Control of β-Site Amyloid Precursor Protein-Cleaving Enzyme-1 Expression by Protein Kinase C-λ/ι and Nuclear Factor κ-B

2021 ◽  
Vol 19 ◽  
Author(s):  
Mini P. Sajan ◽  
Michael Leitges ◽  
Colin Park ◽  
David M. Diamond ◽  
Jin Wu ◽  
...  
Keyword(s):  
Amyloid Precursor Protein ◽  
Proinflammatory Cytokine ◽  
Insulin Treatment ◽  
Precursor Protein ◽  
Nuclear Factor ◽  
Diabetic Mice ◽  
Aβ Peptides ◽  
Protein Levels ◽  
Total Body ◽  
The Brain

Βackground: β-Amyloid precursor protein-cleaving enzyme-1 (BACE1) initiates the production of Aβ-peptides that form Aβ-plaque in Alzheimer’s disease. Methods: Reportedly, acute insulin treatment in normal mice, and hyperinsulinemia in high-fat-fed (HFF) obese/diabetic mice, increase BACE1 activity and levels of Aβ-peptides and phospho- -thr-231-tau in the brain; moreover, these effects are blocked by PKC-λ/ι inhibitors. However, as chemical inhibitors may affect unsuspected targets, we presently used knockout methodology to further examine PKC-λ/ι requirements. We found that total-body heterozygous PKC-λ knockout reduced acute stimulatory effects of insulin and chronic effects of hyperinsulinemia in HFF/obese/diabetic mice, on brain PKC-λ activity and production of Aβ1-40/42 and phospho-thr-231-tau. This protection in HFF mice may reflect that hepatic PKC-λ haploinsufficiency prevents the development of glucose intolerance and hyperinsulinemia. Results: On the other hand, heterozygous knockout of PKC-λ markedly reduced brain levels of BACE1 protein and mRNA, and this may reflect diminished activation of nuclear factor kappa-B (NFκB), which is activated by PKC-λ and increases BACE1 and proinflammatory cytokine transcription. Accordingly, whereas intravenous administration of aPKC inhibitor diminished aPKC activity and BACE1 levels by 50% in the brain and 90% in the liver, nasally-administered inhibitor reduced aPKC activity and BACE1 mRNA and protein levels by 50-70% in the brain while sparing the liver. Additionally, 24-hour insulin treatment in cultured human-derived neurons increased NFκB activity and BACE1 levels, and these effects were blocked by various PKC-λ/ι inhibitors. Conclusion: PKC-λ/ι controls NFκB activity and BACE1 expression; PKC-λ/ι inhibitors may be used nasally to target brain PKC-λ/ι or systemically to block both liver and brain PKC-λ/ι, to regulate NFκB-dependent BACE1 and proinflammatory cytokine expression.

scholarly journals Transmissible Endosomal Intoxication: A Balance between Exosomes and Lysosomes at the Basis of Intercellular Amyloid Propagation

Biomedicines ◽  
2020 ◽  
Vol 8 (8) ◽  
pp. 272
Author(s):  
Anaïs Bécot ◽  
Charlotte Volgers ◽  
Guillaume van Niel
Keyword(s):  
Amyloid Precursor Protein ◽  
Neurodegenerative Diseases ◽  
Multivesicular Body ◽  
Precursor Protein ◽  
Aβ Peptides ◽  
Amyloid Aβ ◽  
Β Amyloid ◽  
Novel Concept ◽  
The Brain

In Alzheimer′s disease (AD), endolysosomal dysfunctions are amongst the earliest cellular features to appear. Each organelle of the endolysosomal system, from the multivesicular body (MVB) to the lysosome, contributes to the homeostasis of amyloid precursor protein (APP) cleavage products including β-amyloid (Aβ) peptides. Hence, this review will attempt to disentangle how changes in the endolysosomal system cumulate to the generation of toxic amyloid species and hamper their degradation. We highlight that the formation of MVBs and the generation of amyloid species are closely linked and describe how the molecular machineries acting at MVBs determine the generation and sorting of APP cleavage products towards their degradation or release in association with exosomes. In particular, we will focus on AD-related distortions of the endolysomal system that divert it from its degradative function to favour the release of exosomes and associated amyloid species. We propose here that such an imbalance transposed at the brain scale poses a novel concept of transmissible endosomal intoxication (TEI). This TEI would initiate a self-perpetuating transmission of endosomal dysfunction between cells that would support the propagation of amyloid species in neurodegenerative diseases.

