1
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Hung SS, Tsai PS, Po CW, Hou PS. Pax6 isoforms shape eye development: Insights from developmental stages and organoid models. Differentiation 2024; 137:100781. [PMID: 38631141 DOI: 10.1016/j.diff.2024.100781] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Revised: 04/05/2024] [Accepted: 04/08/2024] [Indexed: 04/19/2024]
Abstract
Pax6 is a critical transcription factor involved in the development of the central nervous system. However, in humans, mutations in Pax6 predominantly result in iris deficiency rather than neurological phenotypes. This may be attributed to the distinct functions of Pax6 isoforms, Pax6a and Pax6b. In this study, we investigated the spatial and temporal expression patterns of Pax6 isoforms during different stages of mouse eye development. We observed a strong correlation between Pax6a expression and the neuroretina gene Sox2, while Pax6b showed a high correlation with iris-component genes, including the mesenchymal gene Foxc1. During early patterning from E10.5, Pax6b was expressed in the hinge of the optic cup and neighboring mesenchymal cells, whereas Pax6a was absent in these regions. At E14.5, both Pax6a and Pax6b were expressed in the future iris and ciliary body, coinciding with the integration of mesenchymal cells and Mitf-positive cells in the outer region. From E18.5, Pax6 isoforms exhibited distinct expression patterns as lineage genes became more restricted. To further validate these findings, we utilized ESC-derived eye organoids, which recapitulated the temporal and spatial expression patterns of lineage genes and Pax6 isoforms. Additionally, we found that the spatial expression patterns of Foxc1 and Mitf were impaired in Pax6b-mutant ESC-derived eye organoids. This in vitro eye organoids model suggested the involvement of Pax6b-positive local mesodermal cells in iris development. These results provide valuable insights into the regulatory roles of Pax6 isoforms during iris and neuroretina development and highlight the potential of ESC-derived eye organoids as a tool for studying normal and pathological eye development.
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Affiliation(s)
- Shih-Shun Hung
- Institute of Anatomy and Cell Biology, School of Medicine, National Yang Ming Chiao Tung University, No. 155, Sec. 2, Linong St., Beitou Dist, Taipei, 11221, Taiwan.
| | - Po-Sung Tsai
- Institute of Anatomy and Cell Biology, School of Medicine, National Yang Ming Chiao Tung University, No. 155, Sec. 2, Linong St., Beitou Dist, Taipei, 11221, Taiwan.
| | - Ching-Wen Po
- Institute of Anatomy and Cell Biology, School of Medicine, National Yang Ming Chiao Tung University, No. 155, Sec. 2, Linong St., Beitou Dist, Taipei, 11221, Taiwan; Institute of Brain Science, School of Medicine, National Yang Ming Chiao Tung University, Taipei, 11221, Taiwan.
| | - Pei-Shan Hou
- Institute of Anatomy and Cell Biology, School of Medicine, National Yang Ming Chiao Tung University, No. 155, Sec. 2, Linong St., Beitou Dist, Taipei, 11221, Taiwan; Institute of Brain Science, School of Medicine, National Yang Ming Chiao Tung University, Taipei, 11221, Taiwan; Brain Research Center, National Yang Ming Chiao Tung University, Taipei, 11221, Taiwan.
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2
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Matsushita I, Izumi H, Ueno S, Hayashi T, Fujinami K, Tsunoda K, Iwata T, Kiuchi Y, Kondo H. Functional Characteristics of Diverse PAX6 Mutations Associated with Isolated Foveal Hypoplasia. Genes (Basel) 2023; 14:1483. [PMID: 37510387 PMCID: PMC10379490 DOI: 10.3390/genes14071483] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2023] [Revised: 07/14/2023] [Accepted: 07/18/2023] [Indexed: 07/30/2023] Open
Abstract
The human fovea is a specialized pit structure in the central retina. Foveal hypoplasia is a condition where the foveal pit does not fully develop, and it is associated with poor vision. Autosomal dominant isolated foveal hypoplasia (FVH1) is a rare condition of foveal hypoplasia (FH) that lacks any other ocular manifestations. FVH1 is associated with hypomorphic mutations in the PAX6 gene that encodes a sequence-specific DNA-binding transcription factor for morphogenesis and evolution of the eye. We report our findings in 17 patients with PAX6 mutations associated with FVH1 or FH with aniridia and corneal opacities. Patients with three mutations, p.V78E, p.V83F and p.R128H, in the C-terminal subdomain of the paired domain (CTS) consistently have severe FH. Luciferase assays for a single reporter containing a representative PAX6 binding site indicated that the transcriptional activities of these mutations were significantly reduced, comparable to that of the truncation mutation of p.G65Rfs*5. Patients with p.P20S in the N-terminal subdomain of the paired domain, and a patient with p.N365K in the proline-serine-threonine-rich domain (PSTD) had mild FH. A patient with p.Q255L in the homeodomain had severe FH. The P20S and Q255L mutants did not affect the transcriptional activity. Mutant N365K has a retained DNA-binding activity but a reduced transcriptional activity, due to a low PSTD transactivation. These findings demonstrated that mutations associated with FVH1 underlie a functional divergence between DNA-binding ability and transcriptional activity. We conclude that a wide range of mutations in the PAX6 gene is not limited to the CST region and are responsible for FVH1.
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Affiliation(s)
- Itsuka Matsushita
- Department of Ophthalmology, University of Occupational and Environmental Health, Kitakyushu 807-8555, Japan;
| | - Hiroto Izumi
- Department of Occupational Pneumology, University of Occupational and Environmental Health, Kitakyushu 807-8555, Japan;
| | - Shinji Ueno
- Department of Ophthalmology, Hirosaki University Graduate School of Medicine, Hirosaki 036-8562, Japan;
- Department of Ophthalmology, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - Takaaki Hayashi
- Department of Ophthalmology, The Jikei University School of Medicine, Tokyo 105-8461, Japan;
| | - Kaoru Fujinami
- Department of Ophthalmology, National Hospital Organization Tokyo Medical Center, Tokyo 152-8902, Japan; (K.F.); (K.T.)
| | - Kazushige Tsunoda
- Department of Ophthalmology, National Hospital Organization Tokyo Medical Center, Tokyo 152-8902, Japan; (K.F.); (K.T.)
| | - Takeshi Iwata
- Division of Molecular and Cellular Biology, National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center, Tokyo 152-8902, Japan;
| | - Yoshiaki Kiuchi
- Department of Ophthalmology and Visual Science, Graduate School of Biomedical and Health Sciences, Hiroshima 734-8551, Japan;
| | - Hiroyuki Kondo
- Department of Ophthalmology, University of Occupational and Environmental Health, Kitakyushu 807-8555, Japan;
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3
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Daruich A, Duncan M, Robert MP, Lagali N, Semina EV, Aberdam D, Ferrari S, Romano V, des Roziers CB, Benkortebi R, De Vergnes N, Polak M, Chiambaretta F, Nischal KK, Behar-Cohen F, Valleix S, Bremond-Gignac D. Congenital aniridia beyond black eyes: From phenotype and novel genetic mechanisms to innovative therapeutic approaches. Prog Retin Eye Res 2023; 95:101133. [PMID: 36280537 PMCID: PMC11062406 DOI: 10.1016/j.preteyeres.2022.101133] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2022] [Revised: 09/27/2022] [Accepted: 10/03/2022] [Indexed: 11/05/2022]
Abstract
Congenital PAX6-aniridia, initially characterized by the absence of the iris, has progressively been shown to be associated with other developmental ocular abnormalities and systemic features making congenital aniridia a complex syndromic disorder rather than a simple isolated disease of the iris. Moreover, foveal hypoplasia is now recognized as a more frequent feature than complete iris hypoplasia and a major visual prognosis determinant, reversing the classical clinical picture of this disease. Conversely, iris malformation is also a feature of various anterior segment dysgenesis disorders caused by PAX6-related developmental genes, adding a level of genetic complexity for accurate molecular diagnosis of aniridia. Therefore, the clinical recognition and differential genetic diagnosis of PAX6-related aniridia has been revealed to be much more challenging than initially thought, and still remains under-investigated. Here, we update specific clinical features of aniridia, with emphasis on their genotype correlations, as well as provide new knowledge regarding the PAX6 gene and its mutational spectrum, and highlight the beneficial utility of clinically implementing targeted Next-Generation Sequencing combined with Whole-Genome Sequencing to increase the genetic diagnostic yield of aniridia. We also present new molecular mechanisms underlying aniridia and aniridia-like phenotypes. Finally, we discuss the appropriate medical and surgical management of aniridic eyes, as well as innovative therapeutic options. Altogether, these combined clinical-genetic approaches will help to accelerate time to diagnosis, provide better determination of the disease prognosis and management, and confirm eligibility for future clinical trials or genetic-specific therapies.
