Podcasts about bace1

MedLink Neurology Podcast is delighted to feature selected episodes from BrainWaves, courtesy of James E Siegler MD, its originator and host. BrainWaves is an academic audio podcast whose mission is to educate medical providers through clinical cases and topical reviews in neurology, medicine, and the humanities. Episodes originally aired from 2016 to 2021. Originally released: August 8, 2019 Clean up on aisle 4! Or should it be IL-4? In this week's installment of the BrainWaves Podcast, we immerse ourselves into the microscopic environment of Alzheimer disease pathology. It's interesting, it's messy, and whoever made this mess is also responsible for the clean-up. Produced by James E Siegler. Music courtesy of Andy Cohen, Brendan Kinsella, Cuicuitte, Damiano Baldoni, Kai Engel, Nctrnm. Sound effects by Mike Koenig, Blastfx.com, Caroline Ford, Robertv, and Daniel Simion. BrainWaves' podcasts and online content are intended for medical education only and should not be used for clinical decision-making. Be sure to follow us on Twitter (now X) @brainwavesaudio for the latest updates to the podcast. REFERENCES Arranz AM, De Strooper B. The role of astroglia in Alzheimer's disease: pathophysiology and clinical implications. Lancet Neurol 2019;18(4):406-14. PMID 30795987Breitner JC, Baker LD, Montine TJ, et al. Extended results of the Alzheimer's disease anti-inflammatory prevention trial. Alzheimers Dement 2011;7(4):402-11. PMID 21784351Chun H, Lee CJ. Reactive astrocytes in Alzheimer's disease: a double-edged sword. Neurosci Res 2018;126:44-52. PMID 29225140Heneka MT, Carson MJ, El Khoury J, et al. Neuroinflammation in Alzheimer's disease. Lancet Neurol 2015;14(4):388-405. PMID 25792098Kumar A, Singh A, Ekavali. A review on Alzheimer's disease pathophysiology and its management: an update. Pharmacol Rep 2015;67(2):195-203. PMID 25712639Maragakis NJ, Rothstein JD. Mechanisms of disease: astrocytes in neurodegenerative disease. Nat Clin Pract Neurol 2006;2(12):679-89. PMID 17117171Mattsson N, Zetterberg H, Hansson O, et al. CSF biomarkers and incipient Alzheimer disease in patients with mild cognitive impairment. JAMA 2009;302(4):385-93. PMID 19622817Wisniewski T, Konietzko U. Amyloid-beta immunisation for Alzheimer's disease. Lancet Neurol 2008;7(9):805-11. PMID 18667360Yan R, Vassar R. Targeting the β secretase BACE1 for Alzheimer's disease therapy. Lancet Neurol 2014;13(3):319-29. PMID 24556009 We believe that the principles expressed or implied in the podcast remain valid, but certain details may be superseded by evolving knowledge since the episode's original release date.

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2023.04.05.535676v1?rss=1 Authors: Brault, J.-B., Liu, Z., Bardin, S., Ladarre, D., Fraisier, V., Tchenio, A., Lenkei, Z., Salamero, J., Delevoye, C., Goud, B., Miserey, S. Abstract: Alzheimer s disease (AD) is the most common form of dementia worldwide. One of AD s main pathological hallmarks is the cerebral plaque deposits of Beta-amyloid (ABeta). ABeta is generated through sequential enzymatic cleavage of the amyloid precursor protein (APP). The Beta-secretase or Beta-site APP-cleaving enzyme 1 (BACE1) initiates this cleavage and is thus key to regulate ABeta formation. Both APP and BACE1 transit through the endolysosomal system but the exact nature of the compartment(s) where APP cleavage occurs as well as the molecular mechanisms that govern their endosomal sorting remain poorly known. Here we show that RAB11 not only regulates BACE1 transport from early/sorting endosomes (EEs/SEs) and drives the exocytosis of BACE1-containing recycling carriers. Moreover, recycling endosome-associated KIF13A, as well as its closely related homolog KIF13B, which are known RAB11 effectors involved in the biogenesis of recycling endosome (RE) from EEs/SEs, also participate in BACE1 endosomal sorting. Importantly, depletion of KIF13A or KIF13B leads to an increase in ABeta generation. Depletion of the BLOC-1 complex, previously described as an essential partner for KIF13A-dependent RE biogenesis, also induces increased amount of ABeta. Altogether, our findings support a model where the EEs/SEs represent a major organelle for ABeta formation and identify the recycling endosome biogenesis machinery as a master coordinator of BACE1 endosomal sorting and transport. Copy rights belong to original authors. Visit the link for more info Podcast created by Paper Player, LLC

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Gary takes on the real issues that the mainstream media is afraid to tackle. Tune in to find out the latest about health news, healing, politics, and the economy. George Orwell and 1984: How Freedom Dies Orwell's final warning - Picture of the future The Efficacy of Olive Leaf Extract on Healing Herpes Simplex Virus: A Randomized Double-blind Study Lorestan University of Medical Sciences (Iran), January 29, 2021   Herpes simplex virus (HSV), as a common infection in healthy individuals, is treated symptomatically, but drug resistance and the side effects of drugs have drawn the attention of researchers to complementary medicine. Olive Leaf Extract (OLE) has antiviral effects that may treat HSV. The current study aimed to compare the clinical effects of OLE and Acyclovir on HSV-1. Methods This randomized double-blind clinical trial was conducted on 66 patients who had already been diagnosed with HSV-1. The participants were randomized into two groups, receiving 2% OLE cream or 5% acyclovir cream five times a day for six days. The symptoms were evaluated before, and three and six days after the interventions. Data were analyzed using the SPSS software through the Kolmogorov-Smirnov test, chi-squared, t-test, and repeated measures ANOVA. Results The results showed clinical symptoms decreased in both groups during the study and both medications were effective in the treatment of HSV-1. However, the OLE group experienced less bleeding (P=0.038), itching (P=0.002), and pain (P=0.001) on the third day as well as less irritation (P=0.012), itching (P=0.003) and color change (P=0.001) on the sixth day compared to the acyclovir group. The treatment course for participants in the OLE group was shorter than in the acyclovir group (P = 0.001). Conclusion The evidence from these trials suggests the OLE cream is superior in the healing of episodes of HSV-1 over the acyclovir cream. Future studies are recommended to investigate if OLE could be an adjunct to acyclovir treatment.   