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Diacou R, Nandigrami P, Fiser A, Liu W, Ashery-Padan R, Cvekl A. Cell fate decisions, transcription factors and signaling during early retinal development. Prog Retin Eye Res 2022; 91:101093. [PMID: 35817658 PMCID: PMC9669153 DOI: 10.1016/j.preteyeres.2022.101093] [Citation(s) in RCA: 28] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Revised: 06/02/2022] [Accepted: 06/03/2022] [Indexed: 12/30/2022]
Abstract
The development of the vertebrate eyes is a complex process starting from anterior-posterior and dorso-ventral patterning of the anterior neural tube, resulting in the formation of the eye field. Symmetrical separation of the eye field at the anterior neural plate is followed by two symmetrical evaginations to generate a pair of optic vesicles. Next, reciprocal invagination of the optic vesicles with surface ectoderm-derived lens placodes generates double-layered optic cups. The inner and outer layers of the optic cups develop into the neural retina and retinal pigment epithelium (RPE), respectively. In vitro produced retinal tissues, called retinal organoids, are formed from human pluripotent stem cells, mimicking major steps of retinal differentiation in vivo. This review article summarizes recent progress in our understanding of early eye development, focusing on the formation the eye field, optic vesicles, and early optic cups. Recent single-cell transcriptomic studies are integrated with classical in vivo genetic and functional studies to uncover a range of cellular mechanisms underlying early eye development. The functions of signal transduction pathways and lineage-specific DNA-binding transcription factors are dissected to explain cell-specific regulatory mechanisms underlying cell fate determination during early eye development. The functions of homeodomain (HD) transcription factors Otx2, Pax6, Lhx2, Six3 and Six6, which are required for early eye development, are discussed in detail. Comprehensive understanding of the mechanisms of early eye development provides insight into the molecular and cellular basis of developmental ocular anomalies, such as optic cup coloboma. Lastly, modeling human development and inherited retinal diseases using stem cell-derived retinal organoids generates opportunities to discover novel therapies for retinal diseases.
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Affiliation(s)
- Raven Diacou
- Department of Genetics, Albert Einstein College of Medicine, Bronx, NY, 10461, USA; Department of Ophthalmology and Visual Sciences, Albert Einstein College of Medicine, Bronx, NY, 10461, USA
| | - Prithviraj Nandigrami
- Department of Systems and Computational Biology, Albert Einstein College of Medicine, Bronx, NY, 10461, USA; Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY, 10461, USA
| | - Andras Fiser
- Department of Systems and Computational Biology, Albert Einstein College of Medicine, Bronx, NY, 10461, USA; Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY, 10461, USA
| | - Wei Liu
- Department of Genetics, Albert Einstein College of Medicine, Bronx, NY, 10461, USA; Department of Ophthalmology and Visual Sciences, Albert Einstein College of Medicine, Bronx, NY, 10461, USA
| | - Ruth Ashery-Padan
- Sackler School of Medicine, Tel Aviv University, Tel Aviv, 69978, Israel
| | - Ales Cvekl
- Department of Genetics, Albert Einstein College of Medicine, Bronx, NY, 10461, USA; Department of Ophthalmology and Visual Sciences, Albert Einstein College of Medicine, Bronx, NY, 10461, USA.
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2
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Fishman ES, Han JS, La Torre A. Oscillatory Behaviors of microRNA Networks: Emerging Roles in Retinal Development. Front Cell Dev Biol 2022; 10:831750. [PMID: 35186936 PMCID: PMC8847441 DOI: 10.3389/fcell.2022.831750] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Accepted: 01/07/2022] [Indexed: 01/02/2023] Open
Abstract
A broad repertoire of transcription factors and other genes display oscillatory patterns of expression, typically ranging from 30 min to 24 h. These oscillations are associated with a variety of biological processes, including the circadian cycle, somite segmentation, cell cycle, and metabolism. These rhythmic behaviors are often prompted by transcriptional feedback loops in which transcriptional activities are inhibited by their corresponding gene target products. Oscillatory transcriptional patterns have been proposed as a mechanism to drive biological clocks, the molecular machinery that transforms temporal information into accurate spatial patterning during development. Notably, several microRNAs (miRNAs) -small non-coding RNA molecules-have been recently shown to both exhibit rhythmic expression patterns and regulate oscillatory activities. Here, we discuss some of these new findings in the context of the developing retina. We propose that miRNA oscillations are a powerful mechanism to coordinate signaling pathways and gene expression, and that addressing the dynamic interplay between miRNA expression and their target genes could be key for a more complete understanding of many developmental processes.