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Affiliation(s)
- Alejandra Daruich
- Ophthalmology Department, Necker-Enfants Malades University Hospital, AP-HP, Paris Cité University, Paris, France; INSERM, UMRS1138, Team 17, From Physiopathology of Ocular Diseases to Clinical Development, Sorbonne Paris Cité University, Centre de Recherche des Cordeliers, Paris, France
| | - Melinda Duncan
- Department of Biological Sciences, University of Delaware, Newark, DE, USA
| | - Matthieu P Robert
- Ophthalmology Department, Necker-Enfants Malades University Hospital, AP-HP, Paris Cité University, Paris, France; Borelli Centre, UMR 9010, CNRS-SSA-ENS Paris Saclay-Paris Cité University, Paris, France
| | - Neil Lagali
- Division of Ophthalmology, Department of Biomedical and Clinical Sciences, Faculty of Medicine, Linköping University, 581 83, Linköping, Sweden; Department of Ophthalmology, Sørlandet Hospital Arendal, Arendal, Norway
| | - Elena V Semina
- Department of Pediatrics, Children's Research Institute at the Medical College of Wisconsin and Children's Hospital of Wisconsin, Milwaukee, WI, 53226, USA
| | - Daniel Aberdam
- INSERM, UMRS1138, Team 17, From Physiopathology of Ocular Diseases to Clinical Development, Sorbonne Paris Cité University, Centre de Recherche des Cordeliers, Paris, France
| | - Stefano Ferrari
- Fondazione Banca degli Occhi del Veneto, Via Paccagnella 11, Venice, Italy
| | - Vito Romano
- Department of Medical and Surgical Specialties, Radiolological Sciences, and Public Health, Ophthalmology Clinic, University of Brescia, Italy
| | - Cyril Burin des Roziers
- INSERM, UMRS1138, Team 17, From Physiopathology of Ocular Diseases to Clinical Development, Sorbonne Paris Cité University, Centre de Recherche des Cordeliers, Paris, France; Service de Médecine Génomique des Maladies de Système et d'Organe, APHP. Centre Université de Paris, Fédération de Génétique et de Médecine Génomique Hôpital Cochin, 27 rue du Fbg St-Jacques, 75679, Paris Cedex 14, France
| | - Rabia Benkortebi
- Ophthalmology Department, Necker-Enfants Malades University Hospital, AP-HP, Paris Cité University, Paris, France
| | - Nathalie De Vergnes
- Ophthalmology Department, Necker-Enfants Malades University Hospital, AP-HP, Paris Cité University, Paris, France
| | - Michel Polak
- Pediatric Endocrinology, Gynecology and Diabetology, Hôpital Universitaire Necker Enfants Malades, AP-HP, Paris Cité University, INSERM U1016, Institut IMAGINE, France
| | | | - Ken K Nischal
- Division of Pediatric Ophthalmology, Strabismus, and Adult Motility, UPMC Children's Hospital of Pittsburgh, Pittsburgh, PA, USA; UPMC Eye Center, University of Pittsburgh Medical Center, Pittsburgh, PA, USA
| | - Francine Behar-Cohen
- INSERM, UMRS1138, Team 17, From Physiopathology of Ocular Diseases to Clinical Development, Sorbonne Paris Cité University, Centre de Recherche des Cordeliers, Paris, France
| | - Sophie Valleix
- INSERM, UMRS1138, Team 17, From Physiopathology of Ocular Diseases to Clinical Development, Sorbonne Paris Cité University, Centre de Recherche des Cordeliers, Paris, France; Service de Médecine Génomique des Maladies de Système et d'Organe, APHP. Centre Université de Paris, Fédération de Génétique et de Médecine Génomique Hôpital Cochin, 27 rue du Fbg St-Jacques, 75679, Paris Cedex 14, France
| | - Dominique Bremond-Gignac
- Ophthalmology Department, Necker-Enfants Malades University Hospital, AP-HP, Paris Cité University, Paris, France; INSERM, UMRS1138, Team 17, From Physiopathology of Ocular Diseases to Clinical Development, Sorbonne Paris Cité University, Centre de Recherche des Cordeliers, Paris, France.
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4
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Blanco-Kelly F, Tarilonte M, Villamar M, Damián A, Tamayo A, Moreno-Pelayo MA, Ayuso C, Cortón M. Genetics and epidemiology of aniridia: Updated guidelines for genetic study. ARCHIVOS DE LA SOCIEDAD ESPANOLA DE OFTALMOLOGIA 2021; 96 Suppl 1:4-14. [PMID: 34836588 DOI: 10.1016/j.oftale.2021.02.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Accepted: 02/13/2021] [Indexed: 12/16/2022]
Abstract
Aniridia is a panocular disease characterized by iris hypoplasia, accompanied by other ocular manifestations, with a high clinical variability and overlapping with different abnormalities of the anterior and posterior segment. This review focuses on the genetic features of this autosomal dominant pathology, which is caused by the haploinsufficiency of the PAX6 gene. Mutations causing premature stop codons are the most frequent among the wider mutational spectrum of PAX6, with more than 600 different mutations identified so far. Recent advances in next-generation sequencing (NGS) have increased the diagnostic yield in aniridia and contributed to elucidate new etiopathogenic mechanisms leading to PAX6 haploinsufficiency. Here, we also update good practices and recommendations to improve genetic testing and clinical management of aniridia using more cost-effective NGS analysis. Those new approaches also allow studying simultaneously both structural variants and point-mutations in PAX6 as well as other genes for differential diagnosis, simultaneously. Some patients with atypical phenotypes might present mutations in FOXC1 and PITX2, both genes causing a wide spectrum of anterior segment dysgenesis, or in ITPR1, which is responsible for a distinctive form of circumpupillary iris aplasia present in Gillespie syndrome, or other mutations in minor genes. Since aniridia can also associate extraocular anomalies, as it occurs in carriers of PAX6 and WT1 microdeletions leading to WAGR syndrome, genetic studies are crucial to assure a correct diagnosis and clinical management, besides allowing prenatal and preimplantational genetic testing in families.
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Affiliation(s)
- F Blanco-Kelly
- Departamento de Genética, Hospital Universitario Fundación Jiménez Díaz, Madrid, Spain; Área de Genética & Genómica, Instituto de Investigación Sanitaria - Fundación Jiménez Díaz - Universidad Autónoma de Madrid (IIS-FJD, UAM), Madrid, Spain; Centro de Investigación en Red de Enfermedades Raras (CIBERER), ISCIII, Madrid, Spain
| | - M Tarilonte
- Departamento de Genética, Hospital Universitario Fundación Jiménez Díaz, Madrid, Spain; Área de Genética & Genómica, Instituto de Investigación Sanitaria - Fundación Jiménez Díaz - Universidad Autónoma de Madrid (IIS-FJD, UAM), Madrid, Spain
| | - M Villamar
- Servicio de Genética, Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS), Hospital Universitario Ramón y Cajal, Madrid, Spain; Centro de Investigación en Red de Enfermedades Raras (CIBERER), ISCIII, Madrid, Spain
| | - A Damián
- Departamento de Genética, Hospital Universitario Fundación Jiménez Díaz, Madrid, Spain; Área de Genética & Genómica, Instituto de Investigación Sanitaria - Fundación Jiménez Díaz - Universidad Autónoma de Madrid (IIS-FJD, UAM), Madrid, Spain
| | - A Tamayo
- Departamento de Genética, Hospital Universitario Fundación Jiménez Díaz, Madrid, Spain; Área de Genética & Genómica, Instituto de Investigación Sanitaria - Fundación Jiménez Díaz - Universidad Autónoma de Madrid (IIS-FJD, UAM), Madrid, Spain
| | - M A Moreno-Pelayo
- Servicio de Genética, Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS), Hospital Universitario Ramón y Cajal, Madrid, Spain; Centro de Investigación en Red de Enfermedades Raras (CIBERER), ISCIII, Madrid, Spain
| | - C Ayuso
- Departamento de Genética, Hospital Universitario Fundación Jiménez Díaz, Madrid, Spain; Área de Genética & Genómica, Instituto de Investigación Sanitaria - Fundación Jiménez Díaz - Universidad Autónoma de Madrid (IIS-FJD, UAM), Madrid, Spain; Centro de Investigación en Red de Enfermedades Raras (CIBERER), ISCIII, Madrid, Spain
| | - M Cortón
- Departamento de Genética, Hospital Universitario Fundación Jiménez Díaz, Madrid, Spain; Área de Genética & Genómica, Instituto de Investigación Sanitaria - Fundación Jiménez Díaz - Universidad Autónoma de Madrid (IIS-FJD, UAM), Madrid, Spain; Centro de Investigación en Red de Enfermedades Raras (CIBERER), ISCIII, Madrid, Spain.
