Title Promoter Affiliations Abstract "Role y-secretase heterogeneity in intracellular AB production, lysosomal toxicity, and pathogenesis: contribution of familial Alzheimer’s disease mutations in presenilins and late onset Alzheimer’s disease risk factors" "Wim Annaert" "Laboratory of Membrane Trafficking (VIB-KU Leuven)" "Alzheimer’s disease (AD) is characterized by amyloid β (Aβ) plaques and tangles. These hallmarks appear relatively late in disease stirring the debate whether they are a consequence of earlier pathogenic processes. Herein intracellular Aβ accumulation precede their formation, and correlates better with synaptic dysfunction and cognitive decline. Our recent data suggest that the composition of Aβ yielding γ-secretase complexes plays a role in this phenomenon. Here, presenilin 2 (PSEN2) assemblies, unlike those of PSEN1, more prominently affect intracellular Aβ production. Ongoing experiments also imply that PSEN2 expression is under control of PSEN1, suggesting an intriguing molecular crosstalk that could keep the levels of intracellular Aβ in check. Thus, factors that distort the subcellular localization of PSEN2-complexes and/or expression may affect the internal Aβ pool. In this project we aim to: identify key regulators involved in PSEN1 control of PSEN2 levels andtest if these are influenced by familial AD mutations.Furthermore, we will test if PSEN2 localization/levels are affected by altered expression of late onset AD risk genes. This knowledge will be tested in engineered differentiated neurons on lysosome function in turnover and degradation. These complementary approaches may provide further insights into mechanisms that underlie intracellular Aβ pile up and deepen our understanding of processes that govern early stages of AD." "Role of Presenilin2 deficiency and familial Alzheimer's disease mutants in intracellular Abeta accumulation and Alzheimer's disease pathology" "Wim Annaert" "Laboratory of Membrane Trafficking (VIB-KU Leuven)" "Alzheimer’s disease (AD) is characterized by the progressive build-up of amyloid-beta (AB) in plaques. gamma-Secretase processing releases AB from the amyloid precursor protein and comes in different flavours because of the existence of two presenilins and APH1 isoforms. Distinct complexes generate slightly different AB profiles and familial AD linked mutations in PSENs shift the production to longer AB species which aggregate more easily. PSEN1/gamma-secretase is broadly distributed in neurons, whereas PSEN2/gamma-secretase is restricted to late endosomes/lysosomes where it majorly produces the pathological relevant intracellular AB pool. Unexpectedly, PSEN2 deficiency results in higher AB production and increased plaque load in a transgenic AD model pointing to a potential protective role of PSEN2 in AD pathology. I postulate that in normal, healthy conditions, part of APP is processed via PSEN2/gamma-secretase providing a clearance pathway for AB accumulation as long as lysosomes are intact. In PSEN2 deficiency, all APP is processed through PSEN1/gamma-secretase resulting in increased AB secretion and plaque formation. We further predict that in case of FAD-PSEN2 mutations, intracellular toxic AB is strongly promoted leading to its aggregation and ultimately lysosomal dysfunction/damage. To test this hypothesis I will develop new PSEN2-targeted AD models and evaluate in vivo, and including cellular models derived from these models, AD pathology, AB profiles and lysosomal function" "Investigation of the disease modification potential of early life prolonged antiepileptogenic treatments in established Alzheimer's disease mouse models." "Sebastiaan Engelborghs" "Neurochemistry and behaviour" "Alzheimer's disease (AD) is the most frequent global cause of severe cognitive impairment. Epilepsy, characterised by repetitive unprovoked seizures, is more prevalent in AD patients than in healthy controls. We hypothesise that subclinical epileptic phenomena occur in a considerable part of AD patients which aggravates cognitive decline. We therefore propose an intervention with antiseizure drugs early in the disease course as a possible disease modifying therapy. We