scholarly journals Extracellular Hsp90α Detoxifies β-Amyloid Fibrils Through an NRF2 and Autophagy Dependent Pathway

2021 ◽  
Author(s):  
Ayesha Murshid ◽  
Benjamin J Lang ◽  
Thiago J Borges ◽  
Yuka Okusha ◽  
Sachin P Doshi ◽  
...  
Keyword(s):  
Amyloid Fibrils ◽  
Heat Shock Protein 90 ◽  
Microglial Cells ◽  
Related Factor ◽  
Pathological Feature ◽  
Neurotoxic Effects ◽  
Β Amyloid ◽  
Dependent Pathway

We have investigated the role of extracellular Heat shock protein 90 alpha (eHsp90α) in conferring protection of neuronal cells against fibrillary amyloid-beta (f-Aβ1-42) toxicity mediated by microglial cells. The formation of f-Aβ1-42 plaques leads to neurotoxic inflammation, a critical pathological feature of Alzheimer's Disease. We observed increased uptake and clearance of internalized f-Aβ1-42 by microglial cells treated with eHsp90α, an effect associated with activation of NRF2 (NF-E2-related factor 2) - mediated autophagy. eHsp90α thus mitigated the neuronal toxicity of f-Aβ1-42-activated microglia. In addition, eHsp90α facilitated f-Aβ1-42 engulfment by microglial cells in vitro. In summary, eHsp90α triggers NRF2-mediated autophagy in microglia and thus protects against the neurotoxic effects of f-Aβ1-42.

Activation of bovine oocytes by protein synthesis inhibitors: new findings on the role of MPF/MAPKs†

2021 ◽  
Author(s):  
Cecilia Valencia ◽  
Felipe Alonso Pérez ◽  
Carola Matus ◽  
Ricardo Felmer ◽  
María Elena Arias
Keyword(s):  
Protein Synthesis ◽  
Kinase Activity ◽  
Cyclin B1 ◽  
Protein Synthesis Inhibitors ◽  
Vitro Fertilization ◽  
New Findings ◽  
Bovine Oocytes ◽  
Dependent Pathway

Abstract The present study evaluated the mechanism by which protein synthesis inhibitors activate bovine oocytes. The aim was to analyze the dynamics of MPF and MAPKs. MII oocytes were activated with ionomycin (Io), ionomycin+anisomycin (ANY) and ionomycin+cycloheximide (CHX) and by in vitro fertilization (IVF). The expression of cyclin B1, p-CDK1, p-ERK1/2, p-JNK, and p-P38 were evaluated by immunodetection and the kinase activity of ERK1/2 was measured by enzyme assay. Evaluations at 1, 4, and 15 hours postactivation (hpa) showed that the expression of cyclin B1 was not modified by the treatments. ANY inactivated MPF by p-CDK1Thr14-Tyr15 at 4 hpa (P < 0.05), CHX increased pre-MPF (p-CDK1Thr161 and p-CDK1Thr14-Tyr15) at 1 hpa and IVF increased p-CDK1Thr14-Tyr15 at 17 hours postfertilization (hpf) (P < 0.05). ANY and CHX reduced the levels of p-ERK1/2 at 4 hpa (P < 0.05) and its activity at 4 and 1 hpa, respectively (P < 0.05). Meanwhile, IVF increased p-ERK1/2 at 6 hpf (P < 0.05); however, its kinase activity decreased at 6 hpf (P < 0.05). p-JNK in ANY, CHX, and IVF oocytes decreased at 4 hpa (P < 0.05). p-P38 was only observed at 1 hpa, with no differences between treatments. In conclusion, activation of bovine oocytes by ANY, CHX, and IVF inactivates MPF by CDK1-dependent specific phosphorylation without cyclin B1 degradation. ANY or CHX promoted this inactivation, which seemed to be more delayed in the physiological activation (IVF). Both inhibitors modulated MPF activity via an ERK1/2-independent pathway, whereas IVF activated the bovine oocytes via an ERK1/2-dependent pathway. Finally, ANY does not activate the JNK and P38 kinase pathways.

scholarly journals Effect of memantine, an anti-Alzheimer’s drug, on rodent microglial cells in vitro