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5
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Jiang Y, Li S, Xiao X, Sun W, Zhang Q. Genotype-Phenotype of Isolated Foveal Hypoplasia in a Large Cohort: Minor Iris Changes as an Indicator of PAX6 Involvement. Invest Ophthalmol Vis Sci 2021; 62:23. [PMID: 34415986 PMCID: PMC8383911 DOI: 10.1167/iovs.62.10.23] [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] [Indexed: 11/24/2022] Open
Abstract
Purpose Foveal hypoplasia (FVH) is defined as the lack of fovea with a relatively preserved neuroretina, occurring either as an isolated FVH (IFVH) condition or associated with other diseases. This study aimed to systemically molecularly characterize IFVH. Methods Genetic defects in 33 families with IFVH were analyzed by exome sequencing. Variants in three genes (PAX6, SLC38A8, and AHR) were selected and evaluated with multistep bioinformatic tools. Results Mutations in the three genes were identified in 69.7% (23/33) of families with IFVH and infantile nystagmus, including 18 families with PAX6 mutations, 5 with SLC38A8 mutations, but none with AHR mutations. Clinical data from 32 patients in the 23 families showed FVH, infantile nystagmus, and full iris. Careful follow-up visits revealed subtle changes in iris in 9 of 14 patients with PAX6 variants. The PAX6 variants of the 18 families (15 missense and one stop-loss) were mostly located in the C-terminal region of the paired box domain. Variants in AHR, SLC38A8, and PAX6 contributed to IFVH in one (2%), 25 (45%), and 30 (53%) families with identified genetic defects (23 families in this study and 33 reported previously), respectively. Conclusions PAX6 and SLC38A8 mutations are the main cause of IFVH based on our data and a systematic review. IFVH-associated PAX6 variants are mostly missense with a specific location, indicating a specific correlation of these variants with IFVH but not with typical aniridia. Full iris with subtle structural abnormalities is more common in patients with PAX6-associated IFVH, suggesting a potential diagnostic indicator.
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Affiliation(s)
- Yi Jiang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Shiqiang Li
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Xueshan Xiao
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Wenmin Sun
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Qingjiong Zhang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
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Blanco-Kelly F, Tarilonte M, Villamar M, Damián A, Tamayo A, Moreno-Pelayo MA, Ayuso C, Cortón M. Genetics and epidemiology of aniridia: Updated guidelines for genetic study. ARCHIVOS DE LA SOCIEDAD ESPANOLA DE OFTALMOLOGIA 2021; 96:S0365-6691(21)00124-6. [PMID: 34243981 DOI: 10.1016/j.oftal.2021.02.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Revised: 02/09/2021] [Accepted: 02/13/2021] [Indexed: 11/24/2022]
Abstract
Aniridia is a panocular disease characterized by iris hypoplasia, accompanied by other ocular manifestations, with a high clinical variability and overlapping with different abnormalities of the anterior and posterior segment. This review focuses on the genetic features of this autosomal dominant pathology, which is caused by the haploinsufficiency of the PAX6 gene. Mutations causing premature stop codons are the most frequent among the wider mutational spectrum of PAX6, with more than 600 different mutations identified so far. Recent advances in next-generation sequencing (NGS) have increased the diagnostic yield in aniridia and contributed to elucidate new etiopathogenic mechanisms leading to PAX6 haploinsufficiency. Here, we also update good practices and recommendations to improve genetic testing and clinical management of aniridia using more cost-effective NGS analysis. Those new approaches also allow studying simultaneously both structural variants and point-mutations in PAX6 as well as other genes for differential diagnosis, simultaneously. Some patients with atypical phenotypes might present mutations in FOXC1 and PITX2, both genes causing a wide spectrum of anterior segment dysgenesis, or in ITPR1, which is responsible for a distinctive form of circumpupillary iris aplasia present in Gillespie syndrome, or other mutations in minor genes. Since aniridia can also associate extraocular anomalies, as it occurs in carriers of PAX6 and WT1 microdeletions leading to WAGR syndrome, genetic studies are crucial to assure a correct diagnosis and clinical management, besides allowing prenatal and preimplantational genetic testing in families.
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Affiliation(s)
- F Blanco-Kelly
- Departamento de Genética, Hospital Universitario Fundación Jiménez Díaz, Madrid, España; Área de Genética & Genómica, Instituto de Investigación Sanitaria - Fundación Jiménez Díaz - Universidad Autónoma de Madrid (IIS-FJD, UAM), Madrid, España; Centro de Investigación en Red de Enfermedades Raras (CIBERER), ISCIII, Madrid, España
| | - M Tarilonte
- Departamento de Genética, Hospital Universitario Fundación Jiménez Díaz, Madrid, España; Área de Genética & Genómica, Instituto de Investigación Sanitaria - Fundación Jiménez Díaz - Universidad Autónoma de Madrid (IIS-FJD, UAM), Madrid, España
| | - M Villamar
- Servicio de Genética, Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS), Hospital Universitario Ramón y Cajal, Madrid, España; Centro de Investigación en Red de Enfermedades Raras (CIBERER), ISCIII, Madrid, España
| | - A Damián
- Departamento de Genética, Hospital Universitario Fundación Jiménez Díaz, Madrid, España; Área de Genética & Genómica, Instituto de Investigación Sanitaria - Fundación Jiménez Díaz - Universidad Autónoma de Madrid (IIS-FJD, UAM), Madrid, España
| | - A Tamayo
- Departamento de Genética, Hospital Universitario Fundación Jiménez Díaz, Madrid, España; Área de Genética & Genómica, Instituto de Investigación Sanitaria - Fundación Jiménez Díaz - Universidad Autónoma de Madrid (IIS-FJD, UAM), Madrid, España
| | - M A Moreno-Pelayo
- Servicio de Genética, Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS), Hospital Universitario Ramón y Cajal, Madrid, España; Centro de Investigación en Red de Enfermedades Raras (CIBERER), ISCIII, Madrid, España
| | - C Ayuso
- Departamento de Genética, Hospital Universitario Fundación Jiménez Díaz, Madrid, España; Área de Genética & Genómica, Instituto de Investigación Sanitaria - Fundación Jiménez Díaz - Universidad Autónoma de Madrid (IIS-FJD, UAM), Madrid, España; Centro de Investigación en Red de Enfermedades Raras (CIBERER), ISCIII, Madrid, España
| | - M Cortón
- Departamento de Genética, Hospital Universitario Fundación Jiménez Díaz, Madrid, España; Área de Genética & Genómica, Instituto de Investigación Sanitaria - Fundación Jiménez Díaz - Universidad Autónoma de Madrid (IIS-FJD, UAM), Madrid, España; Centro de Investigación en Red de Enfermedades Raras (CIBERER), ISCIII, Madrid, España.
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7
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Tarilonte M, Ramos P, Moya J, Fernandez-Sanz G, Blanco-Kelly F, Swafiri ST, Villaverde C, Romero R, Tamayo A, Gener B, Calvas P, Ayuso C, Corton M. Activation of cryptic donor splice sites by non-coding and coding PAX6 variants contributes to congenital aniridia. J Med Genet 2021; 59:428-437. [PMID: 33782094 DOI: 10.1136/jmedgenet-2020-106932] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Revised: 01/22/2021] [Accepted: 02/14/2021] [Indexed: 12/17/2022]
Abstract
BACKGROUND The paired-domain transcription factor paired box gene 6 (PAX6) causes a wide spectrum of ocular developmental anomalies, including congenital aniridia, Peters anomaly and microphthalmia. Here, we aimed to functionally assess the involvement of seven potentially non-canonical splicing variants on missplicing of exon 6, which represents the main hotspot region for loss-of-function PAX6 variants. METHODS By locus-specific analysis of PAX6 using Sanger and/or targeted next-generation sequencing, we screened a Spanish cohort of 106 patients with PAX6-related diseases. Functional splicing assays were performed by in vitro minigene approaches or directly in RNA from patient-derived lymphocytes cell line, when available. RESULTS Five out seven variants, including three synonymous changes, one small exonic deletion and one non-canonical splice variant, showed anomalous splicing patterns yielding partial exon skipping and/or elongation. CONCLUSION We describe new spliceogenic mechanisms for PAX6 variants mediated by creating or strengthening five different cryptic donor sites at exon 6. Our work revealed that the activation of cryptic PAX6 splicing sites seems to be a recurrent and underestimated cause of aniridia. Our findings pointed out the importance of functional assessment of apparently silent PAX6 variants to uncover hidden genetic alterations and to improve variant interpretation for genetic counselling in aniridia.