How vitamins, steroids and potential antivirals might affect SARS-CoV-2 Study indicates that some vitamins, steroids and antivirals could bind to the Spike protein, and may inhibit virus infectivity, whereas high cholesterol may enable the virus University of Bristol (UK), January 29, 2021   Evidence is emerging that vitamin D - and possibly vitamins K and A - might help combat COVID-19. A new study from the University of Bristol published in the journal of the German Chemical Society Angewandte Chemie has shown how they - and other antiviral drugs - might work. The research indicates that these dietary supplements and compounds could bind to the viral spike protein and so might reduce SARS-CoV-2 infectivity. In contrast, cholesterol may increase infectivity, which could explain why having high cholesterol is considered a risk factor for serious disease. Recently, Bristol researchers showed that linoleic acid binds to a specific site in the viral spike protein, and that by doing so, it locks the spike into a closed, less infective form. Now, a research team has used computational methods to search for other compounds that might have the same effect, as potential treatments. They hope to prevent human cells becoming infected by preventing the viral spike protein from opening enough to interact with a human protein (ACE2). New anti-viral drugs can take years to design, develop and test, so the researchers looked through a library of approved drugs and vitamins to identify those which might bind to this recently discovered 'druggable pocket' inside the SARS-CoV-2 spike protein.  The team first studied the effects of linoleic acid on the spike, using computational simulations to show that it stabilizes the closed form. Further simulations showed that dexamethasone - which is an effective treatment for COVID-19 - might also bind to this site and help reduce viral infectivity in addition to its effects on the human immune system.  The team then conducted simulations to see which other compounds bind to the fatty acid site. This identified some drugs that have been found by experiments to be active against the virus, suggesting that this may be one mechanism by which they prevent viral replication such as, by locking the spike structure in the same way as linoleic acid. The findings suggested several drug candidates among available pharmaceuticals and dietary components, including some that have been found to slow SARS-CoV-2 reproduction in the laboratory. These have the potential to bind to the SARS-CoV-2 spike protein and may help to prevent cell entry.  The simulations also predicted that the fat-soluble vitamins D, K and A bind to the spike in the same way making the spike less able to infect cells.  Dr Deborah Shoemark, Senior Research Associate (Biomolecular Modelling) in the School of Biochemistry, who modelled the spike, explained: "Our findings help explain how some vitamins may play a more direct role in combatting COVID than their conventional support of the human immune system.  "Obesity is a major risk factor for severe COVID. Vitamin D is fat soluble and tends to accumulate in fatty tissue. This can lower the amount of vitamin D available to obese individuals. Countries in which some of these vitamin deficiencies are more common have also suffered badly during the course of the pandemic. Our research suggests that some essential vitamins and fatty acids including linoleic acid may contribute to impeding the spike/ACE2 interaction. Deficiency in any one of them may make it easier for the virus to infect." Pre-existing high cholesterol levels have been associated with increased risk for severe COVID-19. Reports that the SARS-CoV-2 spike protein binds cholesterol led the team to investigate whether it could bind at the fatty acid binding site. Their simulations indicate that it could bind, but that it may have a destabilising effect on the spike's locked conformation, and favour the open, more infective conformation. Dr Shoemark continued: "We know that the use of cholesterol lowering statins reduces the risk of developing severe COVID and shortens recovery time in less severe cases. Whether cholesterol de-stabilises the "benign", closed conformation or not, our results suggest that by directly interacting with the spike, the virus could sequester cholesterol to achieve the local concentrations required to facilitate cell entry and this may also account for the observed loss of circulating cholesterol post infection." Professor Adrian Mulholland, of Bristol's School of Chemistry, added: "Our simulations show how some molecules binding at the linoleic acid site affect the spike's dynamics and lock it closed. They also show that drugs and vitamins active against the virus may work in the same way. Targeting this site may be a route to new anti-viral drugs. A next step would be to look at effects of dietary supplements and test viral replication in cells." Alison Derbenwick Miller, Vice President, Oracle for Research, said: "It's incredibly exciting that researchers are gaining new insights into how SARS-CoV-2 interacts with human cells, which ultimately will lead to new ways to fight COVID-19. We are delighted that Oracle's high-performance cloud infrastructure is helping to advance this kind of world-changing research. Growing a globally-connected community of cloud-powered researchers is exactly what Oracle for Research is designed to do."     Researchers find melatonin is effective against polycystic kidney disease Concordia University (Canada), January 26, 2021 A hormone commonly associated with sleep-wake regulation has been found to reduce cysts in fruit flies, according to Concordia researchers. It's a finding that may affect the way we treat some kidney diseases and reduce the need for kidney transplants. In a new paper published in the journal Molecules, alum Cassandra Millet-Boureima(MSc 19) and Chiara Gamberi, affiliate assistant professor of biology, write that melatonin was found to reduce cysts in the renal tubules of fruit flies. These tubules are also found in more complex mammals, including humans, where they are called nephrons. This study, which builds on previous studies by Millet-Boureima and Gamberi, was co-authored by Roman Rozencwaig and Felix Polyak of BH Bioscience in Montreal. The researchers hope that their findings can be applied to treating people suffering from autosomal dominant polycystic kidney disease. ADPKD is a genetic chronic and progressive disease characterized by the growth of dozens of cysts in the nephrons. It is incurable and affects approximately 12.5 million worldwide. Similarities big and small Because nephrons in vertebrates are embedded in other tissue, the researchers experimented on Drosophila -- the common fruit fly. "Drosophila conserves many of the renal pathway components found in vertebrates and have anatomically isolated renal tubes," Gamberi explains. "With microdissection, we can isolate the tubules and conduct biochemical and molecular analysis." The researchers bred fruit flies bearing the