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Zheng C, Schneider JW, Hsieh J. Role of RB1 in human embryonic stem cell-derived retinal organoids. Dev Biol 2020; 462:197-207. [PMID: 32197890 DOI: 10.1016/j.ydbio.2020.03.011] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Revised: 02/21/2020] [Accepted: 03/11/2020] [Indexed: 01/09/2023]
Abstract
Three-dimensional (3D) organoid models derived from human pluripotent stem cells provide a platform for studying human development and understanding disease mechanisms. Most studies that examine biallelic inactivation of the cell cycle regulator Retinoblastoma 1 (RB1) and the link to retinoblastoma is in mice, however, less is known regarding the pathophysiological role of RB1 during human retinal development. To study the role of RB1 in early human retinal development and tumor formation, we generated retinal organoids from CRISPR/Cas9-derived RB1-null human embryonic stem cells (hESCs). We showed that RB is abundantly expressed in retinal progenitor cells in retinal organoids and loss of RB1 promotes S-phase entry. Furthermore, loss of RB1 resulted in widespread apoptosis and reduced the number of photoreceptor, ganglion, and bipolar cells. Interestingly, RB1 mutation in retinal organoids did not result in retinoblastoma formation in vitro or in the vitreous body of NOD/SCID immunodeficient mice. Together, our work identifies a crucial function for RB1 in human retinal development and suggests that RB1 deletion alone is not sufficient for tumor development, at least in human retinal organoids.
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Affiliation(s)
- Canbin Zheng
- Department of Molecular Biology and Hamon Center for Regenerative Science and Medicine, UT Southwestern Medical Center, Dallas, TX, 75390, USA; Department of Orthopedic and Microsurgery, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, GD, 510080, China
| | - Jay W Schneider
- Wanek Program for Hypoplastic Left Heart Syndrome, Mayo Clinic, Rochester, Minnesota 55905, USA
| | - Jenny Hsieh
- Department of Biology and Brain Health Consortium, The University of Texas at San Antonio, San Antonio, TX, 78249, USA.
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2
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Zocchi L, Mehta A, Wu SC, Wu J, Gu Y, Wang J, Suh S, Spitale RC, Benavente CA. Chromatin remodeling protein HELLS is critical for retinoblastoma tumor initiation and progression. Oncogenesis 2020; 9:25. [PMID: 32071286 PMCID: PMC7028996 DOI: 10.1038/s41389-020-0210-7] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Revised: 02/06/2020] [Accepted: 02/07/2020] [Indexed: 01/08/2023] Open
Abstract
Retinoblastoma is an aggressive childhood cancer of the developing retina that initiates by biallelic RB1 gene inactivation. Tumor progression in retinoblastoma is driven by epigenetics, as retinoblastoma genomes are stable, but the mechanism(s) that drive these epigenetic changes remain unknown. Lymphoid-specific helicase (HELLS) protein is an epigenetic modifier directly regulated by the RB/E2F pathway. In this study, we used novel genetically engineered mouse models to investigate the role of HELLS during retinal development and tumorigenesis. Our results indicate that Hells-null retinal progenitor cells divide, undergo cell-fate specification, and give rise to fully laminated retinae with minor bipolar cells defects, but normal retinal function. Despite the apparent nonessential role of HELLS in retinal development, failure to transcriptionally repress Hells during retinal terminal differentiation due to retinoblastoma (RB) family loss significantly contributes to retinal tumorigenesis. Loss of HELLS drastically reduced ectopic division of differentiating cells in Rb1/p107-null retinae, significantly decreased the incidence of retinoblastoma, delayed tumor progression, and increased overall survival. Despite its role in heterochromatin formation, we found no evidence that Hells loss directly affected chromatin accessibility in the retina but functioned as transcriptional co-activator of E2F3, decreasing expression of cell cycle genes. We propose that HELLS is a critical downstream mediator of E2F-dependent ectopic proliferation in RB-null retinae. Together with the nontoxic effect of HELLS loss in the developing retina, our results suggest that HELLS and its downstream pathways could serve as potential therapeutic targets for retinoblastoma.
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Affiliation(s)
- Loredana Zocchi
- Department of Pharmaceutical Sciences, University of California, Irvine, CA, 92697, USA
| | - Aditi Mehta
- Pediatric Hematology and Pediatric Oncology, Children's Hospital of Orange County, Orange, CA, 92868, USA.,Department of Graduate Medical Education, University of California, Irvine, CA, 92697, USA
| | - Stephanie C Wu
- Department of Developmental and Cell Biology, University of California, Irvine, CA, 92697, USA
| | - Jie Wu
- Department of Biological Chemistry, University of California, Irvine, CA, 92697, USA.,Chao Family Comprehensive Cancer Center, University of California, Irvine, CA, 92697, USA
| | - Yijun Gu
- Department of Pharmaceutical Sciences, University of California, Irvine, CA, 92697, USA
| | - Jingtian Wang
- Department of Molecular Biology and Biochemistry, University of California, Irvine, CA, 92697, USA
| | - Susie Suh
- Gavin Herbert Eye Institute, Department of Ophthalmology, University of California, Irvine, CA, 92697, USA
| | - Robert C Spitale
- Department of Pharmaceutical Sciences, University of California, Irvine, CA, 92697, USA.,Department of Molecular Biology and Biochemistry, University of California, Irvine, CA, 92697, USA
| | - Claudia A Benavente
- Department of Pharmaceutical Sciences, University of California, Irvine, CA, 92697, USA. .,Department of Developmental and Cell Biology, University of California, Irvine, CA, 92697, USA. .,Chao Family Comprehensive Cancer Center, University of California, Irvine, CA, 92697, USA.