will test this hypothesis in well-established transgenic AD mouse models. First, we will investigate the onset and frequency of epileptiform discharges in AD mice and how cognitive performance in memory tasks is influenced. Next, AD mice will be chronically treated with a clinically used antiseizure drug levetiracetam or with a ghrelin receptor agonist in development. Ghrelin is an endogenous mediator, mainly involved in metabolism. Research has indicated that ghrelin inhibits cognitive deficits in AD and reduces seizures in epilepsy mouse models. We will assess the effect of both treatments on epileptiform biomarkers, cognitive performance and various markers indicative of AD progression." "Investigation of the disease modification potential of early life prolonged antiepileptogenic treatments in established Alzheimer's disease mouse models." "Ilse Smolders" "Middelheim General Hospital, University of Antwerp, Pharmaceutical and Pharmacological Sciences" "Alzheimer's disease (AD) is the most frequent global cause of severe cognitive impairment. Epilepsy, characterised by repetitive unprovoked seizures, is more prevalent in AD patients than in healthy controls. We hypothesise that subclinical epileptic phenomena occur in a considerable part of AD patients which aggravates cognitive decline. We therefore propose an intervention with antiseizure drugs early in the disease course as a possible disease modifying therapy. We will test this hypothesis in well-established transgenic AD mouse models. First, we will investigate the onset and frequency of epileptiform discharges in AD mice and how cognitive performance in memory tasks is influenced. Next, AD mice will be chronically treated with a clinically used antiseizure drug levetiracetam or with a ghrelin receptor agonist in development. Ghrelin is an endogenous mediator, mainly involved in metabolism. Research has indicated that ghrelin inhibits cognitive deficits in AD and reduces seizures in epilepsy mouse models. We will assess the effect of both treatments on epileptiform biomarkers, cognitive performance and various markers indicative of AD progression." "Investigating the influence of astrocytes on functional network disruptions and amyloid pathology at early disease stages in a mouse model of Alzheimer's disease" "Bart De Strooper" "Laboratory for the Research of Neurodegenerative Diseases (VIB-KU Leuven)" "Alzheimer’s disease (AD) is the most common type of dementia in the elderly population. There are symptomatic treatments that can delay further symptom progression, but currently there is no cure. Efficient treatment development requires a) knowledge on early mechanisms during AD progression and b) tools that allow follow up of disease and treatment effects in a clinically translational way. AD pathology includes the formation of toxic soluble amyloid beta (Aβ) peptides that aggregate to plaques, followed by tau pathology and neuronal loss. Studies in mouse models show that astrocytes are disrupted before Aβ plaques deposition, possibly leading to brain function deficits. In this project we will apply a powerful combination of techniques in a mouse model of Aβ pathology to evaluate brain function at different scales. Firstly, we will use functional MRI to study functional network in the brain. This imaging method is used routinely in human AD research, facilitating translation of our findings to clinical settings. Secondly, we will use two-photon microscopy and cell type-specific modulations to investigate the contribution of astrocytes to a) the disruptions of brain functional networks measured with MRI and b) to disease progression. This will provide insight into disease mechanisms and potential targets for treatment development. By using the combination of these techniques we aim to bridge the gap between fundamental and translational research. " "The role of protein aggregate maturation in Alzheimer's disease and other neurodegenerative disorders and its potential for disease monitoring and differential diagnosis." "Dietmar Thal" "Translational Cell & Tissue Research" "This project aims at identifying changes in the composition of Alzheimer’s disease (AD)-related