Bicaudal C gene mutation. It is known to cause kidney cysts in all manner of living beings, from flies to frogs to mice to humans. Over 18 days, Millet-Boureima administered melatonin to 50 Drosophila and ethanol to a control group. She then dissected the flies and scored their cysts, a process yielding a cystic index. She found that the melatonin-treated flies had much fewer and smaller cysts than the control. Because Millet-Boureima was skilled at dissecting the insects and evaluating the recovered renal tubules, she was able to avoid bias in the count. She was also able to distinguish three separate sections of the Drosophila tubule, each with its own unique function, and assign the cysts to a particular section. After testing several compounds on the same family of cells, she observed different activities along the length of the tubule. The researchers realized that they could potentially develop targeted treatment depending on the location of the cysts in a patient's nephrons. "Biologically speaking, this has a lot of potential that we will obviously develop," Gamberi says. Helping without harming Though Gamberi says melatonin has not been previously used to treat PKD, she does think it holds some promise. PKD is a chronic disease, so treatment cannot include any toxic components. This rules out chemotherapy and tumour-killing antineoplastics used in oncology, for instance. However, melatonin is entirely non-toxic and shares certain properties with antineoplastics and anti-inflammatory agents. "We know from oncology that melatonin has two effects when it is administered with chemotherapy," Gamberi explains. "First, it acts as a drug adjuvant to the chemotherapy, making it work more effectively against cancer cells. Second, it appears to protect healthy cells from the toxicity of the chemotherapy. Basically, melatonin increases the specificity of the chemotherapy. We hope that it can have a similar positive effect when used with an anti-ADPKD drug like tolvaptan, which can damage the liver." The researchers are keen to share their findings as quickly as possible. "I hope there will be more research on the drugs we tested and that we get more results that will help the PKD community," Millet-Boureima says.     Gallic acid is a dual alpha/beta-secretase modulator that reverses cognitive impairment and remediates pathology in Alzheimer  Saitama Medical Center (Japan), January 20, 2021   According to news reporting from Saitama, Japan, research stated, “Several plant-derived compounds have demonstrated efficacy in pre-clinical Alzheimer’s disease (AD) rodent models. Each of these compounds share a gallic acid (GA) moiety, and initial assays on this isolated molecule indicated that it might be responsible for the therapeutic benefits observed.”  Higher concentrations of GA are found in blueberry, blackberry, strawberry, plums, grapes, mango, cashew nut, hazelnut, walnut and tea.   The news correspondents obtained a quote from the research from Saitama Medical Center, “To test this hypothesis in a more physiologically relevant setting, we investigated the effect of GA in the mutant human amyloid beta-protein precursor/presenilin 1 (APP/PS1) transgenic AD mouse model. Beginning at 12 months, we orally administered GA (20 mg/kg) or vehicle once daily for 6 months to APP/PS1 mice that have accelerated Alzheimer-like pathology. At 18 months of age, GA therapy reversed impaired learning and memory as compared with vehicle, and did not alter behavior in nontransgenic littermates. GA-treated APP/PS1 mice had mitigated cerebral amyloidosis, including brain parenchymal and cerebral vascular beta-amyloid deposits, and decreased cerebral amyloid beta-proteins. Beneficial effects co-occurred with reduced amyloidogenic and elevated nonamyloidogenic APP processing. Furthermore, brain inflammation, gliosis, and oxidative stress were alleviated. We show that GA simultaneously elevates alpha- and reduces beta-secretase activity, inhibits neuroinflammation, and stabilizes brain oxidative stress in a pre-clinical mouse model of AD. We further demonstrate that GA increases abundance of a disintegrin and metalloproteinase domain-containing protein 10 (ADAM10, Adam10) proprotein convertase furin and activates ADAM10, directly inhibits beta-site APP cleaving enzyme 1 (BACE1, Bace1) activity but does not alter Adam10 or Bace1 transcription. Thus, our data reveal novel post-translational mechanisms for GA.” According to the news reporters, the research concluded: “We suggest further examination of GA supplementation in humans will shed light on the exciting therapeutic potential of this molecule.” This research has been peer-reviewed.     Black cumin’s anti-inflammatory potential may have airways/asthma benefits: RCT   University College London, January 27, 2021   Supplements containing oil from black cumin (Nigella sativa) may improve asthma control and lung function, says a new study.   The seed and oil of Nigella sativa have been used extensively in traditional medicine in many Middle Eastern and Asian countries for the treatment of a range of conditions, including some immune and inflammatory disorders.   The new study, published in Phytotherapy Research , found that one gram per day of the oil for four weeks led to significant improvements in scores of asthma control and a “remarkable reduction of peripheral blood eosinophil count,” wrote the authors   “Eosinophil cell plays a major role in asthma inflammation, and blood eosinophil count is considered to be a vital biomarker in asthma trials. To our knowledge, this is the first [randomized, double-blind, placebo-controlled trial] that showed a significant reduction of blood eosinophilia by [Nigella sativa oil (NSO)] among asthmatic patients.”   Scientists from University College London (UK) and King Abdulaziz University (Saudi Arabia) recruited 80 asthmatics and randomly assigned them to one of two equal groups. The participants received either capsules containing 500 mg of NSO twice per day or placebo for four weeks.   Data from the 60 people who completed the study (10 dropouts in each group) indicated that the black cumin supplement was associated with significant improvements in mean score on the Asthma Control Test, compared to placebo.   Black cumin oil products are commercially available through brands such as Life Extension. Structure-function claims made on the products include: “Modulates key regulators of inflammation” In addition, the black cumin group also experienced a significant decrease in blood eosinophils: −50 versus 15 cells/microliter.   A non-statistically significant improvement in lung function, measured as forced expiratory volume in 1 second, was also associated with the black cumin supplements.   “The NSO supplementation appeared to be effective in enhancing the control of asthma symptoms with a trend in pulmonary function improvement,” wrote the researchers. “These findings may provide an evidence for the potential benefits of NSO supplementation in the clinical management of asthma. “Future studies should follow patients for a longer period and use additional outcomes to validate the benefits of NSO in asthma.”   LSD may offer viable treatment for certain mental disorders McGill University (Quebec), January 26, 2021 Researchers from McGill University have discovered, for the first time, one of the possible mechanisms that contributes to the ability of lysergic acid diethylamide (LSD) to increase social interaction. The findings, which could help unlock potential therapeutic applications in treating certain psychiatric diseases, including anxiety and alcohol use disorders, are published in the journal PNAS. Psychedelic drugs, including LSD, were popular in the 1970s and have been gaining popularity over the past decade, with reports of young professionals claiming to regularly take small non-hallucinogenic micro-doses of LSD to boost their productivity and creativity and to increase their empathy. The mechanism of action of LSD on the brain, however, has remained a mystery. Studies in mice provide clues To conduct their study, the researchers administered a low dose of LSD to mice over a period of seven days, resulting in an observable increase in the sociability of the mice. "This increased sociability occurs because the LSD activates the serotonin 5-HT2A receptors and the AMPA receptors -- which is a glutamate receptor, the main brain excitatory neurotransmitters -- in the prefrontal cortex and also activates a cellular protein called mTORC 1," explains Danilo De Gregorio, PharmD, PhD, who is a postdoctoral fellow in the Neurobiological Psychiatry Unit at McGill and the study's first author. "These three factors, taken together, promote social interaction in mice, which is the equivalent of empathy and social behaviour in humans."  The researchers note that the main outcome of their study is the ability to describe, at least in rodents, the underlying mechanism for the behavioural effect that results in LSD increasing feelings of empathy, including a greater connection to the world and sense of being part of a large community. "The fact that LSD binds the 5-HT2A receptor was previously known. The novelty of this research is to have identified that the prosocial effects of LSD activate the 5-HT2 receptors, which in-turn activate the excitatory synapses of the AMPA receptor as well as the protein complex mTORC1, which has been demonstrated to be dysregulated in diseases with social deficits such as autism spectrum disorder," as specified by Prof. Nahum Sonenberg, Professor at the Department of Biochemistry of McGill University, world renowned expert in the molecular biology of diseases and co-lead author of the study. Using the cutting-edge technique of optogenetics, a technique where genes for light-sensitive proteins are introduced into specific types of brain cells in order to monitor and control their activity precisely using light signals, the researchers observed that when the excitatory transmission in the prefrontal cortex is de-activated, the prosocial effect of LSD was nullified, highlighting the importance of this brain region on the modulation of the behavioural effects of LSD. Moving forward to apply the findings to humans Having found that LSD increases social interaction in mice, the researchers are hoping to continue their work and to test the ability of LSD to treat mutant mice displaying the behavioural deficits similar to those seen in human pathologies including autism spectrum disorders and social anxiety disorders. The hope is to eventually explore whether micro-doses of LSD or some novel derivates might have a similar effect in humans and whether it could also be a viable and safe therapeutic option.  "Social interaction is a fundamental characteristic of human behaviour," notes the co-lead author Dr. Gabriella Gobbi, Professor in the Department of Psychiatry at McGill and psychiatrist at the McGill University Health Centre. "These hallucinogenic compounds, which, at low doses, are able to increase sociability may help to better understand the pharmacology and neurobiology of social behavior and, ultimately, to develop and discover novel and safer drugs for mental disorders."   Polyphenol-rich virgin olive oil reduces insulin resistance and liver inflammation and improves mitochondrial dysfunction   University of Naples (Italy), January 28, 2021   Studies from University of Naples Federico II Describe New Findings in Insulin Resistance (Polyphenol-rich virgin olive oil reduces insulin resistance and liver inflammation and improves mitochondrial dysfunction in high-fat diet fed rats)   A new study on Endocrine System Diseases and Conditions - Insulin Resistance is now available. According to news reporting originating in Naples, Italy, research stated, "Virgin olive oil is an essential component of the Mediterranean diet. Its antioxidant and anti-inflammatory properties are mainly linked to phenolic contents."   The news reporters obtained a quote from the research from the University of Naples Federico II, "This study aims to evaluate the beneficial effects of a polyphenol-rich virgin olive oil (HPCOO) or olive oil without polyphenols (WPOO) in rats fed high-fat diet (HFD). Male Sprague-Dawley rats were divided into four groups based on the different types of diet: (I) standard diet (STD); (II) HFD; (III) HFD containing WPOO, and (IV) HFD containing HPCOO. HPCOO and WPOO induced a significant improvement of HFD-induced impaired glucose homeostasis (by hyperglycemia, altered oral glucose tolerance, and HOMA-IR) and inflammatory status modulating pro-and anti-inflammatory cytokines (TNF-a, IL-1, and IL-10) and adipokines. Moreover, HPCOO and less extensively WPOO, limited HFD-induced liver oxidative and nitrosative stress and increased hepatic fatty acid oxidation. To study mitochondrial performance, oxidative capacity and energy efficiency were also evaluated in isolated liver mitochondria. HPCOO, but not WPOO, reduced H O release and aconitase activity by decreasing degree of coupling, which plays a major role in the control of mitochondrial reactive oxygen species emission."   According to the news reporters, the research concluded: "HPCOO limits HFD-induced insulin resistance, inflammation, and hepatic oxidative stress, preventing nonalcoholic fatty liver disease progression."   For more information on this research see: Polyphenol-rich virgin olive oil reduces insulin resistance and liver inflammation and improves mitochondrial dysfunction in high-fat diet fed rats.   

