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Brain pericytes - Understanding basic physiology of intra- and intercellular signaling.

English title Brain pericytes - Understanding basic physiology of intra- and intercellular signaling.
Applicant Weber Bruno
Number 182703
Funding scheme Project funding
Research institution Institut für Pharmakologie und Toxikologie Universität Zürich
Institution of higher education University of Zurich - ZH
Main discipline Neurophysiology and Brain Research
Start/End 01.11.2018 - 31.10.2022
Approved amount 561'018.00
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All Disciplines (2)

Discipline
Neurophysiology and Brain Research
Molecular Biology

Keywords (9)

electrophysiology; energy metabolism; pericytes; capillaries; microvascluar sytsem; cerebral blood flow; optical imaging; gap junctions; two-photon imaging

Lay Summary (German)

Lead
Perizyten sind Zellen, welche sich an Kapillaren in verschiedenen Organen befinden. Unser Forschungsprojekt beschäftigt sich mit der grundlegenden Physiology dieser Zellen im Gehirn.
Lay summary

Perizyten im Gehirn: Wir wollen die Physiologie dieser Zellen besser verstehen.

Das Gehirn ist ein Organ mit äusserst hohem Energieverbrauch. Deshalb stellt es hohe Anforderungen an die Blutversorgung. Die Regulierung der Blutversorgung und die zeitliche und räumliche Anpassung derselben an die jeweiligen Anforderungen ist ein aktives Forschungsfeld. Neue Studien weisen auf eine Beteiligung von Perizyten in der lokalen Veränderung des Gefässwiderstandes hin. Ebenfalls sind Perizyten zentral in der Gefässentwicklung und in der Aufrechterhaltung der Bluthirnschranke. Ziel dieses Projektes ist es, die physiologischen Grundlagen dieser interessanten kleinen Zellen besser zu verstehen.

Ziel 1:    Mittels Zweiphotonen-Mikroskopie sollen intrazelluläre Kalziumsignale der Perizyten aufgezeichnet und charakterisiert werden.

Ziel 2:    Die Rolle der Gap-Junctions, welche Perizyten koppeln soll untersucht werden.

Ziel 3:    Experimente mit genetisch-kodierten Metaboliten-Indikatoren und Zweiphotonen-Mikroskopie sollen Aufschluss über den Energie-Stoffwechsel von Perizyten geben.

Ziel 4:    Die Rolle von Perizyten bei Kleinst-Hirnschlägen soll mit einem neu entwickelten Hirn-Infarktmodell untersucht werden.

Wissenschaftlicher und gesellschaftlicher Kontext des Forschungsprojekts 

Das Projekt befasst sich mit Grundlagenforschung. Neben diesem grundlagen­wissenschaftlichen Aspekt ist unsere Arbeit auch relevant im Bereich der zerebrovaskulären Erkrankungen (wie etwa Schlaganfall).

Direct link to Lay Summary Last update: 01.10.2018

Responsible applicant and co-applicants

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Associated projects

Number Title Start Funding scheme
166707 The role of capillary diameter adaption on the cerebral microcirculation 01.10.2016 Interdisciplinary projects
156965 Brain pericytes - structure, signaling and hemodynamics 01.11.2014 Project funding
205623 High-Sensitivity Fluorescence/Luminescence Plate Reader system for in vitro screening applications 01.12.2021 R'EQUIP

Abstract

The overarching aim of this project is to increase our fundamental understanding of pericyte physiology in the healthy awake brain and under stroke-induced physiological stress.Constant cerebral blood flow is crucial for maintaining neuronal survival and dysfunctions of the vascular system are linked to diseases such as stroke and Alzheimer’s disease. Pericytes are important mural cells in the brain, but their exact function is not known despite recent intensified research. They are known to play key roles in angiogenesis and in sustaining the integrity of the blood brain barrier, and there is evidence that they are involved in the regulation of vascular resistance and in pathophysiology of neurodegenerative diseases. Despite an increasing interest in this cell type, a significant knowledge gap exists regarding their very basic physiological properties, particularly with respect to their intra- and intercellular signaling pathways. The present project aims to contribute to narrowing this gap. Our project has four specific aims, which will be addressed using a wide range of molecular, imaging and electrophysiological tools:Aim 1:Characterize intracellular calcium signaling ex vivo and in vivo. Calcium signals will be recorded in mice expressing the genetically encoded calcium sensor GCaMP6s in mural cells, by two-photon imaging either in vivo or ex vivo acute brain slices. Pharmacological interventions are performed ex vivo to dissect the intracellular calcium pathways. Appropriate drugs with robust effects will subsequently be tested in vivo.Aim 2:Investigate gap junctional communication between pericytes and other cell types. Providing a direct low resistance electrical communication between smooth muscle cells and endothelium, gap junctions play crucial roles in the control of vascular function. Studies on gap junction coupling in pericytes are scarce. We will perform whole-cell patch-clamp recordings from identified capillary pericytes. Cells will be electrophysiologically characterized and gap junctional coupling is verified by biocytin filling. Furthermore, we plan to delete gap junctions in pericytes by crossing stop/flox connexin mice with the Pdgfrß-CreERT2 line, a strategy we have already successfully applied in astrocytes.Aim 3:Investigate energy metabolism of pericytes using a genetically encoded lactate sensor. We will generate a mouse line expressing genetically encoded metabolite sensors in mural cells with the use of new floxed Laconic (for lactate) and floxed FLII12Pglu600µ?6 (for glucose) reporter lines and the existing Pdgfrß-CreERT2 mouse line. We currently develop both reporter lines using Cas9-mediated generation of knock-in. We will measure baseline levels of lactate and glucose as well as concentration changes in response to hypoxia and hypoglycemia.Aim 4:Investigate pericyte physiology in relation to capillary microstrokes. We have recently developed a novel ultra-small all-optical microstroke model that produces reproducible single capillary occlusions. We will use both calcium imaging and metabolite sensing before and after all-optical stroke induction and will assess physiology of identical pericytes over several days following the occlusion. We will investigate the changes in calcium and metabolite transients after stroke induction and will test whether the location of the occlusion relative to pericyte coverage determines the microstroke outcome. Our proposed research aims to glean more about the much-needed underpinnings of pericyte physiology. This information will be key for advancing the field, which is of the utmost relevance for understanding the neurovascular unit and its prominent and insufficiently understood involvement in physiology and pathophysiology.
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