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Affiliation(s)
- Maria Tarilonte
- Department of Genetics & Genomics, Instituto de Investigación Sanitaria - Fundación Jiménez Díaz University Hospital - Universidad Autónoma de Madrid (IIS-FJD-UAM), Madrid, Spain.,Center for Biomedical Network Research on Rare Diseases (CIBERER), ISCIII, Madrid, Spain
| | - Patricia Ramos
- Department of Genetics & Genomics, Instituto de Investigación Sanitaria - Fundación Jiménez Díaz University Hospital - Universidad Autónoma de Madrid (IIS-FJD-UAM), Madrid, Spain
| | - Jennifer Moya
- Department of Genetics & Genomics, Instituto de Investigación Sanitaria - Fundación Jiménez Díaz University Hospital - Universidad Autónoma de Madrid (IIS-FJD-UAM), Madrid, Spain
| | - Guilermo Fernandez-Sanz
- Department of Ophthalmology, Fundación Jiménez Díaz University Hospital, Madrid, Spain.,Department of Ophthalmology, Clínica Universidad de Navarra, Madrid, Spain
| | - Fiona Blanco-Kelly
- Department of Genetics & Genomics, Instituto de Investigación Sanitaria - Fundación Jiménez Díaz University Hospital - Universidad Autónoma de Madrid (IIS-FJD-UAM), Madrid, Spain.,Center for Biomedical Network Research on Rare Diseases (CIBERER), ISCIII, Madrid, Spain
| | - Saoud Tahsin Swafiri
- Department of Genetics & Genomics, Instituto de Investigación Sanitaria - Fundación Jiménez Díaz University Hospital - Universidad Autónoma de Madrid (IIS-FJD-UAM), Madrid, Spain.,Center for Biomedical Network Research on Rare Diseases (CIBERER), ISCIII, Madrid, Spain
| | - Cristina Villaverde
- Department of Genetics & Genomics, Instituto de Investigación Sanitaria - Fundación Jiménez Díaz University Hospital - Universidad Autónoma de Madrid (IIS-FJD-UAM), Madrid, Spain.,Center for Biomedical Network Research on Rare Diseases (CIBERER), ISCIII, Madrid, Spain
| | - Raquel Romero
- Department of Genetics & Genomics, Instituto de Investigación Sanitaria - Fundación Jiménez Díaz University Hospital - Universidad Autónoma de Madrid (IIS-FJD-UAM), Madrid, Spain
| | - Alejandra Tamayo
- Department of Genetics & Genomics, Instituto de Investigación Sanitaria - Fundación Jiménez Díaz University Hospital - Universidad Autónoma de Madrid (IIS-FJD-UAM), Madrid, Spain.,Center for Biomedical Network Research on Rare Diseases (CIBERER), ISCIII, Madrid, Spain
| | - Blanca Gener
- Center for Biomedical Network Research on Rare Diseases (CIBERER), ISCIII, Madrid, Spain.,Department of Genetics, Cruces University Hospital, BioCruces Health Research Institute, Barakaldo, Spain
| | - Patrick Calvas
- Service de Génétique Médicale, Hôpital Purpan, CHU Toulouse, Toulouse, France.,INSERM U1056, Université Toulouse III, Toulouse, France
| | - Carmen Ayuso
- Department of Genetics & Genomics, Instituto de Investigación Sanitaria - Fundación Jiménez Díaz University Hospital - Universidad Autónoma de Madrid (IIS-FJD-UAM), Madrid, Spain.,Center for Biomedical Network Research on Rare Diseases (CIBERER), ISCIII, Madrid, Spain
| | - Marta Corton
- Department of Genetics & Genomics, Instituto de Investigación Sanitaria - Fundación Jiménez Díaz University Hospital - Universidad Autónoma de Madrid (IIS-FJD-UAM), Madrid, Spain .,Center for Biomedical Network Research on Rare Diseases (CIBERER), ISCIII, Madrid, Spain
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8
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Multiple roles for Pax2 in the embryonic mouse eye. Dev Biol 2021; 472:18-29. [PMID: 33428890 DOI: 10.1016/j.ydbio.2020.12.020] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Revised: 12/23/2020] [Accepted: 12/24/2020] [Indexed: 02/07/2023]
Abstract
The vertebrate eye anlage grows out of the brain and folds into bilayered optic cups. The eye is patterned along multiple axes, precisely controlled by genetic programs, to delineate neural retina, pigment epithelium, and optic stalk tissues. Pax genes encode developmental regulators of key morphogenetic events, with Pax2 being essential for interpreting inductive signals, including in the eye. PAX2 mutations cause ocular coloboma, when the ventral optic fissure fails to close. Previous studies established that Pax2 is necessary for fissure closure and to maintain the neural retina -- glial optic stalk boundary. Using a Pax2GFP/+ knock-in allele we discovered that the mutant optic nerve head (ONH) lacks molecular boundaries with the retina and RPE, rendering the ONH larger than normal. This was preceded by ventronasal cup mispatterning, a burst of overproliferation and followed by optic cup apoptosis. Our findings support the hypothesis that ONH cells are tripotential, requiring Pax2 to remain committed to glial fates. This work extends current models of ocular development, contributes to broader understanding of tissue boundary formation and informs the underlying mechanisms of human coloboma.
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9
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Lima Cunha D, Arno G, Corton M, Moosajee M. The Spectrum of PAX6 Mutations and Genotype-Phenotype Correlations in the Eye. Genes (Basel) 2019; 10:genes10121050. [PMID: 31861090 PMCID: PMC6947179 DOI: 10.3390/genes10121050] [Citation(s) in RCA: 89] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Revised: 12/09/2019] [Accepted: 12/12/2019] [Indexed: 12/13/2022] Open
Abstract
The transcription factor PAX6 is essential in ocular development in vertebrates, being considered the master regulator of the eye. During eye development, it is essential for the correct patterning and formation of the multi-layered optic cup and it is involved in the developing lens and corneal epithelium. In adulthood, it is mostly expressed in cornea, iris, and lens. PAX6 is a dosage-sensitive gene and it is highly regulated by several elements located upstream, downstream, and within the gene. There are more than 500 different mutations described to affect PAX6 and its regulatory regions, the majority of which lead to PAX6 haploinsufficiency, causing several ocular and systemic abnormalities. Aniridia is an autosomal dominant disorder that is marked by the complete or partial absence of the iris, foveal hypoplasia, and nystagmus, and is caused by heterozygous PAX6 mutations. Other ocular abnormalities have also been associated with PAX6 changes, and genotype-phenotype correlations are emerging. This review will cover recent advancements in PAX6 regulation, particularly the role of several enhancers that are known to regulate PAX6 during eye development and disease. We will also present an updated overview of the mutation spectrum, where an increasing number of mutations in the non-coding regions have been reported. Novel genotype-phenotype correlations will also be discussed.
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Affiliation(s)
| | - Gavin Arno
- Institute of Ophthalmology, UCL, London EC1V 9EL, UK
- Moorfields Eye Hospital NHS Foundation Trust, London EC1V 2PD, UK
- Great Ormond Street Hospital for Children NHS Foundation Trust, London WC1N 3JH, UK
| | - Marta Corton
- Department of Genetics & Genomics, Instituto de Investigación Sanitaria-Fundación Jiménez Díaz University Hospital—Universidad Autónoma de Madrid (IIS-FJD, UAM), 28040 Madrid, Spain
- Centre for Biomedical Network Research on Rare Diseases (CIBERER), 28029 Madrid, Spain
| | - Mariya Moosajee
- Institute of Ophthalmology, UCL, London EC1V 9EL, UK
- Moorfields Eye Hospital NHS Foundation Trust, London EC1V 2PD, UK
- Great Ormond Street Hospital for Children NHS Foundation Trust, London WC1N 3JH, UK
- Correspondence:
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10
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Bringmann A, Syrbe S, Görner K, Kacza J, Francke M, Wiedemann P, Reichenbach A. The primate fovea: Structure, function and development. Prog Retin Eye Res 2018; 66:49-84. [PMID: 29609042 DOI: 10.1016/j.preteyeres.2018.03.006] [Citation(s) in RCA: 187] [Impact Index Per Article: 31.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Revised: 03/20/2018] [Accepted: 03/27/2018] [Indexed: 01/31/2023]
Abstract
A fovea is a pitted invagination in the inner retinal tissue (fovea interna) that overlies an area of photoreceptors specialized for high acuity vision (fovea externa). Although the shape of the vertebrate fovea varies considerably among the species, there are two basic types. The retina of many predatory fish, reptilians, and birds possess one (or two) convexiclivate fovea(s), while the retina of higher primates contains a concaviclivate fovea. By refraction of the incoming light, the convexiclivate fovea may function as image enlarger, focus indicator, and movement detector. By centrifugal displacement of the inner retinal layers, which increases the transparency of the central foveal tissue (the foveola), the primate fovea interna improves the quality of the image received by the central photoreceptors. In this review, we summarize ‒ with the focus on Müller cells of the human and macaque fovea ‒ data regarding the structure of the primate fovea, discuss various aspects of the optical function of the fovea, and propose a model of foveal development. The "Müller cell cone" of the foveola comprises specialized Müller cells which do not support neuronal activity but may serve optical and structural functions. In addition to the "Müller cell cone", structural stabilization of the foveal morphology may be provided by the 'z-shaped' Müller cells of the fovea walls, via exerting tractional forces onto Henle fibers. The spatial distribution of glial fibrillary acidic protein may suggest that the foveola and the Henle fiber layer are subjects to mechanical stress. During development, the foveal pit is proposed to be formed by a vertical contraction of the centralmost Müller cells. After widening of the foveal pit likely mediated by retracting astrocytes, Henle fibers are formed by horizontal contraction of Müller cell processes in the outer plexiform layer and the centripetal displacement of photoreceptors. A better understanding of the molecular, cellular, and mechanical factors involved in the developmental morphogenesis and the structural stabilization of the fovea may help to explain the (patho-) genesis of foveal hypoplasia and macular holes.
