N1-methylation of adenosine (m1A) in ND5 mRNA leads to complex I dysfunction in Alzheimer's disease.

One mechanism of particular interest to regulate mRNA fate post-transcriptionally is mRNA modification. Especially the extent of m1A mRNA methylation is highly discussed due to methodological differences. However, one single m1A site in mitochondrial ND5 mRNA was unanimously reported by different groups. ND5 is a subunit of complex I of the respiratory chain. It is considered essential for the coupling of oxidation and proton transport. Here we demonstrate that this m1A site might be involved in the pathophysiology of Alzheimer's disease (AD). One of the pathological hallmarks of this neurodegenerative disease is mitochondrial dysfunction, mainly induced by Amyloid ß (Aß). Aß mainly disturbs functions of complex I and IV of the respiratory chain. However, the molecular mechanism of complex I dysfunction is still not fully understood. We found enhanced m1A methylation of ND5 mRNA in an AD cell model as well as in AD patients. Formation of this m1A methylation is catalyzed by increased TRMT10C protein levels, leading to translation repression of ND5. As a consequence, here demonstrated for the first time, TRMT10C induced m1A methylation of ND5 mRNA leads to mitochondrial dysfunction. Our findings suggest that this newly identified mechanism might be involved in Aß-induced mitochondrial dysfunction.

Amyloid beta and its naturally occurring N-terminal variants are potent activators of human and mouse formyl peptide receptor 1.

Formyl peptide receptors (FPRs) may contribute to inflammation in Alzheimer's disease through interactions with neuropathological Amyloid beta (Aß) peptides. Previous studies reported activation of FPR2 by Aß1-42, but further investigation of other FPRs and Aß variants is needed. This study provides a comprehensive overview of the interactions of mouse and human FPRs with different physiologically relevant Aß-peptides using transiently transfected cells in combination with calcium imaging. We observed that, in addition to hFPR2, all other hFPRs also responded to Aß1-42, Aß1-40, and the naturally occurring variants Aß11-40 and Aß17-40. Notably, Aß11-40 and Aß17-40 are very potent activators of mouse and human FPR1, acting at nanomolar concentrations. Buffer composition and aggregation state are extremely crucial factors that critically affect the interaction of Aß with different FPR subtypes. To investigate the physiological relevance of these findings, we examined the effects of Aß11-40 and Aß17-40 on the human glial cell line U87. Both peptides induced a strong calcium flux at concentrations that are very similar to those obtained in experiments for hFPR1 in HEK cells. Further immunocytochemistry, qPCR, and pharmacological experiments verified that these responses were primarily mediated through hFPR1. Chemotaxis experiments revealed that Aß11-40 but not Aß17-40 evoked cell migration, which argues for a functional selectivity of different Aß peptides. Together, these findings provide the first evidence that not only hFPR2 but also hFPR1 and hFPR3 may contribute to neuroinflammation in Alzheimer's disease through an interaction with different Aß variants.

Assessment of technical and clinical utility of a bead-based flow cytometry platform for multiparametric phenotyping of CNS-derived extracellular vesicles.

