Project description:During retinal development, progenitor cells give rise to six different types of neurons, and one glial cell. This process requires the expression of genes that confer specific functions and identity to each cell. Previous works have reported the miRNAs expression profile in retina, but is still necessary to further define individual retinal cell populations profiles. We isolated postmitotic mice CD73-positive Rods, Müller glial cells and Retinal Progenitors Cells (E17.5); we then analyzed their miRNA profile expression by microarrays. Using wild type mice we FACS-isolated postmitotic CD73-positive Rods (posnatal day 5). We isolated primary Müller glia cultures from postnatal day 8 mice and retinal progenitors cells from E17.5 mouse embryos; we then sent the samples to the gene expression unit at Instituto de Medicina Genomica (INMEGEN), to analyze their miRNA profile expression by microarrays.
Project description:During retinal development, progenitor cells give rise to six different types of neurons, and one glial cell. This process requires the expression of genes that confer specific functions and identity to each cell. Previous works have reported the miRNAs expression profile in retina, but is still necessary to further define individual retinal cell populations profiles. We isolated postmitotic mice CD73-positive Rods, Müller glial cells and Retinal Progenitors Cells (E17.5); we then analyzed their miRNA profile expression by microarrays.
Project description:In the lesioned zebrafish retina, Müller glia produce multipotent retinal progenitors that generate all retinal neurons, replacing lost cell types. To study the molecular mechanisms linking Müller glia reactivity to progenitor production and neuronal differentiation, we used single cell RNA sequencing of Müller glia, progenitors and regenerated progeny from uninjured and light-lesioned retinae. We discover an injury-induced Müller glia differentiation trajectory that leads into a cell population with a hybrid identity expressing marker genes of Müller glia and progenitors. A glial self-renewal and a neurogenic trajectory depart from the hybrid cell population. We further observe that neurogenic progenitors progressively differentiate to generate retinal ganglion cells first and bipolar cells last, similar to the events observed during retinal development. Our work provides a comprehensive description of Müller glia and progenitor transcriptional changes and fate decisions in the regenerating retina, which are key to tailor cell differentiation and replacement therapies for retinal dystrophies in humans.
Project description:Non-mammalian vertebrates have a robust ability to regenerate injured retinal neurons from Müller glia cells (MG) that activate the proneural factor Achaete-scute homolog 1 (Ascl1/Mash1) and de-differentiate into progenitors cells. In contrast, mammalian MG have a limited regenerative response and fail to upregulate Ascl1 after injury. To test whether Ascl1 could restore a neurogenic potential to mammalian MG, we over-expressed Ascl1 in dissociated mouse MG cultures and intact retinal explants. Ascl1-infected MG upregulate retinal progenitor-specific genes, while downregulating glial genes. Furthermore, Ascl1 remodeled the chromatin at its targets from a repressive to active configuration. MG-derived progenitors differentiated into cells that exhibited neuronal morphologies, expressed retinal subtype-specific neuronal markers, and displayed neuron-like physiological responses. These results indicate that a single transcription factor, Ascl1, can produce a neurogenic state in mature Muller glia. Expresssion profiling was used to determine the genes that were changed after Ascl1 infection of P12 cultured Müller glia compared with those present in P0 progenitors and P7-P21 Müller glia Retinas were dissociated and FAC-sorted from Hes5-GFP mice at P0, P7, P10, P14 or P21 and submitted for profiling. WT Retinas were dissociated at P12, grown for 1 week in culture, and infected with lentiviruses expressing Ascl1 or GFP for four days. Total RNA was extracted and submitted for profiling.
Project description:In mammals, retinal damage is followed by Müller glia cell activation and proliferation. While retinal gliosis persists in adult mammals after an insult or disease, some vertebrates, including zebrafish, have the capacity to regenerate. We believe we are the first group to show that gliosis is a fibrotic-like process in mammals’ eyes caused by differential activation of canonical and non-canonical TGFβ signaling pathways.
