Dokument: Role of CXCR4 in mediating axon sprouting after local intrathecal infusion of CXCL12 in a mouse model of spinal cord injury
| Titel: | Role of CXCR4 in mediating axon sprouting after local intrathecal infusion of CXCL12 in a mouse model of spinal cord injury | |||||||
| URL für Lesezeichen: | https://docserv.uni-duesseldorf.de/servlets/DocumentServlet?id=49911 | |||||||
| URN (NBN): | urn:nbn:de:hbz:061-20190619-110255-6 | |||||||
| Kollektion: | Dissertationen | |||||||
| Sprache: | Englisch | |||||||
| Dokumententyp: | Wissenschaftliche Abschlussarbeiten » Dissertation | |||||||
| Medientyp: | Text | |||||||
| Autor: | M.Sc. Tundo-Lavalle, Federica [Autor] | |||||||
| Dateien: |
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| Beitragende: | Prof. Dr. Müller, Hans Werner [Gutachter] Prof. Dr. Aberle, Hermann [Gutachter] | |||||||
| Stichwörter: | CXCL12, CXCR4, chemokine, spinal cord injury, mouse | |||||||
| Dewey Dezimal-Klassifikation: | 500 Naturwissenschaften und Mathematik » 570 Biowissenschaften; Biologie | |||||||
| Beschreibung: | The regeneration of injured axons is limited in the central nervous system (CNS). The major goal of researchers is to identify the cause of CNS regenerative failure and to target these factors to promote CNS repair and regeneration, particularly, in spinal cord injured people. One therapeutic aim for example is the stimulation of regenerative axon growth of the lesioned spinal cord. The chemotactic cytokine CXCL12, also named stromal cell-derived factor 1α (SDF-1α), is disinhibitory towards CNS myelin and plays a key role during development of the nervous system. Furthermore, recent studies revealed that CXCL12 enhances sprouting of dorsal corticospinal tract (dCST) axons rostral to the lesion site in a rat spinal cord injury (SCI) model. CXCL12 reportedly interacts with two G-protein-coupled receptors, CXCR4 and CXCR7. However, which of these receptor(s) is involved in the sprouting effect is still unknown. In a pharmacological approach, by applying the CXCR4 antagonist AMD3100 on myelin cultured adult mouse DRG neurons, the involvement of the CXCR4 receptor in CXCL12 mediated neurite outgrowth in vitro was assessed in this study. Furthermore, the presence of the chemokine receptor CXCR4 on adult mouse DRG neurons was confirmed via immunocytochemical staining.
In order to determine the individual functional roles of the chemokine receptors in mediating the axon growth promoting and disinhibitory effects of CXCL12 after local intrathecal infusion, the initial idea of the project was to generate a mouse model with conditional knockout in the mouse dCST of CXCR4 and CXCR7 as well as the generation of receptor-deficient double mutants. As the local intrathecal infusion method is rarely used in mice due to the very thin dura mater and the narrow epidural space, a newly epidural catheterization method was established in this species. In order to investigate the sprouting effect of lesioned dCST neurons after CXCL12 treatment in conditional knockout mice, the procedure was first performed in CXCR4 wild type and ROSA floxed mice (CXCR4wt/wt/ROSAfl/wt). An AAV2-Cre stereotactic injection into layer V of the hind limb sensorimotor cortex to target the pyramidal neurons was used for anterograde labeling of the dCST. We found that CXCL12 infusion did neither promote sprouting of the injured dCST nor enhance functional recovery in these mice. Immunofluorescence staining of CXCR4 did not reveal presence of this receptor in the mouse dCST. In contradiction to previous publication (Opatz et al., 2009) the CXCR4 receptor could not be detected in the rat dCST. Therefore, the generation of the conditional reporter mouse was futile for the intended purpose. A subcellular localization of the CXCR4 receptor in adult mouse and rat spinal cords using immunofluorescence staining revealed that CXCR4 is expressed in the axons. According to that, CXCR4 seems to be expressed in subtypes of neurons, such as spinal motoneurons, but not in CGRP-positive sensory neurons. Furthermore, it is expressed in some glial cells, such as oligodendrocytes, but not in astrocytes. Due to the absence of a commercially available and suitable antibody directed against the second CXCL12 receptor CXCR7 the involvement of the latter could not be analyzed as planned. In situ hybridization studies confirmed the absence of CXCR4 receptor expression in layer V neurons of adult mouse and rat brains. However, CXCR7 and CXCL12 mRNAs were expressed in these neurons. Additionally, no injury-dependent increase was observed in the mRNA expression of CXCL12 and its receptors. Hence, the results suggest that other mechanisms rather than direct ligand-receptor interactions are responsible for CXCL12-mediated neurite sprouting in the rat spinal cord. | |||||||
| Lizenz: |  Urheberrechtsschutz | |||||||
| Fachbereich / Einrichtung: | Medizinische Fakultät | |||||||
| Dokument erstellt am: | 19.06.2019 | |||||||
| Dateien geändert am: | 19.06.2019 | |||||||
| Promotionsantrag am: | 26.02.2019 | |||||||
| Datum der Promotion: | 24.05.2019 |