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Co-activation of Sonic hedgehog and Wnt signaling in murine retinal precursor cells drives ocular lesions with features of intraocular medulloepithelioma. Oncogenesis 2021; 10:78. [PMID: 34785636 PMCID: PMC8595639 DOI: 10.1038/s41389-021-00369-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Revised: 10/19/2021] [Accepted: 10/28/2021] [Indexed: 11/12/2022] Open
Abstract
Intraocular medulloepithelioma (IO-MEPL) is a rare embryonal ocular neoplasm, prevalently occurring in children. IO-MEPLs share histomorphological features with CNS embryonal tumors with multilayered rosettes (ETMRs), referred to as intracranial medulloepitheliomas. While Sonic hedgehog (SHH) and WNT signaling pathways are crucial for ETMR pathogenesis, the impact of these pathways on human IO-MEPL development is unclear. Gene expression analyses of human embryonal tumor samples revealed similar gene expression patterns and significant overrepresentation of SHH and WNT target genes in both IO-MEPL and ETMR. In order to unravel the function of Shh and Wnt signaling for IO-MEPL pathogenesis in vivo, both pathways were activated in retinal precursor cells in a time point specific manner. Shh and Wnt co-activation in early Sox2- or Rax-expressing precursor cells resulted in infiltrative ocular lesions that displayed extraretinal expansion. Histomorphological, immunohistochemical, and molecular features showed a strong concordance with human IO-MEPL. We demonstrate a relevant role of WNT and SHH signaling in IO-MEPL and report the first mouse model to generate tumor-like lesions with features of IO-MEPL. The presented data may be fundamental for comprehending IO-MEPL initiation and developing targeted therapeutic approaches.
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dnmt1 function is required to maintain retinal stem cells within the ciliary marginal zone of the zebrafish eye. Sci Rep 2020; 10:11293. [PMID: 32647199 PMCID: PMC7347529 DOI: 10.1038/s41598-020-68016-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Accepted: 05/15/2020] [Indexed: 12/22/2022] Open
Abstract
The ciliary marginal zone (CMZ) of the zebrafish retina contains a population of actively proliferating resident stem cells, which generate retinal neurons throughout life. The maintenance methyltransferase, dnmt1, is expressed within the CMZ. Loss of dnmt1 function results in gene misregulation and cell death in a variety of developmental contexts, however, its role in retinal stem cell (RSC) maintenance is currently unknown. Here, we demonstrate that zebrafish dnmt1s872 mutants possess severe defects in RSC maintenance within the CMZ. Using a combination of immunohistochemistry, in situ hybridization, and a transgenic reporter assay, our results demonstrate a requirement for dnmt1 activity in the regulation of RSC proliferation, gene expression and in the repression of endogenous retroelements (REs). Ultimately, cell death is elevated in the dnmt1−/− CMZ, but in a p53-independent manner. Using a transgenic reporter for RE transposition activity, we demonstrate increased transposition in the dnmt1−/− CMZ. Taken together our data identify a critical role for dnmt1 function in RSC maintenance in the vertebrate eye.
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5
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Xu B, Tang X, Jin M, Zhang H, Du L, Yu S, He J. Unifying developmental programs for embryonic and postembryonic neurogenesis in the zebrafish retina. Development 2020; 147:dev.185660. [PMID: 32467236 DOI: 10.1242/dev.185660] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2019] [Accepted: 05/13/2020] [Indexed: 01/14/2023]
Abstract
The zebrafish retina grows for a lifetime. Whether embryonic and postembryonic retinogenesis conform to the same developmental program is an outstanding question that remains under debate. Using single-cell RNA sequencing of ∼20,000 cells of the developing zebrafish retina at four different stages, we identified seven distinct developmental states. Each state explicitly expresses a gene set. Disruption of individual state-specific marker genes results in various defects ranging from small eyes to the loss of distinct retinal cell types. Using a similar approach, we further characterized the developmental states of postembryonic retinal stem cells (RSCs) and their progeny in the ciliary marginal zone. Expression pattern analysis of state-specific marker genes showed that the developmental states of postembryonic RSCs largely recapitulated those of their embryonic counterparts, except for some differences in rod photoreceptor genesis. Thus, our findings reveal the unifying developmental program used by the embryonic and postembryonic retinogenesis in zebrafish.