Project description:During development, neural progenitor cells modify their output over time to produce different types of neurons and glia in chronological sequences. Previous studies have shown that epigenetic processes play a crucial role in regulating neural progenitor potential, but the underlying mechanisms are not well understood. Here, we hypothesized that nucleosome remodelling would regulate the competence transitions of retinal progenitors. We generated retina-specific conditional knockouts (cKOs) in the key nucleosome remodelling enzyme Chd4. Chd4 cKOs overproduced early-born retinal ganglion and amacrine cells. Postnatally, later-born rod photoreceptors were drastically underproduced. Concomitantly, progenitors failed to be exhausted at late phases of development and ultimately overproduced Müller glia. To determine how Chd4 regulates the genome, we used cut&run-seq to reveal Chd4 genome occupancy, and ATAC-seq experiments to visualize nucleosome remodelling. These data revealed that genome accessibility was significantly increased at ∼10,000 regulatory elements and ∼4,000 genes in the Chd4 cKO. Together, these results suggest that Chd4 restricts the genome to repress progenitor identity and promote rod photoreceptor production. Accordingly, multiplexed single-cell transcriptomics demonstrated that deletion of Chd4 led to markedly divergent gene expression profiles. However, despite overproduction of early fates and underproduction of later-born rods, the perinatal transition between early and late progenitor competence was not altered as determined by birthdating experiments and transcriptomic signatures. Taken together, our data suggest that Chd4-dependent chromatin remodelling regulates cell fate specification, and is also required to terminate retinal neurogenesis, but that it does not regulate the progenitor competence windows that restrict early-vs. late-cell-type production.
Project description:The RNA-binding protein Ptbp1 has been proposed as a master regulator of neuronal fate, repressing neurogenesis through its effects on alternative splicing and miRNA maturation. While prior studies using RNA interference suggested that Ptbp1 loss promotes neurogenesis, recent genetic studies have failed to replicate glia-to-neuron conversion following Ptbp1 loss of function. To evaluate the role of Ptbp1 in developmental neurogenesis in vivo, we conditionally disrupted Ptbp1 in retinal progenitors. Ptbp1 was robustly expressed in both retinal progenitors and Müller glia but absent from postmitotic neurons, and efficient loss of function in mutant animals was confirmed using immunostaining for Ptbp1. Furthermore, bulk RNA-Seq at E16 revealed accelerated expression of late-stage progenitor and photoreceptor-specific genes and altered splicing patterns in Ptbp1 mutants, including increased inclusion of neuron- and retina-specific exons. However, we observed no defects in retinal lamination, progenitor proliferation, or cell fate specification in mature retina. ScRNA-Seq of mature mutant retinas revealed only modest transcriptional changes limited to Müller glia, recapitulating alterations seen following selective deletion of Ptbp1 in mature glia. Our findings demonstrate that Ptbp1 is fully dispensable for retinal development and suggest that its proposed role as a central repressor of neurogenesis should be reevaluated
Project description:The RNA-binding protein Ptbp1 has been proposed as a master regulator of neuronal fate, repressing neurogenesis through its effects on alternative splicing and miRNA maturation. While prior studies using RNA interference suggested that Ptbp1 loss promotes neurogenesis, recent genetic studies have failed to replicate glia-to-neuron conversion following Ptbp1 loss of function. To evaluate the role of Ptbp1 in developmental neurogenesis in vivo, we conditionally disrupted Ptbp1 in retinal progenitors. Ptbp1 was robustly expressed in both retinal progenitors and Müller glia but absent from postmitotic neurons, and efficient loss of function in mutant animals was confirmed using immunostaining for Ptbp1. Furthermore, bulk RNA-Seq at E16 revealed accelerated expression of late-stage progenitor and photoreceptor-specific genes and altered splicing patterns in Ptbp1 mutants, including increased inclusion of neuron- and retina-specific exons. However, we observed no defects in retinal lamination, progenitor proliferation, or cell fate specification in mature retina. ScRNA-Seq of mature mutant retinas revealed only modest transcriptional changes limited to Müller glia, recapitulating alterations seen following selective deletion of Ptbp1 in mature glia. Our findings demonstrate that Ptbp1 is fully dispensable for retinal development and suggest that its proposed role as a central repressor of neurogenesis should be reevaluated
Project description:Müller glia play very important and diverse roles in retinal homeostasis and disease, bur very little is known of their development during human retinal embryogenesis. Since they share several markers with retinal progenitors, they are often considered as a different cell population. In this study we isolated CD29+/CD44+cells from retinal organoids formed by hEPSC cells in vitro, and examined their transcriptome profile at various stages of organoid development to identify their transcriptomic profile.