BACKGROUND: Extracellular vesicles (EVs) originating from the central nervous system (CNS) can enter the blood stream and carry molecules characteristic of disease states. Therefore, circulating CNS-derived EVs have the potential to serve as liquid-biopsy markers for early diagnosis and follow-up of neurodegenerative diseases and brain tumors. Monitoring and profiling of CNS-derived EVs using multiparametric analysis would be a major advance for biomarker as well as basic research. Here, we explored the performance of a multiplex bead-based flow-cytometry assay (EV Neuro) for semi-quantitative detection of CNS-derived EVs in body fluids. METHODS: EVs were separated from culture of glioblastoma cell lines (LN18, LN229, NCH82) and primary human astrocytes and measured at different input amounts in the MACSPlex EV Kit Neuro, human. In addition, EVs were separated from blood samples of small cohorts of glioblastoma (GB), multiple sclerosis (MS) and Alzheimer's disease patients as well as healthy controls (HC) and subjected to the EV Neuro assay. To determine statistically significant differences between relative marker signal intensities, an unpaired samples t-test or Wilcoxon rank sum test were computed. Data were subjected to tSNE, heatmap clustering, and correlation analysis to further explore the relationships between disease state and EV Neuro data. RESULTS: Glioblastoma cell lines and primary human astrocytes showed distinct EV profiles. Signal intensities were increasing with higher EV input. Data normalization improved identification of markers that deviate from a common profile. Overall, patient blood-derived EV marker profiles were constant, but individual EV populations were significantly increased in disease compared to healthy controls, e.g. CD36+EVs in glioblastoma and GALC+EVs in multiple sclerosis. tSNE and heatmap clustering analysis separated GB patients from HC, but not MS patients from HC. Correlation analysis revealed a potential association of CD107a+EVs with neurofilament levels in blood of MS patients and HC. CONCLUSIONS: The semi-quantitative EV Neuro assay demonstrated its utility for EV profiling in complex samples. However, reliable statistical results in biomarker studies require large sample cohorts and high effect sizes. Nonetheless, this exploratory trial confirmed the feasibility of discovering EV-associated biomarkers and monitoring circulating EV profiles in CNS diseases using the EV Neuro assay. Video Abstract.

Extracellular vesicles (EVs) are tiny particles released by cells, carrying unique biomolecules specific to their cell of origin. EVs from the central nervous system (CNS) can reach the blood, where they could serve as liquid-biopsy markers for diagnosing brain diseases like neurodegenerative disorders and tumors. This study evaluated a flow cytometry platform (here termed EV Neuro assay), which can detect multiple EV-associated markers simultaneously, to assess its potential for identifying CNS-derived EVs and disease-specific markers in complex samples including the blood. The study compared different sample materials and methods for isolating EVs. We found distinct EV profiles in EVs derived from glioblastoma and human astrocytes, with signal intensities increasing as more EVs were present. Analyzing serum or plasma from patients with brain diseases and healthy individuals, we observed that EV marker intensities were varying between individuals. Importantly, data normalization improved the identification of disease-specific markers, such as CD36⁺EVs in glioblastoma and GALC⁺EVs in multiple sclerosis, which were significantly higher in disease compared to healthy controls. Advanced clustering analysis techniques effectively distinguished glioblastoma patients from controls. Furthermore, a potential correlation between CD107a⁺EVs and neurofilament levels in multiple sclerosis patients was discovered. Overall, the semi-quantitative EV Neuro assay proved useful for profiling EVs in complex samples. However, for more reliable results in biomarker studies, larger sample cohorts and higher effect sizes are necessary. Nonetheless, this initial trial confirmed the potential of the EV Neuro assay for discovering disease-associated EV markers and monitoring circulating EV profiles in CNS diseases.

Talk to Me-Interplay between Mitochondria and Microbiota in Aging.

The existence of mitochondria in eukaryotic host cells as a remnant of former microbial organisms has been widely accepted, as has their fundamental role in several diseases and physiological aging. In recent years, it has become clear that the health, aging, and life span of multicellular hosts are also highly dependent on the still-residing microbiota, e.g., those within the intestinal system. Due to the common evolutionary origin of mitochondria and these microbial commensals, it is intriguing to investigate if there might be a crosstalk based on preserved common properties. In the light of rising knowledge on the gut-brain axis, such crosstalk might severely affect brain homeostasis in aging, as neuronal tissue has a high energy demand and low tolerance for according functional decline. In this review, we summarize what is known about the impact of both mitochondria and the microbiome on the host's aging process and what is known about the aging of both entities. For a long time, bacteria were assumed to be immortal; however, recent evidence indicates their aging and similar observations have been made for mitochondria. Finally, we present pathways by which mitochondria are affected by microbiota and give information about therapeutic anti-aging approaches that are based on current knowledge.

The Aging Enteric Nervous System.