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Affiliation(s)
- Baijie Xu
- Institute of Neuroscience, State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai 200031, China.,University of Chinese Academy of Sciences, Beijing 100049, China.,Shanghai Center for Brain Science and Brain-Inspired Intelligence Technology, Shanghai 201210, China
| | - Xia Tang
- Institute of Neuroscience, State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai 200031, China .,Shanghai Center for Brain Science and Brain-Inspired Intelligence Technology, Shanghai 201210, China
| | - Mengmeng Jin
- Institute of Neuroscience, State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai 200031, China.,University of Chinese Academy of Sciences, Beijing 100049, China.,Shanghai Center for Brain Science and Brain-Inspired Intelligence Technology, Shanghai 201210, China
| | - Hui Zhang
- Institute of Neuroscience, State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai 200031, China.,University of Chinese Academy of Sciences, Beijing 100049, China.,Shanghai Center for Brain Science and Brain-Inspired Intelligence Technology, Shanghai 201210, China
| | - Lei Du
- Institute of Neuroscience, State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai 200031, China.,University of Chinese Academy of Sciences, Beijing 100049, China.,Shanghai Center for Brain Science and Brain-Inspired Intelligence Technology, Shanghai 201210, China
| | - Shuguang Yu
- Institute of Neuroscience, State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai 200031, China.,University of Chinese Academy of Sciences, Beijing 100049, China.,Shanghai Center for Brain Science and Brain-Inspired Intelligence Technology, Shanghai 201210, China
| | - Jie He
- Institute of Neuroscience, State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai 200031, China .,Shanghai Center for Brain Science and Brain-Inspired Intelligence Technology, Shanghai 201210, China
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6
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Wang Z, Gao F, Zhang M, Zheng Y, Zhang F, Xu L, Cao L, He W. Intravitreal Injection of Human Retinal Progenitor Cells for Treatment of Retinal Degeneration. Med Sci Monit 2020; 26:e921184. [PMID: 32221273 PMCID: PMC7139196 DOI: 10.12659/msm.921184] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Background Retinal degeneration causes irreversible blindness. Human retinal progenitor cells (hRPCs) have the potential to treat retinal diseases. The vitreous cavity is a relatively immune-privileged site that is suitable for stem cell transplantation in the treatment of retinal diseases. This study aimed to evaluate the therapeutic efficacy and safety of intravitreal injection of hRPCs in retinal degeneration therapy. Material/Methods hRPCs were primary-cultured and injected into the vitreous cavity of RCS rats. To determine whether hRPCs formed teratomas in immune-deficient mice, hRPCs at different passages were transplanted into BALB/c-nu mice. The visual function was detected by electroretinography recording. Changes in the outer nuclear layer (ONL) were analyzed by histological testing and cell counting. The protective mechanism was further assessed by cytokine antibody array. Results Intravitreal transplantation of hRPCs maintained retinal function and preserved retinal morphology. Importantly, grafted cells in the vitreous cavity were well tolerated, with no adverse effects. Teratoma was not formed in BALB/c-nu mice after hRPCs transplantation. The number of hRPCs-injected eyes and thickness of ONL in the hRPCs-treated group were higher than those in the untreated group and HBSS injection group. The cytokine antibody array revealed that hRPCs expressed GDF-15, PDGF-AA, EGF, and NT-4. Conclusions Our findings show that intravitreal injection of hRPCs is effective and safe in protecting photoreceptor cells in RCS rats, but were no longer effective at 12 weeks after transplantation. Moreover, hRPCs released multiple neurotrophic factors that may be involved in treating retinal disease.
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Affiliation(s)
- Zhuoshi Wang
- Key Laboratory of Medical Cell Biology, Institute of Translational Medicine, China Medical University, Shenyang, Liaoning, China (mainland).,Clinical Research Center, He Eye Hospital of He University, Shenyang, Liaoning, China (mainland)
| | - Fei Gao
- Stem Cell Research Center, Precision Medical Innovation Institute, He University, Shenyang, Liaoning, China (mainland)
| | - Mingqi Zhang
- Stem Cell Research Center, Precision Medical Innovation Institute, He University, Shenyang, Liaoning, China (mainland)
| | - Yuqiang Zheng
- Stem Cell Research Center, Precision Medical Innovation Institute, He University, Shenyang, Liaoning, China (mainland)
| | - Fenglei Zhang
- Stem Cell Research Center, Precision Medical Innovation Institute, He University, Shenyang, Liaoning, China (mainland)
| | - Ling Xu
- Clinical Research Center, He Eye Hospital of He University, Shenyang, Liaoning, China (mainland)
| | - Liu Cao
- Key Laboratory of Medical Cell Biology, Institute of Translational Medicine, China Medical University, Shenyang, Liaoning, China (mainland)
| | - Wei He
- Key Laboratory of Medical Cell Biology, Institute of Translational Medicine, China Medical University, Shenyang, Liaoning, China (mainland).,Clinical Research Center, He Eye Hospital of He University, Shenyang, Liaoning, China (mainland)
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7
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Markitantova Y, Simirskii V. Inherited Eye Diseases with Retinal Manifestations through the Eyes of Homeobox Genes. Int J Mol Sci 2020; 21:E1602. [PMID: 32111086 PMCID: PMC7084737 DOI: 10.3390/ijms21051602] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Revised: 02/21/2020] [Accepted: 02/24/2020] [Indexed: 12/14/2022] Open
Abstract
Retinal development is under the coordinated control of overlapping networks of signaling pathways and transcription factors. The paper was conceived as a review of the data and ideas that have been formed to date on homeobox genes mutations that lead to the disruption of eye organogenesis and result in inherited eye/retinal diseases. Many of these diseases are part of the same clinical spectrum and have high genetic heterogeneity with already identified associated genes. We summarize the known key regulators of eye development, with a focus on the homeobox genes associated with monogenic eye diseases showing retinal manifestations. Recent advances in the field of genetics and high-throughput next-generation sequencing technologies, including single-cell transcriptome analysis have allowed for deepening of knowledge of the genetic basis of inherited retinal diseases (IRDs), as well as improve their diagnostics. We highlight some promising avenues of research involving molecular-genetic and cell-technology approaches that can be effective for IRDs therapy. The most promising neuroprotective strategies are aimed at mobilizing the endogenous cellular reserve of the retina.
