scholarly journals Endosomal Acidification by NHE6-depletion Corrects ApoE4-mediated Synaptic Impairments and Reduces Amyloid Plaque Load

2021 ◽  
Author(s):  
Theresa Pohlkamp ◽  
Xunde Xian ◽  
Connie H Wong ◽  
Murat Durakoglugil ◽  
Takaomi Saido ◽  
...  
Keyword(s):  
Late Onset ◽  
Amyloid Plaque ◽  
Plaque Formation ◽  
Vesicular Trafficking ◽  
Synaptic Homeostasis ◽  
Sodium Hydrogen ◽  
Activated State ◽  
Endosomal Acidification ◽  
Sodium Hydrogen Exchanger ◽  
Plaque Load

ABSTRACTApolipoprotein E4 (ApoE4) is the most important and prevalent risk factor for late-onset Alzheimer’s disease (AD). The isoelectric point of ApoE4 matches the pH of the early endosome (EE), causing its delayed dissociation from ApoE receptors and hence impaired endolysosomal trafficking, disruption of synaptic homeostasis and reduced amyloid clearance. We have shown that enhancing endosomal acidification by inhibiting the EE-specific sodium-hydrogen exchanger NHE6 restores vesicular trafficking and normalizes synaptic homeostasis. Using NHE6 conditional KO mice we now also show that disruption of NHE6 activates the resident microglia and thus reduces early and advanced amyloid plaque formation in humanized APPNL-F knockin mice in the presence or absence of ApoE4 by approximately 80%. These findings suggest a novel therapeutic approach for the prevention of AD by which partial NHE6 inhibition reverses the ApoE4 induced endolysosomal trafficking defect, while at the same time shifting the resident microglia from the dormant, homeostatic to the damage-associated, activated state.

scholarly journals NHE6-depletion corrects ApoE4-mediated synaptic impairments and reduces amyloid plaque load

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Theresa Pohlkamp ◽  
Xunde Xian ◽  
Connie H Wong ◽  
Murat S Durakoglugil ◽  
Gordon Chandler Werthmann ◽  
...  
Keyword(s):  
Late Onset ◽  
Amyloid Plaque ◽  
Vesicular Trafficking ◽  
Synaptic Homeostasis ◽  
Sodium Hydrogen ◽  
Early Endosomes ◽  
Endosomal Acidification ◽  
Sodium Hydrogen Exchanger ◽  
Plaque Load ◽  
The Brain

Apolipoprotein E4 (ApoE4) is the most important and prevalent risk factor for late-onset Alzheimer's disease (AD). The isoelectric point of ApoE4 matches the pH of the early endosome (EE), causing its delayed dissociation from ApoE receptors and hence impaired endolysosomal trafficking, disruption of synaptic homeostasis and reduced amyloid clearance. We have shown that enhancing endosomal acidification by inhibiting the EE-specific sodium-hydrogen exchanger 6 (NHE6) restores vesicular trafficking and normalizes synaptic homeostasis. Remarkably and unexpectedly, loss of NHE6 (encoded by the gene Slc9a6) in mice effectively suppressed amyloid deposition even in the absence of ApoE4, suggesting that accelerated acidification of early endosomes caused by the absence of NHE6 occludes the effect of ApoE on amyloid plaque formation. NHE6 suppression or inhibition may thus be a universal, ApoE-independent approach to prevent amyloid buildup in the brain. These findings suggest a novel therapeutic approach for the prevention of AD by which partial NHE6 inhibition reverses the ApoE4 induced endolysosomal trafficking defect and reduces plaque load.

scholarly journals Bacterial sepsis increases hippocampal fibrillar amyloid plaque load and neuroinflammation in a mouse model of Alzheimer's disease