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Affiliation(s)
- Andreas Bringmann
- Department of Ophthalmology and Eye Hospital, Medical Faculty, University of Leipzig, 04103 Leipzig, Germany
| | - Steffen Syrbe
- Paul Flechsig Institute of Brain Research, Medical Faculty, University of Leipzig, 04103 Leipzig, Germany
| | - Katja Görner
- Paul Flechsig Institute of Brain Research, Medical Faculty, University of Leipzig, 04103 Leipzig, Germany
| | - Johannes Kacza
- Saxon Incubator for Clinical Translation (SIKT), Leipzig University, 04103 Leipzig, Germany
| | - Mike Francke
- Paul Flechsig Institute of Brain Research, Medical Faculty, University of Leipzig, 04103 Leipzig, Germany; Saxon Incubator for Clinical Translation (SIKT), Leipzig University, 04103 Leipzig, Germany
| | - Peter Wiedemann
- Department of Ophthalmology and Eye Hospital, Medical Faculty, University of Leipzig, 04103 Leipzig, Germany
| | - Andreas Reichenbach
- Paul Flechsig Institute of Brain Research, Medical Faculty, University of Leipzig, 04103 Leipzig, Germany.
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11
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Abstract
Paired box protein 6 (PAX6) is a master regulator of the eye development. Over the last past two decades, our understanding of eye development, especially the molecular function of PAX6, has focused on transcriptional control of the Pax6 expression. However, other regulatory mechanisms for gene expression, including alternative splicing (AS), have been understudied in the eye development. Recent findings suggest that two PAX6 isoforms generated by AS of Pax6 pre-mRNA may play previously underappreciated role(s) during eye development, especially, the corneal development.
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Affiliation(s)
- Jung Woo Park
- Faculty of Health Sciences, University of Macau , Macau, China
| | - Juan Yang
- Faculty of Health Sciences, University of Macau , Macau, China
| | - Ren-He Xu
- Faculty of Health Sciences, University of Macau , Macau, China
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12
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Remez LA, Onishi A, Menuchin-Lasowski Y, Biran A, Blackshaw S, Wahlin KJ, Zack DJ, Ashery-Padan R. Pax6 is essential for the generation of late-born retinal neurons and for inhibition of photoreceptor-fate during late stages of retinogenesis. Dev Biol 2017; 432:140-150. [PMID: 28993200 DOI: 10.1016/j.ydbio.2017.09.030] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2016] [Revised: 12/08/2016] [Accepted: 09/23/2017] [Indexed: 12/16/2022]
Abstract
In the developing retina, as in other regions of the CNS, neural progenitors give rise to individual cell types during discrete temporal windows. Pax6 is expressed in retinal progenitor cells (RPCs) throughout the course of retinogenesis, and has been shown to be required during early retinogenesis for generation of most early-born cell types. In this study, we examined the function of Pax6 in postnatal mouse retinal development. We found that Pax6 is essential for the generation of late-born interneurons, while inhibiting photoreceptor differentiation. Generation of bipolar interneurons requires Pax6 expression in RPCs, while Pax6 is required for the generation of glycinergic, but not for GABAergic or non-GABAergic-non-glycinergic (nGnG) amacrine cell subtypes. In contrast, overexpression of either full-length Pax6 or its 5a isoform in RPCs induces formation of cells with nGnG amacrine features, and suppresses generation of other inner retinal cell types. Moreover, overexpression of both Pax6 variants prevents photoreceptor differentiation, most likely by inhibiting Crx expression. Taken together, these data show that Pax6 acts in RPCs to control differentiation of multiple late-born neuronal cell types.
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Affiliation(s)
- Liv Aleen Remez
- Department of Human Molecular Genetics and Biochemistry, Faculty of Medicine and Sagol School of Neuroscience, Tel-Aviv University, Tel Aviv, Israel
| | - Akishi Onishi
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21287, United States
| | - Yotam Menuchin-Lasowski
- Department of Human Molecular Genetics and Biochemistry, Faculty of Medicine and Sagol School of Neuroscience, Tel-Aviv University, Tel Aviv, Israel
| | - Assaf Biran
- Department of Human Molecular Genetics and Biochemistry, Faculty of Medicine and Sagol School of Neuroscience, Tel-Aviv University, Tel Aviv, Israel
| | - Seth Blackshaw
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21287, United States
| | - Karl J Wahlin
- Shiley Eye Institute, University of California San Diego, La Jolla, CA, United States
| | - Donlad J Zack
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21287, United States; Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD 21287, United States
| | - Ruth Ashery-Padan
- Department of Human Molecular Genetics and Biochemistry, Faculty of Medicine and Sagol School of Neuroscience, Tel-Aviv University, Tel Aviv, Israel.
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13
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Shafei EV, Kurinov AM, Kuznetsova AV, Aleksandrova MA. Reprogramming of Human Retinal Pigment Epithelial Cells under the Effect of bFGF In Vitro. Bull Exp Biol Med 2017; 163:574-582. [PMID: 28853082 DOI: 10.1007/s10517-017-3852-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2017] [Indexed: 01/08/2023]
Abstract
We studied the effect of bFGF on human retinal pigment epithelial cells in vitro In ARPE-19 cells, enhanced expression of KLF4 mRNA and reduced expression of PAX6, MITF, and OTX2 mRNA specific for retinal pigment epithelium were observed after bFGF application. The expression of KLF4 mRNA peaked in 72 h after bFGF application and then sharply decreased, which was accompanied by a 3-fold increase in TUBB3 mRNA expression (neuronal marker). Immunocytochemical analysis showed that in the presence of bFGF, some cells retained epithelial properties and showed positive staining for connexin-43, while others had long axon-like processes and demonstrated positive staining for βIII-tubulin, which attests to their neuronal transdifferentiation. Despite the prevalence of the epithelial properties, ARPE-19 cells under the influence of bFGF can show proneuronal properties.
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Affiliation(s)
- E V Shafei
- N. K. Koltsov Institute of Developmental Biology, Russian Academy of Sciences, Moscow, Russia
| | - A M Kurinov
- N. K. Koltsov Institute of Developmental Biology, Russian Academy of Sciences, Moscow, Russia
| | - A V Kuznetsova
- N. K. Koltsov Institute of Developmental Biology, Russian Academy of Sciences, Moscow, Russia
| | - M A Aleksandrova
- N. K. Koltsov Institute of Developmental Biology, Russian Academy of Sciences, Moscow, Russia.