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8
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Clark BS, Stein-O'Brien GL, Shiau F, Cannon GH, Davis-Marcisak E, Sherman T, Santiago CP, Hoang TV, Rajaii F, James-Esposito RE, Gronostajski RM, Fertig EJ, Goff LA, Blackshaw S. Single-Cell RNA-Seq Analysis of Retinal Development Identifies NFI Factors as Regulating Mitotic Exit and Late-Born Cell Specification. Neuron 2019; 102:1111-1126.e5. [PMID: 31128945 PMCID: PMC6768831 DOI: 10.1016/j.neuron.2019.04.010] [Citation(s) in RCA: 255] [Impact Index Per Article: 51.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2018] [Revised: 02/07/2019] [Accepted: 04/03/2019] [Indexed: 12/26/2022]
Abstract
Precise temporal control of gene expression in neuronal progenitors is necessary for correct regulation of neurogenesis and cell fate specification. However, the cellular heterogeneity of the developing CNS has posed a major obstacle to identifying the gene regulatory networks that control these processes. To address this, we used single-cell RNA sequencing to profile ten developmental stages encompassing the full course of retinal neurogenesis. This allowed us to comprehensively characterize changes in gene expression that occur during initiation of neurogenesis, changes in developmental competence, and specification and differentiation of each major retinal cell type. We identify the NFI transcription factors (Nfia, Nfib, and Nfix) as selectively expressed in late retinal progenitor cells and show that they control bipolar interneuron and Müller glia cell fate specification and promote proliferative quiescence.
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Affiliation(s)
- Brian S Clark
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Genevieve L Stein-O'Brien
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Department of Oncology, Division of Biostatistics and Bioinformatics, Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; McKusick-Nathans Institute for Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Institute for Data Intensive Engineering and Science, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Fion Shiau
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Gabrielle H Cannon
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; McKusick-Nathans Institute for Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Emily Davis-Marcisak
- Department of Oncology, Division of Biostatistics and Bioinformatics, Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; McKusick-Nathans Institute for Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Thomas Sherman
- Department of Oncology, Division of Biostatistics and Bioinformatics, Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Clayton P Santiago
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Thanh V Hoang
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Fatemeh Rajaii
- Department of Ophthalmology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Rebecca E James-Esposito
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Richard M Gronostajski
- Department of Biochemistry, Genetics, Genomics and Bioinformatics Graduate Program, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY 14203, USA
| | - Elana J Fertig
- Department of Oncology, Division of Biostatistics and Bioinformatics, Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Institute for Data Intensive Engineering and Science, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Department of Ophthalmology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Institute for Computational Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Mathematical Institute for Data Science, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Department of Applied Mathematics and Statistics, Johns Hopkins University, Baltimore, MD 21205, USA; Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Loyal A Goff
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; McKusick-Nathans Institute for Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Kavli Neuroscience Discovery Institute, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Seth Blackshaw
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Department of Ophthalmology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Kavli Neuroscience Discovery Institute, Johns Hopkins University, Baltimore, MD 21205, USA; Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Center for Human Systems Biology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
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9
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Dennis DJ, Han S, Schuurmans C. bHLH transcription factors in neural development, disease, and reprogramming. Brain Res 2018; 1705:48-65. [PMID: 29544733 DOI: 10.1016/j.brainres.2018.03.013] [Citation(s) in RCA: 120] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Revised: 03/07/2018] [Accepted: 03/10/2018] [Indexed: 01/16/2023]
Abstract
The formation of functional neural circuits in the vertebrate central nervous system (CNS) requires that appropriate numbers of the correct types of neuronal and glial cells are generated in their proper places and times during development. In the embryonic CNS, multipotent progenitor cells first acquire regional identities, and then undergo precisely choreographed temporal identity transitions (i.e. time-dependent changes in their identity) that determine how many neuronal and glial cells of each type they will generate. Transcription factors of the basic-helix-loop-helix (bHLH) family have emerged as key determinants of neural cell fate specification and differentiation, ensuring that appropriate numbers of specific neuronal and glial cell types are produced. Recent studies have further revealed that the functions of these bHLH factors are strictly regulated. Given their essential developmental roles, it is not surprising that bHLH mutations and de-regulated expression are associated with various neurological diseases and cancers. Moreover, the powerful ability of bHLH factors to direct neuronal and glial cell fate specification and differentiation has been exploited in the relatively new field of cellular reprogramming, in which pluripotent stem cells or somatic stem cells are converted to neural lineages, often with a transcription factor-based lineage conversion strategy that includes one or more of the bHLH genes. These concepts are reviewed herein.