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3
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de Almeida-Pereira L, Magalhães CF, Repossi MG, Thorstenberg MLP, Sholl-Franco A, Coutinho-Silva R, Ventura ALM, Fragel-Madeira L. Adenine Nucleotides Control Proliferation In Vivo of Rat Retinal Progenitors by P2Y 1 Receptor. Mol Neurobiol 2016; 54:5142-5155. [PMID: 27558237 DOI: 10.1007/s12035-016-0059-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2016] [Accepted: 08/15/2016] [Indexed: 11/30/2022]
Abstract
Previous studies demonstrated that exogenous ATP is able to regulate proliferation of retinal progenitor cells (RPCs) in vitro possibly via P2Y1 receptor, a G protein-coupled receptor. Here, we evaluated the function of adenine nucleotides in vivo during retinal development of newborn rats. Intravitreal injection of apyrase, an enzyme that hydrolyzes nucleotides, reduced cell proliferation in retinas at postnatal day 2 (P2). This decrease was reversed when retinas were treated together with ATPγ-S or ADPβ-S, two hydrolysis-resistant analogs of ATP and ADP, respectively. During early postnatal days (P0 to P5), an increase in ectonucleotidase (E-NTPDase) activity was observed in the retina, suggesting a decrease in the availability of adenine nucleotides, coinciding with the end of proliferation. Interestingly, intravitreal injection of the E-NTPDase inhibitor ARL67156 increased proliferation by around 60 % at P5 rats. Furthermore, immunolabeling against P2Y1 receptor was observed overall in retina layers from P2 rats, including proliferating Ki-67-positive cells in the neuroblastic layer (NBL), suggesting that this receptor could be responsible for the action of adenine nucleotides upon proliferation of RPCs. Accordingly, intravitreal injection of MRS2179, a selective antagonist of P2Y1 receptors, reduced cell proliferation by approximately 20 % in P2 rats. Moreover, treatment with MRS 2179 caused an increase in p57KIP2 and cyclin D1 expression, a reduction in cyclin E and Rb phosphorylated expression and in BrdU-positive cell number. These data suggest that the adenine nucleotides modulate the proliferation of rat RPCs via activation of P2Y1 receptors regulating transition from G1 to S phase of the cell cycle.
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Affiliation(s)
- Luana de Almeida-Pereira
- Department of Neurobiology, Institute of Biology, Fluminense Federal University, Niterói, Brazil
| | - Camila Feitosa Magalhães
- Department of Neurobiology, Institute of Biology, Fluminense Federal University, Niterói, Brazil
| | - Marinna Garcia Repossi
- Department of Neurobiology, Institute of Biology, Fluminense Federal University, Niterói, Brazil
| | | | - Alfred Sholl-Franco
- Institute of Biophysics Carlos Chagas Filho, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Robson Coutinho-Silva
- Institute of Biophysics Carlos Chagas Filho, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | | | - Lucianne Fragel-Madeira
- Department of Neurobiology, Institute of Biology, Fluminense Federal University, Niterói, Brazil.
- Laboratório de Desenvolvimento e Regeneração Neural, Departmento de Neurobiologia, Universidade Federal Fluminense, Cx. Postal 100180, Niterói, RJ, 24020-141, Brazil.
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4
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Dyer MA. Lessons from Retinoblastoma: Implications for Cancer, Development, Evolution, and Regenerative Medicine. Trends Mol Med 2016; 22:863-876. [PMID: 27567287 DOI: 10.1016/j.molmed.2016.07.010] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Revised: 07/31/2016] [Accepted: 07/31/2016] [Indexed: 12/14/2022]
Abstract
Retinoblastoma is a rare childhood cancer of the developing retina, and studies on this orphan disease have led to fundamental discoveries in cancer biology. Retinoblastoma has also emerged as a model for translational research for pediatric solid tumors, which is particularly important as personalized medicine expands in oncology. Research on retinoblastomas has been combined with the exploration of retinal development and retinal degeneration to advance a new model of cell type-specific disease susceptibility termed 'cellular pliancy'. The concept can even be extended to species-specific regeneration. This review discusses the remarkable path of retinoblastoma research and how it has shaped the most current efforts in basic, translational, and clinical research in oncology and beyond.
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Affiliation(s)
- Michael A Dyer
- Department of Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA; Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA.
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5
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Aldiri I, Ajioka I, Xu B, Zhang J, Chen X, Benavente C, Finkelstein D, Johnson D, Akiyama J, Pennacchio LA, Dyer MA. Brg1 coordinates multiple processes during retinogenesis and is a tumor suppressor in retinoblastoma. Development 2016; 142:4092-106. [PMID: 26628093 PMCID: PMC4712833 DOI: 10.1242/dev.124800] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Retinal development requires precise temporal and spatial coordination of cell cycle exit, cell fate specification, cell migration and differentiation. When this process is disrupted, retinoblastoma, a developmental tumor of the retina, can form. Epigenetic modulators are central to precisely coordinating developmental events, and many epigenetic processes have been implicated in cancer. Studying epigenetic mechanisms in development is challenging because they often regulate multiple cellular processes; therefore, elucidating the primary molecular mechanisms involved can be difficult. Here we explore the role of Brg1 (Smarca4) in retinal development and retinoblastoma in mice using molecular and cellular approaches. Brg1 was found to regulate retinal size by controlling cell cycle length, cell cycle exit and cell survival during development. Brg1 was not required for cell fate specification but was required for photoreceptor differentiation and cell adhesion/polarity programs that contribute to proper retinal lamination during development. The combination of defective cell differentiation and lamination led to retinal degeneration in Brg1-deficient retinae. Despite the hypocellularity, premature cell cycle exit, increased cell death and extended cell cycle length, retinal progenitor cells persisted in Brg1-deficient retinae, making them more susceptible to retinoblastoma. ChIP-Seq analysis suggests that Brg1 might regulate gene expression through multiple mechanisms. Summary: The SWI/SNF protein Brg1 controls cell cycle length, cell cycle exit and cell survival, and is required for cell differentiation and retinal lamination, in the developing mouse retina.
