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Yin Z, Kang J, Cheng X, Gao H, Huo S, Xu H. Investigating Müller glia reprogramming in mice: a retrospective of the last decade, and a look to the future. Neural Regen Res 2025; 20:946-959. [PMID: 38989930 DOI: 10.4103/nrr.nrr-d-23-01612] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2023] [Accepted: 02/05/2024] [Indexed: 07/12/2024] Open
Abstract
Müller glia, as prominent glial cells within the retina, plays a significant role in maintaining retinal homeostasis in both healthy and diseased states. In lower vertebrates like zebrafish, these cells assume responsibility for spontaneous retinal regeneration, wherein endogenous Müller glia undergo proliferation, transform into Müller glia-derived progenitor cells, and subsequently regenerate the entire retina with restored functionality. Conversely, Müller glia in the mouse and human retina exhibit limited neural reprogramming. Müller glia reprogramming is thus a promising strategy for treating neurodegenerative ocular disorders. Müller glia reprogramming in mice has been accomplished with remarkable success, through various technologies. Advancements in molecular, genetic, epigenetic, morphological, and physiological evaluations have made it easier to document and investigate the Müller glia programming process in mice. Nevertheless, there remain issues that hinder improving reprogramming efficiency and maturity. Thus, understanding the reprogramming mechanism is crucial toward exploring factors that will improve Müller glia reprogramming efficiency, and for developing novel Müller glia reprogramming strategies. This review describes recent progress in relatively successful Müller glia reprogramming strategies. It also provides a basis for developing new Müller glia reprogramming strategies in mice, including epigenetic remodeling, metabolic modulation, immune regulation, chemical small-molecules regulation, extracellular matrix remodeling, and cell-cell fusion, to achieve Müller glia reprogramming in mice.
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Affiliation(s)
- Zhiyuan Yin
- Key Lab of Visual Damage and Regeneration & Restoration of Chongqing, Southwest Eye Hospital, Southwest Hospital, Third Military Medical University (Army Medical University), Chongqing, China
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2
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Wohlschlegel J, Finkbeiner C, Hoffer D, Kierney F, Prieve A, Murry AD, Haugan AK, Ortuño-Lizarán I, Rieke F, Golden SA, Reh TA. ASCL1 induces neurogenesis in human Müller glia. Stem Cell Reports 2023; 18:2400-2417. [PMID: 38039971 PMCID: PMC10724232 DOI: 10.1016/j.stemcr.2023.10.021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Revised: 10/27/2023] [Accepted: 10/30/2023] [Indexed: 12/03/2023] Open
Abstract
In mammals, loss of retinal cells due to disease or trauma is an irreversible process that can lead to blindness. Interestingly, regeneration of retinal neurons is a well established process in some non-mammalian vertebrates and is driven by the Müller glia (MG), which are able to re-enter the cell cycle and reprogram into neurogenic progenitors upon retinal injury or disease. Progress has been made to restore this mechanism in mammals to promote retinal regeneration: MG can be stimulated to generate new neurons in vivo in the adult mouse retina after the over-expression of the pro-neural transcription factor Ascl1. In this study, we applied the same strategy to reprogram human MG derived from fetal retina and retinal organoids into neurons. Combining single cell RNA sequencing, single cell ATAC sequencing, immunofluorescence, and electrophysiology we demonstrate that human MG can be reprogrammed into neurogenic cells in vitro.
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Affiliation(s)
| | - Connor Finkbeiner
- Department of Biological Structure, University of Washington, Seattle, WA, USA
| | - Dawn Hoffer
- Department of Biological Structure, University of Washington, Seattle, WA, USA
| | - Faith Kierney
- Department of Biological Structure, University of Washington, Seattle, WA, USA
| | - Aric Prieve
- Department of Biological Structure, University of Washington, Seattle, WA, USA
| | - Alexandria D Murry
- Department of Biological Structure, University of Washington, Seattle, WA, USA
| | - Alexandra K Haugan
- Department of Biological Structure, University of Washington, Seattle, WA, USA
| | | | - Fred Rieke
- Department of Physiology and Biophysics, University of Washington, Seattle, WA, USA
| | - Sam A Golden
- Department of Biological Structure, University of Washington, Seattle, WA, USA; Center of Excellence in Neurobiology of Addiction, Pain, and Emotion (NAPE), University of Washington, Seattle, WA, USA
| | - Thomas A Reh
- Department of Biological Structure, University of Washington, Seattle, WA, USA; Institute for Stem Cells and Regenerative Medicine, University of Washington, Seattle, WA, USA.