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.09.13.295642v1?rss=1 Authors: Hata, S., Kikuchi, K., Kano, K., Saito, H., Sobu, Y., Kinoshita, S., Saito, T., Saido, T. C., Sano, Y., Taru, H., Aoki, J., Komano, H., Tomita, T., Natori, S., Suzuki, T. Abstract: Conjugated linoleic acid (CLA) comprises several geometric and positional isomers of the parental linoleic acid (LA). Two of the isomers, cis-9, trans-11 CLA (c9,t11 CLA) and trans-10, cis-12 CLA (t10,c12 CLA) exert various biological activities. However, the effect of CLA on generation of neurotoxic amyloid-{beta} (A{beta}) protein remains unclear. We found that c9,t11CLA significantly suppressed generation of A{beta} in primary cultures of mouse neurons. CLA treatment did not affect the levels of {beta}-site APP-cleaving enzyme 1 (BACE1), a component of active {gamma}-secretase complex presenilin 1 amino-terminal fragment (PS1 NTF), or A{beta} protein precursor (APP) in cultured neurons. BACE1 activity in lysate of neurons treated with c9,t11 CLA, but not t10,c12 CLA, decreased slightly, although c9,t11 CLA did not directly affect the activity of recombinant BACE1. Interestingly, localization of BACE1 and APP in early endosomes increased in neurons treated with c9,t11 CLA; concomitantly, the localization of both proteins was reduced in late endosomes, where APP is predominantly cleaved by BACE1. c9,t11 CLA and t10,c12 CLA appeared to be incorporated into membrane phospholipids, as the level of CLA-containing lysophosphatidylcholine (CLA-LPC) increased dramatically in neurons incubated with CLA. Taken together, our findings indicate that accumulation of c9,t11 CLA-LPC, but not t10,c12 CLA-LPC, in neuronal membranes suppresses amyloidogenic cleavage of APP, thereby contributing to preservation of brain neurons by suppressing neurotoxic A{beta} production in aged subjects. Copy rights belong to original authors. Visit the link for more info

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.07.22.215616v1?rss=1 Authors: Guyon, A., Rousseau, J., Lamothe, G., Tremblay, J. P. Abstract: The accumulation of plaque in the brain leads to the onset and development of Alzheimers disease. The Amyloid precursor protein (APP) is usually cut by a-secretase, however an abnormal cleavage profile by {beta}-secretase (BACE1) leads to the accumulation of A{beta} peptides, which forms these plaques. Numerous APP gene mutations favor plaque accumulation, causing Familial Alzheimer Disease (FAD). However, a variant of the APP gene (A673T) in Icelanders reduces BACE1 cleavage by 40 %. A library of plasmids containing APP genes with 29 FAD mutations with or without the additional A673T mutation was generated and transfected in neuroblastomas to assess the effect of this mutation on A{beta} peptide production. In most cases the production of A{beta} peptides was decreased by the co-dominant A673T mutation. The reduction of A{beta} peptide concentrations for the London mutation (V717I) even reached the same level as A673T carriers. These results suggest that the insertion of A673T in the APP gene of genetically susceptible FAD patients may prevent the onset of, slow down, or stop the progression of the disease. Copy rights belong to original authors. Visit the link for more info

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.05.22.110023v1?rss=1 Authors: Tüshaus, J., Müller, S. A., Kataka, E. S., Zaucha, J., Sebastian Monasor, L., Su, M., Güner, G., Jocher, G., Tahirovic, S., Frishman, D., Simons, M., Lichtenthaler, S. F. Abstract: To understand how cells communicate in the nervous system, it is essential to define their secretome, which is challenging for primary cells because of large cell numbers being required. Here, we miniaturized secretome analysis by developing the high-performance secretome-protein-enrichment-with-click-sugars method (hiSPECS). To demonstrate its broad utility, hiSPECS was used to identify the secretory response of brain slices upon LPS-induced neuroinflammation and to establish the cell type-resolved mouse brain secretome resource using primary astrocytes, microglia, neurons and oligodendrocytes. This resource allowed mapping the cellular origin of CSF proteins and revealed that an unexpectedly high number of secreted proteins in vitro and in vivo are proteolytically-cleaved membrane protein ectodomains. Two examples are neuronally secreted ADAM22 and CD200, which we identified as substrates of the Alzheimer-linked protease BACE1. hiSPECS and the brain secretome resource can be widely exploited to systematically study protein secretion, brain function and to identify cell type-specific biomarkers for CNS diseases. Copy rights belong to original authors. Visit the link for more info

Clean up on aisle 4! Or should it be IL-4? In this week's installment of the BrainWaves Podcast, we submerge ourselves into the microscopic environment of Alzheimer's pathology. It's interesting, it's messy, and whoever made this mess is also responsible for the clean up. Produced by James E. Siegler. Music courtesy of Andy Cohen, Brendan Kinsella, Cuicuitte, Damiano Baldoni, Kai Engel, Nctrnm. Sound effects by Mike Koenig, Blastfx.com, Caroline Ford, Robertv, and Daniel Simion. BrainWaves' podcasts and online content are intended for medical education only and should not be used for clinical decision making. Be sure to follow us on Twitter @brainwavesaudio for the latest updates to the podcast. REFERENCES Arranz AM and De Strooper B. The role of astroglia in Alzheimer's disease: pathophysiology and clinical implications. The Lancet Neurology. 2019;18:406-414. Maragakis NJ and Rothstein JD. Mechanisms of Disease: astrocytes in neurodegenerative disease. Nat Clin Pract Neurol. 2006;2:679-89. Wisniewski T and Konietzko U. Amyloid-beta immunisation for Alzheimer's disease. The Lancet Neurology. 2008;7:805-11. Mattsson N, Zetterberg H, Hansson O, Andreasen N, Parnetti L, Jonsson M, Herukka SK, van der Flier WM, Blankenstein MA, Ewers M, Rich K, Kaiser E, Verbeek M, Tsolaki M, Mulugeta E, Rosen E, Aarsland D, Visser PJ, Schroder J, Marcusson J, de Leon M, Hampel H, Scheltens P, Pirttila T, Wallin A, Jonhagen ME, Minthon L, Winblad B and Blennow K. CSF biomarkers and incipient Alzheimer disease in patients with mild cognitive impairment. JAMA : the journal of the American Medical Association. 2009;302:385-93. Breitner JC, Baker LD, Montine TJ, Meinert CL, Lyketsos CG, Ashe KH, Brandt J, Craft S, Evans DE, Green RC, Ismail MS, Martin BK, Mullan MJ, Sabbagh M, Tariot PN and Group AR. Extended results of the Alzheimer's disease anti-inflammatory prevention trial. Alzheimers Dement. 2011;7:402-11. Yan R and Vassar R. Targeting the beta secretase BACE1 for Alzheimer's disease therapy. The Lancet Neurology. 2014;13:319-29. Heneka MT, Carson MJ, El Khoury J, Landreth GE, Brosseron F, Feinstein DL, Jacobs AH, Wyss-Coray T, Vitorica J, Ransohoff RM, Herrup K, Frautschy SA, Finsen B, Brown GC, Verkhratsky A, Yamanaka K, Koistinaho J, Latz E, Halle A, Petzold GC, Town T, Morgan D, Shinohara ML, Perry VH, Holmes C, Bazan NG, Brooks DJ, Hunot S, Joseph B, Deigendesch N, Garaschuk O, Boddeke E, Dinarello CA, Breitner JC, Cole GM, Golenbock DT and Kummer MP. Neuroinflammation in Alzheimer's disease. The Lancet Neurology. 2015;14:388-405. Kumar A, Singh A and Ekavali. A review on Alzheimer's disease pathophysiology and its management: an update. Pharmacol Rep. 2015;67:195-203. Rodriguez-Arellano JJ, Parpura V, Zorec R and Verkhratsky A. Astrocytes in physiological aging and Alzheimer's disease. Neuroscience. 2016;323:170-82. Chun H and Lee CJ. Reactive astrocytes in Alzheimer's disease: A double-edged sword. Neurosci Res. 2018;126:44-52.