protein aggregates throughout preclinical and clinical stages of the disease. Moreover, we want to find out whether such “maturation changes” can be clinically detected by specific biomarkers or may represent potential therapeutic targets. To address these aims we analyze human brain tissue samples from non-AD, preclinical AD, and symptomatic AD cases pathologically and biochemically. Thus, we will employ immunoprecipitation techniques and mass spectrometry to identify novel proteins bound to AD-related protein aggregates, i.e. amyloid aggregates and tau-protein containing neurofibrillary tangles. Moreover, PET-tracer candidates will be tested in vitro for their binding properties to such aggregates in different stages of the AD pathogenesis. Thereby, we will find out which pathologies and what stages of the respective pathologies can be detected with these biomarkers. To test the disease propagating potential of protein aggregates at different stages of the disease we will isolate them from respective human brain samples and inject them into the brains of transgenic mouse models for AD-related pathologies. With the results from these experiments we will know which steps in the disease progression of AD are suited for therapeutic interaction and which potential target proteins exist to interact with." "Unraveling molecular pathways underlying synergistic cellular toxicity of Aß peptides and protein Tau, the two key players involved in Alzheimer’s disease." "Joris Winderickx" "Molecular Biotechnology of Plants and Micro-organisms" "Alzheimers’s Disease (AD) is the most common neurodegenerative disorder. Today, more than 35 million people are suffering from dementia such as AD, a number that has been estimated to double every 20 years. Brains from AD patients have two major hallmarks. They contain intracellular deposits of hyperphosphorylated protein Tau, known as neurofibrillary tangles as well as extracellular deposits of Aß peptides, known as amyloid plaques. Despite enormous efforts, the exact molecular mechanisms underlying the pathology and neuronal loss in AD brain are still not known. According to the current working hypothesis, the accumulation of intracellular oligomeric complexes of Aß-peptides induces cytotoxicity and cellular stress, which in turn activates stresssensitive kinases that hyper-phosphorylate and induce oligomerization and aggregation of protein Tau. For this project, we recently validated a yeast-based model displaying synergistic toxicity when human Aß and protein Tau are co-expressed. This offers us a unique and valuable tool to decipher the molecular mechanisms and processes underlying the observed toxicity. As such, we will perform genome-wide screenings to identify proteins that modulate Aß and Tau toxicity in yeast and confirm their mode of action in mammalian models for AD. Besides obtaining fundamental insight, our data will allow to characterize potential novel biomarkers and targets for therapeutic intervention." "The role of microglia in the pathogenesis of Alzheimer’s Disease" "Bart De Strooper" "Laboratory for the Research of Neurodegenerative Diseases (VIB-KU Leuven)" "Accumulation of misfolded, aggregated proteins and the associated neuronal cell loss are characteristic hallmarks of neurodegenerative diseases, including Alzheimer’s disease (AD). AD is characterized by the deposition of extracellular amyloid β (Aβ)-plaques, intracellular hyperphosphorylated Tau tangles, neuroinflammation, and neuronal loss. The classical dogma of AD describes Aβ as causing factor, which then, by uncharacterized mechanisms, induces Tau hyperphosphorylation and aggregation, and finally leads to neuronal degeneration1–3. Microglia, the resident immune cells of the brain, orchestrate the neuroinflammation in response to the accumulating Aβ plaques and have been hypothesized as an important player AD progression. This hypothesis is further fueled by the observations from recent genome-wide association studies (GWAS)4–6. Many AD risk genes are expressed in microglia7–9. However, the role of inflammation in the pathological cascade of AD is not well understood10–13. In this study, we aim to establish