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Affiliation(s)
- Issam Aldiri
- Department of Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Itsuki Ajioka
- Center for Brain Integration Research (CBIR), Tokyo Medical and Dental University (TMDU), Tokyo 113-8510, Japan
| | - Beisi Xu
- Department of Computational Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Jiakun Zhang
- Department of Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Xiang Chen
- Department of Computational Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Claudia Benavente
- Department of Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - David Finkelstein
- Department of Computational Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Dianna Johnson
- Department of Ophthalmology, University of Tennessee Health Science Center, Memphis, TN 38163, USA
| | - Jennifer Akiyama
- Lawrence Berkeley National Laboratory, Genomics Division, Berkeley, CA 94701, USA Department of Energy, Joint Genome Institute, Walnut Creek, CA 94598, USA
| | - Len A Pennacchio
- Lawrence Berkeley National Laboratory, Genomics Division, Berkeley, CA 94701, USA Department of Energy, Joint Genome Institute, Walnut Creek, CA 94598, USA
| | - Michael A Dyer
- Department of Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA Department of Ophthalmology, University of Tennessee Health Science Center, Memphis, TN 38163, USA Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA
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6
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Johnson V, Xiang M, Chen Z, Junge HJ. Neurite Mistargeting and Inverse Order of Intraretinal Vascular Plexus Formation Precede Subretinal Vascularization in Vldlr Mutant Mice. PLoS One 2015; 10:e0132013. [PMID: 26177550 PMCID: PMC4503745 DOI: 10.1371/journal.pone.0132013] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2015] [Accepted: 06/09/2015] [Indexed: 02/07/2023] Open
Abstract
In the retina blood vessels are required to support a high metabolic rate, however, uncontrolled vascular growth can lead to impaired vision and blindness. Subretinal vascularization (SRV), one type of pathological vessel growth, occurs in retinal angiomatous proliferation and proliferative macular telangiectasia. In these diseases SRV originates from blood vessels within the retina. We use mice with a targeted disruption in the Vldl-receptor (Vldlr) gene as a model to study SRV with retinal origin. We find that Vldlr mRNA is strongly expressed in the neuroretina, and we observe both vascular and neuronal phenotypes in Vldlr-/- mice. Unexpectedly, horizontal cell (HC) neurites are mistargeted prior to SRV in this model, and the majority of vascular lesions are associated with mistargeted neurites. In Foxn4-/- mice, which lack HCs and display reduced amacrine cell (AC) numbers, we find severe defects in intraretinal capillary development. However, SRV is not suppressed in Foxn4-/-;Vldlr-/- mice, which reveals that mistargeted HC neurites are not required for vascular lesion formation. In the absence of VLDLR, the intraretinal capillary plexuses form in an inverse order compared to normal development, and subsequent to this early defect, vascular proliferation is increased. We conclude that SRV in the Vldlr-/- model is associated with mistargeted neurites and that SRV is preceded by altered retinal vascular development.
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Affiliation(s)
- Verity Johnson
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, Colorado, 80309, United States of America
| | - Mengqing Xiang
- Center for Advanced Biotechnology and Medicine and Department of Pediatrics, Rutgers University-Robert Wood Johnson Medical School, Piscataway, New Jersey, 08901, United States of America
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, 54 South Xianlie Road, Guangzhou, 510060, China
| | - Zhe Chen
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, Colorado, 80309, United States of America
| | - Harald J. Junge
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, Colorado, 80309, United States of America
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7
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Benavente CA, Finkelstein D, Johnson DA, Marine JC, Ashery-Padan R, Dyer MA. Chromatin remodelers HELLS and UHRF1 mediate the epigenetic deregulation of genes that drive retinoblastoma tumor progression. Oncotarget 2015; 5:9594-608. [PMID: 25338120 PMCID: PMC4259422 DOI: 10.18632/oncotarget.2468] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2014] [Accepted: 09/06/2014] [Indexed: 12/14/2022] Open
Abstract
The retinoblastoma (Rb) family of proteins are key regulators of cell cycle exit during development and their deregulation is associated with cancer. Rb is critical for normal retinal development and germline mutations lead to retinoblastoma making retinae an attractive system to study Rb family signaling. Rb coordinates proliferation and differentiation through the E2f family of transcription factors, a critical interaction for the role of Rb in retinal development and tumorigenesis. However, whether the roles of the different E2fs are interchangeable in controlling development and tumorigenesis in the retina or if they have selective functions remains unknown. In this study, we found that E2f family members play distinct roles in the development and tumorigenesis. In Rb;p107-deficient retinae, E2f1 and E2f3 inactivation rescued tumor formation but only E2f1 rescued the retinal development phenotype. This allowed the identification of key target genes for Rb/E2f family signaling contributing to tumorigenesis and those contributing to developmental defects. We found that Sox4 and Sox11 genes contribute to the developmental phenotype and Hells and Uhrf1 contribute to tumorigenesis. Using orthotopic human xenografts, we validated that upregulation of HELLS and UHRF1 is essential for the tumor phenotype. Also, these epigenetic regulators are important for the regulation of SYK.