Neuregulin-1 (NRG1) type III is a growth factor on the surface of neurons in the peripheral nervous system (PNS). It is required for initial myelination of nerves by Schwann cells after birth and for remyelination after injury. Neuregulin-1 type III is activated by cleavage (shedding) in its extracellular juxtamembrane region generating a membrane-bound N-terminal fragment (NTF) that contains a bioactive epidermal growth factor (EGF)-like domain. This domain signals to neighboring Schwann cells in a contact-dependent manner prompting the cells to initiate myelination. The β-site APP cleaving enzyme 1 (BACE1) was identified as the enzyme that cleaves NRG1 type III and promotes myelination. Consequently, loss of BACE1 cleavage results in dramatically reduced myelin sheaths around nerves in the PNS of BACE1 knockout mice. Besides its role in myelination, BACE1, better known as β-secretase, is also involved in the generation of the neurotoxic amyloid β-peptide (Aβ) which is the main component of amyloid plaques in the brain of patients suffering from Alzheimer’s disease (AD). The Aβ peptide is derived through sequential cleavage of the amyloid precursor protein APP, first by BACE1 in the extracellular domain and subsequently by the γ-secretase in the transmembrane domain (TMD). Inhibition of BACE1 and γ-secretase is therefore considered a promising therapeutic strategy for AD. However, this approach harbors the risk of mechanism-based side effects due to impaired processing of substrates beside APP such as NRG1 type III which is not only a substrate for BACE1 but like APP is also cleaved in its TMD by the γ-secretase. Adding another layer of complexity, ADAM10 and ADAM17, the so-called α-secretases of AD, also cleave NRG1 type III. In the first part of this study, the proteolytic processing of NRG1 type III in its ectodomain was investigated in detail. The precise juxtamembrane shedding sites of BACE1, ADAM10 and ADAM17 were determined by mass spectrometry and two novel cleavage sites of BACE1 and ADAM17 N-terminal of the EGF-like domain were discovered. Cleavage at these novel sites by ADAM17 and BACE1 results in the secretion of the EGF-like domain from NRG1 type III as α-sEGF and β-sEGF, respectively. Using novel monoclonal antibodies generated against the identified cleavage sites the processing of NRG1 type III could also be confirmed in primary neurons. The soluble EGF-like domains were found to be functionally active and induced signaling pathways required for myelination in cultured Schwann cells. Furthermore, β-sEGF rescued the myelination deficit in the PNS of a zebrafish model lacking BACE1, thereby demonstrating its activity in vivo. Using cell culture and the zebrafish model the effects of BACE1- and ADAM17-mediated shedding on the activity of the soluble EGF-like domains were carefully dissected. In contrast to published evidence, however, both the BACE1- as well as the ADAM17-shed sEGF were found to be equally active and to promote myelination in vivo. Together this suggests that NRG1 type III dependent myelination is not only controlled by membrane-retained NRG1 type III but also in a contact-independent manner via proteolytic liberation of the EGF-like domain. The second part of this study investigates the processing of the C-terminal fragment (CTF) which remains after shedding of NRG1 type III. Intramembranous cleavage of the CTF by the γ-secretase was previously shown to release the NRG1 intracellular domain, which acts as transcriptional regulator of proteins involved in neuronal maturation and brain plasticity. Interestingly, a mutation within the TMD of NRG1 type III is associated with an increased risk of schizophrenia linking γ-secretase processing of NRG1 type III to this neurological disorder. Using a novel antibody against the N-terminus of the NRG1 CTF it was possible to detect a NRG1 β-peptide that is secreted during γ-secretase cleavage and could potentially serve as marker for this processing. Moreover, by means of mass spectrometry, the precise cleavage sites within the TMD of NRG1 could be identified. Strikingly, the ɛ-like cleavage site was found to be located exactly at the position of the schizophrenia-associated mutation providing a possible mechanism for the reported interference of this mutation with γ-secretase cleavage. The evidence presented unambiguously establishes NRG1 type III as a γ-secretase substrate and provides a basis for further investigation of the mechanisms which link its processing to the development of schizophrenia. In summary and with regard to BACE1 and γ-secretase being prime targets for a potential AD therapy, the results of this work call for further careful investigation of the consequences of altered NRG1 type III signaling due to chronic treatment with inhibitors.