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Affiliation(s)
- Daniel J Dennis
- Sunnybrook Research Institute, 2075 Bayview Ave, Toronto, ON M4N3M5, Canada
| | - Sisu Han
- Sunnybrook Research Institute, 2075 Bayview Ave, Toronto, ON M4N3M5, Canada; Department of Biochemistry, University of Toronto, Toronto, ON, Canada
| | - Carol Schuurmans
- Sunnybrook Research Institute, 2075 Bayview Ave, Toronto, ON M4N3M5, Canada; Department of Biochemistry, University of Toronto, Toronto, ON, Canada.
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Pten Regulates Retinal Amacrine Cell Number by Modulating Akt, Tgfβ, and Erk Signaling. J Neurosci 2017; 36:9454-71. [PMID: 27605619 DOI: 10.1523/jneurosci.0936-16.2016] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Accepted: 07/18/2016] [Indexed: 12/11/2022] Open
Abstract
UNLABELLED All tissues are genetically programmed to acquire an optimal size that is defined by total cell number and individual cellular dimensions. The retina contains stereotyped proportions of one glial and six neuronal cell types that are generated in overlapping waves. How multipotent retinal progenitors know when to switch from making one cell type to the next so that appropriate numbers of each cell type are generated is poorly understood. Pten is a phosphatase that controls progenitor cell proliferation and differentiation in several lineages. Here, using a conditional loss-of-function strategy, we found that Pten regulates retinal cell division and is required to produce the full complement of rod photoreceptors and amacrine cells in mouse. We focused on amacrine cell number control, identifying three downstream Pten effector pathways. First, phosphoinositide 3-kinase/Akt signaling is hyperactivated in Pten conditional knock-out (cKO) retinas, and misexpression of constitutively active Akt (Akt-CA) in retinal explants phenocopies the reduction in amacrine cell production observed in Pten cKOs. Second, Akt-CA activates Tgfβ signaling in retinal explants, which is a negative feedback pathway for amacrine cell production. Accordingly, Tgfβ signaling is elevated in Pten cKO retinas, and epistatic analyses placed Pten downstream of TgfβRII in amacrine cell number control. Finally, Pten regulates Raf/Mek/Erk signaling levels to promote the differentiation of all amacrine cell subtypes, which are each reduced in number in Pten cKOs. Pten is thus a positive regulator of amacrine cell production, acting via multiple downstream pathways, highlighting its diverse actions as a mediator of cell number control. SIGNIFICANCE STATEMENT Despite the importance of size for optimal organ function, how individual cell types are generated in correct proportions is poorly understood. There are several ways to control cell number, including readouts of organ function (e.g., secreted hormones reach functional levels when enough cells are made) or counting of cell divisions or cell number. The latter applies to the retina, where cell number is regulated by negative feedback signals, which arrest differentiation of particular cell types at threshold levels. Herein, we show that Pten is a critical regulator of amacrine cell number in the retina, acting via multiple downstream pathways. Our studies provide molecular insights into how PTEN loss in humans may lead to uncontrolled cell division in several pathological conditions.
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11
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Ledford KL, Martinez-De Luna RI, Theisen MA, Rawlins KD, Viczian AS, Zuber ME. Distinct cis-acting regions control six6 expression during eye field and optic cup stages of eye formation. Dev Biol 2017; 426:418-428. [PMID: 28438336 PMCID: PMC5500183 DOI: 10.1016/j.ydbio.2017.04.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Revised: 04/07/2017] [Accepted: 04/12/2017] [Indexed: 02/06/2023]
Abstract
The eye field transcription factor, Six6, is essential for both the early (specification and proliferative growth) phase of eye formation, as well as for normal retinal progenitor cell differentiation. While genomic regions driving six6 optic cup expression have been described, the sequences controlling eye field and optic vesicle expression are unknown. Two evolutionary conserved regions 5' and a third 3' to the six6 coding region were identified, and together they faithfully replicate the endogenous X. laevis six6 expression pattern. Transgenic lines were generated and used to determine the onset and expression patterns controlled by the regulatory regions. The conserved 3' region was necessary and sufficient for eye field and optic vesicle expression. In contrast, the two conserved enhancer regions located 5' of the coding sequence were required together for normal optic cup and mature retinal expression. Gain-of-function experiments indicate endogenous six6 and GFP expression in F1 transgenic embryos are similarly regulated in response to candidate trans-acting factors. Importantly, CRISPR/CAS9-mediated deletion of the 3' eye field/optic vesicle enhancer in X. laevis, resulted in a reduction in optic vesicle size. These results identify the cis-acting regions, demonstrate the modular nature of the elements controlling early versus late retinal expression, and identify potential regulators of six6 expression during the early stages of eye formation.
