Molecular mechanisms of neurodegeneration and repair
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Circadian regulation of myeloid cell function in neurodegenerative diseases
Sleep problems and circadian disturbances are early features of many neurodegenerative diseases, including Alzheimer’s disease (AD) and Huntington’s disease (HD). Both diseases are also associated with central and peripheral immune system dysfunction. Here, we hypothesize that circadian and immune abnormalities are closely interconnected in neurodegenerative diseases. In order to test this hypothesis, we shall first examine wild type mice and characterize diurnal/circadian rhythms in microglia and border-associated macrophages of the central nervous system (CNS). In comparison, we shall examine diurnal/circadian rhythms in liver macrophages, skin Langerhans cells and circulating monocytes. The impact of entrainment (light, nutrition) and conflicting Zeitgeber will be explored in microglia versus liver macrophages. We shall then conditionally delete the circadian clock gene Bmal1 in microglia to test the consequences for neural function. Next, we shall probe whether diurnal/circadian rhythms are dysregulated in myeloid cells from transgenic mouse models of HD and AD and how this relates to the disease process. We shall compare microglia from different brain regions that are differentially affected by neuronal dysfunction. In addition, we shall assess diurnal/circadian rhythms in peripheral myeloid cells. Finally, we shall translate our findings to humans by using induced pluripotent stem cells (iPSCs) to generate microglia-like cells. CRISPR/Cas9-mediated knockout of BMAL1 in iPSCs will allow us to explore the impact of clock disruption in human iPSC-derived microglia. The results will enhance our understanding of the pathogenic role of circadian disruption in myeloid cells for neurodegenerative diseases.
Contact: Koliane Ouk
Non-hematopoietic erythropoietin splice variants as human endogen neuroprotective substances
Erythropoietin (EPO) is a glycoprotein induced by hypoxia, which inhibits apoptosis and promotes differentiation of progenitor cells. Due to effects on hematopoietic cells, EPO is applied in anemia therapy. Through the same mechanisms, EPO protects neurons from apoptosis and promotes generation of new neurons. However, these endogen repair mechanisms are not sufficient to compensate a damage induced by a stroke for example. Therefore, the therapeutic use of EPO in neurological disease is obvious but limited by hematopoietic side effects causing thromboembolism. In preliminary studies, we showed that hypoxia induced paracrine neuroprotection is transmitted by EPO but not hypoxia induced paracrine neuroprotection. The detection of endogenous EPO splice variants revealed potential candidates transmitting autocrine neuroprotection. Especially one splice variant, showed comparable neuroprotective effects without hematopoietic function in the mouse model. We are now testing this promising variant in the human model using iPSC-derived neurons. The variant is produced by Anne Zemella’s group at the Fraunhofer Institute Potsdam with a highly modern cell free technique. Furthermore, we want to answer the question in which cells and in which neurological disease we find this variant expressed. Therefore, we apply a new RNA hybridization method named BaseScope in post mortem human brain. With this method very short mRNAs can be detected as single dots. Our hypothesis is that the EPO splice variant is upregulated in neurodegeneration as part of endogenous repair mechanisms, that it inhibits apoptosis of postmitotic neurons and promotes neurogenesis. Confirming our hypothesis we could derive a new neuroprotective and regenerative therapy.
Contact: Theresa Hartung
Genome engineering and stem cell-based disease modeling of neurodevelopmental disorders
The project is focused on genome engineering of patient specific stem cells for disease modeling and development of tools to perform effective and safe genome editing in patients derived stem cells including post mitotic neurons. The aim of the project is to advance genome editing technology to overcome major technical challenges that prevent the widespread use of somatic gene editing. In particular specific aims are: 1) To develop a stem cell model (ESCs, iPSCs) resource, including a panel of reporter models, for disease phenotypic screening and to robustly monitor genome editing activity and cell-type specificity in vitro in a brain preclinical model of HD and newly discovered by us IRF2BPL related disease called NEDAMSS. 2) To apply new tools for post mitotic somatic cell gene repair in 2D neuronal cultures and 3D brain organoids derived from patients iPSCs followed by the phenotypic characterization. 3) To develop a scalable platform to support precise disease phenotyping, delivery of genome editing components and analysis of editing outcomes. The successful completion of these tasks aims to improve precise phenotypic screening and genome editing technologies to accelerate the translation of such technology into clinical applications and maximize the potential neurodevelopmental diseases treatment.
Contact: Pawel Lisowski