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Affiliation(s)
- Claudia A Benavente
- Department of Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, TN, USA
| | - David Finkelstein
- Department of Computational Biology, St. Jude Children's Research Hospital, Memphis, TN, USA
| | - Dianna A Johnson
- Department of Ophtalmology, The University of Tennessee Health Science Center, Memphis, TN, USA. Department of Anatomy and Neurobiology, The University of Tennessee Health Science Center, Memphis, TN, USA
| | - Jean-Christophe Marine
- Laboratory for Molecular Cancer Biology, Center for the Biology of Disease, VIB, Leuven, Belgium
| | - Ruth Ashery-Padan
- Department of Human Molecular Genetics and Biochemistry, Tel-Aviv University, Tel Aviv, Israel
| | - Michael A Dyer
- Department of Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, TN, USA. Department of Human Molecular Genetics and Biochemistry, Tel-Aviv University, Tel Aviv, Israel. Howard Hughes Medical Institute, Chevy Chase, MD, USA
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8
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Nittner D, Lambertz I, Clermont F, Mestdagh P, Köhler C, Nielsen SJ, Jochemsen A, Speleman F, Vandesompele J, Dyer MA, Schramm A, Schulte JH, Marine JC. Synthetic lethality between Rb, p53 and Dicer or miR-17-92 in retinal progenitors suppresses retinoblastoma formation. Nat Cell Biol 2012; 14:958-65. [PMID: 22864477 DOI: 10.1038/ncb2556] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2012] [Accepted: 07/09/2012] [Indexed: 12/14/2022]
Abstract
Synthetic lethality is a promising strategy for specific targeting of cancer cells that carry mutations that are absent in normal cells. This approach may help overcome the challenge associated with targeting dysfunctional tumour suppressors, such as p53 and Rb (refs 1, 2). Here we show that Dicer1 targeting prevents retinoblastoma formation in mice by synthetic lethality with combined inactivation of p53 and Rb. Although Dicer1 functions as a haploinsufficient tumour suppressor, its complete loss of function is selected against during tumorigenesis(3-5). We show that Dicer1 deficiency is tolerated in Rb-deficient retinal progenitor cells harbouring an intact p53 pathway, but not in the absence of p53. This synthetic lethality is mediated by the oncogenic miR-17-92 cluster because its deletion phenocopies Dicer1 loss in this context. miR-17-92 inactivation suppresses retinoblastoma formation in mice and co-silencing of miR-17/20a and p53 cooperatively decreases the viability of human retinoblastoma cells. These data provide an explanation for the selective pressure against loss of Dicer1 during tumorigenesis and a proof-of-concept that targeting miRNAs may potentially represent a general approach for synthetic lethal targeting of cancer cells that harbour specific cancer-inducing genotypes.
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Affiliation(s)
- David Nittner
- Laboratory for Molecular Cancer Biology, Center for the Biology of Disease, VIB, 3000 Leuven, Belgium
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Kerekes RA, Martins RAP, Davis D, Karakaya M, Gleason S, Dyer MA. Automated tracing of horizontal neuron processes during retinal development. Neurochem Res 2011; 36:583-93. [PMID: 21221777 PMCID: PMC3097172 DOI: 10.1007/s11064-010-0390-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/23/2010] [Indexed: 01/01/2023]
Abstract
In the developing mammalian retina, horizontal neurons undergo a dramatic reorganization of their processes shortly after they migrate to their appropriate laminar position. This is an important process because it is now understood that the apical processes are important for establishing the regular mosaic of horizontal cells in the retina and proper reorganization during lamination is required for synaptogenesis with photoreceptors and bipolar neurons. However, this process is difficult to study because the analysis of horizontal neuron anatomy is labor intensive and time-consuming. In this paper, we present a computational method for automatically tracing the three-dimensional (3-D) dendritic structure of horizontal retinal neurons in two-photon laser scanning microscope (TPLSM) imagery. Our method is based on 3-D skeletonization and is thus able to preserve the complex structure of the dendritic arbor of these cells. We demonstrate the effectiveness of our approach by comparing our tracing results against two sets of semi-automated traces over a set of 10 horizontal neurons ranging in age from P1 to P5. We observe an average agreement level of 81% between our automated trace and the manual traces. This automated method will serve as an important starting point for further refinement and optimization.
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Affiliation(s)
- Ryan A Kerekes
- Measurement Science and Systems Engineering Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA.
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10
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Matsushima D, Heavner W, Pevny LH. Combinatorial regulation of optic cup progenitor cell fate by SOX2 and PAX6. Development 2011; 138:443-54. [PMID: 21205789 DOI: 10.1242/dev.055178] [Citation(s) in RCA: 89] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
In humans, haploinsufficiency of either SOX2 or PAX6 is associated with microphthalmia, anophthalmia or aniridia. In this study, through the genetic spatiotemporal specific ablation of SOX2 on both wild-type and Pax6-haploinsufficent backgrounds in the mouse, we have uncovered a transcriptionally distinct and developmentally transient stage of eye development. We show that genetic ablation of SOX2 in the optic cup results in complete loss of neural competence and eventual cell fate conversion to non-neurogenic ciliary epithelium. This cell fate conversion is associated with a striking increase in PAX6, and genetically ablating SOX2 on a Pax6-haploinsufficient background partially rescues the Sox2-mutant phenotype. Collectively, these results demonstrate that precise regulation of the ratio of SOX2 to PAX6 is necessary to ensure accurate progenitor cell specification, and place SOX2 as a decisive factor of neural competence in the retina.