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3
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Lee J, Lee BK, Gross JM. Brd activity regulates Müller glia-dependent retinal regeneration in zebrafish. Glia 2023; 71:2866-2883. [PMID: 37584502 DOI: 10.1002/glia.24457] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Revised: 07/28/2023] [Accepted: 07/31/2023] [Indexed: 08/17/2023]
Abstract
The zebrafish retina possesses tremendous regenerative potential. Müller glia underlie retinal regeneration through their ability to reprogram and generate multipotent neuronal progenitors that re-differentiate into lost neurons. Many factors required for Müller glia reprogramming and proliferation have been identified; however, we know little about the epigenetic and transcriptional regulation of these genes during regeneration. Here, we determined whether transcriptional regulation by members of the Bromodomain (Brd) family is required for Müller glia-dependent retinal regeneration. Our data demonstrate that three brd genes were expressed in Müller glia upon injury. brd2a and brd2b were expressed in all Müller glia and brd4 was expressed only in reprogramming Müller glia. Utilizing (+)-JQ1, a pharmacological inhibitor of Brd function, we demonstrate that transcriptional regulation by Brds plays a critical role in Müller glia reprogramming and regeneration. (+)-JQ1 treatment prevented cell cycle re-entry of Müller glia and the generation of neurogenic progenitors. Modulating the (+)-JQ1 exposure window, we identified the first 48 h post-injury as the time-period during which Müller glia reprogramming occurs. (+)-JQ1 treatments after 48 h post-injury had no effect on the re-differentiation of UV cones, indicating that Brd function is required only for Müller glia reprogramming and not subsequent specification/differentiation events. Brd inhibition also prevented the expression of reprogramming genes like ascl1a and lepb in Müller glia, but not effector genes like mmp9, nor did it affect microglial recruitment after injury. These results demonstrate that transcriptional regulation by Brds plays a critical role during Müller glia-dependent retinal regeneration in zebrafish.
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Affiliation(s)
- Jiwoon Lee
- Departments of Ophthalmology and Developmental Biology, Louis J. Fox Center for Vision Restoration, The University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Bum-Kyu Lee
- Department of Biomedical Sciences, Cancer Research Center, University at Albany, State University of New York, Rensselaer, New York, USA
| | - Jeffrey M Gross
- Departments of Ophthalmology and Developmental Biology, Louis J. Fox Center for Vision Restoration, The University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas, USA
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4
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Si TE, Li Z, Zhang J, Su S, Liu Y, Chen S, Peng GH, Cao J, Zang W. Epigenetic mechanisms of Müller glial reprogramming mediating retinal regeneration. Front Cell Dev Biol 2023; 11:1157893. [PMID: 37397254 PMCID: PMC10309042 DOI: 10.3389/fcell.2023.1157893] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Accepted: 06/08/2023] [Indexed: 07/04/2023] Open
Abstract
Retinal degenerative diseases, characterized by retinal neuronal death and severe vision loss, affect millions of people worldwide. One of the most promising treatment methods for retinal degenerative diseases is to reprogram non-neuronal cells into stem or progenitor cells, which then have the potential to re-differentiate to replace the dead neurons, thereby promoting retinal regeneration. Müller glia are the major glial cell type and play an important regulatory role in retinal metabolism and retinal cell regeneration. Müller glia can serve as a source of neurogenic progenitor cells in organisms with the ability to regenerate the nervous system. Current evidence points toward the reprogramming process of Müller glia, involving changes in the expression of pluripotent factors and other key signaling molecules that may be regulated by epigenetic mechanisms. This review summarizes recent knowledge of epigenetic modifications involved in the reprogramming process of Müller glia and the subsequent changes to gene expression and the outcomes. In living organisms, epigenetic mechanisms mainly include DNA methylation, histone modification, and microRNA-mediated miRNA degradation, all of which play a crucial role in the reprogramming process of Müller glia. The information presented in this review will improve the understanding of the mechanisms underlying the Müller glial reprogramming process and provide a research basis for the development of Müller glial reprogramming therapy for retinal degenerative diseases.