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14
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Chen T, Cavari B, Schartl M, Hong Y. Identification and Expression of Conserved and Novel RNA Variants of Medakapax6bGene. JOURNAL OF EXPERIMENTAL ZOOLOGY PART B-MOLECULAR AND DEVELOPMENTAL EVOLUTION 2017; 328:412-422. [PMID: 28547909 DOI: 10.1002/jez.b.22742] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2016] [Revised: 03/18/2017] [Accepted: 03/24/2017] [Indexed: 11/10/2022]
Affiliation(s)
- Tiansheng Chen
- Key Laboratory of Freshwater Animal Breeding; Ministry of Agriculture and College of Fisheries; Huazhong Agricultural University; Wuhan Hubei China
| | - Benzion Cavari
- Israel Oceanographic and Limnological Research; Tel Shikmona; Halfa Israel
| | - Manfred Schartl
- Department of Physiological Chemistry I, Biocenter; University of Würzburg; Würzburg Germany
| | - Yunhan Hong
- Department of Biological Sciences; National University of Singapore; Singapore
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15
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Trincado JL, Sebestyén E, Pagés A, Eyras E. The prognostic potential of alternative transcript isoforms across human tumors. Genome Med 2016; 8:85. [PMID: 27535130 PMCID: PMC4989457 DOI: 10.1186/s13073-016-0339-3] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Accepted: 07/27/2016] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Phenotypic changes during cancer progression are associated with alterations in gene expression, which can be exploited to build molecular signatures for tumor stage identification and prognosis. However, it is not yet known whether the relative abundance of transcript isoforms may be informative for clinical stage and survival. METHODS Using information theory and machine learning methods, we integrated RNA sequencing and clinical data from The Cancer Genome Atlas project to perform the first systematic analysis of the prognostic potential of transcript isoforms in 12 solid tumors to build new signatures for stage and prognosis. This study was also performed in breast tumors according to estrogen receptor (ER) status and melanoma tumors with proliferative and invasive phenotypes. RESULTS Transcript isoform signatures accurately separate early from late-stage groups and metastatic from non-metastatic tumors, and are predictive of the survival of patients with undetermined lymph node invasion or metastatic status. These signatures show similar, and sometimes better, accuracies compared with known gene expression signatures in retrospective data and are largely independent of gene expression changes. Furthermore, we show frequent transcript isoform changes in breast tumors according to ER status, and in melanoma tumors according to the invasive or proliferative phenotype, and derive accurate predictive models of stage and survival within each patient subgroup. CONCLUSIONS Our analyses reveal new signatures based on transcript isoform abundances that characterize tumor phenotypes and their progression independently of gene expression. Transcript isoform signatures appear especially relevant to determine lymph node invasion and metastasis and may potentially contribute towards current strategies of precision cancer medicine.
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Affiliation(s)
- Juan L Trincado
- Universitat Pompeu Fabra (UPF), Dr. Aiguader 88, E08003, Barcelona, Spain
| | - E Sebestyén
- IFOM, the FIRC Institute of Molecular Oncology, Via Adamello 16, 20139, Milan, Italy
| | - A Pagés
- Universitat Pompeu Fabra (UPF), Dr. Aiguader 88, E08003, Barcelona, Spain
| | - E Eyras
- Universitat Pompeu Fabra (UPF), Dr. Aiguader 88, E08003, Barcelona, Spain. .,Catalan Institution for Research and Advanced Studies (ICREA), Passeig Lluís Companys 23, E08010, Barcelona, Spain.
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16
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Identification of an Alternative Splicing Product of the Otx2 Gene Expressed in the Neural Retina and Retinal Pigmented Epithelial Cells. PLoS One 2016; 11:e0150758. [PMID: 26985665 PMCID: PMC4795653 DOI: 10.1371/journal.pone.0150758] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Accepted: 01/20/2016] [Indexed: 12/16/2022] Open
Abstract
To investigate the complexity of alternative splicing in the retina, we sequenced and analyzed a total of 115,706 clones from normalized cDNA libraries from mouse neural retina (66,217) and rat retinal pigmented epithelium (49,489). Based upon clustering the cDNAs and mapping them with their respective genomes, the estimated numbers of genes were 9,134 for the mouse neural retina and 12,050 for the rat retinal pigmented epithelium libraries. This unique collection of retinal of messenger RNAs is maintained and accessible through a web-base server to the whole community of retinal biologists for further functional characterization. The analysis revealed 3,248 and 3,202 alternative splice events for mouse neural retina and rat retinal pigmented epithelium, respectively. We focused on transcription factors involved in vision. Among the six candidates suitable for functional analysis, we selected Otx2S, a novel variant of the Otx2 gene with a deletion within the homeodomain sequence. Otx2S is expressed in both the neural retina and retinal pigmented epithelium, and encodes a protein that is targeted to the nucleus. OTX2S exerts transdominant activity on the tyrosinase promoter when tested in the physiological environment of primary RPE cells. By overexpressing OTX2S in primary RPE cells using an adeno associated viral vector, we identified 10 genes whose expression is positively regulated by OTX2S. We find that OTX2S is able to bind to the chromatin at the promoter of the retinal dehydrogenase 10 (RDH10) gene.
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17
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Mayran A, Pelletier A, Drouin J. Pax factors in transcription and epigenetic remodelling. Semin Cell Dev Biol 2015; 44:135-44. [PMID: 26234816 DOI: 10.1016/j.semcdb.2015.07.007] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2015] [Revised: 07/22/2015] [Accepted: 07/24/2015] [Indexed: 11/25/2022]
Abstract
The nine Pax transcription factors that constitute the mammalian family of paired domain (PD) factors play key roles in many developmental processes. As DNA binding transcription factors, they exhibit tremendous variability and complexity in their DNA recognition patterns. This is ascribed to the presence of multiple DNA binding structural domains, namely helix-turn-helix (HTH) domains. The PD contains two HTH subdomains and four of the nine Pax factors have an additional HTH domain, the homeodomain (HD). We now review these diverse DNA binding modalities together with their properties as transcriptional activators and repressors. The action of Pax factors on gene expression is also exerted through recruitment of chromatin remodelling complexes that introduce either activating or repressive chromatin marks. Interestingly, the recent demonstration that Pax7 has pioneer activity, the unique property to "open" chromatin, further underlines the mechanistic versatility and the developmental importance of these factors.
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Affiliation(s)
- Alexandre Mayran
- Laboratoire de Génétique Moléculaire, Institut de Recherches Cliniques de Montréal (IRCM), Montréal, QC H2W 1R7, Canada
| | - Audrey Pelletier
- Laboratoire de Génétique Moléculaire, Institut de Recherches Cliniques de Montréal (IRCM), Montréal, QC H2W 1R7, Canada
| | - Jacques Drouin
- Laboratoire de Génétique Moléculaire, Institut de Recherches Cliniques de Montréal (IRCM), Montréal, QC H2W 1R7, Canada.
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18
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Fabian P, Kozmikova I, Kozmik Z, Pantzartzi CN. Pax2/5/8 and Pax6 alternative splicing events in basal chordates and vertebrates: a focus on paired box domain. Front Genet 2015; 6:228. [PMID: 26191073 PMCID: PMC4488758 DOI: 10.3389/fgene.2015.00228] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2015] [Accepted: 06/15/2015] [Indexed: 12/19/2022] Open
Abstract
Paired box transcription factors play important role in development and tissue morphogenesis. The number of Pax homologs varies among species studied so far, due to genome and gene duplications that have affected PAX family to a great extent. Based on sequence similarity and functional domains, four Pax classes have been identified in chordates, namely Pax1/9, Pax2/5/8, Pax3/7, and Pax4/6. Numerous splicing events have been reported mainly for Pax2/5/8 and Pax6 genes. Of significant interest are those events that lead to Pax proteins with presumed novel properties, such as altered DNA-binding or transcriptional activity. In the current study, a thorough analysis of Pax2/5/8 splicing events from cephalochordates and vertebrates was performed. We focused more on Pax2/5/8 and Pax6 splicing events in which the paired domain is involved. Three new splicing events were identified in Oryzias latipes, one of which seems to be conserved in Acanthomorphata. Using representatives from deuterostome and protostome phyla, a comparative analysis of the Pax6 exon-intron structure of the paired domain was performed, during an attempt to estimate the time of appearance of the Pax6(5a) mRNA isoform. As shown in our analysis, this splicing event is characteristic of Gnathostomata and is absent in the other chordate subphyla. Moreover, expression pattern of alternative spliced variants was compared between cephalochordates and fish species. In summary, our data indicate expansion of alternative mRNA variants in paired box region of Pax2/5/8 and Pax6 genes during the course of vertebrate evolution.