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Affiliation(s)
- Danielle Matsushima
- UNC Neuroscience Center, University of North Carolina at Chapel Hill, NC 27599, USA
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11
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Abstract
Novel murine models of retinoblastoma based on Rb gene deletion in concert with inactivation of Rb family members have recently been developed. These new Rb knockout models of retinoblastoma provide excellent tools for pre-clinical studies and for the exploration of the genetics of tumorigenesis driven by RB inactivation. This review focuses on the developmental consequences of Rb deletion in the retina and the genetic interactions between Rb and the two other members of the pocket protein family, p107 (Rbl1) and p130 (Rbl2). There is increasing appreciation that homozygous RB mutations are insufficient for human retinoblastoma. Identifying and understanding secondary gene alterations that cooperate with RB inactivation in tumorigenesis may be facilitated by mouse models. Recent investigation of the p53 pathway in retinoblastoma, and evidence of spatial topology to early murine retinoblastoma are also discussed in this review.
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12
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Peng GH, Chen S. Crx activates opsin transcription by recruiting HAT-containing co-activators and promoting histone acetylation. Hum Mol Genet 2007; 16:2433-52. [PMID: 17656371 PMCID: PMC2276662 DOI: 10.1093/hmg/ddm200] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
The homeodomain transcription factor Crx is required for expression of many photoreceptor genes in the mammalian retina. The mechanism by which Crx activates transcription remains to be determined. Using protein-protein interaction assays, Crx was found to interact with three co-activator proteins (complexes): STAGA, Cbp and p300, all of which possess histone acetyl-transferase (HAT) activity. To determine the role of Crx-HAT interactions in target gene chromatin modification and transcriptional activation, quantitative RT-PCR and chromatin immunoprecipitation were performed on Crx target genes, rod and cone opsins, in developing mouse retina. Although cone opsins are transcribed earlier than rhodopsin during development, the transcription of each gene is preceded by the same sequence of events in their promoter and enhancer regions: (i) binding of Crx, followed by (ii) binding of HATs, (iii) the acetylation of histone H3, then (iv) binding of other photoreceptor transcription factors (Nrl and Nr2e3) and RNA polymerase II. In Crx knockout mice (Crx(-/-)), the association of HATs and AcH3 with target promoter/enhancer regions was significantly decreased, which correlates with aberrant opsin transcription and photoreceptor dysfunction in these mice. Similar changes to the opsin chromatin were seen in Y79 retinoblastoma cells, where opsin genes are barely transcribed. These defects in Y79 cells can be reversed by expressing a recombinant Crx or applying histone deacetylase inhibitors. Altogether, these results suggest that one mechanism for Crx-mediated transcriptional activation is to recruit HATs to photoreceptor gene chromatin for histone acetylation, thereby inducing and maintaining appropriate chromatin configurations for transcription.
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Affiliation(s)
- Guang-Hua Peng
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St Louis, MO 63110, USA
| | - Shiming Chen
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St Louis, MO 63110, USA
- Department of Molecular Biology and Pharmacology, Washington University School of Medicine, St Louis, MO 63110, USA
- *To whom correspondence should be addressed at: Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, 660 South Euclid Avenue, Campus Box 8096, St Louis, MO 63110, USA. Tel: +1 3147474350; Fax: +1 3147474211;
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13
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Johnson DA, Zhang J, Frase S, Wilson M, Rodriguez-Galindo C, Dyer MA. Neuronal differentiation and synaptogenesis in retinoblastoma. Cancer Res 2007; 67:2701-11. [PMID: 17363591 DOI: 10.1158/0008-5472.can-06-3754] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Retinoblastomas initiate in the developing retina in utero and are diagnosed during the first few years of life. We have recently generated a series of knockout mouse models of retinoblastoma that recapitulate the timing, location, and progression of human retinoblastoma. One of the most important benefits of these preclinical models is that we can study the earliest stages of tumor initiation and expansion. This is not possible in human retinoblastoma because tumors initiate in utero and are not diagnosed until they are at an advanced stage. We found that mouse retinoblastoma cells exhibit a surprising degree of differentiation, which has not been previously reported for any neural tumor. Early-stage mouse retinoblastoma cells express proteins found normally in retinal plexiform layers. They also extend neurites and form synapses. All of these features, which were characterized by immunostaining, Golgi-Cox staining, scanning electron microscopy, and transmission electron microscopy, suggest that mouse retinoblastoma cells resemble amacrine/horizontal cells from the retina. As late-stage retinoblastoma cells expand and invade the surrounding tissue, they lose their differentiated morphology and become indistinguishable from human retinoblastomas. Taken together, our data suggest that neuronal differentiation is a hallmark of early-stage retinoblastoma and is lost as cells become more aggressive and invasive. We also show that rosette formation is not a hallmark of retinoblastoma differentiation, as previously believed. Instead, rosette formation reflects extensive cell-cell contacts between retinoblastoma cells in both early-stage (differentiated) and late-stage (dedifferentiated) tumors.