2021 ◽  
Vol 152 ◽  
pp. 105292
Author(s):  
Jacob M. Basak ◽  
Aura Ferreiro ◽  
Lucy S. Cohen ◽  
Patrick W. Sheehan ◽  
Collin J. Nadarajah ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Mouse Model ◽  
Amyloid Plaque ◽  
Bacterial Sepsis ◽  
Model Of Alzheimer’S Disease ◽  
Plaque Load

scholarly journals Screening of 5- and 6-Substituted Amiloride Libraries Identifies Dual-uPA/NHE1 Active and Single Target-Selective Inhibitors

2021 ◽  
Vol 22 (6) ◽  
pp. 2999
Author(s):  
Benjamin J. Buckley ◽  
Ashna Kumar ◽  
Ashraf Aboelela ◽  
Richard S. Bujaroski ◽  
Xiuju Li ◽  
...  
Keyword(s):  
Selectivity Ratio ◽  
Dual Targeting ◽  
Sodium Hydrogen ◽  
Type Plasminogen Activator ◽  
Single Target ◽  
Urokinase Type Plasminogen Activator ◽  
Anti Cancer ◽  
Sodium Hydrogen Exchanger ◽  
A Cell ◽  
Cell Invasiveness

The K+-sparing diuretic amiloride shows off-target anti-cancer effects in multiple rodent models. These effects arise from the inhibition of two distinct cancer targets: the trypsin-like serine protease urokinase-type plasminogen activator (uPA), a cell-surface mediator of matrix degradation and tumor cell invasiveness, and the sodium-hydrogen exchanger isoform-1 (NHE1), a central regulator of transmembrane pH that supports carcinogenic progression. In this study, we co‑screened our library of 5- and 6-substituted amilorides against these two targets, aiming to identify single-target selective and dual-targeting inhibitors for use as complementary pharmacological probes. Closely related analogs substituted at the 6-position with pyrimidines were identified as dual-targeting (pyrimidine 24 uPA IC50 = 175 nM, NHE1 IC50 = 266 nM, uPA selectivity ratio = 1.5) and uPA-selective (methoxypyrimidine 26 uPA IC50 = 86 nM, NHE1 IC50 = 12,290 nM, uPA selectivity ratio = 143) inhibitors, while high NHE1 potency and selectivity was seen with 5-morpholino (29 NHE1 IC50 = 129 nM, uPA IC50 = 10,949 nM; NHE1 selectivity ratio = 85) and 5-(1,4-oxazepine) (30 NHE1 IC50 = 85 nM, uPA IC50 = 5,715 nM; NHE1 selectivity ratio = 67) analogs. Together, these amilorides comprise a new toolkit of chemotype-matched, non-cytotoxic probes for dissecting the pharmacological effects of selective uPA and NHE1 inhibition versus dual-uPA/NHE1 inhibition.

scholarly journals Phosphoproteomic Analysis of Two Contrasting Maize Inbred Lines Provides Insights into the Mechanism of Salt-Stress Tolerance

2019 ◽  
Vol 20 (8) ◽  
pp. 1886 ◽  
Author(s):  
Xiaoyun Zhao ◽  
Xue Bai ◽  
Caifu Jiang ◽  
Zhen Li
Keyword(s):  
Salt Stress ◽  
Inbred Line ◽  
Carbon Metabolism ◽  
Phosphoenolpyruvate Carboxykinase ◽  
Glutathione Metabolism ◽  
Label Free ◽  
Plasma Membrane Intrinsic Protein ◽  
Sodium Hydrogen ◽  
Salt Response ◽  
Sodium Hydrogen Exchanger