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Affiliation(s)
- Kelley L Ledford
- Department of Ophthalmology and The Center for Vision Research, SUNY Upstate Medical University, Syracuse, NY 13210, United States; Department of Biochemistry & Molecular Biology, SUNY Upstate Medical University, Syracuse, NY 13210, United States
| | - Reyna I Martinez-De Luna
- Department of Ophthalmology and The Center for Vision Research, SUNY Upstate Medical University, Syracuse, NY 13210, United States
| | - Matthew A Theisen
- Department of Ophthalmology and The Center for Vision Research, SUNY Upstate Medical University, Syracuse, NY 13210, United States
| | - Karisa D Rawlins
- Department of Ophthalmology and The Center for Vision Research, SUNY Upstate Medical University, Syracuse, NY 13210, United States
| | - Andrea S Viczian
- Department of Ophthalmology and The Center for Vision Research, SUNY Upstate Medical University, Syracuse, NY 13210, United States; Department of Biochemistry & Molecular Biology, SUNY Upstate Medical University, Syracuse, NY 13210, United States; Department of Cell & Developmental Biology, SUNY Upstate Medical University, Syracuse, NY 13210, United States; Department of Neuroscience & Physiology, SUNY Upstate Medical University, Syracuse, NY 13210, United States.
| | - Michael E Zuber
- Department of Ophthalmology and The Center for Vision Research, SUNY Upstate Medical University, Syracuse, NY 13210, United States; Department of Biochemistry & Molecular Biology, SUNY Upstate Medical University, Syracuse, NY 13210, United States; Department of Neuroscience & Physiology, SUNY Upstate Medical University, Syracuse, NY 13210, United States
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12
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Olsen JB, Wong L, Deimling S, Miles A, Guo H, Li Y, Zhang Z, Greenblatt JF, Emili A, Tropepe V. G9a and ZNF644 Physically Associate to Suppress Progenitor Gene Expression during Neurogenesis. Stem Cell Reports 2016; 7:454-470. [PMID: 27546533 PMCID: PMC5031922 DOI: 10.1016/j.stemcr.2016.06.012] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Revised: 06/28/2016] [Accepted: 06/29/2016] [Indexed: 01/05/2023] Open
Abstract
Proliferating progenitor cells undergo changes in competence to give rise to post-mitotic progeny of specialized function. These cell-fate transitions typically involve dynamic regulation of gene expression by histone methyltransferase (HMT) complexes. However, the composition, roles, and regulation of these assemblies in regulating cell-fate decisions in vivo are poorly understood. Using unbiased affinity purification and mass spectrometry, we identified the uncharacterized C2H2-like zinc finger protein ZNF644 as a G9a/GLP-interacting protein and co-regulator of histone methylation. In zebrafish, functional characterization of ZNF644 orthologs, znf644a and znf644b, revealed complementary roles in regulating G9a/H3K9me2-mediated gene silencing during neurogenesis. The non-overlapping requirements for znf644a and znf644b during retinal differentiation demarcate critical aspects of retinal differentiation programs regulated by differential G9a-ZNF644 associations, such as transitioning proliferating progenitor cells toward differentiation. Collectively, our data point to ZNF644 as a critical co-regulator of G9a/H3K9me2-mediated gene silencing during neuronal differentiation.
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Affiliation(s)
- Jonathan B Olsen
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON M5S 3E1, Canada; Department of Molecular Genetics, University of Toronto, Medical Science Building, Toronto, ON M5S 3E1, Canada
| | - Loksum Wong
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON, M5S 3G5, Canada
| | - Steven Deimling
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON, M5S 3G5, Canada
| | - Amanda Miles
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON, M5S 3G5, Canada
| | - Hongbo Guo
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON M5S 3E1, Canada
| | - Yue Li
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON M5S 3E1, Canada; Department of Molecular Genetics, University of Toronto, Medical Science Building, Toronto, ON M5S 3E1, Canada; Department of Computer Science, University of Toronto, Toronto, ON M5S 3G4, Canada
| | - Zhaolei Zhang
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON M5S 3E1, Canada; Department of Molecular Genetics, University of Toronto, Medical Science Building, Toronto, ON M5S 3E1, Canada; Department of Computer Science, University of Toronto, Toronto, ON M5S 3G4, Canada
| | - Jack F Greenblatt
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON M5S 3E1, Canada; Department of Molecular Genetics, University of Toronto, Medical Science Building, Toronto, ON M5S 3E1, Canada
| | - Andrew Emili
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON M5S 3E1, Canada; Department of Molecular Genetics, University of Toronto, Medical Science Building, Toronto, ON M5S 3E1, Canada.
| | - Vincent Tropepe
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON, M5S 3G5, Canada; Department of Ophthalmology and Vision Sciences, University of Toronto, Toronto, ON M5T 3A9, Canada; Centre for the Analysis of Genome Evolution and Function, University of Toronto, Toronto, ON M5S 3B2, Canada.
