimulation of astrocyte Na+/H+ exchange activity in response to in vitro ischemia depends in part on activation of ERK1/2

2005 ◽  
Vol 289 (4) ◽  
pp. C934-C945 ◽  
Author(s):  
Douglas B. Kintner ◽  
Andy Look ◽  
Gary E. Shull ◽  
Dandan Sun
Keyword(s):  
Glucose Deprivation ◽  
Oxygen And Glucose Deprivation ◽  
In Vitro Ischemia ◽  
Reverse Mode ◽  
Intracellular Ca ◽  
Nhe1 Activity ◽  
Underlying Mechanisms ◽  
Stimulation Of

We recently reported that Na+/H+ exchanger isoform 1 (NHE1) activity in astrocytes is stimulated and leads to intracellular Na+ loading after oxygen and glucose deprivation (OGD). However, the underlying mechanisms for this stimulation of NHE1 activity and its impact on astrocyte function are unknown. In the present study, we investigated the role of the ERK1/2 pathway in NHE1 activation. NHE1 activity was elevated by ∼75% in NHE1+/+ astrocytes after 2-h OGD and 1-h reoxygenation (REOX). The OGD/REOX-mediated stimulation of NHE1 was partially blocked by 30 μM PD-98059. Increased expression of phosphorylated ERK1/2 was detected in NHE1+/+ astrocytes after OGD/REOX. Moreover, stimulation of NHE1 activity disrupted not only Na+ but also Ca2+ homeostasis via reverse-mode operation of Na+/Ca2+ exchange. OGD/REOX led to a 103% increase in intracellular Ca2+ concentration ([Ca2+]i) in NHE1+/+ astrocytes in the presence of thapsigargin. Inhibition of NHE1 activity with the NHE1 inhibitor HOE-642 decreased OGD/REOX-induced elevation of [Ca2+]i by 73%. To further investigate changes of Ca2+ signaling, bradykinin-mediated Ca2+ release was evaluated. Bradykinin-mediated intracellular Ca2+ transient in NHE1+/+ astrocytes was increased by ∼84% after OGD/REOX. However, in NHE1−/− astrocytes or NHE1+/+ astrocytes treated with HOE-642, the bradykinin-induced Ca2+ release was increased by only ∼34%. Inhibition of the reverse mode of Na+/Ca2+ exchange abolished OGD/REOX-mediated Ca2+ rise. Together, our data suggest that ERK1/2 is involved in activation of NHE1 in astrocytes after in vitro ischemia. NHE1-mediated Na+ accumulation subsequently alters Ca2+ homeostasis via Na+/Ca2+ exchange.

scholarly journals Urea activates ribosomal S6 kinase (RSK) in a MEK-dependent fashion in renal mIMCD3 cells

1998 ◽  
Vol 274 (1) ◽  
pp. F73-F78 ◽  
Author(s):  
Zheng Zhang ◽  
David M. Cohen
Keyword(s):  
Nuclear Translocation ◽  
Collecting Duct ◽  
Renal Medulla ◽  
Mek Inhibitor ◽  
Mitogen Activated Protein Kinase ◽  
S6 Kinase ◽  
Erk Activation ◽  
Extracellular Signal ◽  
Mitogen Activated Protein ◽  
Ribosomal S6 Kinase

Urea activates a characteristic subset of signaling pathways in a tissue-specific fashion, including transcription of immediate early genes through activation of the mitogen-activated protein kinase (MAPK), ERK (extracellular signal-regulated kinase), and activation of its transcription factor substrate, Elk-1. The ability of urea to activate the ERK effector and pivotal regulatory kinase, ribosomal S6 kinase (RSK), was investigated in mIMCD3 renal inner medullary collecting duct cells. Urea upregulated RSK activity in a time-dependent fashion in serum-deprived mIMCD3 cells; the effect was maximal at 5 min. Activation by hypertonic NaCl, in contrast, was negligible at 5 min and peaked at 15 min. Both stimuli induced the nuclear translocation of cytosolic RSK, as determined via immunofluorescence. Importantly, activation of RSK by both solutes was MAPK/ERK kinase (MEK) dependent, as determined by the ability of the specific MEK inhibitor, PD-98059, to abrogate the response. Taken together, these data indicate that urea activates the ERK effector, RSK, in cells of the renal medulla in an ERK-dependent fashion, further emphasizing the functional significance of urea signaling through ERK activation in renal medullary cells.

