The TGFβ/Notch axis facilitates Müller cell-to-epithelial transition to ultimately form a chronic glial scar

Abstract Background Contrasting with zebrafish, retinal regeneration from Müller cells (MCs) is largely limited in mammals, where they undergo reactive gliosis that consist of a hypertrophic response and ultimately results in vision loss. Transforming growth factor β (TGFβ) is essential for wound he...

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Main Authors: Federica Maria Conedera, Ana Maria Quintela Pousa, Nadia Mercader, Markus Tschopp, Volker Enzmann
Format: Article
Language:English
Published: BMC 2021-09-01
Series:Molecular Neurodegeneration
Subjects:
Online Access:https://doi.org/10.1186/s13024-021-00482-z
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author Federica Maria Conedera
Ana Maria Quintela Pousa
Nadia Mercader
Markus Tschopp
Volker Enzmann
author_facet Federica Maria Conedera
Ana Maria Quintela Pousa
Nadia Mercader
Markus Tschopp
Volker Enzmann
author_sort Federica Maria Conedera
collection DOAJ
description Abstract Background Contrasting with zebrafish, retinal regeneration from Müller cells (MCs) is largely limited in mammals, where they undergo reactive gliosis that consist of a hypertrophic response and ultimately results in vision loss. Transforming growth factor β (TGFβ) is essential for wound healing, including both scar formation and regeneration. However, targeting TGFβ may affect other physiological mechanisms, owing its pleiotropic nature. The regulation of various cellular activities by TGFβ relies on its interaction with other pathways including Notch. Here, we explore the interplay of TGFβ with Notch and how this regulates MC response to injury in zebrafish and mice. Furthermore, we aimed to characterize potential similarities between murine and human MCs during chronic reactive gliosis. Methods Focal damage to photoreceptors was induced with a 532 nm diode laser in TgBAC (gfap:gfap-GFP) zebrafish (ZF) and B6-Tg (Rlbp1-GFP) mice. Transcriptomics, immunofluorescence, and flow cytometry were employed for a comparative analysis of MC response to laser-induced injury between ZF and mouse. The laser-induced injury was paired with pharmacological treatments to inhibit either Notch (DAPT) or TGFβ (Pirfenidone) or TGFβ/Notch interplay (SIS3). To determine if the murine laser-induced injury model translates to the human system, we compared the ensuing MC response to human donors with early retinal degeneration. Results Investigations into injury-induced changes in murine MCs revealed TGFβ/Notch interplay during reactive gliosis. We found that TGFβ1/2 and Notch1/2 interact via Smad3 to reprogram murine MCs towards an epithelial lineage and ultimately to form a glial scar. Similar to what we observed in mice, we confirmed the epithelial phenotype of human Müller cells during gliotic response. Conclusion The study indicates a pivotal role for TGFβ/Notch interplay in tuning MC stemness during injury response and provides novel insights into the remodeling mechanism during retinal degenerative diseases. Graphical abstract
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spelling doaj.art-43ff539d4e9d4da8a930484e568856aa2022-12-21T19:16:58ZengBMCMolecular Neurodegeneration1750-13262021-09-0116112110.1186/s13024-021-00482-zThe TGFβ/Notch axis facilitates Müller cell-to-epithelial transition to ultimately form a chronic glial scarFederica Maria Conedera0Ana Maria Quintela Pousa1Nadia Mercader2Markus Tschopp3Volker Enzmann4Department of Ophthalmology, University Hospital of Bern, University of BernDepartment of Ophthalmology, University Hospital of Bern, University of BernInstitute of Anatomy, University of BernDepartment of Ophthalmology, University Hospital of Bern, University of BernDepartment of Ophthalmology, University Hospital of Bern, University of BernAbstract Background Contrasting with zebrafish, retinal regeneration from Müller cells (MCs) is largely limited in mammals, where they undergo reactive gliosis that consist of a hypertrophic response and ultimately results in vision loss. Transforming growth factor β (TGFβ) is essential for wound healing, including both scar formation and regeneration. However, targeting TGFβ may affect other physiological mechanisms, owing its pleiotropic nature. The regulation of various cellular activities by TGFβ relies on its interaction with other pathways including Notch. Here, we explore the interplay of TGFβ with Notch and how this regulates MC response to injury in zebrafish and mice. Furthermore, we aimed to characterize potential similarities between murine and human MCs during chronic reactive gliosis. Methods Focal damage to photoreceptors was induced with a 532 nm diode laser in TgBAC (gfap:gfap-GFP) zebrafish (ZF) and B6-Tg (Rlbp1-GFP) mice. Transcriptomics, immunofluorescence, and flow cytometry were employed for a comparative analysis of MC response to laser-induced injury between ZF and mouse. The laser-induced injury was paired with pharmacological treatments to inhibit either Notch (DAPT) or TGFβ (Pirfenidone) or TGFβ/Notch interplay (SIS3). To determine if the murine laser-induced injury model translates to the human system, we compared the ensuing MC response to human donors with early retinal degeneration. Results Investigations into injury-induced changes in murine MCs revealed TGFβ/Notch interplay during reactive gliosis. We found that TGFβ1/2 and Notch1/2 interact via Smad3 to reprogram murine MCs towards an epithelial lineage and ultimately to form a glial scar. Similar to what we observed in mice, we confirmed the epithelial phenotype of human Müller cells during gliotic response. Conclusion The study indicates a pivotal role for TGFβ/Notch interplay in tuning MC stemness during injury response and provides novel insights into the remodeling mechanism during retinal degenerative diseases. Graphical abstracthttps://doi.org/10.1186/s13024-021-00482-zLaser injuryMüller cellsNotch pathwayRetinal degenerationRetinal regenerationSmad3
spellingShingle Federica Maria Conedera
Ana Maria Quintela Pousa
Nadia Mercader
Markus Tschopp
Volker Enzmann
The TGFβ/Notch axis facilitates Müller cell-to-epithelial transition to ultimately form a chronic glial scar
Molecular Neurodegeneration
Laser injury
Müller cells
Notch pathway
Retinal degeneration
Retinal regeneration
Smad3
title The TGFβ/Notch axis facilitates Müller cell-to-epithelial transition to ultimately form a chronic glial scar
title_full The TGFβ/Notch axis facilitates Müller cell-to-epithelial transition to ultimately form a chronic glial scar
title_fullStr The TGFβ/Notch axis facilitates Müller cell-to-epithelial transition to ultimately form a chronic glial scar
title_full_unstemmed The TGFβ/Notch axis facilitates Müller cell-to-epithelial transition to ultimately form a chronic glial scar
title_short The TGFβ/Notch axis facilitates Müller cell-to-epithelial transition to ultimately form a chronic glial scar
title_sort tgfβ notch axis facilitates muller cell to epithelial transition to ultimately form a chronic glial scar
topic Laser injury
Müller cells
Notch pathway
Retinal degeneration
Retinal regeneration
Smad3
url https://doi.org/10.1186/s13024-021-00482-z
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