Vielversprechende Therapieansätze für die Alzheimer Erkrankung basieren auf der Amyloid-Hypothese und beinhalten die Inhibition der β-Sekretase BACE1 und des γ-Sekretase-Komplexes sowie die Aktivierung der α-Sekretase ADAM10. Für die Einschätzung und Minimierung von Nebenwirkungsprofilen ist die Kenntnis weiterer Substrate dieser Sekretasen essentiell. Als ein solches Substrat wurde Typ I Neuregulin1-β (Typ I NRG1-β), ein Mitglied der EGF-Familie von Wachstumsfaktoren, vermutet. In der vorliegenden Arbeit konnte in vitro gezeigt werden, dass Typ I NRG1-β ein Substrat für den γ-Sekretase-Komplex darstellt. Nach erfolgtem Shedding von Typ I NRG1-β katalysiert der γ-Sekretase-Komplex die intramembranäre Proteolyse durch einen Schnitt innerhalb der Transmembrandomäne. Ferner konnte in vitro gezeigt werden, dass BACE1 das Shedding der Isoformen Typ I NRG1-β1 und Typ I NRG1-β4 katalysiert, wobei die β1-Isoform das bevorzugte Substrat von BACE1 darstellt. Typ I NRG1-β2 wird dagegen nicht oder nur in sehr geringem Ausmaß durch BACE1 prozessiert. Für die β1-Isoform wurde die BACE1-Schnittstelle innerhalb der juxtamembranären Region zwischen der Aminosäure-Position Glu236-Phe237 und Met238-Glu239 (EF-ME) von humanem Typ I NRG1-β1 charakterisiert. Es konnte gezeigt werden, dass diese Schnittstelle spezifisch für BACE1 ist und dass keine weiteren BACE1-Schnittstellen innerhalb der juxtamembranären Region von Typ I NRG1-β1 existieren. Neben BACE1 wird das Shedding der β1-Isoform durch α-Sekretasen katalysiert, wobei das Shedding der β1-Isoform hauptsächlich durch ADAM10 erfolgt. Im Gegensatz zur β1-Isoform werden die Isoformen β2 und β4 nicht durch ADAM10 geschnitten. Für die β2-Isoform konnte jedoch ein Shedding durch andere α-Sekretasen in vitro nachgewiesen werden. Die vorliegenden Ergebnisse ermöglichen allerdings keine Aussage dazu, um welche spezifischen α-Sekretasen es sich handelt. Für α-Sekretasen wird kontrovers eine fehlende Schnittstellen-Sequenzspezifität diskutiert. Vermutlich sind für die Substraterkennung neben einer spezifischen Schnittstellensequenz weitere Faktoren von Bedeutung. So konnte in dieser Arbeit gezeigt werden, dass die Länge der juxtamembranären Region von Typ I NRG1-β einen entscheidenden Einfluss auf das Shedding durch α-Sekretasen hat. Dabei stellen die Isoformen mit einer kürzeren juxtamembranären Region das bevorzugte Substrat für α-Sekretasen dar. Diese Arbeit zeigt, dass Typ I NRG1-β ein Substrat von allen drei Sekretasen ist, die vielversprechende Therapieansatzpunkte in der Alzheimertherapie darstellen. Durch die Beeinflussung der Aktivität dieser Sekretasen wird somit auch die Proteolyse von Typ NRG1-β beeinflusst und damit letztendlich auch die physiologischen Funktionen von Typ NRG1-β. Im Hinblick auf daraus resultierende Nebenwirkungen ist es daher essentiell, die physiologische Bedeutung der Sekretasen ADAM10, BACE1 und des γ-Sekretase-Komplexes bezüglich der Funktionen von Typ NRG1-β weiter zu analysieren.

The processing of APP occurs in two alternative ways: upon release of the ectodomain by α-secretase, the neuroprotective APPsα-fragment is produced. But if APP is cleaved by the β-secretase the Aβ-peptide can be produced. To be able to influence the production of Aβ-peptides, it is essential to understand how it is decided if cleavage occurs by α- or β-secretase. At present little is known about the control of the alternate processing. Until now, the molecular mechanisms and especially the responsible cellular modulators are not understood in detail or not yet identified. To get a better understanding of cellular regulatory processes and to identify novel cellular modulators of APP ectodomain shedding, the present work chose two approaches: on the one hand cellular mechanisms of TMEM59-mediated inhibition ectodomain shedding of APP were investigated. On the other hand a genome-wide RNAi screening in Drosophila cells was performed in order to identify novel cellular modulators of APP ectodomain shedding in human cells. TMEM59 was identified as a novel modulator of APP ectodomain shedding in a cDNA expression screening in the lab (Neumann et al., 2006; Schobel et al., 2008; Schobel et al., 2006). TMEM59 is a Golgi protein that inhibits on the one hand processing and maturation of APP and on the other hand Golgi glycosylation reactions (Fischer, 2008). My own work could verify these effects of TMEM59 and its homolog TMEM59L on processing and maturation of APP. In particular, it was shown that these effects are not only true for transiently expressed APP but also for endogenous levels of APP. In detailed immunofluorescence studies it was shown that TMEM59 colocalizes with different markers of the Golgi subcompartments and that therefore TMEM59 is present throughout the whole Golgi apparatus. This finding points to a more general modulation of Golgi glycosylation reactions by TMEM59. To test if TMEM59-dependet modulation of Golgi glycosylation reactions also affects APP secretases ADAM10 and BACE1, which are also glycosylated proteins, the activities of these proteases were investigated. It was shown that proteolytic activities were not changed, ruling out that impairment of secretase activities by TMEM59 could cause the observed inhibition of APP processing. But interestingly, studies of intracellular APP transport could show that TMEM59 caused retention of APP in the Golgi apparatus and blockage of transport towards the cell surface and into endosomal compartments. Since APP is cleaved by α-secretase at the plasma membrane and by β-secretase in endosomes it is likely that a TMEM59-dependent APP transport block causes the observed inhibition of APP ectodomain shedding. For further validation of TMEM59 and its homolog TMEM59L as modulators of APP ectodomain shedding, a double knockdown study was performed. In this approach effects on APP ectodomain shedding could also be established, affirming TMEM59 and its homolog TMEM59L as modulators of APP ectodomain shedding with novel cellular mechanisms. In order to identify novel cellular modulators of APP ectodomain shedding a genome wide RNAi screening in Drosophila cells was performed and candidate genes were investigated in human cells in present work. Initially a suitable Drosophila reporter cell line expressing a reporter construct of APP ectodomain shedding (HRP-APP) was established. Other constructs were used to monitor general secretion (GLuc) and transfection efficiency (FLuc). Using Kuzbanian, the α-secretase in Drosophila (Sapir et al., 2005), as a positive control guaranteed that transfection of cDNAs into Drosophila cells did not interfere with uptake of dsRNAs or efficiency of RNAi and that the reporter construct HRP-APP is normally produced and processed in reporter cells. After successful establishment of the reporter cell line the genome wide RNAi was performed in two steps: a primary screening revealed approx. 300 candidate genes out of which 43 could be confirmed in a secondary screening to be modulators of APP ectodomain shedding. The RNAi screening was verified by the several-fold appearance of Kuzbanian among the top modulators. For further investigation of the top candidates human ortholog genes were identified. The 30 human candidate genes were investigated in RNAi studies in human SH-SY5Y cells. In these cells, APP is processed by α-secretase ADAM10 as well as by β-secretase BACE1. Therefore effects on both shedding products (APPsα and APPsβ) were investigated upon depletion of candidate genes using siRNAs. It is known that siRNAs produce a high rate of off target effects, to this end a robust validation strategy was developed. Candidate genes were first depleted with two different siRNA pools and their effects on APP shedding were compared. Afterwards the remaining 12 candidate genes were depleted using single siRNA sequences and the effects were compared to those of the siRNA pool. Only when a reproduction of effects was obtained in a next step correlation of knockdown and phenotype were assessed. Using these steps of validation 5 candidate genes could be verified as modulators of APP shedding in human cells: next to genes coding for a histone protein (HIST1H4C), a ribosomal protein (RPL36AL), a protein of the minor spliceosom (ZMAT5), an unknown gene (METTL16) and the gene VPS24 („vacuolar protein sorting-associated protein 24“), coding for a protein of intracellular protein transport, were identified. VPS24 was chosen for further validation by a pathway analysis. VPS24 belongs to the ESCRT machinery („endosomal sorting complex required for transport“) and therefore participates in endosomal-lysosomal protein transport. In further RNAi studies other members of the ESCRT machinery were depleted in human cells and effects on APP shedding were compared to VPS24 depletion. For most of the ESCRT members a consistent reduction in APPsβ production could be observed. To engross these results VPS24 was depleted by using an alternative RNAi system. With this stable knockdown approach, the knockdown phenotype could be confirmed. This stepwise validation strategy for candidate genes of the initial Drosophila RNAi screening verified VPS24 as a modulator of APP ectodomain shedding in human cells.