The gut and the brain communicate via the nervous system, hormones, microbiota-mediated substances, and the immune system. These intricate interactions have led to the term "gut-brain axis". Unlike the brain-which is somewhat protected-the gut is exposed to a variety of factors throughout life and, consequently, might be either more vulnerable or better adapted to respond to these challenges. Alterations in gut function are common in the elder population and associated with many human pathologies, including neurodegenerative diseases. Different studies suggest that changes in the nervous system of the gut, the enteric nervous system (ENS), during aging may result in gastrointestinal dysfunction and initiate human pathologies of the brain via its interconnection with the gut. This review aims at summarizing the contribution of normal cellular aging to the age-associated physiological changes of the ENS. Morphological alterations and degeneration of the aging ENS are observed in different animal models and humans, albeit with considerable variability. The aging phenotypes and pathophysiological mechanisms of the aging ENS have highlighted the involvement of enteric neurons in age-related diseases of the central nervous system such as Alzheimer's or Parkinson's disease. To further elucidate such mechanisms, the ENS constitutes a promising source of material for diagnosis and therapeutic predictions, as it is more accessible than the brain.

How biological sex of the host shapes its gut microbiota.

The gut microbiota is a complex system, consisting of a dynamic population of microorganisms, involved in the regulation of the host's homeostasis. A vast number of factors are driving the gut microbiota composition including diet, antibiotics, environment, and lifestyle. However, in the past decade, a growing number of studies also focused on the role of sex in relationship to changes in the gut microbiota composition in animal experiments as well as in human beings. Despite the progress in investigation techniques, still little is known about the mechanism behind the observed sex-related differences. In this review, we summarized current knowledge on the sex-dependent differences of the intestinal commensals and discuss the probable direct impact of sex hormones and more indirect effects such as dietary habits or antibiotics. While we have to conclude limited data on specific developmental stages, a clear role for sexual hormones and most probably for testosterone emerges.

Brothers in arms: proBDNF/BDNF and sAPPα/Aß-signaling and their common interplay with ADAM10, TrkB, p75NTR, sortilin, and sorLA in the progression of Alzheimer's disease.

Brain-derived neurotrophic factor (BDNF) is an important modulator for a variety of functions in the central nervous system (CNS). A wealth of evidence, such as reduced mRNA and protein level in the brain, cerebrospinal fluid (CSF), and blood samples of Alzheimer's disease (AD) patients implicates a crucial role of BDNF in the progression of this disease. Especially, processing and subcellular localization of BDNF and its receptors TrkB and p75 are critical determinants for survival and death in neuronal cells. Similarly, the amyloid precursor protein (APP), a key player in Alzheimer's disease, and its cleavage fragments sAPPα and Aß are known for their respective roles in neuroprotection and neuronal death. Common features of APP- and BDNF-signaling indicate a causal relationship in their mode of action. However, the interconnections of APP- and BDNF-signaling are not well understood. Therefore, we here discuss dimerization properties, localization, processing by α- and γ-secretase, relevance of the common interaction partners TrkB, p75, sorLA, and sortilin as well as shared signaling pathways of BDNF and sAPPα.

A liquid-culture-based screening approach to study compounds affecting inflammatory processes in Caenorhabditis elegans.

Discovery of biomedical drugs makes use of novel biological sources of limited availability and is often in need of fast, small-scale initial screening approaches. Here, we present a screening, based on the reporter Caenorhabditis elegans strain IG692, for identification of anti- and pro-inflammatory properties. The elaborated workflow is based on cultivation in fluid and by this, allows fast and reproducible seeding in 96 well plates. LPS and dexamethasone served as reliable controls, comparable to application in the human cell line THP-1. This in vivo approach offers a first step for selection of e.g. natural products or for repurposing of compounds from drug libraries and by this can serve as a tool in drug discovery for inflammatory human diseases.

The role of mycotoxins in neurodegenerative diseases: current state of the art and future perspectives of research.

Mycotoxins are fungal metabolites that can cause various diseases in humans and animals. The adverse health effects of mycotoxins such as liver failure, immune deficiency, and cancer are well-described. However, growing evidence suggests an additional link between these fungal metabolites and neurodegenerative diseases. Despite the wealth of these initial reports, reliable conclusions are still constrained by limited access to human patients and availability of suitable cell or animal model systems. This review summarizes knowledge on mycotoxins associated with neurodegenerative diseases and the assumed underlying pathophysiological mechanisms. The limitations of the common in vivo and in vitro experiments to identify the role of mycotoxins in neurotoxicity and thereby in neurodegenerative diseases are elucidated and possible future perspectives to further evolve this research field are presented.