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Affiliation(s)
- Tian-En Si
- Department of Anatomy, Basic Medical College, Zhengzhou University, Zhengzhou, China
| | - Zhixiao Li
- Department of Anatomy, Basic Medical College, Zhengzhou University, Zhengzhou, China
| | - Jingjing Zhang
- Department of Anatomy, Basic Medical College, Zhengzhou University, Zhengzhou, China
| | - Songxue Su
- Department of Anatomy, Basic Medical College, Zhengzhou University, Zhengzhou, China
| | - Yupeng Liu
- Department of Anatomy, Basic Medical College, Zhengzhou University, Zhengzhou, China
| | - Shiyue Chen
- Department of Anatomy, Basic Medical College, Zhengzhou University, Zhengzhou, China
| | - Guang-Hua Peng
- Department of Pathophysiology, Basic Medical College, Zhengzhou University, Zhengzhou, China
- Laboratory of Visual Cell Differentiation and Regulation, Basic Medical College, Zhengzhou University, Zhengzhou, China
| | - Jing Cao
- Department of Anatomy, Basic Medical College, Zhengzhou University, Zhengzhou, China
| | - Weidong Zang
- Department of Anatomy, Basic Medical College, Zhengzhou University, Zhengzhou, China
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5
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Eastlake K, Luis J, Wang W, Lamb W, Khaw PT, Limb GA. Transcriptomics of CD29 +/CD44 + cells isolated from hPSC retinal organoids reveals a single cell population with retinal progenitor and Müller glia characteristics. Sci Rep 2023; 13:5081. [PMID: 36977817 PMCID: PMC10050419 DOI: 10.1038/s41598-023-32058-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Accepted: 03/21/2023] [Indexed: 03/30/2023] Open
Abstract
Müller glia play very important and diverse roles in retinal homeostasis and disease. Although much is known of the physiological and morphological properties of mammalian Müller glia, there is still the need to further understand the profile of these cells during human retinal development. Using human embryonic stem cell-derived retinal organoids, we investigated the transcriptomic profiles of CD29+/CD44+ cells isolated from early and late stages of organoid development. Data showed that these cells express classic markers of retinal progenitors and Müller glia, including NFIX, RAX, PAX6, VSX2, HES1, WNT2B, SOX, NR2F1/2, ASCL1 and VIM, as early as days 10-20 after initiation of retinal differentiation. Expression of genes upregulated in CD29+/CD44+ cells isolated at later stages of organoid development (days 50-90), including NEUROG1, VSX2 and ASCL1 were gradually increased as retinal organoid maturation progressed. Based on the current observations that CD24+/CD44+ cells share the characteristics of early and late-stage retinal progenitors as well as of mature Müller glia, we propose that these cells constitute a single cell population that upon exposure to developmental cues regulates its gene expression to adapt to functions exerted by Müller glia in the postnatal and mature retina.
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Affiliation(s)
- Karen Eastlake
- NIHR Biomedical Research Centre at Moorfields Eye Hospital, UCL Institute of Ophthalmology, 11-43 Bath Street, London, EC1V 9EL, UK.
| | - Joshua Luis
- NIHR Biomedical Research Centre at Moorfields Eye Hospital, UCL Institute of Ophthalmology, 11-43 Bath Street, London, EC1V 9EL, UK
| | - Weixin Wang
- NIHR Biomedical Research Centre at Moorfields Eye Hospital, UCL Institute of Ophthalmology, 11-43 Bath Street, London, EC1V 9EL, UK
| | - William Lamb
- NIHR Biomedical Research Centre at Moorfields Eye Hospital, UCL Institute of Ophthalmology, 11-43 Bath Street, London, EC1V 9EL, UK
| | - Peng T Khaw
- NIHR Biomedical Research Centre at Moorfields Eye Hospital, UCL Institute of Ophthalmology, 11-43 Bath Street, London, EC1V 9EL, UK
| | - G Astrid Limb
- NIHR Biomedical Research Centre at Moorfields Eye Hospital, UCL Institute of Ophthalmology, 11-43 Bath Street, London, EC1V 9EL, UK.
