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The role of ependymoglial cells in the regeneration of zebrafish telencephalon
The role of ependymoglial cells in the regeneration of zebrafish telencephalon
Achieving successful brain regeneration in humans is currently one of the biggest challenges in the field of regeneration studies. In contrast, regeneration competent species such as the zebrafish, have a remarkable capacity for regeneration and neurogenesis after injury. Ependymoglial cells of the zebrafish brain, among which a subset act as progenitors, react to an injury and generate new neurons that subsequently migrate towards the lesion site and contribute to repair. Understanding the cellular and molecular details of regeneration in zebrafish could potentially offer targets for therapeutically relevant interventions in humans. In order to study ependymoglia behavior in depth, I developed an electroporation technique to reliably label high numbers of ependymoglial cells in vivo. Additionally, I adapted functional usage of StagR-Cas9 method in the adult zebrafish telencephalon in vivo, which allowed us to genetically manipulate multiple genes in ependymoglial cells. I then used the developed live imaging methodology to analyze the diversity of ependymoglial response to injury in the Tg (gfap:GFP) zebrafish line and discovered two subpopulations of ependymoglial cells – GFP high and GFP low with their different reactions. I observed that the GFP low subpopulation directly converts to post-mitotic neurons in response to the injury and engages in restorative neurogenesis. To understand the molecular mechanisms underlying successful regenerative neurogenesis, I focused on the behavior of the GFP low ependymoglia. I made use of the existing transcriptome analysis of this glial population and identified aryl hydrocarbon receptor (AhR) to be involved in regulation of ependymoglia behavior after injury. More specifically, inactivation of AhR signaling shortly after the injury promoted ependymoglia proliferation, whereas return of AhR to basal levels - around 7 days post-injury, promoted direct conversion of ependymoglial cells into neurons. Moreover, I was able to show that GFP low ependymoglia have high AhR signaling levels and regulate it in response to the injury. Interfering with proper regulation of AhR signaling after the injury led to inappropriate timing of generation of new-neurons and failed restorative neurogenesis. Taken together, the core data I present in this thesis identified AhR to be an important regulator of ependymoglia behavior and their timely coordination after the injury. More precisely, AhR is a crucial factor involved in proper timing of restorative neurogenesis and successful regeneration in zebrafish, which has insofar been previously unknown.
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Đurović, Tamara
2020
English
Universitätsbibliothek der Ludwig-Maximilians-Universität München
Đurović, Tamara (2020): The role of ependymoglial cells in the regeneration of zebrafish telencephalon. Dissertation, LMU München: Graduate School of Systemic Neurosciences (GSN)
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Abstract

Achieving successful brain regeneration in humans is currently one of the biggest challenges in the field of regeneration studies. In contrast, regeneration competent species such as the zebrafish, have a remarkable capacity for regeneration and neurogenesis after injury. Ependymoglial cells of the zebrafish brain, among which a subset act as progenitors, react to an injury and generate new neurons that subsequently migrate towards the lesion site and contribute to repair. Understanding the cellular and molecular details of regeneration in zebrafish could potentially offer targets for therapeutically relevant interventions in humans. In order to study ependymoglia behavior in depth, I developed an electroporation technique to reliably label high numbers of ependymoglial cells in vivo. Additionally, I adapted functional usage of StagR-Cas9 method in the adult zebrafish telencephalon in vivo, which allowed us to genetically manipulate multiple genes in ependymoglial cells. I then used the developed live imaging methodology to analyze the diversity of ependymoglial response to injury in the Tg (gfap:GFP) zebrafish line and discovered two subpopulations of ependymoglial cells – GFP high and GFP low with their different reactions. I observed that the GFP low subpopulation directly converts to post-mitotic neurons in response to the injury and engages in restorative neurogenesis. To understand the molecular mechanisms underlying successful regenerative neurogenesis, I focused on the behavior of the GFP low ependymoglia. I made use of the existing transcriptome analysis of this glial population and identified aryl hydrocarbon receptor (AhR) to be involved in regulation of ependymoglia behavior after injury. More specifically, inactivation of AhR signaling shortly after the injury promoted ependymoglia proliferation, whereas return of AhR to basal levels - around 7 days post-injury, promoted direct conversion of ependymoglial cells into neurons. Moreover, I was able to show that GFP low ependymoglia have high AhR signaling levels and regulate it in response to the injury. Interfering with proper regulation of AhR signaling after the injury led to inappropriate timing of generation of new-neurons and failed restorative neurogenesis. Taken together, the core data I present in this thesis identified AhR to be an important regulator of ependymoglia behavior and their timely coordination after the injury. More precisely, AhR is a crucial factor involved in proper timing of restorative neurogenesis and successful regeneration in zebrafish, which has insofar been previously unknown.