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Miles A, Tropepe V. Coordinating progenitor cell cycle exit and differentiation in the developing vertebrate retina. NEUROGENESIS 2016; 3:e1161697. [PMID: 27604453 PMCID: PMC4974023 DOI: 10.1080/23262133.2016.1161697] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/29/2015] [Revised: 01/09/2016] [Accepted: 02/29/2016] [Indexed: 02/06/2023]
Abstract
The proper development of the vertebrate retina relies heavily on producing the correct number and type of differentiated retinal cell types. To achieve this, proliferating retinal progenitor cells (RPCs) must exit the cell cycle at an appropriate time and correctly express a subset of differentiation markers that help specify retinal cell fate. Homeobox genes, which encode a family of transcription factors, have been accredited to both these processes, implicated in the transcriptional regulation of important cell cycle components, such as cyclins and cyclin-dependent kinases, and proneural genes. This dual regulation of homeobox genes allows these factors to help co-ordinate the transition from the proliferating RPC to postmitotic, differentiated cell. However, understanding the exact molecular targets of these factors remains a challenging task. This commentary highlights the current knowledge we have about how these factors regulate cell cycle progression and differentiation, with particular emphasis on a recent discovery from our lab demonstrating an antagonistic relationship between Vsx2 and Dmbx1 to control RPC proliferation. Future studies should aim to further understand the direct transcriptional targets of these genes, additional co-factors/interacting proteins and the possible recruitment of epigenetic machinery by these homeobox genes.
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Affiliation(s)
- Amanda Miles
- Department of Cell & Systems Biology, University of Toronto , Toronto, Ontario, Canada
| | - Vincent Tropepe
- Department of Cell & Systems Biology, University of Toronto, Toronto, Ontario, Canada; Department of Ophthalmology & Vision Sciences; Centre for the Analysis of Genome Evolution and Function, University of Toronto, Toronto, Ontario, Canada
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14
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Mattar P, Cayouette M. Mechanisms of temporal identity regulation in mouse retinal progenitor cells. NEUROGENESIS 2015; 2:e1125409. [PMID: 27606333 PMCID: PMC4973599 DOI: 10.1080/23262133.2015.1125409] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Revised: 11/19/2015] [Accepted: 11/20/2015] [Indexed: 10/29/2022]
Abstract
While much progress has been made in recent years toward elucidating the transcription factor codes controlling how neural progenitor cells generate the various glial and neuronal cell types in a particular spatial domain, much less is known about how these progenitors alter their output over time. In the past years, work in the developing mouse retina has provided evidence that a transcriptional cascade similar to the one used in Drosophila neuroblasts might control progenitor temporal identity in vertebrates. The zinc finger transcription factor Ikzf1 (Ikaros), an ortholog of Drosophila hunchback, was reported to confer early temporal identity in retinal progenitors and, more recently, the ortholog of Drosophila castor, Casz1, was found to function as a mid/late temporal identity factor that is negatively regulated by Ikzf1. The molecular mechanisms by which these temporal identity factors function in retinal progenitors, however, remain unknown. Here we briefly review previous work on the vertebrate temporal identity factors in the retina, and propose a model by which they might operate.
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Affiliation(s)
- Pierre Mattar
- Cellular Neurobiology Research Unit; Institut de recherches cliniques de Montréal Montréal, QC, Canada
| | - Michel Cayouette
- Cellular Neurobiology Research Unit; Institut de recherches cliniques de Montréal Montréal, QC, Canada; Department of Medicine; Université de Montréal Montréal, QC, Canada; Department of Anatomy and Cell Biology and Division of Experimental Medicine; McGill University Montréal, QC, Canada
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15
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Mitchell DM, Stevens CB, Frey RA, Hunter SS, Ashino R, Kawamura S, Stenkamp DL. Retinoic Acid Signaling Regulates Differential Expression of the Tandemly-Duplicated Long Wavelength-Sensitive Cone Opsin Genes in Zebrafish. PLoS Genet 2015; 11:e1005483. [PMID: 26296154 PMCID: PMC4546582 DOI: 10.1371/journal.pgen.1005483] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Accepted: 08/05/2015] [Indexed: 12/12/2022] Open
Abstract
The signaling molecule retinoic acid (RA) regulates rod and cone photoreceptor fate, differentiation, and survival. Here we elucidate the role of RA in differential regulation of the tandemly-duplicated long wavelength-sensitive (LWS) cone opsin genes. Zebrafish embryos were treated with RA from 48 hours post-fertilization (hpf) to 75 hpf, and RNA was isolated from eyes for microarray analysis. ~170 genes showed significantly altered expression, including several transcription factors and components of cellular signaling pathways. Of interest, the LWS1 opsin gene was strongly upregulated by RA. LWS1 is the upstream member of the tandemly duplicated LWS opsin array and is normally not expressed embryonically. Embryos treated with RA 48 hpf to 100 hpf or beyond showed significant reductions in LWS2-expressing cones in favor of LWS1-expressing cones. The LWS reporter line, LWS-PAC(H) provided evidence that individual LWS cones switched from LWS2 to LWS1 expression in response to RA. The RA signaling reporter line, RARE:YFP indicated that increased RA signaling in cones was associated with this opsin switch, and experimental reduction of RA signaling in larvae at the normal time of onset of LWS1 expression significantly inhibited LWS1 expression. A role for endogenous RA signaling in regulating differential expression of the LWS genes in postmitotic cones was further supported by the presence of an RA signaling domain in ventral retina of juvenile zebrafish that coincided with a ventral zone of LWS1 expression. This is the first evidence that an extracellular signal may regulate differential expression of opsin genes in a tandemly duplicated array.