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Campbell WA, El‐Hodiri HM, Torres D, Hawthorn EC, Kelly LE, Volkov L, Akanonu D, Fischer AJ. Chromatin access regulates the formation of Müller glia‐derived progenitor cells in the retina. Glia 2023; 71:1729-1754. [PMID: 36971459 DOI: 10.1002/glia.24366] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Revised: 03/06/2023] [Accepted: 03/12/2023] [Indexed: 03/29/2023]
Abstract
Chromatin access and epigenetic control over gene expression play important roles in regulating developmental processes. However, little is known about how chromatin access and epigenetic gene silencing influence mature glial cells and retinal regeneration. Herein, we investigate the expression and functions of S-adenosylhomocysteine hydrolase (SAHH; AHCY) and histone methyltransferases (HMTs) during the formation of Müller glia (MG)-derived progenitor cells (MGPCs) in the chick and mouse retinas. In chick, AHCY, AHCYL1 and AHCYL2, and many different HMTs are dynamically expressed by MG and MGPCs in damaged retinas. Inhibition of SAHH reduced levels of H3K27me3 and potently blocks the formation of proliferating MGPCs. By using a combination of single cell RNA-seq and single cell ATAC-seq, we find significant changes in gene expression and chromatin access in MG with SAHH inhibition and NMDA-treatment; many of these genes are associated with glial and neuronal differentiation. A strong correlation across gene expression, chromatin access, and transcription factor motif access in MG was observed for transcription factors known to convey glial identity and promote retinal development. By comparison, in the mouse retina, inhibition of SAHH has no influence on the differentiation of neuron-like cells from Ascl1-overexpressing MG. We conclude that in the chick the activity of SAHH and HMTs are required for the reprogramming of MG into MGPCs by regulating chromatin access to transcription factors associated with glial differentiation and retinal development.
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Chen J, Huang L, Yang Y, Xu W, Qin Q, Qin R, Liang X, Lai X, Huang X, Xie M, Chen L. Somatic Cell Reprogramming for Nervous System Diseases: Techniques, Mechanisms, Potential Applications, and Challenges. Brain Sci 2023; 13:brainsci13030524. [PMID: 36979334 PMCID: PMC10046178 DOI: 10.3390/brainsci13030524] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2023] [Revised: 03/14/2023] [Accepted: 03/20/2023] [Indexed: 03/30/2023] Open
Abstract
Nervous system diseases present significant challenges to the neuroscience community due to ethical and practical constraints that limit access to appropriate research materials. Somatic cell reprogramming has been proposed as a novel way to obtain neurons. Various emerging techniques have been used to reprogram mature and differentiated cells into neurons. This review provides an overview of somatic cell reprogramming for neurological research and therapy, focusing on neural reprogramming and generating different neural cell types. We examine the mechanisms involved in reprogramming and the challenges that arise. We herein summarize cell reprogramming strategies to generate neurons, including transcription factors, small molecules, and microRNAs, with a focus on different types of cells.. While reprogramming somatic cells into neurons holds the potential for understanding neurological diseases and developing therapeutic applications, its limitations and risks must be carefully considered. Here, we highlight the potential benefits of somatic cell reprogramming for neurological disease research and therapy. This review contributes to the field by providing a comprehensive overview of the various techniques used to generate neurons by cellular reprogramming and discussing their potential applications.