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Toru Murakawa-Hirachi ◽  
Yoshito Mizoguchi ◽  
Masahiro Ohgidani ◽  
Yoshinori Haraguchi ◽  
Akira Monji
Keyword(s):  
Neuronal Death ◽  
Phagocytic Activity ◽  
Microglial Cell ◽  
Cell Function ◽  
Microglial Cells ◽  
Phagocytosis Assay ◽  
Intracellular Ca ◽  
Β Amyloid ◽  
The Brain

AbstractThe pathophysiology of Alzheimer’s disease (AD) is related to neuroinflammatory responses mediated by microglia. Memantine, an antagonist of N-methyl-d-aspartate (NMDA) receptors used as an anti-Alzheimer’s drug, protects from neuronal death accompanied by suppression of proliferation and activation of microglial cells in animal models of AD. However, it remains to be tested whether memantine can directly affect microglial cell function. In this study, we examined whether pretreatment with memantine affects intracellular NO and Ca2+ mobilization using DAF-2 and Fura-2 imaging, respectively, and tested the effects of memantine on phagocytic activity by human β-Amyloid (1–42) phagocytosis assay in rodent microglial cells. Pretreatment with memantine did not affect production of NO or intracellular Ca2+ elevation induced by TNF in rodent microglial cells. Pretreatment with memantine also did not affect the mRNA expression of pro-inflammatory (TNF, IL-1β, IL-6 and CD45) or anti-inflammatory (IL-10, TGF-β and arginase) phenotypes in rodent microglial cells. In addition, pretreatment with memantine did not affect the amount of human β-Amyloid (1–42) phagocytosed by rodent microglial cells. Moreover, we observed that pretreatment with memantine did not affect 11 major proteins, which mainly function in the phagocytosis and degradation of β-Amyloid (1–42), including TREM2, DAP12 and neprilysin in rodent microglial cells. To the best of our knowledge, this is the first report to suggest that memantine does not directly modulate intracellular NO and Ca2+ mobilization or phagocytic activity in rodent microglial cells. Considering the neuroinflammation hypothesis of AD, the results might be important to understand the effect of memantine in the brain.

Role of iPLA2 and store-operated channels in agonist-induced Ca2+ influx and constriction in cerebral, mesenteric, and carotid arteries

2008 ◽  
Vol 294 (3) ◽  
pp. H1183-H1187 ◽  
Author(s):  
Kristen M. Park ◽  
Mario Trucillo ◽  
Nicolas Serban ◽  
Richard A. Cohen ◽  
Victoria M. Bolotina
Keyword(s):  
Carotid Arteries ◽  
Cerebral Arteries ◽  
Present Evidence ◽  
Voltage Gated ◽  
Functional Inhibition ◽  
Intracellular Ca ◽  
Dependent Pathway ◽  
Secondary Activation

Store-operated channels (SOC) and store-operated Ca2+ entry are known to play a major role in agonist-induced constriction of smooth muscle cells (SMC) in conduit vessels. In microvessels the role of SOC remains uncertain, in as much as voltage-gated L-type Ca2+ (CaL2+) channels are thought to be fully responsible for agonist-induced Ca2+ influx and vasoconstriction. We present evidence that SOC and their activation via a Ca2+-independent phospholipase A2 (iPLA2)-mediated pathway play a crucial role in agonist-induced constriction of cerebral, mesenteric, and carotid arteries. Intracellular Ca2+ in SMC and intraluminal diameter were measured simultaneously in intact pressurized vessels in vitro. We demonstrated that 1) Ca2+ and contractile responses to phenylephrine (PE) in cerebral and carotid arteries were equally abolished by nimodipine (a CaL2+ inhibitor) and 2-aminoethyl diphenylborinate (an inhibitor of SOC), suggesting that SOC and CaL2+ channels may be involved in agonist-induced constriction of cerebral arteries, and 2) functional inhibition of iPLA2β totally inhibited PE-induced Ca2+ influx and constriction in cerebral, mesenteric, and carotid arteries, whereas K+-induced Ca2+ influx and vasoconstriction mediated by CaL2+ channels were not affected. Thus iPLA2-dependent activation of SOC is crucial for agonist-induced Ca2+ influx and vasoconstriction in cerebral, mesenteric, and carotid arteries. We propose that, on PE-induced depletion of Ca2+ stores, nonselective SOC are activated via an iPLA2-dependent pathway and may produce a depolarization of SMC, which could trigger a secondary activation of CaL2+ channels and lead to Ca2+ entry and vasoconstriction.