the role of microglia in the pathogenesis of AD. While AD is characterized by Aβ plaques, Tau tangles, and neuronal loss, currently available rodent models do not sufficiently model the AD pathology14–16. Interestingly, iPSC-derived human neurons grafted into amyloid-bearing mice showed that the neurons integrate well, and develop AD-relevant pathologies16,17. Intriguingly these human neurons display Tau pathology and cell death which is not apparent in control mice. It is important to note that these changes are specific to human neurons and not observed in the host mouse neurons16,17. Therefore, this model represents a superior approach to model phenotypes related to AD. In this project, we investigate to what extent neuroinflammation mediated by microglia contribute to pTau and neuronal cell death in the chimeric model of AD. To delineate the role of neuroinflammation in the pathogenesis of AD, we use AppNL-G-F/ Rag2-/- (amyloid mice) which develop amyloid pathology as early as 3 months old, and Apphu/hu/ Rag2-/- (control) mice. We will transplant human stem cell-derived neuronal precursor cells into the brains of immunodeficient AppNL-G-F/ Rag2-/- and Apphu/hu/ Rag2-/-. To study the role of microglia, we will deplete microglia in AppNL-G-F/Rag2-/- mice using PLX3397 treatment. Myeloid lineage cells are dependent on colony-stimulating factor 1 receptor (CSF1R) signaling. Using a selective CSF1R inhibitor like PLX3397, almost all microglia in the brain are depleted in about 21 days18. We will quantify the cell death of the grafted neurons in these models at different time points and perform immunofluorescence analysis. We will mainly focus on necroptosis since the necroptosis pathway is activated in AD brains and correlates well with Braak stages and neurodegeneration3,19. Additionally, we will conduct single nuclei sequencing, as well as bulk sequencing of the grafted neurons. With this approach, we hope to identify differences in neuronal death, morphology, and transcriptional profile of the xenografted cells and the pathology of the mouse brains, which we will explore further. References 1. Hardy, J. A. & Higgins, G. A. Alzheimer’s disease: the amyloid cascade hypothesis. Science 256, 184–185 (1992). 2. Hardy, J. & Selkoe, D. J. The amyloid hypothesis of Alzheimer’s disease: Progress and problems on the road to therapeutics. Science 297, 353–356 (2002). 3. Koper, M. J. et al. Necrosome complex detected in granulovacuolar degeneration is associated with neuronal loss in Alzheimer’s disease. Acta Neuropathol. 139, 463–484 (2020). 4. Jansen, I. E. et al. Genome-wide meta-analysis identifies new loci and functional pathways influencing Alzheimer’s disease risk. Nat. Genet. 51, 404–413 (2019). 5. Bertram, L. et al. Genome-wide Association Analysis Reveals Putative Alzheimer’s Disease Susceptibility Loci in Addition to APOE. Am. J. Hum. Genet. 83, 623–632 (2008). 6. Guerreiro, R. et al. TREM2 variants in AD. N. Engl. J. Med. 368, 117–127 (2013). 7. Sala Frigerio, C. et al. The Major Risk Factors for Alzheimer’s Disease: Age, Sex, and Genes Modulate the Microglia Response to Aβ Plaques. Cell Rep. 27, 1293-1306.e6 (2019). 8. Sierksma, A., Escott-Price, V. & De Strooper, B. Translating genetic risk of Alzheimer’s disease into mechanistic insight and drug targets. Science (80-. ). 370, 61–66 (2020). 9. Sierksma, A. et al. Novel Alzheimer risk genes determine the microglia response to amyloid‐β but not to TAU pathology. EMBO Mol. Med. 12, 1–18 (2020). 10. Hansen, D. V, Hanson, J. E. & Sheng, M. Microglia in Alzheimer ’ s disease. J. Cell Biol. 217, 459–472 (2018). 11. Ulland, T. K. & Colonna, M. TREM2 - a key player in microglial biology and Alzheimer disease. Nat. Rev. Neurol. 14, 667–675 (2018). 12. Kepp, K. P. Ten Challenges of the Amyloid Hypothesis of Alzheimer’s Disease. J. Alzheimer’s Dis. 55, 447–457 (2017). 13. De Strooper, B. & Karran, E. The Cellular Phase of Alzheimer’s Disease. Cell 164, 603–615 (2016). 14. Kuo, Y. M. et al. Comparative Analysis of Amyloid-β Chemical Structure and Amyloid Plaque Morphology of Transgenic Mouse and Alzheimer’s Disease Brains. J. Biol. Chem. 276, 12991–12998 (2001). 