scholarly journals Matrix Metalloproteinase-13 is Activated and is found in the Nucleus of Neural Cells after Cerebral Ischemia

2008 ◽  
Vol 29 (2) ◽  
pp. 398-410 ◽  
Author(s):  
Eloy Cuadrado ◽  
Anna Rosell ◽  
Maria Borrell-Pagès ◽  
Lidia García-Bonilla ◽  
Mar Hernández-Guillamon ◽  
...  
Keyword(s):  
Cerebral Ischemia ◽  
Time Course ◽  
Nuclear Translocation ◽  
Glucose Deprivation ◽  
Neural Cells ◽  
Primary Neuronal Culture ◽  
Oxygen And Glucose Deprivation ◽  
Matrix Metalloproteinase 13 ◽  
Nuclear Extracts

Matrix metalloproteinases (MMPs) have been implicated in the pathophysiology of ischemic stroke. In this study, we investigated the time course of gelatinolytic activation in a rat model of permanent ischemia. We observed an activation of MMPs as early as 30 mins after the ischemic insult, mainly in the nuclei of brain cells. Besides, we explored MMP-13 expression in brain samples of the animal model and stroke deceased patients. We observed an upregulation of active MMP-13 in rat brains ( P< 0.05) after 90 mins of cerebral ischemia. Human infarct/periinfarct samples also showed higher levels of active MMP-13 ( P< 0.05) compared with contralateral ones. Interestingly, we found that MMP-13 colocalized with 46-diamidino-2-phenyl indole signal by immunohistochemistry in both humans and rats, suggesting an intranuclear localization for MMP-13. Immunohistochemistry also revealed that MMP-13 was mainly produced by neurons, in both species, but also by oligodendrocytes in rats, and by astrocytes in humans. Finally we subjected a rat primary neuronal culture to oxygen and glucose deprivation (OGD) and we reproduced the nuclear translocation of MMP-13 in vitro. Nuclear extracts from cells confirmed upregulation of active MMP-13 after OGD ( P< 0.05). These results suggest that MMP-13 activation and its nuclear translocation is an early consequence of an ischemic stimulus.

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 ERK signaling mediates resistance to immunomodulatory drugs in the bone marrow microenvironment

2021 ◽  
Vol 7 (23) ◽  
pp. eabg2697
Author(s):  
Jiye Liu ◽  
Teru Hideshima ◽  
Lijie Xing ◽  
Su Wang ◽  
Wenrong Zhou ◽  
...  
Keyword(s):  
Patient Outcome ◽  
Bone Marrow ◽  
Nuclear Factor Κb ◽  
Mek Inhibitor ◽  
Erk Signaling ◽  
Immunomodulatory Drugs ◽  
Pathway Activation ◽  
Extracellular Signal

Immunomodulatory drugs (IMiDs) have markedly improved patient outcome in multiple myeloma (MM); however, resistance to IMiDs commonly underlies relapse of disease. Here, we identify that tumor necrosis factor (TNF) receptor-associated factor 2 (TRAF2) knockdown (KD)/knockout (KO) in MM cells mediates IMiD resistance via activation of noncanonical nuclear factor κB (NF-κB) and extracellular signal–regulated kinase (ERK) signaling. Within MM bone marrow (BM) stromal cell supernatants, TNF-α induces proteasomal degradation of TRAF2, noncanonical NF-κB, and downstream ERK signaling in MM cells, whereas interleukin-6 directly triggers ERK activation. RNA sequencing of MM patient samples shows nearly universal ERK pathway activation at relapse on lenalidomide maintenance therapy, confirming its clinical relevance. Combination MEK inhibitor treatment restores IMiD sensitivity of TRAF2 KO cells both in vitro and in vivo. Our studies provide the framework for clinical trials of MEK inhibitors to overcome IMiD resistance in the BM microenvironment and improve patient outcome in MM.