The Role of Calcium and Magnesium Ions in Uptake of β-Amyloid Peptides by Microglial Cells

2006 ◽  
Vol 19 (3) ◽  
pp. 683-696 ◽  
Author(s):  
N. Choucair ◽  
V. Laporte ◽  
R. Levy ◽  
C. Tranchant ◽  
J.-P. Gies ◽  
...  
Keyword(s):  
Microglial Cells ◽  
Magnesium Ions ◽  
Amyloid Peptides ◽  
Β Amyloid ◽  
Calcium And Magnesium ◽  
Calcium And Magnesium Ions

ROLE OF PAF AND OXIDANT AGENTS ON VASCULAR CELL PROLIFERATION. IN VITRO IMPLICATION OF MTOR-DEPENDENT PATHWAY.

2004 ◽  
Vol 78 ◽  
pp. 741-742
Author(s):  
I Rama ◽  
M Riera ◽  
J Torras ◽  
J M Cruzado ◽  
I Herrero-Fresneda ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Vascular Cell ◽  
Proliferation In Vitro ◽  
Dependent Pathway

scholarly journals Purinergic Modulation of Interleukin-1β Release from Microglial Cells Stimulated with Bacterial Endotoxin

1997 ◽  
Vol 185 (3) ◽  
pp. 579-582 ◽  
Author(s):  
Davide Ferrari ◽  
Paola Chiozzi ◽  
Simonetta Falzoni ◽  
Stefania Hanau ◽  
Francesco Di  Virgilio
Keyword(s):  
Plasma Membrane ◽  
P2x7 Receptor ◽  
Purinergic Receptor ◽  
Present Report ◽  
Physiological Role ◽  
Bacterial Endotoxin ◽  
Microglial Cells

Microglial cells express a peculiar plasma membrane receptor for extracellular ATP, named P2Z/P2X7 purinergic receptor, that triggers massive transmembrane ion fluxes and a reversible permeabilization of the plasma membrane to hydrophylic molecules of up to 900 dalton molecule weight and eventual cell death (Di Virgilio, F. 1995. Immunol. Today. 16:524–528). The physiological role of this newly cloned (Surprenant, A., F. Rassendren, E. Kawashima, R.A. North and G. Buell. 1996. Science (Wash. DC). 272:735–737) cytolytic receptor is unknown. In vitro and in vivo activation of the macrophage and microglial cell P2Z/P2X7 receptor by exogenous ATP causes a large and rapid release of mature IL-1β. In the present report we investigated the role of microglial P2Z/P2X7 receptor in IL-1β release triggered by LPS. Our data suggest that LPS-dependent IL-1β release involves activation of this purinergic receptor as it is inhibited by the selective P2Z/P2X7 blocker oxidized ATP and modulated by ATP-hydrolyzing enzymes such as apyrase or hexokinase. Furthermore, microglial cells release ATP when stimulated with LPS. LPS-dependent release of ATP is also observed in monocyte-derived human macrophages. It is suggested that bacterial endotoxin activates an autocrine/paracrine loop that drives ATP-dependent IL-1β secretion.

scholarly journals BAG3 contributes to HGF-mediated cell proliferation, migration, and invasion via the Egr1 pathway in gastric cancer

2018 ◽  
Vol 105 (1) ◽  
pp. 63-75
Author(s):  
Jae Chang Lee ◽  
Sung Ae Koh ◽  
Kyung Hee Lee ◽  
Jae-Ryong Kim
Keyword(s):  
Gastric Cancer ◽  
Cell Proliferation ◽  
Cell Invasion ◽  
Molecular Mechanisms ◽  
Migration And Invasion ◽  
Human Gastric Cancer ◽  
Protein Levels ◽  
Dependent Pathway