Salinity is a major abiotic stress that limits maize yield and quality throughout the world. We investigated phosphoproteomics differences between a salt-tolerant inbred line (Zheng58) and a salt-sensitive inbred line (Chang7-2) in response to short-term salt stress using label-free quantitation. A total of 9448 unique phosphorylation sites from 4116 phosphoproteins in roots and shoots of Zheng58 and Chang7-2 were identified. A total of 209 and 243 differentially regulated phosphoproteins (DRPPs) in response to NaCl treatment were detected in roots and shoots, respectively. Functional analysis of these DRPPs showed that they were involved in carbon metabolism, glutathione metabolism, transport, and signal transduction. Among these phosphoproteins, the expression of 6-phosphogluconate dehydrogenase 2, pyruvate dehydrogenase, phosphoenolpyruvate carboxykinase, glutamate decarboxylase, glutamate synthase, l-gulonolactone oxidase-like, potassium channel AKT1, high-affinity potassium transporter, sodium/hydrogen exchanger, and calcium/proton exchanger CAX1-like protein were significantly regulated in roots, while phosphoenolpyruvate carboxylase 1, phosphoenolpyruvate carboxykinase, sodium/hydrogen exchanger, plasma membrane intrinsic protein 2, glutathione transferases, and abscisic acid-insensitive 5-like protein were significantly regulated in shoots. Zheng58 may activate carbon metabolism, glutathione and ascorbic acid metabolism, potassium and sodium transportation, and the accumulation of glutamate to enhance its salt tolerance. Our results help to elucidate the mechanisms of salt response in maize seedlings. They also provide a basis for further study of the mechanism underlying salt response and tolerance in maize and other crops.

scholarly journals Mineralocorticoid Action and Sodium-Hydrogen Exchange: Studies in Experimental Cardiac Fibrosis

Endocrinology ◽  
2003 ◽  
Vol 144 (9) ◽  
pp. 3848-3851 ◽  
Author(s):  
Morag Young ◽  
John Funder
Keyword(s):  
Smooth Muscle ◽  
Vascular Smooth Muscle ◽  
Hydrogen Exchange ◽  
Cardiac Fibrosis ◽  
Inflammatory Cell ◽  
Mineralocorticoid Receptor Antagonist ◽  
Sodium Hydrogen ◽  
Sodium Hydrogen Exchanger ◽  
Coronary Vasculitis ◽  
Potassium Canrenoate

Abstract There is increasing evidence that the trigger for cardiac fibrosis in response to mineralocorticoid/salt administration is coronary vasculitis and that effects can be seen within days of deoxycorticosterone acetate (DOCA) administration. Furthermore, rapid, nongenomic mineralocorticoid effects on the sodium-hydrogen exchanger (NHE-1) in vascular smooth muscle cells have recently been described. That this mechanism may act as an inflammatory or profibrotic signal was tested by comparing the specific NHE-1 antagonist cariporide and the mineralocorticoid receptor antagonist K canrenoate in the rat model of mineralocorticoid/salt perivascular fibrosis over 8 d of DOCA/salt administration. Interstitial collagen, inflammatory cell infiltration, and inflammatory markers were determined. DOCA elevated blood pressure above control, cariporide +DOCA, or K canrenoate +DOCA rats, without cardiac hypertrophy. At 8 d interstitial collagen was significantly elevated in the DOCA-alone group, with levels in cariporide- and K canrenoate-treated rats not different from control. Expression of osteopontin, cyclooxygenase-2, and ED-1 were elevated by DOCA treatment, blocked by potassium canrenoate, and (for ED-1 and osteopontin) partially reduced by cariporide. These results suggest mineralocorticoid/salt-induced cardiac fibrosis may involve coronary vascular smooth muscle cell NHE-1 activity as a possible contributor to the cascade of transcriptional events that produce the characteristic coronary vasculitis seen with excess mineralocorticoid and salt.

scholarly journals Ube3a deficiency inhibits amyloid plaque formation in APPswe/PS1δE9 mouse model of Alzheimer’s disease

2017 ◽  
Vol 26 (20) ◽  
pp. 4042-4054 ◽  
Author(s):  
Brijesh Kumar Singh ◽  
Naman Vatsa ◽  
Vipendra Kumar ◽  
Shashi Shekhar ◽  
Ankit Sharma ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Mouse Model ◽  
Amyloid Plaque ◽  
Plaque Formation ◽  
Model Of Alzheimer’S Disease
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