The regeneration-responsive careg element monitors activation of Müller glia after MNU-induced damage in the zebrafish retina
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ABSTRACT: We found that the zebrafish non-coding element careg, which is induced in regenerating fins and heart, also participates in retina regeneration. Its activation persisted mostly in Müller glia from the onset to the termination of retina restoration. To assess the involvement of the careg:EGFP reporter during retina regeneration, we used a chemical injury model with MNU treatment. To identify the molecular profile of these cells, we performed a single-cell RNA sequencing (scRNA-seq) experiment of retinas dissected from adult careg:EGFP zebrafish at 3, 7, and 10 dpMNU. Our control retinas were dissected from fish at 3 days after treatment with heat-inactivated MNU
Project description:We elucidate the role of prospero-related homeobox 1 (Prox1) in rendering the mammalian retina incompetent for MG(Muller glia cell)-derived regeneration. Prox1 accumulates in MG in the degenerating human and mouse retinas but not in those in the regenerating zebrafish retina. We investigated whether the transition of MG to proliferative MGPCs occurred in MNU-injured Prox1fg/fg;Chx10-CreERT2 mouse retinas through single-cell RNA sequencing analysis.
Project description:Müller cells are the primary glia of the neural retina and play crucial roles in maintaining the structural and functional homeostasis of the retina. Müller cells also possess certain levels of retinal regeneration capacity, especially in lower vertebrates. In this study, we deep sequenced the transcriptomes and methylomes of mouse Müller cells and early retinal progenitor cells (RPCs), as well as Müller cells from injured retinas and aged retinas, which will help to reveal molecular mechanisms governing Müller cells development, physiological functions and regeneration activities.
Project description:Background: Adult zebrafish spontaneously regenerate their retinas after damage. Although a number of genes and signaling pathways involved in regeneration have been identified, the extent of mechanisms regulating regeneration is unclear. Small non-coding RNAs, microRNAs (miRNAs), that regulate regeneration of various tissues in lower vertebrates were examined for their potential roles in regulating zebrafish retinal regeneration. Results: To investigate the requirement of miRNAs during zebrafish retinal regeneration, we knocked down the expression of the miRNA-processing enzyme Dicer in retinas prior to light-induced damage. Dicer loss significantly reduced proliferation of Müller glia-derived neuronal progenitor cells during regeneration. To identify individual miRNAs with roles in retina regeneration, we collected retinas at different stages of light damage and performed small RNA high-throughput sequencing. We identified subsets of miRNAs that were differentially expressed during active regeneration but returned to basal levels once regeneration was completed. To validate the roles of differentially expressed miRNAs, we knocked down 6 different miRNAs that were upregulated in expression during regeneration and demonstrated that they have distinct effects on neuronal progenitor cell proliferation and migration during retina regeneration. Conclusions: miRNAs are necessary for retinal regeneration. miRNA expression is dynamic during regeneration. miRNAs function during initiation and progression of retinal regeneration. Identification of miRNAs before, during and after completion of zebrafish retinal regeneration
Project description:Purpose: Investigate the molecular determinants of retinal regeneration in adult vertebrates by analyzing the gene expression profiles of control and post-lesion retina of adult zebrafish, a system that regenerates following injury. Methods: Gene expression profiles of zebrafish retina and brain were determined with DNA microarray, RT-PCR, and real-time quantitative PCR analyses. Damaged retinas and their corresponding controls were analyzed 2-5 days post-lesion (acute injury condition) or 14 d post-lesion (cell regeneration condition). Results: Expected similarities and differences in the gene expression profile of zebrafish retina and brain were observed, confirming the applicability of the gene expression techniques. Mechanical lesion of retina triggered significant, time-dependent changes in retinal gene expression. The induced transcriptional changes were consistent with cellular phenomena known to occur, in a time-dependent manner, subsequent to retinal lesion, including cell cycle progression, axonal regeneration, and regenerative cytogenesis. Conclusions: The results indicate that retinal regeneration in adult zebrafish involves a complex set of induced, targeted changes in gene transcription, and suggest that these molecular changes underlie the ability of the adult vertebrate retina to regenerate. Keywords: time course; injury response; cellular correlation Control brain and retina (unlesioned); Control and lesioned retina (matched animals, at least n = 8 for each condition).
Project description:We further investigated injury-induced gene expression changes selectively in MG cell lineages. The tdTom-labeled MG and their descendant cells were isolated via FACS from uninjured or MNU-injured Glast-CreERT;R26tdTom/+ mouse retinas, which were infected with either AAV2-Ctrl Ab or AAV2-alpha Prox1, and mRNA expression patterns of individual cells were analyzed using SMART (Switching Mechanism At the 5' end of RNA Template) sequencing methods. We could identify a lineage flow from resting MG to RPC-like cells via activated MG, along with pseudo-time progression.