Introduction: Bcl2-associated athanogene 3 (BAG3) is elevated in several types of cancers. However, the role of BAG3 in progression of gastric cancer is unknown. Therefore, the present study aims to find out the role of BAG3 in hepatocyte growth factor (HGF)–mediated tumor progression and the molecular mechanisms by which HGF regulates BAG3 expression. Methods: BAG3 mRNA and protein were measured using reverse transcription polymerase chain reaction and Western blot in the 2 human gastric cancer cell lines, NUGC3 and MKN28, treated with or without HGF. The effects of BAG3 knockdown on cell proliferation, cell invasion, and apoptosis were analyzed by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, the in vitro 2-chamber invasion assay, and flow cytometry in BAG3 short hairpin RNA (shRNA)–transfected cells and control cells. The signaling pathways involved in BAG3 that are regulated by HGF were analyzed. The chromatin immunoprecipitation assay was used to determine binding of Egr1 to the BAG3 promoter. Results: BAG3 mRNA and protein levels were increased following treatment with HGF. HGF-mediated BAG3 upregulation increased cell proliferation and cell invasion; however, it decreased apoptosis. HGF-mediated BAG3 upregulation is regulated by an ERK and Egr1-dependent pathway. BAG3 may have an important role in HGF-mediated cell proliferation and metastasis in gastric cancer through an ERK and Egr1-dependent pathway. Conclusion: This pathway may provide novel therapeutic targets and provide information for further identification of other targets of therapeutic significance in gastric cancer.

Inhibitory activity of stilbenes on Alzheimer’s β-amyloid fibrils in vitro

2007 ◽  
Vol 15 (2) ◽  
pp. 1160-1167 ◽  
Author(s):  
Céline Rivière ◽  
Tristan Richard ◽  
Lysiane Quentin ◽  
Stéphanie Krisa ◽  
Jean-Michel Mérillon ◽  
...  
Keyword(s):  
Inhibitory Activity ◽  
Amyloid Fibrils ◽  
Β Amyloid

Nicotine breaks down preformed Alzheimer’s β-amyloid fibrils in vitro

2002 ◽  
Vol 52 (9) ◽  
pp. 880-886 ◽  
Author(s):  
Kenjiro Ono ◽  
Kazuhiro Hasegawa ◽  
Masahito Yamada ◽  
Hironobu Naiki
Keyword(s):  
Amyloid Fibrils ◽  
Β Amyloid

scholarly journals SHP-2 phosphatase is required for hematopoietic cell transformation by Bcr-Abl

Blood ◽  
2006 ◽  
Vol 109 (2) ◽  
pp. 778-785 ◽  
Author(s):  
Jing Chen ◽  
Wen-Mei Yu ◽  
Hanako Daino ◽  
Hal E. Broxmeyer ◽  
Brian J. Druker ◽  
...  
Keyword(s):  
Cell Transformation ◽  
Biological Effects ◽  
Present Report ◽  
Proteasome Inhibitors ◽  
Heat Shock Protein 90 ◽  
Hematopoietic Cell ◽  
Serum Starvation ◽  
Oncogenic Signaling

Abstract SHP-2 phosphatase forms a stable protein complex with and is heavily tyrosine-phosphorylated by the oncogenic tyrosine kinase Bcr-Abl. However, the role of SHP-2 in Bcr-Abl–mediated leukemogenesis is unclear. In the present report, we provide evidence that SHP-2 is required for hematopoietic cell transformation by Bcr-Abl. In vitro biological effects of Bcr-Abl transduction were diminished in SHP-2Δ/Δ hematopoietic cells, and the leukemic potential of Bcr-Abl–transduced SHP-2Δ/Δ cells in recipient animals was compromised. Further analyses showed that Bcr-Abl protein (p210) was degraded, and its oncogenic signaling was greatly decreased in SHP-2Δ/Δ cells. Treatment with proteasome inhibitors or reintroduction of SHP-2 restored p210 level in Bcr-Abl–transduced SHP-2Δ/Δ cells. Subsequent investigation revealed that SHP-2 interacted with heat shock protein 90, an important chaperone protein protecting p210 from proteasome-mediated degradation. The role of SHP-2 in the stability of p210 is independent of its catalytic activity. Blockade of SHP-2 expression in p210-expressing cells by antisense or small-interfering RNA approaches decreased p210 level, causing cell death. Inhibition of SHP-2 enzymatic activity by overexpression of catalytically inactive SHP-2 mutant did not destabilize p210 but enhanced serum starvation-induced apoptosis, suggesting that SHP-2 also plays an important role in downstream signaling of p210 kinase. These studies identified a novel function of SHP-2 and suggest that SHP-2 might be a useful target for controlling Bcr-Abl–positive leukemias.

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