Emerging contributions of formyl peptide receptors to neurodegenerative diseases.

Inflammation is a central element of many neurodegenerative diseases. Formyl peptide receptors (FPRs) can trigger several receptor-dependent signal transduction pathways that play a key role in neuroinflammation and neurodegeneration. They are chemotactic receptors that help to regulate pro- and anti-inflammatory responses in most mammals. FPRs are primarily expressed in the immune and nervous systems where they interact with a complex pattern of pathogen-derived and host-endogenous molecules. Mounting evidence points towards a contribution of FPRs - via neuropathological ligands such as Amyloid beta, and neuroprotective ligands such as Humanin, Lipoxin A4, and Annexin A1 - to multiple pathological aspects of neurodegenerative diseases. In this review, we aim to summarize the interplay of FPRs with neuropathological and neuroprotective ligands. Next, we depict their capability to trigger a number of ligand-dependent cell signaling pathways and their potential to interact with additional intracellular cofactors. Moreover, we highlight first studies, demonstrating that a pharmacological inhibition of FPRs helps to ameliorate neuroinflammation, which may pave the way towards novel therapeutic strategies.

Artemisinin-treatment in pre-symptomatic APP-PS1 mice increases gephyrin phosphorylation at Ser270: a modification regulating postsynaptic GABAAR density.

Artemisinins, a group of plant-derived sesquiterpene lactones, are efficient antimalarial agents. They also share anti-inflammatory and anti-viral activities and were considered for treatment of neurodegenerative disorders like Alzheimer's disease (AD). Additionally, artemisinins bind to gephyrin, the multifunctional scaffold of GABAergic synapses, and modulate inhibitory neurotransmission in vitro. We previously reported an increased expression of gephyrin and GABAA receptors in early pre-symptomatic stages of an AD mouse model (APP-PS1) and in parallel enhanced CDK5-dependent phosphorylation of gephyrin at S270. Here, we studied the effects of artemisinin on gephyrin in the brain of young APP-PS1 mice. We detected an additional increase of gephyrin protein level, elevated gephyrin phosphorylation at Ser270, and an increased amount of GABAAR-γ2 subunits after artemisinin-treatment. Interestingly, the CDK5 activator p35 was also upregulated. Moreover, we demonstrate decreased density of postsynaptic gephyrin and GABAAR-γ2 immunoreactivities in cultured hippocampal neurons expressing gephyrin with alanine mutations at two CDK5 phosphorylation sites. In addition, the activity-dependent modulation of synaptic protein density was abolished in neurons expressing gephyrin lacking one or both of these phosphorylation sites. Thus, our results reveal that artemisinin modulates expression as well as phosphorylation of gephyrin at sites that might have important impact on GABAergic synapses in AD.

Behavioral Phenotyping of Bbs6 and Bbs8 Knockout Mice Reveals Major Alterations in Communication and Anxiety.

The primary cilium is an organelle with a central role in cellular signal perception. Mutations in genes that encode cilia-associated proteins result in a collection of human syndromes collectively termed ciliopathies. Of these, the Bardet-Biedl syndrome (BBS) is considered one of the archetypical ciliopathies, as patients exhibit virtually all respective clinical phenotypes, such as pathological changes of the retina or the kidney. However, the behavioral phenotype associated with ciliary dysfunction has received little attention thus far. Here, we extensively characterized the behavior of two rodent models of BBS, Bbs6/Mkks, and Bbs8/Ttc8 knockout mice concerning social behavior, anxiety, and cognitive abilities. While learning tasks remained unaffected due to the genotype, we observed diminished social behavior and altered communication. Additionally, Bbs knockout mice displayed reduced anxiety. This was not due to altered adrenal gland function or corticosterone serum levels. However, hypothalamic expression of Lsamp, the limbic system associated protein, and Adam10, a protease acting on Lsamp, were reduced. This was accompanied by changes in characteristics of adult hypothalamic neurosphere cultures. In conclusion, we provide evidence that behavioral changes in Bbs knockout mice are mainly found in social and anxiety traits and might be based on an altered architecture of the hypothalamus.