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Affiliation(s)
- Dianna A Johnson
- Department of Ophthalmology, College of Medicine, University of Tennessee Health Sciences Center, Memphis, USA
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14
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Haider NB, Demarco P, Nystuen AM, Huang X, Smith RS, McCall MA, Naggert JK, Nishina PM. The transcription factor Nr2e3 functions in retinal progenitors to suppress cone cell generation. Vis Neurosci 2007; 23:917-29. [PMID: 17266784 DOI: 10.1017/s095252380623027x] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2006] [Accepted: 10/20/2006] [Indexed: 12/27/2022]
Abstract
The transcription factor Nr2e3 is an essential component for development and specification of rod and cone photoreceptors; however, the mechanism through which it acts is not well understood. In this study, we use Nr2e3(rd7/rd7) mice that harbor a mutation in Nr2e3, to serve as a model for the human retinal disease Enhanced S Cone Syndrome. Our studies reveal that NR2E3 is expressed in late retinal progenitors and differentiating photoreceptors of the developing retina and localized to the cell bodies of mature rods and cones. In particular, we demonstrate that the abnormal increase in cone photoreceptors observed in Nr2e3(rd7/rd7) mice arise from ectopic mitotic progenitor cells that are present in the outer nuclear layer of the mature Nr2e3(rd7/rd7) retina. A prolonged phase of proliferation is observed followed by abnormal retinal lamination with fragmented and disorganized photoreceptor synapses that result in a progressive loss of rod and cone function. An extended and pronounced wave of apoptosis is also detected at P30 and temporally correlates with the phase of prolonged proliferation. Approximately twice as many apoptotic cells were detected compared to proliferating cells. This wave of apoptosis appears to affect both rod and cone cells and thus may account for the concurrent loss of rod and cone function. We further show that Nr2e3(rd7/rd7) cones do not express rod specific genes and Nr2e3(rd7/rd7) rods do not express cone specific genes. Our studies suggest that, based on its temporal and spatial expression, NR2E3 acts simultaneously in different cell types: in late mitotic progenitors, newly differentiating post mitotic cells, and mature rods and cones. In particular, this study reveals the function of NR2E3 in mitotic progenitors is to repress the cone generation program. NR2E3 is thus one of the few genes known to influence the competency of retinal progenitors while simultaneously directing the rod and cone differentiation.
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MESH Headings
- Adaptation, Ocular/genetics
- Animals
- Animals, Newborn
- Bromodeoxyuridine/metabolism
- Electroretinography/methods
- Embryo, Mammalian
- Eye Proteins/metabolism
- Gene Expression Regulation, Developmental/genetics
- In Situ Nick-End Labeling/methods
- Ki-67 Antigen/metabolism
- Mice
- Mice, Inbred C57BL
- Mice, Transgenic
- Microscopy, Electron, Transmission/methods
- Orphan Nuclear Receptors
- RNA, Messenger/biosynthesis
- Receptors, Cytoplasmic and Nuclear/genetics
- Receptors, Cytoplasmic and Nuclear/physiology
- Retina/cytology
- Retinal Cone Photoreceptor Cells/physiology
- Retinal Cone Photoreceptor Cells/ultrastructure
- Retinal Degeneration/genetics
- Reverse Transcriptase Polymerase Chain Reaction/methods
- Stem Cells/physiology
- Stem Cells/ultrastructure
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Affiliation(s)
- Neena B Haider
- Department of Genetics, University of Nebraska Medical Center, Omaha, Nebraska 68198, USA.
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15
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Johnson DA, Donovan SL, Dyer MA. Mosaic deletion of Rb arrests rod differentiation and stimulates ectopic synaptogenesis in the mouse retina. J Comp Neurol 2006; 498:112-28. [PMID: 16856163 DOI: 10.1002/cne.21059] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The retinoblastoma gene (Rb) regulates neural progenitor cell proliferation and cell fate specification and differentiation. For the developing mouse retina, two distinct functions of Rb have been described: regulation of retinal progenitor cell proliferation and rod photoreceptor development. Cells that would normally become rods fail to mature and remain as immature cells in the outer nuclear layer in the adult. By using Chx10-Cre;Rb(Lox/-) mice, we generated a chimeric retina with alternating apical-basal stripes of wild-type and Rb-deficient tissue. This provides a unique model with which to study synaptogenesis at the outer plexiform layer within regions that lack differentiated rods. In regions where rods failed to differentiate, the outer plexiform layer (OPL) was disrupted. Horizontal cells formed, and their somata were appropriately aligned, but their neurites did not project laterally. Instead many horizonal cell neurites extended apically, forming ectopic synapses with photoreceptors at all levels of the outer nuclear layer. These ectopic photoreceptor terminals contained synaptic ribbons, horizontal cell processes with synaptic vesicles, and a single mitochrondrion characteristic of rod spherules. Rb-deficient bipolar cells differentiated normally, extended dendrites to the OPL, and formed synapses that were indistinguishable from adjacent wild-type cells. In contrast to OPL-positioned synapses, ectopic synapses did not contain bipolar dendrites. This finding suggests that horizontal cells and photoreceptors can form stable synapses that are devoid of bipolar dendrites outside the normal boundaries of the OPL. Finally, analysis of P4, P7, P12, and P15 retinae suggests that the apical horizontal cell processes result from their failure to establish their normal lateral projections during development.
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Affiliation(s)
- Dianna A Johnson
- Department of Ophthalmology, College of Medicine, University of Tennessee Health Science Center, Memphis, Tennessee 38105, USA
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16
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Abstract
The retinoblastoma tumor-suppressor gene (Rb1) is centrally important in cancer research. Mutational inactivation of Rb1 causes the pediatric cancer retinoblastoma, while deregulation of the pathway in which it functions is common in most types of human cancer. The Rb1-encoded protein (pRb) is well known as a general cell cycle regulator, and this activity is critical for pRb-mediated tumor suppression. The main focus of this review, however, is on more recent evidence demonstrating the existence of additional, cell type-specific pRb functions in cellular differentiation and survival. These additional functions are relevant to carcinogenesis suggesting that the net effect of Rb1 loss on the behavior of resulting tumors is highly dependent on biological context. The molecular mechanisms underlying pRb functions are based on the cellular proteins it interacts with and the functional consequences of those interactions. Better insight into pRb-mediated tumor suppression and clinical exploitation of pRb as a therapeutic target will require a global view of the complex, interdependent network of pocket protein complexes that function simultaneously within given tissues.