Regulated intramembrane proteolysis of the amyloid precursor protein (APP) by the protease activities α-, β- and γ-secretase controls the generation of the neurotoxic amyloid β peptide. APLP2, the amyloid precursor-like protein 2, is a homolog of APP, which shows functional overlap with APP, but lacks an amyloid β domain. Compared to APP, less is known about the proteolytic processing of APLP2, in particular in neurons, and the cleavage sites have not yet been determined. APLP2 is cleaved by the β-secretase BACE1 and additionally by an α-secretase activity. The two metalloproteases ADAM10 and ADAM17 have been suggested as candidate APLP2 α-secretases in cell lines. Here, we used RNA interference and found that ADAM10, but not ADAM17, is required for the constitutive α-secretase cleavage of APLP2 in HEK293 and SH-SY5Y cells. Likewise, in primary murine neurons knock-down of ADAM10 suppressed APLP2 α-secretase cleavage. Using mass spectrometry we determined the proteolytic cleavage sites in the APLP2 sequence. ADAM10 was found to cleave APLP2 after arginine 670, whereas BACE1 cleaves after leucine 659. Both cleavage sites are located in close proximity to the membrane. γ-secretase cleavage was found to occur at different peptide bonds between alanine 694 and valine 700, which is close to the N-terminus of the predicted APLP2 transmembrane domain. Determination of the APLP2 cleavage sites enables functional studies of the different APLP2 ectodomain fragments and the production of cleavage-site specific antibodies for APLP2, which may be used for biomarker development.

Ektodomänenspaltung und Intramembranproteolyse des Amyloiden Vorläufer Proteins (APP) durch Alpha-, Beta- und gamma-Sekretase sind in die Pathogenese der Alzheimer Erkrankung (AD) involviert. Eine vermehrte proteolytische Prozessierung und Sekretion eines anderen Membranproteins, des Typ II Interleukin-1 Rezeptors (IL-1R2) wurde mit der Pathogenese der Alzheimer Erkrankung in Verbindung gebracht. IL-1R2 ist ein Abfangrezeptor, welcher vermutlich in der Lage ist, die schädlichen Effekte von Interleukin-1 im Gehirn zu begrenzen. Bis jetzt ist die proteolytische Prozessierung von IL-1R2 nur wenig verstanden. In dieser Arbeit wird gezeigt, dass IL-1R2 ähnlich wie auch APP prozessiert wird. In humanen embryonalen Nierenzellen (HEK293) exprimiertes IL-1R2 unterläuft zuerst eine Spaltung der Ektodomäne durch eine Metalloprotease, was zur Freisetzung der Ektodomäne und einem in der Membran verbleibenden C-terminalen Fragment führt. Dieses Fragment wird durch Intramembranproteolyse des Gamma-Sekretase-Komplexes in eine intrazelluläre Domäne (ICD) gespalten. Die Intramembranproteolyse von IL-1R2 konnte durch einen hochspezifischen Gammasekretase-Inhibitor gehemmt werden und fehlte in Gamma-Sekretase-defizienten embryonalen Mausfibroblasten. Überraschenderweise erhöhen die Beta-Sekretase BACE1 und ihr Homolog BACE2 die Sekretion von IL-1R2, welche zu ähnlich großen C-terminalen Fragmenten wie auch bei der Alpha-Spaltung von IL-1R2 führen. Dies könnte bedeuten, dass beide Proteasen als alternative Alpha-Sekretasen agieren könnten. Darüber hinaus werden zahlreiche andere Membranproteine, die in dieser Arbeit untersucht wurden, nicht durch BACE1 und BACE2 geschnitten, was zeigt, dass beide Proteasen nicht am generellen Membranproteinumsatz beteiligt sind. Diese Arbeit zeigt, dass Il-1R2 und APP eine ähnliche proteolytische Prozessierung durchlaufen. Dies könnte somit eine Erklärung für die erhöhte Sekretion von IL-1R2 im Rahmen der Alzheimer Erkrankung sein.

Alzheimer-disease-associated beta-amyloid (A beta) is produced by sequential endoproteolysis of beta-amyloid protein precursor (beta APP): the extracellular portion is shed by cleavage in the juxtamembrane region by beta-amyloid-cleaving enzyme (BACE)/beta-secretase, after which it is cleaved by presenilin (PS)/gamma-secretase near the middle of the transmembrane domain. Thus, inhibition of either of the secretases reduces A beta generation and is a fundamental strategy for the development of drugs to prevent Alzheimer disease. However, it is not clear how small compounds reduce A beta production without inhibition of the secretases. Such compounds are expected to avoid some of the side effects of secretase inhibitors. Here, we report that destruxin E (Dx-E), a natural cyclic hexadepsipeptide, reduces A beta generation without affecting BACE or PS/gamma-secretase activity. In agreement with this, Dx-E did not inhibit Notch signaling. We found that Dx-E decreases colocalization of BACE1 and beta APP, which reduces beta-cleavage of beta APP. Therefore, the data demonstrate that Dx-E represents a novel A beta-reducing process which could have fewer side effects than secretase inhibitors. Copyright (C) 2009 S. Karger AG, Basel