The Influence of Acitretin on Brain Lipidomics in Adolescent Mice-Implications for Pediatric and Adolescent Dermatological Therapy.

Administration of systemic retinoids such as acitretin has not been approved yet for pediatric patients. An adverse event of retinoid-therapy that occurs with lower prevalence in children than in adults is hyperlipidemia. This might be based on the lack of comorbidities in young patients, but must not be neglected. Especially for the development of the human brain up to young adulthood, dysbalance of lipids might be deleterious. Here, we provide for the first time an in-depth analysis of the influence of subchronic acitretin-administration on lipid composition of brain parenchyma of young wild type mice. For comparison and to evaluate the systemic effect of the treatment, liver lipids were analogously investigated. As expected, triglycerides increased in liver as well as in brain and a non-significant increase in cholesterol was observed. However, specifically brain showed an increase in lyso-phosphatidylcholine and carnitine as well as in sphingomyelin. Group analysis of lipid classes revealed no statistical effects, while single species were tissue-dependently changed: effects in brain were in general more subtly as compared to those in liver regarding the mere number of changed lipid species. Thus, while the overall impact of acitretin seems comparably small regarding brain, the change in individual species and their role in brain development and maturation has to be considered.

Alzheimer's disease in the gut-Major changes in the gut of 5xFAD model mice with ApoA1 as potential key player.

Alzheimer's disease (AD) affects around 33 million people worldwide, which makes it the most prominent form of dementia. The main focus of AD research has been on the central nervous system (CNS) for long, but in recent years, the gut gained more attention. The intestinal tract is innervated by the enteric nervous system (ENS), built of numerous different types of neurons showing great similarity to neurons of the CNS. It already has been demonstrated that the amyloid precursor protein, which plays a major role in AD pathology, is also expressed in these cells. We analyzed gut tissue of AD model mice (5xFAD) and the respective wild-type littermates at different pathological stages: pre-pathological, early pathological and late pathological. Our results show significant difference in function of the intestine of 5xFAD mice as compared to wild-type mice. Using a pathway array detecting 84 AD-related gene products, we found ApoA1 expression significantly altered in colon tissue of 5xFAD mice. Furthermore, we unveil ApoA1's beneficial impact on cell viability and calcium homeostasis of cultured enteric neurons of 5xFAD animals. With this study, we demonstrate that the intestine is altered in AD-like pathology and that ApoA1 might be one key player within the gut.

Influence of Acetylcholine Esterase Inhibitors and Memantine, Clinically Approved for Alzheimer's Dementia Treatment, on Intestinal Properties of the Mouse.

Four drugs are currently approved for the treatment of Alzheimer's disease (AD) by the FDA. Three of these drugs-donepezil, rivastigmine, and galantamine-belong to the class of acetylcholine esterase inhibitors. Memantine, a NMDA receptor antagonist, represents the fourth and a combination of donepezil and memantine the fifth treatment option. Recently, the gut and its habitants, its microbiome, came into focus of AD research and added another important factor to therapeutic considerations. While the first data provide evidence that AD patients might carry an altered microbiome, the influence of administered drugs on gut properties and commensals have been largely ignored so far. However, the occurrence of digestive side effects with these drugs and the knowledge that cholinergic transmission is crucial for several gut functions enforces the question if, and how, this medication influences the gastrointestinal system and its microbial stocking. Here, we investigated aspects such as microbial viability, colonic propulsion, and properties of enteric neurons, affected by assumed intestinal concentration of the four drugs using the mouse as a model organism. All ex vivo administered drugs revealed no direct effect on fecal bacteria viability and only a high dosage of memantine resulted in reduced biofilm formation of E. coli. Memantine was additionally the only compound that elevated calcium influx in enteric neurons, while all acetylcholine esterase inhibitors significantly reduced esterase activity in colonic tissue specimen and prolonged propulsion time. Both, acetylcholine esterase inhibitors and memantine, had no effect on general viability and neurite outgrowth of enteric neurons. In sum, our findings indicate that all AD symptomatic drugs have the potential to affect distinct intestinal functions and with this-directly or indirectly-microbial commensals.

mTOR Driven Gene Transcription Is Required for Cholesterol Production in Neurons of the Developing Cerebral Cortex.