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Affiliation(s)
- Jiafeng Chen
- Department of Neurology, the First Affiliated Hospital of Guangxi Medical University, Nanning 530021, China
| | - Lijuan Huang
- Department of Neurology, the First Affiliated Hospital of Guangxi Medical University, Nanning 530021, China
| | - Yue Yang
- Department of Neurology, the First Affiliated Hospital of Guangxi Medical University, Nanning 530021, China
| | - Wei Xu
- Department of Neurology, the First Affiliated Hospital of Guangxi Medical University, Nanning 530021, China
| | - Qingchun Qin
- Department of Neurology, the First Affiliated Hospital of Guangxi Medical University, Nanning 530021, China
| | - Rongxing Qin
- Department of Neurology, the First Affiliated Hospital of Guangxi Medical University, Nanning 530021, China
| | - Xiaojun Liang
- Department of Neurology, the First Affiliated Hospital of Guangxi Medical University, Nanning 530021, China
| | - Xinyu Lai
- Key Laboratory of Longevity and Aging-Related Diseases of Chinese Ministry of Education, Nanning 530021, China
| | - Xiaoying Huang
- Department of Neurology, the First Affiliated Hospital of Guangxi Medical University, Nanning 530021, China
| | - Minshan Xie
- Department of Neurology, the First Affiliated Hospital of Guangxi Medical University, Nanning 530021, China
| | - Li Chen
- Department of Neurology, the First Affiliated Hospital of Guangxi Medical University, Nanning 530021, China
- Key Laboratory of Longevity and Aging-Related Diseases of Chinese Ministry of Education, Nanning 530021, China
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8
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Chucair-Elliott AJ, Ocañas SR, Pham K, Van Der Veldt M, Cheyney A, Stanford D, Gurley J, Elliott MH, Freeman WM. Translatomic response of retinal Müller glia to acute and chronic stress. Neurobiol Dis 2022; 175:105931. [PMID: 36423879 PMCID: PMC9875566 DOI: 10.1016/j.nbd.2022.105931] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Revised: 11/14/2022] [Accepted: 11/19/2022] [Indexed: 11/23/2022] Open
Abstract
Analysis of retina cell type-specific epigenetic and transcriptomic signatures is crucial to understanding the pathophysiology of retinal degenerations such as age-related macular degeneration (AMD) and delineating cell autonomous and cell-non-autonomous mechanisms. We have discovered that Aldh1l1 is specifically expressed in the major macroglia of the retina, Müller glia, and, unlike the brain, is not expressed in retinal astrocytes. This allows use of Aldh1l1 cre drivers and Nuclear Tagging and Translating Ribosome Affinity Purification (NuTRAP) constructs for temporally controlled labeling and paired analysis of Müller glia epigenomes and translatomes. As validated through a variety of approaches, the Aldh1l1cre/ERT2-NuTRAP model provides Müller glia specific translatomic and epigenomic profiles without the need to isolate whole cells. Application of this approach to models of acute injury (optic nerve crush) and chronic stress (aging) uncovered few common Müller glia-specific transcriptome changes in inflammatory pathways, and mostly differential signatures for each stimulus. The expression of members of the IL-6 and integrin-linked kinase signaling pathways was enhanced in Müller glia in response to optic nerve crush but not aging. Unique changes in neuroinflammation and fibrosis signaling pathways were observed in response to aging but not with optic nerve crush. The Aldh1l1cre/ERT2-NuTRAP model allows focused molecular analyses of a single, minority cell type within the retina, providing more substantial effect sizes than whole tissue analyses. The NuTRAP model, nucleic acid isolation, and validation approaches presented here can be applied to any retina cell type for which a cell type-specific cre is available.
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Affiliation(s)
- Ana J. Chucair-Elliott
- Genes & Human Disease Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, USA,Corresponding authors at: Genes & Human Disease Program, Oklahoma Medical Research Foundation, 825 NE 13th Street, Oklahoma City, OK 73104, USA. (A.J. Chucair-Elliott), (W.M. Freeman)
| | - Sarah R. Ocañas
- Genes & Human Disease Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, USA,Department of Physiology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Kevin Pham
- Genes & Human Disease Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, USA
| | - Michael Van Der Veldt
- Genes & Human Disease Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, USA
| | - Ashley Cheyney
- Genes & Human Disease Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, USA,Department of Physiology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - David Stanford
- Genes & Human Disease Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, USA
| | - Jami Gurley
- Department of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Michael H. Elliott
- Department of Physiology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA,Department of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Willard M. Freeman
- Genes & Human Disease Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, USA,Oklahoma City Veterans Affairs Medical Center, Oklahoma City, OK, USA,Corresponding authors at: Genes & Human Disease Program, Oklahoma Medical Research Foundation, 825 NE 13th Street, Oklahoma City, OK 73104, USA. (A.J. Chucair-Elliott), (W.M. Freeman)
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Wang WZ, Shulman A, Amann JM, Carbone DP, Tsichlis PN. Small cell lung cancer: Subtypes and therapeutic implications. Semin Cancer Biol 2022; 86:543-554. [DOI: 10.1016/j.semcancer.2022.04.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Revised: 03/23/2022] [Accepted: 04/04/2022] [Indexed: 12/20/2022]
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10
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Xie Y, Chen B. Critical Examination of Müller Glia-Derived in vivo Neurogenesis in the Mouse Retina. Front Cell Dev Biol 2022; 10:830382. [PMID: 35433694 PMCID: PMC9008276 DOI: 10.3389/fcell.2022.830382] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Accepted: 02/10/2022] [Indexed: 01/02/2023] Open
Abstract
Müller glia (MG) are a potential source of stem cells in the mammalian retina that could replenish lost retinal neurons for vision restoration. Unlike their counterpart in zebrafish, mammalian MG are quiescent and they do not spontaneously generate new retinal neurons. In recent years, extensive research efforts have been made to unlock the regenerative capabilities of Müller glia (MG) for de novo regeneration of retinal neurons in mice. Here, we discuss current research progress on MG-derived in vivo neurogenesis in the mouse retina, focusing on the use of stringent fate mapping techniques to evaluate and validate de novo regeneration of retinal neurons through the reprogramming of endogenous MG. Establishing stringent experimental criteria is critical for examining current and future studies on MG-derived regeneration of photoreceptors, retinal inter-neurons, and retinal ganglion cells.