Project description:Background: Adult zebrafish spontaneously regenerate their retinas after damage. Although a number of genes and signaling pathways involved in regeneration have been identified, the extent of mechanisms regulating regeneration is unclear. Small non-coding RNAs, microRNAs (miRNAs), that regulate regeneration of various tissues in lower vertebrates were examined for their potential roles in regulating zebrafish retinal regeneration. Results: To investigate the requirement of miRNAs during zebrafish retinal regeneration, we knocked down the expression of the miRNA-processing enzyme Dicer in retinas prior to light-induced damage. Dicer loss significantly reduced proliferation of Müller glia-derived neuronal progenitor cells during regeneration. To identify individual miRNAs with roles in retina regeneration, we collected retinas at different stages of light damage and performed small RNA high-throughput sequencing. We identified subsets of miRNAs that were differentially expressed during active regeneration but returned to basal levels once regeneration was completed. To validate the roles of differentially expressed miRNAs, we knocked down 6 different miRNAs that were upregulated in expression during regeneration and demonstrated that they have distinct effects on neuronal progenitor cell proliferation and migration during retina regeneration. Conclusions: miRNAs are necessary for retinal regeneration. miRNA expression is dynamic during regeneration. miRNAs function during initiation and progression of retinal regeneration.
Project description:In the retina of adult teleosts, stem cells are sustained in two specialized niches: the ciliary marginal zone (CMZ) and the microenvironment surrounding adult Müller glia. Recently, Müller glia were identified as the regenerative stem cells in the teleost retina. Secreted signaling molecules that regulate neuronal regeneration in the retina are largely unknown. In a microarray screen to discover such factors, we identified midkine-b (mdkb). Midkine is a highly conserved heparin-binding growth factor with numerous biological functions. The zebrafish genome encodes two distinct midkine genes: mdka and mdkb. Here, we describe the cellular expression of mdka and mdkb during retinal development and the initial, proliferative phase of photoreceptor regeneration. The results show that in the embryonic and larval retina mdka and mdkb are expressed in stem cells, retinal progenitors and neurons in distinct patterns that suggest different functions for the two molecules. Following the selective death of photoreceptors in the adult, mdka and mdkb are co-expressed in horizontal cells and proliferating Müller glia and their neurogenic progeny. These data reveal that Mdka and Mdkb are signaling factors present in the retinal stem cell niches in both embryonic and mature retinas, and that their cellular expression is actively modulated during retinal development and regeneration. Experiment Overall Design: As a means to identify genes necessary for photoreceptor regeneration, we evaluated transcriptional in the retina of the zebrafish as photoreceptors are regenerated. Albino zebrafish were dark adapted, then half were exposed to bright constant light and half were returned to normal lighting. After 72hrs of light exposure, retinal RNA was isolated and analysis of gene expression was performed using Affymetriz zebrafish gene arrays.
Project description:Purpose: Investigate the molecular determinants of retinal regeneration in adult vertebrates by analyzing the gene expression profiles of control and post-lesion retina of adult zebrafish, a system that regenerates following injury. Methods: Gene expression profiles of zebrafish retina and brain were determined with DNA microarray, RT-PCR, and real-time quantitative PCR analyses. Damaged retinas and their corresponding controls were analyzed 2-5 days post-lesion (acute injury condition) or 14 d post-lesion (cell regeneration condition). Results: Expected similarities and differences in the gene expression profile of zebrafish retina and brain were observed, confirming the applicability of the gene expression techniques. Mechanical lesion of retina triggered significant, time-dependent changes in retinal gene expression. The induced transcriptional changes were consistent with cellular phenomena known to occur, in a time-dependent manner, subsequent to retinal lesion, including cell cycle progression, axonal regeneration, and regenerative cytogenesis. Conclusions: The results indicate that retinal regeneration in adult zebrafish involves a complex set of induced, targeted changes in gene transcription, and suggest that these molecular changes underlie the ability of the adult vertebrate retina to regenerate. Keywords: time course; injury response; cellular correlation
Project description:Photoreceptor damage in adult mammals results in permanent cell loss and glial scarring in the retina. In contrast, adult zebrafish can regenerate photoreceptors following injury. By using a stable transgenic line in which GFP is driven by the cis-regulatory sequences of a glial specific marker gfap, Tg(gfap:GFP)mi2002, previous studies showed that Müller glia, the radial glial cells in the retina, proliferate after photoreceptor loss and give rise to neuronal progenitors that eventually differentiate into regenerated photoreceptors. To identify the molecular mechanisms that initiate this regenerative response, Müller glia were isolated from Tg(gfap:GFP)mi2002 fish during the early stages of regeneration after light lesion and gene expression profiles were generated by microarray analyses. Keywords: time course Retinas were dissected from Tg(gfap:GFP)mi2002 zebrafish at 8, 16, 24, 36 hour post-lesion (hpl) and non-light-treated controls (0 hpl) and were dissociated by enzymatic digestion. GFP+ Müller glia were isolated by fluorescence-activated cell sorting (FACS) for RNA extraction and hybridization on Affymetrix microarrays. Independent hybridization of three biological replicates were performed for each time point.