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Affiliation(s)
- Peter Fabian
- Department of Transcriptional Regulation, Institute of Molecular Genetics Prague, Czech Republic
| | - Iryna Kozmikova
- Department of Transcriptional Regulation, Institute of Molecular Genetics Prague, Czech Republic
| | - Zbynek Kozmik
- Department of Transcriptional Regulation, Institute of Molecular Genetics Prague, Czech Republic
| | - Chrysoula N Pantzartzi
- Department of Transcriptional Regulation, Institute of Molecular Genetics Prague, Czech Republic
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19
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Manuel MN, Mi D, Mason JO, Price DJ. Regulation of cerebral cortical neurogenesis by the Pax6 transcription factor. Front Cell Neurosci 2015; 9:70. [PMID: 25805971 PMCID: PMC4354436 DOI: 10.3389/fncel.2015.00070] [Citation(s) in RCA: 100] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2014] [Accepted: 02/18/2015] [Indexed: 12/19/2022] Open
Abstract
Understanding brain development remains a major challenge at the heart of understanding what makes us human. The neocortex, in evolutionary terms the newest part of the cerebral cortex, is the seat of higher cognitive functions. Its normal development requires the production, positioning, and appropriate interconnection of very large numbers of both excitatory and inhibitory neurons. Pax6 is one of a relatively small group of transcription factors that exert high-level control of cortical development, and whose mutation or deletion from developing embryos causes major brain defects and a wide range of neurodevelopmental disorders. Pax6 is very highly conserved between primate and non-primate species, is expressed in a gradient throughout the developing cortex and is essential for normal corticogenesis. Our understanding of Pax6’s functions and the cellular processes that it regulates during mammalian cortical development has significantly advanced in the last decade, owing to the combined application of genetic and biochemical analyses. Here, we review the functional importance of Pax6 in regulating cortical progenitor proliferation, neurogenesis, and formation of cortical layers and highlight important differences between rodents and primates. We also review the pathological effects of PAX6 mutations in human neurodevelopmental disorders. We discuss some aspects of Pax6’s molecular actions including its own complex transcriptional regulation, the distinct molecular functions of its splice variants and some of Pax6’s known direct targets which mediate its actions during cortical development.
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Affiliation(s)
- Martine N Manuel
- Centre for Integrative Physiology, The University of Edinburgh, Edinburgh UK
| | - Da Mi
- Centre for Integrative Physiology, The University of Edinburgh, Edinburgh UK
| | - John O Mason
- Centre for Integrative Physiology, The University of Edinburgh, Edinburgh UK
| | - David J Price
- Centre for Integrative Physiology, The University of Edinburgh, Edinburgh UK
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20
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Wei F, Li M, Cheng SY, Wen L, Liu MH, Shuai J. Cloning, expression, and functional characterization of the rat Pax6 5a orthologous splicing variant. Gene 2014; 547:169-74. [PMID: 24952136 DOI: 10.1016/j.gene.2014.06.032] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2013] [Revised: 05/23/2014] [Accepted: 06/17/2014] [Indexed: 02/07/2023]
Abstract
Pax6 functions as a pleiotropic regulator in eye development and neurogenesis. Its splice variant Pax6 5a has been cloned in many vertebrate species including human and mouse, but never in rat. This study focused on the cloning and characterization of the Pax6 5a orthologous splicing variant in rat. It was cloned from Sprague-Dawley rats 10 days post coitum (E10) by RT-PCR and was sequenced for comparison with Pax6 sequences in the GenBank by BLAST. The rat Pax6 5a was revealed to contain an additional 42 bp insertion at the paired domain. At the nucleotide level, the rat Pax6 5a coding sequence (1,311 bp) had a higher degree of homology to the mouse (96% identical) than to the human (93% identical) sequence. At the amino acid (aa) level, rat PAX6 5a shares 99.8% identity with the mouse sequence and 99.5% with the human sequence. The splice variant is preferentially expressed in the rat E10 embryonic headfolds and not in the trunk of neurula. Its effects on the proliferation of rat mesenchymal stem cells (rMSCs) were preliminarily evaluated by the MTT assay. Both pLEGFP-Pax6 5a-transfected cells and pLEGFP-Pax6-transfected cells exhibited a similar growth curve (P>0.05), suggesting that the Pax6 5a has a similar effect on the proliferation of rMSCs as Pax6.
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Affiliation(s)
- Fei Wei
- Department of Neurology, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China.
| | - Min Li
- Reproductive Center & Gynecology Department of Southwest Hospital, Third Military Medical University, Chongqing 400038, China
| | - Sai-Yu Cheng
- Department of Neurology, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China
| | - Liang Wen
- Trauma Center & Emergency Room of Southwest Hospital, Third Military Medical University, Chongqing 400038, China
| | - Ming-Hua Liu
- Trauma Center & Emergency Room of Southwest Hospital, Third Military Medical University, Chongqing 400038, China
| | - Jie Shuai
- Department of Neurology, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China
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21
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Rezanejad H, Soheili ZS, Haddad F, Matin MM, Samiei S, Manafi A, Ahmadieh H. In vitro differentiation of adipose-tissue-derived mesenchymal stem cells into neural retinal cells through expression of human PAX6 (5a) gene. Cell Tissue Res 2014; 356:65-75. [PMID: 24562376 DOI: 10.1007/s00441-014-1795-y] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2013] [Accepted: 01/08/2014] [Indexed: 12/31/2022]
Abstract
The neural retina is subjected to various degenerative conditions. Regenerative stem-cell-based therapy holds great promise for treating severe retinal degeneration diseases, although many drawbacks remain to be overcome. One important problem is to gain authentically differentiated cells for replacement. Paired box 6 protein (5a) (PAX6 (5a)) is a highly conserved master control gene that has an essential role in the development of the vertebrate visual system. Human adipose-tissue-derived stem cell (hADSC) isolation was performed by using fat tissues and was confirmed by the differentiation potential of the cells into adipocytes and osteocytes and by their surface marker profile. The coding region of the human PAX6 (5a) gene isoform was cloned and lentiviral particles were propagated in HEK293T. The differentiation of hADSCs into retinal cells was characterized by morphological characteristics, quantitative real-time reverse transcription plus the polymerase chain reaction (qPCR) and immunocytochemistry (ICC) for some retinal cell-specific and retinal pigmented epithelial (RPE) cell-specific markers. hADSCs were successfully isolated. Flow cytometric analysis of surface markers indicated the high purity (~97 %) of isolated hADSCs. After 30 h of post-transduction, cells gradually showed the characteristic morphology of neuronal cells and small axon-like processes emerged. qPCR and ICC confirmed the differentiation of some neural retinal cells and RPE cells. Thus, PAX6 (5a) transcription factor expression, together with medium supplemented with fibronectin, is able to induce the differentiation of hADSCs into retinal progenitors, RPE cells and photoreceptors.
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Affiliation(s)
- Habib Rezanejad
- Department of Biology, Faculty of Science, Ferdowsi University of Mashhad, Mashhad, Iran,
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Gregory-Evans CY, Gregory-Evans K. Foveal hypoplasia: the case for arrested development. EXPERT REVIEW OF OPHTHALMOLOGY 2014. [DOI: 10.1586/eop.11.60] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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23
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Carbe C, Garg A, Cai Z, Li H, Powers A, Zhang X. An allelic series at the paired box gene 6 (Pax6) locus reveals the functional specificity of Pax genes. J Biol Chem 2013; 288:12130-41. [PMID: 23515312 DOI: 10.1074/jbc.m112.436865] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The advent of the ocular and nervous system in metazoan evolution coincides with the diversification of a single ancestral paired box (Pax) gene into Pax6, Pax6(5a), and Pax2. To investigate the role of these Pax genes in neural development, we have generated an allelic series of knock-in models at the Pax6 locus. We showed that although Pax6(5a) and Pax2 could not replace Pax6 for its autoregulation in lens induction or for neural differentiation in retina, Pax6(5a) was sufficient for corneal-lenticular detachment. In brain development, cell proliferation in the cerebral cortex and dorsoventral patterning of the telencephalon and neural tube were partially rescued in either knock-in mutant. Contrary to the previous belief, our genetic studies showed that the Pax6 isoform Pax6(5a) could potentially play a role in neuronal differentiation in brain development. Importantly, Pax2 showed greater rescue efficiency than Pax6(5a) in the telencephalon even though the latter was identical to Pax6 outside the paired domain. In studying Ngn2, a Pax6 direct target gene in telencephalon, we showed that the level of Ngn2 expression correlated with the in vitro binding of Pax2, Pax6, and Pax6(5a) paired domain on its enhancer. Our results show that Pax6 is uniquely required for eye development, but in brain development, Pax6 can be functionally substituted by related Pax family genes that share a similar paired domain binding specificity.
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Affiliation(s)
- Christian Carbe
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA
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Lu CC, Chen TH, Wu JR, Chen HH, Yu HY, Tarn WY. Phylogenetic and molecular characterization of the splicing factor RBM4. PLoS One 2013; 8:e59092. [PMID: 23527094 PMCID: PMC3602429 DOI: 10.1371/journal.pone.0059092] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2013] [Accepted: 02/11/2013] [Indexed: 12/13/2022] Open
Abstract
The mammalian multi-functional RNA-binding motif 4 (RBM4) protein regulates alterative splicing of precursor mRNAs and thereby affects pancreas and muscle cell differentiation. RBM4 homologs exist in all metazoan lineages. The C-terminal unstructured domain of RBM4 is evolutionarily divergent and contains stretches of low-complexity sequences, including single amino acid and/or dipeptide repeats. Here we examined the splicing activity, phosphorylation potential, and subcellular localization of RBM4 homologs from a wide range of species. The results show that these RBM4 homologs exert different effects on 5′ splice site utilization and exon selection, and exhibit different subnuclear localization patterns. Therefore, the C-terminal domain of RBM4 may contribute to functional divergence between homologs. On the other hand, analysis of chimeric human RBM4 proteins containing heterologous sequences at the C-terminus revealed that the N-terminal RNA binding domain of RBM4 could have a dominant role in determining splicing outcome. Finally, all RBM4 homologs examined could be phosphorylated by an SR protein kinase, suggesting that they are regulated by a conserved mechanism in different species. This study offers a first clue to functional evolution of a splicing factor.