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Zibetti C. Deciphering the Retinal Epigenome during Development, Disease and Reprogramming: Advancements, Challenges and Perspectives. Cells 2022; 11:cells11050806. [PMID: 35269428 PMCID: PMC8908986 DOI: 10.3390/cells11050806] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Revised: 02/15/2022] [Accepted: 02/18/2022] [Indexed: 02/01/2023] Open
Abstract
Retinal neurogenesis is driven by concerted actions of transcription factors, some of which are expressed in a continuum and across several cell subtypes throughout development. While seemingly redundant, many factors diversify their regulatory outcome on gene expression, by coordinating variations in chromatin landscapes to drive divergent retinal specification programs. Recent studies have furthered the understanding of the epigenetic contribution to the progression of age-related macular degeneration, a leading cause of blindness in the elderly. The knowledge of the epigenomic mechanisms that control the acquisition and stabilization of retinal cell fates and are evoked upon damage, holds the potential for the treatment of retinal degeneration. Herein, this review presents the state-of-the-art approaches to investigate the retinal epigenome during development, disease, and reprogramming. A pipeline is then reviewed to functionally interrogate the epigenetic and transcriptional networks underlying cell fate specification, relying on a truly unbiased screening of open chromatin states. The related work proposes an inferential model to identify gene regulatory networks, features the first footprinting analysis and the first tentative, systematic query of candidate pioneer factors in the retina ever conducted in any model organism, leading to the identification of previously uncharacterized master regulators of retinal cell identity, such as the nuclear factor I, NFI. This pipeline is virtually applicable to the study of genetic programs and candidate pioneer factors in any developmental context. Finally, challenges and limitations intrinsic to the current next-generation sequencing techniques are discussed, as well as recent advances in super-resolution imaging, enabling spatio-temporal resolution of the genome.
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Affiliation(s)
- Cristina Zibetti
- Department of Ophthalmology, Institute of Clinical Medicine, University of Oslo, Kirkeveien 166, Building 36, 0455 Oslo, Norway
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12
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Abstract
Cellular identity is established through complex layers of genetic regulation, forged over a developmental lifetime. An expanding molecular toolbox is allowing us to manipulate these gene regulatory networks in specific cell types in vivo. In principle, if we found the right molecular tricks, we could rewrite cell identity and harness the rich repertoire of possible cellular functions and attributes. Recent work suggests that this rewriting of cell identity is not only possible, but that newly induced cells can mitigate disease phenotypes in animal models of major human diseases. So, is the sky the limit, or do we need to keep our feet on the ground? This Spotlight synthesises key concepts emerging from recent efforts to reprogramme cellular identity in vivo. We provide our perspectives on recent controversies in the field of glia-to-neuron reprogramming and identify important gaps in our understanding that present barriers to progress.