15. Maeda, J. et al. Longitudinal, quantitative assessment of amyloid, neuroinflammation, and anti-amyloid treatment in a living mouse model of Alzheimer’s disease enabled by positron emission tomography. J. Neurosci. 27, 10957–10968 (2007). 16. Espuny-Camacho, I. et al. Hallmarks of Alzheimer’s Disease in Stem-Cell-Derived Human Neurons Transplanted into Mouse Brain. Neuron 93, 1066-1081.e8 (2017). 17. Linaro, D. et al. Xenotransplanted Human Cortical Neurons Reveal Species-Specific Development and Functional Integration into Mouse Visual Circuits. Neuron 104, 972-986.e6 (2019). 18. Elmore, M. R. P. et al. Colony-stimulating factor 1 receptor signaling is necessary for microglia viability, unmasking a microglia progenitor cell in the adult brain. Neuron 82, 380–397 (2014). 19. Caccamo, A. et al. Necroptosis activation in Alzheimer’s disease. Nat. Neurosci. 20, 1236–1246 (2017)." "Cellular Vulnerability in the Early Stage of Alzheimer’s Disease Revealed by Single-Cell Transcriptomics" "Bart De Strooper" "Laboratory for the Research of Neurodegenerative Diseases (VIB-KU Leuven)" "It is increasingly clear that in the course of Alzheimer disease a long period of action and reaction occurs between the first appearance of the biochemical lesions (amyloid plaques and tangles) and the clinical dementia. This phase encompasses cellular reactions and many different molecular pathways. We know indeed that several molecular pathways and genes are critically involved in the pathogenesis of Alzheimer disease including the amyloid and Tau biochemical pathways. However, little is known which cells and at what time in the course of the disease these genes are expressed. Moreover, it is very likely that additional genes and pathways are expressed in cell specific ways that remain undetected and are important in the pathogenesis of the disorder. In the current project we want to initiate the study of the complex prodromal, cellular phase of Alzheimer disease by starting to chart the initial cellular reactions on A βstress in the hippocampus as discussed in a recent review of the lab (‘The cellular phase of Alzheimer’s disease’, Cell, 2016). The goal is to provide proof of concept and a basis for further similar studies in human and mouse models. We aim to initiate novel functional research addressing the role of these pathways in the development of the disease. It is expected that this work will lead to insights in the cellular phase of Alzheimer disease, to a more comprehensive approach to study the disorder and that such work will yield novel drug targets." "Targeting dysregulated IP3 receptor-mediated calcium signaling as an early event in Alzheimer’s disease through its Bcl-2-interaction network" "Geert Bultynck" "Laboratory of Membrane Trafficking (VIB-KU Leuven), Laboratory of Molecular and Cellular Signaling" "Alzheimer’s disease, the most frequent form of dementia, has an enormous impact on the quality of life and society. At late stages, the disease is characterized by toxic protein aggregates (amyloid beta) and the demise of cells in the brain (neurons). While neuronal loss cannot be reverted, it is possible to delay this process. Thus, it is instrumental to focus on the early stages in Alzheimer’s disease development, with one of the key features being deranged calcium (Ca2+) signaling. This project will focus on the role of IP3 receptors, intracellular Ca2+ channels, and their modulation by Bcl-2, a major anti-cell death protein. Bcl-2 serves as an inhibitor of IP3 receptors keeping these channels in check. The question is whether alterations in IP3 receptor / Bcl-2-complex formation and modulation could underlie Ca2+-signaling dysregulation in Alzheimer’s disease. In addition, the properties of Bcl-2 proteins in inhibiting IP3 receptors could be exploited to prevent or at least delay Alzheimer’s disease features by supporting memory function, maintaining neuronal morphology and sustaining neuronal survival. Thanks to the complementary expertise of its partners, the project will apply an integrated approach, from biochemical & cell biological studies at the (sub)cellular level to ex vivo work in brain samples and in vivo studies in mice."