Dysregulated mammalian target of rapamycin (mTOR) activity is associated with various neurodevelopmental disorders ranging from idiopathic autism spectrum disorders (ASD) to syndromes caused by single gene defects. This suggests that maintaining mTOR activity levels in a physiological range is essential for brain development and functioning. Upon activation, mTOR regulates a variety of cellular processes such as cell growth, autophagy, and metabolism. On a molecular level, however, the consequences of mTOR activation in the brain are not well understood. Low levels of cholesterol are associated with a wide variety of neurodevelopmental disorders. We here describe numerous genes of the sterol/cholesterol biosynthesis pathway to be transcriptionally regulated by mTOR complex 1 (mTORC1) signaling in vitro in primary neurons and in vivo in the developing cerebral cortex of the mouse. We find that these genes are shared targets of the transcription factors SREBP, SP1, and NF-Y. Prenatal as well as postnatal mTORC1 inhibition downregulated expression of these genes which directly translated into reduced cholesterol levels, pointing towards a substantial metabolic function of the mTORC1 signaling cascade. Altogether, our results indicate that mTORC1 is an essential transcriptional regulator of the expression of sterol/cholesterol biosynthesis genes in the developing brain. Altered expression of these genes may be an important factor contributing to the pathogenesis of neurodevelopmental disorders associated with dysregulated mTOR signaling.

Primary Cilia Structure Is Prolonged in Enteric Neurons of 5xFAD Alzheimer's Disease Model Mice.

Neurodegenerative diseases such as Alzheimer's disease (AD) have long been acknowledged as mere disorders of the central nervous system (CNS). However, in recent years the gut with its autonomous nervous system and the multitude of microbial commensals has come into focus. Changes in gut properties have been described in patients and animal disease models such as altered enzyme secretion or architecture of the enteric nervous system. The underlying cellular mechanisms have so far only been poorly investigated. An important organelle for integrating potentially toxic signals such as the AD characteristic A-beta peptide is the primary cilium. This microtubule-based signaling organelle regulates numerous cellular processes. Even though the role of primary cilia in a variety of developmental and disease processes has recently been recognized, the contribution of defective ciliary signaling to neurodegenerative diseases such as AD, however, has not been investigated in detail so far. The AD mouse model 5xFAD was used to analyze possible changes in gut functionality by organ bath measurement of peristalsis movement. Subsequently, we cultured primary enteric neurons from mutant mice and wild type littermate controls and assessed for cellular pathomechanisms. Neurite mass was quantified within transwell culturing experiments. Using a combination of different markers for the primary cilium, cilia number and length were determined using fluorescence microscopy. 5xFAD mice showed altered gut anatomy, motility, and neurite mass of enteric neurons. Moreover, primary cilia could be demonstrated on the surface of enteric neurons and exhibited an elongated phenotype in 5xFAD mice. In parallel, we observed reduced ß-Catenin expression, a key signaling molecule that regulates Wnt signaling, which is regulated in part via ciliary associated mechanisms. Both results could be recapitulated via in vitro treatments of enteric neurons from wild type mice with A-beta. So far, only a few reports on the probable role of primary cilia in AD can be found. Here, we reveal for the first time an architectural altered phenotype of primary cilia in the enteric nervous system of AD model mice, elicited potentially by neurotoxic A-beta. Potential changes on the sub-organelle level-also in CNS-derived neurons-require further investigations.

Transcriptional repression of the ectodomain sheddase ADAM10 by TBX2 and potential implication for Alzheimer's disease.