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Affiliation(s)
- D W Goodrich
- Department of Pharmacology & Therapeutics, Roswell Park Cancer Institute, Buffalo, NY 14263, USA.
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17
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Donovan SL, Schweers B, Martins R, Johnson D, Dyer MA. Compensation by tumor suppressor genes during retinal development in mice and humans. BMC Biol 2006; 4:14. [PMID: 16672052 PMCID: PMC1481602 DOI: 10.1186/1741-7007-4-14] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2006] [Accepted: 05/03/2006] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The RB1 gene was the first tumor suppressor gene cloned from humans by studying genetic lesions in families with retinoblastoma. Children who inherit one defective copy of the RB1 gene have an increased susceptibility to retinoblastoma. Several years after the identification of the human RB1 gene, a targeted deletion of Rb was generated in mice. Mice with one defective copy of the Rb gene do not develop retinoblastoma. In this manuscript, we explore the different roles of the Rb family in human and mouse retinal development in order to better understand the species-specific difference in retinoblastoma susceptibility. RESULTS We found that the Rb family of proteins (Rb, p107 and p130) are expressed in a dynamic manner during mouse retinal development. The primary Rb family member expressed in proliferating embryonic retinal progenitor cells in mice is p107, which is required for appropriate cell cycle exit during retinogenesis. The primary Rb family member expressed in proliferating postnatal retinal progenitor cells is Rb. p130 protein is expressed redundantly with Rb in postmitotic cells of the inner nuclear layer and the ganglion cell layer of the mouse retina. When Rb is inactivated in an acute or chronic manner during mouse retinal development, p107 is upregulated in a compensatory manner. Similarly, when p107 is inactivated in the mouse retina, Rb is upregulated. No changes in p130 expression were seen when p107, Rb or both were inactivated in the developing mouse retina. In the human retina, RB1 was the primary family member expressed throughout development. There was very little if any p107 expressed in the developing human retina. In contrast to the developing mouse retina, when RB1 was acutely inactivated in the developing human fetal retina, p107 was not upregulated in a compensatory manner. CONCLUSION We propose that intrinsic genetic compensation between Rb and p107 prevents retinoblastoma in Rb- or p107-deficient mice, but this compensation does not occur in humans. Together, these data suggest a model that explains why humans are susceptible to retinoblastoma following RB1 loss, but mice require both Rb and p107 gene inactivation.
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Affiliation(s)
- Stacy L Donovan
- Department of Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Brett Schweers
- Department of Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Rodrigo Martins
- Department of Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Dianna Johnson
- Department of Ophthalmology, University of Tennessee Health Science Center, Memphis, TN 38163, USA
| | - Michael A Dyer
- Department of Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
- Department of Ophthalmology, University of Tennessee Health Science Center, Memphis, TN 38163, USA
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18
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Sun H, Chang Y, Schweers B, Dyer MA, Zhang X, Hayward SW, Goodrich DW. An E2F binding-deficient Rb1 protein partially rescues developmental defects associated with Rb1 nullizygosity. Mol Cell Biol 2006; 26:1527-37. [PMID: 16449662 PMCID: PMC1367194 DOI: 10.1128/mcb.26.4.1527-1537.2006] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Rb1 is essential for normal embryonic development, as null mice die in midgestation with widespread unscheduled cell proliferation. Rb1 protein (pRb) mediates cell cycle control by binding E2F transcription factors and repressing expression from E2F-dependent promoters. An increasing amount of evidence suggests that pRb loss also compromises cellular differentiation. Since differentiation is often dependent on cell cycle exit, it is currently unclear whether the effects of pRb on differentiation are an indirect consequence of pRb/E2F-mediated cell cycle control or whether they reflect direct cell-type-specific pRb functions. We have mutated Rb1 in the mouse to express a protein (R654W) specifically deficient in binding E2F1, E2F2, and E2F3. R654W mutant embryos exhibit cell cycle defects the same as those of Rb1 null embryos, reinforcing the importance of the interactions of pRb with E2F1, E2F2, and E2F3 for cell cycle control. However, R654W embryos survive at least 2 days longer than Rb1 null embryos, and increased life span is associated with improved erythrocyte and fetal liver macrophage differentiation. In contrast, R654W pRb does not rescue differentiation defects associated with pRb-deficient retinae. These data indicate that Rb1 makes important cell-type-specific contributions to cellular differentiation that are genetically separable from its general ability to stably bind E2F1, E2F2, and E2F3 and regulate the cell cycle.
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Affiliation(s)
- Huifang Sun
- Department of Pharmacology & Therapeutics, Roswell Park Cancer Institute, Elm & Carlton Streets, Buffalo, NY 14263, USA
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19
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Schweers BA, Dyer MA. Perspective: new genetic tools for studying retinal development and disease. Vis Neurosci 2006; 22:553-60. [PMID: 16332265 DOI: 10.1017/s0952523805225026] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2005] [Accepted: 06/10/2005] [Indexed: 12/21/2022]
Abstract
The use of knock-out and transgenic mice has been instrumental for advancing our understanding of retinal development and disease. In this perspective, we review existing genetic approaches to studying retinal development and present a series of new genetic tools that complement the use of standard knock-out and transgenic mice. Particular emphasis is placed on elucidating cell-autonomous and non-cell-autonomous roles of genes important for retinal development and disease in vivo. In addition, a series of gene-swapping vectors can be used to elucidate the function of proteins that regulate key processes in retinal development and a wide variety of retinopathies.