scholarly journals Neuroinflammatory Cytokines Induce Amyloid Beta Neurotoxicity through Modulating Amyloid Precursor Protein Levels/Metabolism

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Fawaz Alasmari ◽  
Musaad A. Alshammari ◽  
Abdullah F. Alasmari ◽  
Wael A. Alanazi ◽  
Khalid Alhazzani
Keyword(s):  
Amyloid Precursor Protein ◽  
Neurofibrillary Tangles ◽  
Beta Amyloid ◽  
Precursor Protein ◽  
Cytokine Release ◽  
Efflux Transport ◽  
Protein Levels ◽  
Amyloid A ◽  
The Brain

Neuroinflammation has been observed in association with neurodegenerative diseases including Alzheimer’s disease (AD). In particular, a positive correlation has been documented between neuroinflammatory cytokine release and the progression of the AD, which suggests these cytokines are involved in AD pathophysiology. A histological hallmark of the AD is the presence of beta-amyloid (Aβ) plaques and tau neurofibrillary tangles. Beta-amyloid is generated by the sequential cleavage of beta (β) and gamma (γ) sites in the amyloid precursor protein (APP) by β- and γ-secretase enzymes and its accumulation can result from either a decreased Aβ clearance or increased metabolism of APP. Previous studies reported that neuroinflammatory cytokines reduce the efflux transport of Aβ, leading to elevated Aβ concentrations in the brain. However, less is known about the effects of neuroinflammatory mediators on APP expression and metabolism. In this article, we review the modulatory role of neuroinflammatory cytokines on APP expression and metabolism, including their effects on β- and γ-secretase enzymes.

Unchanged rat brain amyloid precursor protein levels after exposure to benzodiazepines in vivo

2006 ◽  
Vol 23 (9) ◽  
pp. 772-775 ◽  
Author(s):  
J. Kálmán ◽  
M. Palotás ◽  
M. Pákáski ◽  
M. Hugyecz ◽  
Z. Janka ◽  
...  
Keyword(s):  
Amyloid Precursor Protein ◽  
Rat Brain ◽  
Precursor Protein ◽  
Protein Levels

scholarly journals Nitrous Oxide Plus Isoflurane Induces Apoptosis and Increases β-Amyloid Protein Levels

2009 ◽  
Vol 111 (4) ◽  
pp. 741-752 ◽  
Author(s):  
Yu Zhen ◽  
Yuanlin Dong ◽  
Xu Wu ◽  
Zhipeng Xu ◽  
Yan Lu ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Amyloid Precursor Protein ◽  
Caspase 3 ◽  
Precursor Protein ◽  
Primary Neurons ◽  
Gamma Secretase ◽  
Protein Levels ◽  
Secretase Inhibitor

Background Some anesthetics have been suggested to induce neurotoxicity, including promotion of Alzheimer's disease neuropathogenesis. Nitrous oxide and isoflurane are common anesthetics. The authors set out to assess the effects of nitrous oxide and/or isoflurane on apoptosis and beta-amyloid (Abeta) levels in H4 human neuroglioma cells and primary neurons from naïve mice. Methods The cells or neurons were exposed to 70% nitrous oxide and/or 1% isoflurane for 6 h. The cells or neurons and conditioned media were harvested at the end of the treatment. Caspase-3 activation, apoptosis, processing of amyloid precursor protein, and Abeta levels were determined. Results Treatment with a combination of 70% nitrous oxide and 1% isoflurane for 6 h induced caspase-3 activation and apoptosis in H4 naïve cells and primary neurons from naïve mice. The 70% nitrous oxide plus 1% isoflurane, but neither alone, for 6 h induced caspase-3 activation and apoptosis, and increased levels of beta-site amyloid precursor protein-cleaving enzyme and Abeta in H4-amyloid precursor protein cells. In addition, the nitrous oxide plus isoflurane-induced Abeta generation was reduced by a broad caspase inhibitor, Z-VAD. Finally, the nitrous oxide plus isoflurane-induced caspase-3 activation was attenuated by gamma-secretase inhibitor L-685,458, but potentiated by exogenously added Abeta. Conclusion These results suggest that the common anesthetics nitrous oxide plus isoflurane may promote neurotoxicity by inducing apoptosis and increasing Abeta levels. The generated Abeta may further potentiate apoptosis to form another round of apoptosis and Abeta generation. More studies, especially the in vivo confirmation of these in vitro findings, are needed.

scholarly journals COPS5 (Jab1) Protein Increases β Site Processing of Amyloid Precursor Protein and Amyloid β Peptide Generation by Stabilizing RanBP9 Protein Levels