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Affiliation(s)
- Sydney Leaman
- Centre for Developmental Neurobiology, Institute of Psychiatry, Psychology & Neuroscience, King's College London, London SE1 1UL, UK.,MRC Centre for Neurodevelopmental Disorders, King's College London, London SE1 1UL, UK
| | - Nicolás Marichal
- Centre for Developmental Neurobiology, Institute of Psychiatry, Psychology & Neuroscience, King's College London, London SE1 1UL, UK
| | - Benedikt Berninger
- Centre for Developmental Neurobiology, Institute of Psychiatry, Psychology & Neuroscience, King's College London, London SE1 1UL, UK.,MRC Centre for Neurodevelopmental Disorders, King's College London, London SE1 1UL, UK.,Institute of Physiological Chemistry, University Medical Center of the Johannes Gutenberg University Mainz, Mainz 55128, Germany.,The Francis Crick Institute, London NW1 1AT, UK
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13
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Abstract
The retina was historically considered as an “approachable part of the brain”; advantageous, for its simplicity, to use as a model organ for deciphering cellular and molecular mechanisms underlying physiology and pathology of the nervous system. However, the most relevant discoveries arise precisely from unveiling the complexity of the retina. A complexity that partially relies on the layered organization of an extended variety of specialized neuronal and glial cellular types and subtypes. Based on functional, morphological or transcriptome data, over 40 subtypes of retinal ganglion cells or 60 subtypes of retinal amacrine cells have been described. A high degree of specialization, that may lead to segregation into functionally diverse subtypes, is also conceivable for Müller cells, a pleiotropic glial component of all vertebrate retinas. The essential role of Müller glia in retinal homeostasis maintenance involves participation in structural, metabolic and intercellular communication processes. Additionally, they are the only retinal cells that possess regenerative potential in response to injury or disease, and thus may be considered as therapeutic tools. In the assumption that functional heterogeneity might be driven by molecular heterogeneity this review aims to compile emerging evidence that could broaden our understanding of Müller cell biology and retinal physiology. Summary statement Müller glial cells exert multiple essential functions in retinal physiology and retinopathies reflecting perhaps the existence of distinct Müller cellular subpopulations. Harnessing Müller cell heterogeneity may serve to enhance new therapeutic approaches for retinal disease.
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Affiliation(s)
- Monica Lamas
- Departamento de Farmacobiología. CINVESTAV-Sede Sur. México D.F. México
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14
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Daghsni M, Aldiri I. Building a Mammalian Retina: An Eye on Chromatin Structure. Front Genet 2021; 12:775205. [PMID: 34764989 PMCID: PMC8576187 DOI: 10.3389/fgene.2021.775205] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Accepted: 10/08/2021] [Indexed: 11/13/2022] Open
Abstract
Regulation of gene expression by chromatin structure has been under intensive investigation, establishing nuclear organization and genome architecture as a potent and effective means of regulating developmental processes. The substantial growth in our knowledge of the molecular mechanisms underlying retinogenesis has been powered by several genome-wide based tools that mapped chromatin organization at multiple cellular and biochemical levels. Studies profiling the retinal epigenome and transcriptome have allowed the systematic annotation of putative cis-regulatory elements associated with transcriptional programs that drive retinal neural differentiation, laying the groundwork to understand spatiotemporal retinal gene regulation at a mechanistic level. In this review, we outline recent advances in our understanding of the chromatin architecture in the mammalian retina during development and disease. We focus on the emerging roles of non-coding regulatory elements in controlling retinal cell-type specific transcriptional programs, and discuss potential implications in untangling the etiology of eye-related disorders.
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Affiliation(s)
- Marwa Daghsni
- Department of Ophthalmology, School of Medicine, University of Pittsburgh, Pittsburgh, PA, United States
| | - Issam Aldiri
- Department of Ophthalmology, School of Medicine, University of Pittsburgh, Pittsburgh, PA, United States.,Department of Developmental Biology, School of Medicine, University of Pittsburgh, Pittsburgh, PA, United States.,Louis J. Fox Center for Vision Restoration, University of Pittsburgh, Pittsburgh, PA, United States
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15
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Features of Retinal Neurogenesis as a Key Factor of Age-Related Neurodegeneration: Myth or Reality? Int J Mol Sci 2021; 22:ijms22147373. [PMID: 34298993 PMCID: PMC8303671 DOI: 10.3390/ijms22147373] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Revised: 07/05/2021] [Accepted: 07/05/2021] [Indexed: 11/16/2022] Open
Abstract
Age-related macular degeneration (AMD) is a complex multifactorial neurodegenerative disease that constitutes the most common cause of irreversible blindness in the elderly in the developed countries. Incomplete knowledge about its pathogenesis prevents the search for effective methods of prevention and treatment of AMD, primarily of its "dry" type which is by far the most common (90% of all AMD cases). In the recent years, AMD has become "younger": late stages of the disease are now detected in relatively young people. It is known that AMD pathogenesis-according to the age-related structural and functional changes in the retina-is linked with inflammation, hypoxia, oxidative stress, mitochondrial dysfunction, and an impairment of neurotrophic support, but the mechanisms that trigger the conversion of normal age-related changes to the pathological process as well as the reason for early AMD development remain unclear. In the adult mammalian retina, de novo neurogenesis is very limited. Therefore, the structural and functional features that arise during its maturation and formation can exert long-term effects on further ontogenesis of this tissue. The aim of this review was to discuss possible contributions of the changes/disturbances in retinal neurogenesis to the early development of AMD.