BACKGROUND: The ADAM10-mediated cleavage of transmembrane proteins regulates cellular processes such as proliferation or migration. Substrate cleavage by ADAM10 has also been implicated in pathological situations such as cancer or Morbus Alzheimer. Therefore, identifying endogenous molecules, which modulate the amount and consequently the activity of ADAM10, might contribute to a deeper understanding of the enzyme's role in both, physiology and pathology. METHOD: To elucidate the underlying cellular mechanism of the TBX2-mediated repression of ADAM10 gene expression, we performed overexpression, RNAi-mediated knockdown and pharmacological inhibition studies in the human neuroblastoma cell line SH-SY5Y. Expression analysis was conducted by e.g. real-time RT-PCR or western blot techniques. To identify the binding region of TBX2 within the ADAM10 promoter, we used luciferase reporter assay on deletion constructs and EMSA/WEMSA experiments. In addition, we analyzed a TBX2 loss-of-function Drosophila model regarding the expression of ADAM10 orthologs by qPCR. Furthermore, we quantified the mRNA level of TBX2 in post-mortem brain tissue of AD patients. RESULTS: Here, we report TBX2 as a transcriptional repressor of ADAM10 gene expression: both, the DNA-binding domain and the repression domain of TBX2 were necessary to effect transcriptional repression of ADAM10 in neuronal SH-SY5Y cells. This regulatory mechanism required HDAC1 as a co-factor of TBX2. Transcriptional repression was mediated by two functional TBX2 binding sites within the core promoter sequence (- 315 to - 286 bp). Analysis of a TBX2 loss-of-function Drosophila model revealed that kuzbanian and kuzbanian-like, orthologs of ADAM10, were derepressed compared to wild type. Vice versa, analysis of cortical brain samples of AD-patients, which showed reduced ADAM10 mRNA levels, revealed a 2.5-fold elevation of TBX2, while TBX3 and TBX21 levels were not affected. CONCLUSION: Our results characterize TBX2 as a repressor of ADAM10 gene expression and suggest that this regulatory interaction is conserved across tissues and species.

Dietary Wheat Amylase Trypsin Inhibitors Impact Alzheimer's Disease Pathology in 5xFAD Model Mice.

Wheat amylase trypsin inhibitors (ATIs) represent a common dietary protein component of gluten-containing cereals (wheat, rye, and barley). They act as toll-like receptor 4 ligands, and are largely resistant to intestinal proteases, eliciting a mild inflammatory response within the intestine after oral ingestion. Importantly, nutritional ATIs exacerbated inflammatory bowel disease and features of fatty liver disease and the metabolic syndrome in mice. For Alzheimer's disease (AD), both inflammation and altered insulin resistance are major contributing factors, impacting onset as well as progression of this devastating brain disorder in patients. In this study, we evaluated the impact of dietary ATIs on a well-known rodent model of AD (5xFAD). We assessed metabolic, behavioral, inflammatory, and microbial changes in mice consuming different dietary regimes with and without ATIs, consumed ad libitum for eight weeks. We demonstrate that ATIs, with or without a gluten matrix, had an impact on the metabolism and gut microbiota of 5xFAD mice, aggravating pathological hallmarks of AD. If these findings can be translated to patients, an ATI-depleted diet might offer an alternative therapeutic option for AD and warrants clinical intervention studies.

Amyloidogenic Peptides in Human Neuro-Degenerative Diseases and in Microorganisms: A Sorrow Shared Is a Sorrow Halved?

The term "amyloid" refers to proteinaceous deposits of peptides that might be generated from larger precursor proteins e.g., by proteolysis. Common to these peptides is a stable cross-ß dominated secondary structure which allows self-assembly, leading to insoluble oligomers and lastly to fibrils. These highly ordered protein aggregates have been, for a long time, mainly associated with human neurodegenerative diseases such as Alzheimer's disease (Amyloid-ß peptides). However, they also exert physiological functions such as in release of deposited hormones in human beings. In the light of the rediscovery of our microbial commensals as important companions in health and disease, the fact that microbes also possess amyloidogenic peptides is intriguing. Transmission of amyloids by iatrogenic means or by consumption of contaminated meat from diseased animals is a well-known fact. What if also our microbial commensals might drive human amyloidosis or suffer from our aggregated amyloids? Moreover, as the microbial amyloids are evolutionarily older, we might learn from these organisms how to cope with the sword of Damocles forged of endogenous, potentially toxic peptides. This review summarizes knowledge about the interplay between human amyloids involved in neurodegenerative diseases and microbial amyloids.