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Affiliation(s)
- Diana M. Mitchell
- Department of Biological Sciences, University of Idaho, Moscow, Idaho, United States of America
| | - Craig B. Stevens
- Department of Biological Sciences, University of Idaho, Moscow, Idaho, United States of America
| | - Ruth A. Frey
- Department of Biological Sciences, University of Idaho, Moscow, Idaho, United States of America
| | - Samuel S. Hunter
- Department of Biological Sciences, University of Idaho, Moscow, Idaho, United States of America
- Bioinformatics and Computational Biology Graduate Program, University of Idaho, Moscow, Idaho, United States of America
| | - Ryuichi Ashino
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, Chiba, Japan
| | - Shoji Kawamura
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, Chiba, Japan
| | - Deborah L. Stenkamp
- Department of Biological Sciences, University of Idaho, Moscow, Idaho, United States of America
- Bioinformatics and Computational Biology Graduate Program, University of Idaho, Moscow, Idaho, United States of America
- Neuroscience Graduate Program, University of Idaho, Moscow, Idaho, United States of America
- * E-mail:
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Touahri Y, Adnani L, Mattar P, Markham K, Klenin N, Schuurmans C. Non-isotopic RNA In Situ Hybridization on Embryonic Sections. ACTA ACUST UNITED AC 2015; 70:1.22.1-1.22.25. [PMID: 25559002 DOI: 10.1002/0471142301.ns0122s70] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
This unit describes methods for non-isotopic RNA in situ hybridization on embryonic mouse sections. These methods can be used to follow the spatiotemporal dynamics of gene expression in an embryonic tissue of interest. They involve the use of labeled (e.g., digoxygenin, FITC) antisense riboprobes that hybridize to a specific mRNA in the target tissue. The probes are detected using an alkaline phosphatase-conjugated antibody recognizing the label and a chromogenic substrate. This method can be used to: (1) assess the expression of a single gene within a tissue, (2) compare the expression profiles of two genes within a tissue, or (3) compare the distribution of a transcript and protein within a tissue. While this approach is not quantitative, it provides a qualitative assessment of the precise cell types where a gene is expressed, which is not easily achievable with other more quantitative methods such as quantitative PCR.
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Affiliation(s)
- Yacine Touahri
- Department of Biochemistry and Molecular Biology, Hotchkiss Brain Institute, Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada
| | - Lata Adnani
- Department of Biochemistry and Molecular Biology, Hotchkiss Brain Institute, Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada
| | - Pierre Mattar
- Department of Biochemistry and Molecular Biology, Hotchkiss Brain Institute, Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada.,Current address: Cellular Neurobiology Research Unit, Institut de Recherches Cliniques de Montréal, Montréal, Quebec, Canada
| | - Kathryn Markham
- Department of Biochemistry and Molecular Biology, Hotchkiss Brain Institute, Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada
| | - Natalia Klenin
- Department of Biochemistry and Molecular Biology, Hotchkiss Brain Institute, Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada
| | - Carol Schuurmans
- Department of Biochemistry and Molecular Biology, Hotchkiss Brain Institute, Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada
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Abstract
Proneural genes encode evolutionarily conserved basic-helix-loop-helix transcription factors. In Drosophila, proneural genes are required and sufficient to confer a neural identity onto naïve ectodermal cells, inducing delamination and subsequent neuronal differentiation. In vertebrates, proneural genes are expressed in cells that already have a neural identity, but they are still required and sufficient to initiate neurogenesis. In all organisms, proneural genes control neurogenesis by regulating Notch-mediated lateral inhibition and initiating the expression of downstream differentiation genes. The general mode of proneural gene function has thus been elucidated. However, the regulatory mechanisms that spatially and temporally control proneural gene function are only beginning to be deciphered. Understanding how proneural gene function is regulated is essential, as aberrant proneural gene expression has recently been linked to a variety of human diseases-ranging from cancer to neuropsychiatric illnesses and diabetes. Recent insights into proneural gene function in development and disease are highlighted herein.
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Affiliation(s)
- Carol Huang
- Department of Pediatrics, Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada
| | - Jennifer A Chan
- Department of Pathology & Laboratory Medicine, Southern Alberta Cancer Research Institute, University of Calgary, Calgary, Alberta, Canada.
| | - Carol Schuurmans
- Department of Biochemistry and Molecular Biology, Alberta Children's Hospital Research Institute, Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada.
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