Fibronectin maintains survival of mouse natural killer (NK) cells via CD11b/Src/β-catenin pathway

Blood ◽  
2009 ◽  
Vol 114 (19) ◽  
pp. 4081-4088 ◽  
Author(s):  
Ting Zhang ◽  
Shuxun Liu ◽  
Pengyuan Yang ◽  
Chaofeng Han ◽  
Jianli Wang ◽  
...  
Keyword(s):  
Nk Cells ◽  
Natural Killer ◽  
Nuclear Translocation ◽  
Nk Cell ◽  
Ex Vivo ◽  
Interleukin 12 ◽  
Erk Phosphorylation ◽  
Extracellular Signal ◽  
B Cell Leukemia

Abstract Tissue microenvironment and stroma-derived extracellular matrix (ECM) molecules play important roles in the survival and differentiation of cells. Mouse natural killer (NK) cells usually die within 24 hours once isolated ex vivo. Exogenous cytokines such as interleukin-12 (IL-12) and IL-15 are required to maintain the survival and activity of mouse NK cells cultured in vitro. Whether and how ECM molecules such as fibronectin can support the survival of NK cells remain unknown. We demonstrate that fibronectin, just like IL-15, can maintain survival of mouse NK cells in vitro. Furthermore, we show that fibronectin binds to the CD11b on NK cells, and then CD11b recruits and activates Src. Src can directly interact with β-catenin and trigger nuclear translocation of β-catenin. The activation of β-catenin promotes extracellular signal-related kinase (ERK) phosphorylation, resulting in the increased expression of antiapoptotic protein B-cell leukemia 2 (Bcl-2), which may contribute to the maintenance of NK-cell survival. Consistently, fibronectin cannot maintain the survival of CD11b− NK cells and β-catenin–deficient NK cells in vitro, and the number of NK cells is dramatically decreased in the β-catenin–deficient mice. Therefore, fibronectin can maintain survival of mouse NK cells by activating ERK and up-regulating Bcl-2 expression via CD11b/Src/β-catenin pathway.

Artemisinin improves neurocognitive deficits associated with sepsis by activating the AMPK axis in the microglia.

2020 ◽  
Author(s):  
Shao-Peng Lin ◽  
Jue-Xian Wei ◽  
Shan Ye ◽  
Jiasong Hu ◽  
Jingyi Bu ◽  
...  
Keyword(s):  
Cognitive Impairment ◽  
Inflammatory Cytokines ◽  
Nuclear Translocation ◽  
Neuronal Damage ◽  
Protective Mechanism ◽  
Protective Effects ◽  
Neurocognitive Deficits ◽  
Anti Inflammatory ◽  
Pro Inflammatory Cytokines

Abstract Background and purpose: Artemisinin has been in use as an anti-malarial drug for almost half a century in the world. There is growing evidence that artemisinin also possesses potent anti-inflammatory and immunoregulatory properties. However, the efficacy of artemisinin treatment in neurocognitive deficits associated with sepsis remains unknown. Here, we evaluate the possible protective effects and explore the underlying mechanism of artemisinin on cognitive impairment resulting from sepsis.Methods: Male C57BL/6 mice were pretreated with either vehicle or artemisinin, and then injected with LPS to establish an animal model of sepsis. The cognitive function was then assessed using the Morris water maze. Neuronal damage and neuroinflammation in the hippocampus were evaluated by immunohistochemical and ELISA analysis. Additionally, the protective mechanism of artemisinin was determined in vitro.Results: The results showed that artemisinin preconditioning attenuated LPS-induced cognitive impairment, neural damage, and microglial activation in the mouse brain. The in vitro experiment revealed that artemisinin could reduce the production of pro-inflammatory cytokines and suppress the microglial migration in the BV2 microglia cells. Meanwhile, western blot demonstrated that artemisinin suppressed nuclear translocation of nuclear factor kappa-B and the expression of pro-inflammatory cytokines (i.e. tumor necrosis factor alpha, interleukin-6) by activating adenosine monophosphate-activated protein kinaseα1 (AMPKα1) pathway. Furthermore, knock-down of AMPKα1 markedly abolished the anti-inflammatory effects of artemisinin.Conclusion: Artemisinin is a potential therapeutic agent for sepsis-associated neuroinflammation and cognitive impairment, and its effect was probably mediated by the activation of AMPKα1 signalling pathway in microglia.

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