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16
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Nagashima M, Hitchcock PF. Inflammation Regulates the Multi-Step Process of Retinal Regeneration in Zebrafish. Cells 2021; 10:cells10040783. [PMID: 33916186 PMCID: PMC8066466 DOI: 10.3390/cells10040783] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2021] [Revised: 03/25/2021] [Accepted: 03/27/2021] [Indexed: 12/20/2022] Open
Abstract
The ability to regenerate tissues varies between species and between tissues within a species. Mammals have a limited ability to regenerate tissues, whereas zebrafish possess the ability to regenerate almost all tissues and organs, including fin, heart, kidney, brain, and retina. In the zebrafish brain, injury and cell death activate complex signaling networks that stimulate radial glia to reprogram into neural stem-like cells that repair the injury. In the retina, a popular model for investigating neuronal regeneration, Müller glia, radial glia unique to the retina, reprogram into stem-like cells and undergo a single asymmetric division to generate multi-potent retinal progenitors. Müller glia-derived progenitors then divide rapidly, numerically matching the magnitude of the cell death, and differentiate into the ablated neurons. Emerging evidence reveals that inflammation plays an essential role in this multi-step process of retinal regeneration. This review summarizes the current knowledge of the inflammatory events during retinal regeneration and highlights the mechanisms whereby inflammatory molecules regulate the quiescence and division of Müller glia, the proliferation of Müller glia-derived progenitors and the survival of regenerated neurons.
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17
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Abstract
The vertebrate eye is derived from the neuroepithelium, surface ectoderm, and extracellular mesenchyme. The neuroepithelium forms an optic cup in which the spatial separation of three domains is established, namely, the region of multipotent retinal progenitor cells (RPCs), the ciliary margin zone (CMZ)-which possesses both a neurogenic and nonneurogenic potential-and the optic disk (OD), the interface between the optic stalk and the neuroretina. Here, we show by genetic ablation in the developing optic cup that Meis1 and Meis2 homeobox genes function redundantly to maintain the retinal progenitor pool while they simultaneously suppress the expression of genes characteristic of CMZ and OD fates. Furthermore, we demonstrate that Meis transcription factors bind regulatory regions of RPC-, CMZ-, and OD-specific genes, thus providing a mechanistic insight into the Meis-dependent gene regulatory network. Our work uncovers the essential role of Meis1 and Meis2 as regulators of cell fate competence, which organize spatial territories in the vertebrate eye.
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18
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Konar GJ, Ferguson C, Flickinger Z, Kent MR, Patton JG. miRNAs and Müller Glia Reprogramming During Retina Regeneration. Front Cell Dev Biol 2021; 8:632632. [PMID: 33537319 PMCID: PMC7848101 DOI: 10.3389/fcell.2020.632632] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Accepted: 12/21/2020] [Indexed: 12/15/2022] Open
Abstract
The use of model systems that are capable of robust, spontaneous retina regeneration has allowed for the identification of genetic pathways and components that are required for retina regeneration. Complemented by mouse models in which retina regeneration can be induced after forced expression of key factors, altered chromatin accessibility, or inhibition of kinase/signaling cascades, a clearer picture of the key regulatory events that control retina regeneration is emerging. In all cases, Müller glia (MG) serve as an adult retinal stem cell that must be reprogrammed to allow for regeneration, with the end goal being to understand why regenerative pathways are blocked in mammals, but spontaneous in other vertebrates such as zebrafish. miRNAs have emerged as key gene regulatory molecules that control both development and regeneration in vertebrates. Here, we focus on a small subset of miRNAs that control MG reprogramming during retina regeneration and have the potential to serve as therapeutic targets for treatment of visual disorders and damage.
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Affiliation(s)
- Gregory J Konar
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, United States
| | - Claire Ferguson
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, United States
| | - Zachary Flickinger
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, United States
| | - Matthew R Kent
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, United States
| | - James G Patton
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, United States
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