2013 ◽  
Vol 288 (37) ◽  
pp. 26668-26677 ◽  
Author(s):  
Hongjie Wang ◽  
Debleena Dey ◽  
Ivan Carrera ◽  
Dmitriy Minond ◽  
Elisabetta Bianchi ◽  
...  
Keyword(s):  
Amyloid Precursor Protein ◽  
Amyloid Β ◽  
Precursor Protein ◽  
Amyloid Β Peptide ◽  
Protein Levels

scholarly journals Impairment of amyloid precursor protein alpha-processing in cerebral microvessels of type 1 diabetic mice

2017 ◽  
Vol 39 (6) ◽  
pp. 1085-1098
Author(s):  
Tongrong He ◽  
Ruohan Sun ◽  
Anantha VR Santhanam ◽  
Livius V d'Uscio ◽  
Tong Lu ◽  
...  
Keyword(s):  
Amyloid Precursor Protein ◽  
Precursor Protein ◽  
Local Concentration ◽  
Microvascular Endothelium ◽  
Cerebral Microvessels ◽  
Protein Levels ◽  
Enhanced Production ◽  
Amyloidogenic Processing

The mechanisms underlying dysfunction of cerebral microvasculature induced by type 1 diabetes (T1D) are not fully understood. We hypothesized that in cerebral microvascular endothelium, α-processing of amyloid precursor protein (APP) is impaired by T1D. In cerebral microvessels derived from streptozotocin (STZ)-induced T1D mice protein levels of APP and its α-processing enzyme, a disintegrin and metalloprotease 10 (ADAM10) were significantly decreased, along with down-regulation of adenylate cyclase 3 (AC3) and enhanced production of thromboxane A2 (TXA2). In vitro studies in human brain microvascular endothelial cells (BMECs) revealed that knockdown of AC3 significantly suppressed ADAM10 protein levels, and that activation of TXA2 receptor decreased APP expression. Furthermore, levels of soluble APPα (sAPPα, a product of α-processing of APP) were significantly reduced in hippocampus of T1D mice. In contrast, amyloidogenic processing of APP was not affected by T1D in both cerebral microvessels and hippocampus. Most notably, studies in endothelial specific APP knockout mice established that genetic inactivation of APP in endothelium was sufficient to significantly reduce sAPPα levels in the hippocampus. In aggregate, our findings suggest that T1D impairs non-amyloidogenic processing of APP in cerebral microvessels. This may exert detrimental effect on local concentration of neuroprotective molecule, sAPPα, in the hippocampus.

scholarly journals Amyloid precursor protein in pancreatic islets

2017 ◽  
Vol 235 (1) ◽  
pp. 49-67 ◽  
Author(s):  
Joshua A Kulas ◽  
Kendra L Puig ◽  
Colin K Combs
Keyword(s):  
Type 2 Diabetes ◽  
Amyloid Precursor Protein ◽  
Pancreatic Islets ◽  
Culture Media ◽  
Glucagon Secretion ◽  
Human Islets ◽  
Precursor Protein ◽  
Protein Levels ◽  
Glucose Levels

The amyloid precursor protein (APP) has been extensively investigated for its role in the production of amyloid beta (Aβ), a plaque-forming peptide in Alzheimer’s disease (AD). Epidemiological evidence suggests type 2 diabetes is a risk factor for AD. The pancreas is an essential regulator of blood glucose levels through the secretion of the hormones insulin and glucagon. Pancreatic dysfunction is a well-characterized consequence of type 1 and type 2 diabetes. In this study, we have examined the expression and processing of pancreatic APP to test the hypothesis that APP may play a role in pancreatic function and the pathophysiology of diabetes. Our data demonstrate the presence of APP within the pancreas, including pancreatic islets in both mouse and human samples. Additionally, we report that the APP/PS1 mouse model of AD overexpresses APP within pancreatic islets, although this did not result in detectable levels of Aβ. We compared whole pancreas and islet culture lysates by Western blot from C57BL/6 (WT), APP−/− and APP/PS1 mice and observed APP-dependent differences in the total protein levels of GLUT4, IDE and BACE2. Immunohistochemistry for BACE2 detected high levels in pancreatic α cells. Additionally, both mouse and human islets processed APP to release sAPP into cell culture media. Moreover, sAPP stimulated insulin but not glucagon secretion from islet cultures. We conclude that APP and its metabolites are capable of influencing the basic physiology of the pancreas, possibly through the release of sAPP acting in an autocrine or paracrine manner.

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