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Affiliation(s)
- Brett A Schweers
- Department of Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis
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20
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Dannenberg JH, te Riele HPJ. The retinoblastoma gene family in cell cycle regulation and suppression of tumorigenesis. Results Probl Cell Differ 2006; 42:183-225. [PMID: 16903212 DOI: 10.1007/400_002] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Since its discovery in 1986, as the first tumor suppressor gene, the retinoblastoma gene (Rb) has been extensively studied. Numerous biochemical and genetic studies have elucidated in great detail the function of the Rb gene and placed it at the heart of the molecular machinery controlling the cell cycle. As more insight was gained into the genetic events required for oncogenic transformation, it became clear that the retinoblastoma gene is connected to biochemical pathways that are dysfunctional in virtually all tumor types. Besides regulating the E2F transcription factors, pRb is involved in numerous biological processes such as apoptosis, DNA repair, chromatin modification, and differentiation. Further complexity was added to the system with the discovery of p107 and p130, two close homologs of Rb. Although the three family members share similar functions, it is becoming clear that these proteins also have unique functions in differentiation and regulation of transcription. In contrast to Rb, p107 and p130 are rarely found inactivated in human tumors. Yet, evidence is accumulating that these proteins are part of a "tumor-surveillance" mechanism and can suppress tumorigenesis. Here we provide an overview of the knowledge obtained from studies involving the retinoblastoma gene family with particular focus on its role in suppressing tumorigenesis.
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Affiliation(s)
- Jan-Hermen Dannenberg
- Department of Medical Oncology, Dana-Farber Cancer Institute and Harvard Medical School, Boston, Massachusetts, USA.
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21
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Abstract
Dyer and colleagues examine the most promising preclinical models that recapitulate the molecular, genetic, and cellular features of retinoblastoma.
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Affiliation(s)
- Michael A Dyer
- Department of Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, Tennessee, United States of America.
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22
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Abstract
The cellular effects of the genetic defects associated with tumorigenesis are context dependent. To better understand the reasons that different cell types require distinct combinations of mutations to form tumours, it is essential to identify and characterize a tumour's 'cell of origin'. Retinoblastoma, a rare childhood cancer of the retina that is caused by RB inactivation, is a good model in which to search for a tumour cell of origin, because retinal development is well understood and the initiating genetic lesion is well characterized. Identifying the cell of origin for this tumour would advance our understanding of how cellular context affects the requirement of specific mutations for cancer initiation and progression.
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Affiliation(s)
- Michael A Dyer
- Department of Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, Tennessee 38105, USA.
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23
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Dyer MA, Donovan SL, Zhang J, Gray J, Ortiz A, Tenney R, Kong J, Allikmets R, Sohocki MM. Retinal degeneration in Aipl1-deficient mice: a new genetic model of Leber congenital amaurosis. BRAIN RESEARCH. MOLECULAR BRAIN RESEARCH 2004; 132:208-20. [PMID: 15582159 DOI: 10.1016/j.molbrainres.2004.10.011] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 10/08/2004] [Indexed: 01/10/2023]
Abstract
Leber congenital amaurosis (LCA) is the most severe inherited retinopathy, with the earliest age of onset. Because this currently incurable disease is present from birth and is a relatively rare disorder, the development of animal models that closely resemble the phenotype in patients is especially important. Our previous genetic analyses of LCA patients identified mutations in the aryl-hydrocarbon interacting protein-like 1 (AIPL1) gene. Here we present development of an animal model of AIPL1-associated LCA, the Aipl1-deficient mouse. Aipl1 is expressed at low levels throughout human and mouse retinal development and is rapidly upregulated as photoreceptors differentiate. The mouse displays rapid retinal degeneration and massive Müler cell gliosis, resembling the phenotype of the rd mouse, which is caused by a mutation in the gene for the beta-subunit of the rod-specific phosphodiesterase. We confirm that this phenotype is consistent with the human disease using electroretinograms, and document the disease pathogenesis by analyzing the development of all retinal cell types and synaptogenesis during retinal histogenesis. Ectopic expression of AIPL1 led to deregulated retinal progenitor cell proliferation and alterations in cell fate specification; however, no gross abnormalities of proliferation during retinal development were detected. Data from analysis of proliferation and cell fate specification during retinal development of Aipl1-deficient mice suggests that there may be redundancy or compensation for Aipl1 loss by other related proteins. Because this mouse model closely mimics the human retinopathy caused by homozygous mutations in this gene, it provides a preclinical model for testing therapies to rescue the vision of children whose blindness is caused by AIPL1 mutations.
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MESH Headings
- Adaptor Proteins, Signal Transducing
- Animals
- Carrier Proteins/genetics
- Cell Division
- Disease Models, Animal
- Electroretinography
- Mice
- Mice, Inbred C57BL
- Mice, Mutant Strains
- Optic Atrophy, Hereditary, Leber/genetics
- Optic Atrophy, Hereditary, Leber/pathology
- Optic Atrophy, Hereditary, Leber/physiopathology
- Retinal Degeneration/genetics
- Retinal Degeneration/pathology
- Retinal Degeneration/physiopathology
- Stem Cells/cytology
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Affiliation(s)
- Michael A Dyer
- Department of Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA.
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