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Affiliation(s)
- Chia-Chen Lu
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Tz-Hao Chen
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Jhe-Rong Wu
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Hung-Hsi Chen
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Hsin-Yi Yu
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Woan-Yuh Tarn
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
- * E-mail:
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Kelemen O, Convertini P, Zhang Z, Wen Y, Shen M, Falaleeva M, Stamm S. Function of alternative splicing. Gene 2013; 514:1-30. [PMID: 22909801 PMCID: PMC5632952 DOI: 10.1016/j.gene.2012.07.083] [Citation(s) in RCA: 509] [Impact Index Per Article: 46.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2012] [Revised: 07/21/2012] [Accepted: 07/30/2012] [Indexed: 12/15/2022]
Abstract
Almost all polymerase II transcripts undergo alternative pre-mRNA splicing. Here, we review the functions of alternative splicing events that have been experimentally determined. The overall function of alternative splicing is to increase the diversity of mRNAs expressed from the genome. Alternative splicing changes proteins encoded by mRNAs, which has profound functional effects. Experimental analysis of these protein isoforms showed that alternative splicing regulates binding between proteins, between proteins and nucleic acids as well as between proteins and membranes. Alternative splicing regulates the localization of proteins, their enzymatic properties and their interaction with ligands. In most cases, changes caused by individual splicing isoforms are small. However, cells typically coordinate numerous changes in 'splicing programs', which can have strong effects on cell proliferation, cell survival and properties of the nervous system. Due to its widespread usage and molecular versatility, alternative splicing emerges as a central element in gene regulation that interferes with almost every biological function analyzed.
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Affiliation(s)
- Olga Kelemen
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky, United States of America
| | - Paolo Convertini
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky, United States of America
| | - Zhaiyi Zhang
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky, United States of America
| | - Yuan Wen
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky, United States of America
| | - Manli Shen
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky, United States of America
| | - Marina Falaleeva
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky, United States of America
| | - Stefan Stamm
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky, United States of America
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Joo JH, Correia GP, Li JL, Lopez MC, Baker HV, Sugrue SP. Transcriptomic analysis of PNN- and ESRP1-regulated alternative pre-mRNA splicing in human corneal epithelial cells. Invest Ophthalmol Vis Sci 2013; 54:697-707. [PMID: 23299472 DOI: 10.1167/iovs.12-10695] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE We investigated the impact of PININ (PNN) and epithelial splicing regulatory protein 1 (ESRP1) on alternative pre-mRNA splicing in the corneal epithelial context. METHODS Isoform-specific RT-PCR assays were performed on wild-type and Pnn knockout mouse cornea. Protein interactions were examined by deconvolution microscopy and co-immunoprecipitation. For genome-wide alternative splicing study, immortalized human corneal epithelial cells (HCET) harboring doxycycline-inducible shRNA against PNN or ESRP1 were created. Total RNA was isolated from four biological replicates of control and knockdown HCET cells, and subjected to hGlue3_0 transcriptome array analysis. RESULTS Pnn depletion in developing mouse corneal epithelium led to disrupted alternative splicing of multiple ESRP-regulated epithelial-type exons. In HCET cells, ESRP1 and PNN displayed close localization in and around nuclear speckles, and their physical association in protein complexes was identified. Whole transcriptome array analysis on ESRP1 or PNN knockdown HCET cells revealed clear alterations in transcript profiles and splicing patterns of specific subsets of genes. Separate RT-PCR validation assays confirmed successfully specific changes in exon usage of several representative splice variants, including PAX6(5a), FOXJ3, ARHGEF11, and SLC37A2. Gene ontologic analyses on ESRP1- or PNN-regulated alternative exons suggested their roles in epithelial phenotypes, such as cell morphology and movement. CONCLUSIONS Our data suggested that ESRP1 and PNN modulate alternative splicing of a specific subset of target genes, but not general splicing events, in HCET cells to maintain or enhance epithelial characteristics.
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Affiliation(s)
- Jeong-Hoon Joo
- Department of Anatomy and Cell Biology, University of Florida College of Medicine, Gainesville, Florida 32610, USA.
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27
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Shi F, Fan Y, Zhang L, Meng L, Zhi H, Hu H, Lin A. The expression of Pax6 variants is subject to posttranscriptional regulation in the developing mouse eyelid. PLoS One 2013; 8:e53919. [PMID: 23326536 PMCID: PMC3542254 DOI: 10.1371/journal.pone.0053919] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2012] [Accepted: 12/04/2012] [Indexed: 01/09/2023] Open
Abstract
Pax6 is a pivotal transcription factor that plays a role during early eye morphogenesis, but its expression and function in eyelid development remain unknown. In this study, the expression patterns of Pax6 mRNA and protein were examined in the developing mouse eyelid at embryonic days 14.5, 15.5, and 16.5. The function of Pax6 in eyelid development was determined by comparing it to that in the eyes-open-at-birth mutant mouse. In the normally developing eyelid, Pax6 and Pax6(5a) mRNA levels were low at E14.5, increased at E15.5, and then declined at E16.5, accompanied by a change in the Pax6/Pax6(5a) ratio. Pax6 protein was mainly located in the mesenchyme and conjunctiva. It was expressed at low levels in the epidermis at E14.5, severely reduced at E15.5, but re-expressed in the keratinocyte cells of the periderm at E16.5. In contrast, Pax6 and the Pax6/Pax6(5a) ratio were considerably higher with strong nuclear expression in the mutant at E15.5. Next, we examined the relationship of Pax6 to epidermal cell proliferation, migration, and the associated signalling pathways. The Pax6 protein in the developing eyelid was negatively correlated with epidermal cell proliferation but not migration, and it is in contrast to the activation of the EGFR-ERK pathway. Our in vivo data suggest that Pax6 expression and the Pax6/Pax6(5a) ratio are at relatively low levels in the eyelid, and acting as a transcription factor, Pax6 is required for the initiation of eyelid formation and for differential development of the keratinised cells in the closed eyelid. The Pax6 protein is likely to be controlled by the EGFR-ERK pathways. An abnormal increase in Pax6 expression and the Pax6/Pax6(5a) ratio due to alteration of the pathway activity could suppress epidermal cell proliferation leading to the eyes-open-at-birth defect. This study offers insight into the function of the Pax6 protein in eyelid development.
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Affiliation(s)
- Fangyu Shi
- State Key Laboratory for Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Yannan Fan
- State Key Laboratory for Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Laiguang Zhang
- State Key Laboratory for Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Lu Meng
- State Key Laboratory for Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Huifang Zhi
- State Key Laboratory for Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Hongyu Hu
- State Key Laboratory for Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, China
- * E-mail: (AL); (HH)
| | - Aixin Lin
- State Key Laboratory for Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, China
- * E-mail: (AL); (HH)
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Shaham O, Menuchin Y, Farhy C, Ashery-Padan R. Pax6: a multi-level regulator of ocular development. Prog Retin Eye Res 2012; 31:351-76. [PMID: 22561546 DOI: 10.1016/j.preteyeres.2012.04.002] [Citation(s) in RCA: 160] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2011] [Revised: 04/19/2012] [Accepted: 04/24/2012] [Indexed: 02/08/2023]
Abstract
Eye development has been a paradigm for the study of organogenesis, from the demonstration of lens induction through epithelial tissue morphogenesis, to neuronal specification and differentiation. The transcription factor Pax6 has been shown to play a key role in each of these processes. Pax6 is required for initiation of developmental pathways, patterning of epithelial tissues, activation of tissue-specific genes and interaction with other regulatory pathways. Herein we examine the data accumulated over the last few decades from extensive analyses of biochemical modules and genetic manipulation of the Pax6 gene. Specifically, we describe the regulation of Pax6's expression pattern, the protein's DNA-binding properties, and its specific roles and mechanisms of action at all stages of lens and retinal development. Pax6 functions at multiple levels to integrate extracellular information and execute cell-intrinsic differentiation programs that culminate in the specification and differentiation of a distinct ocular lineage.
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Affiliation(s)
- Ohad Shaham
- Sackler Faculty of Medicine, Department of Human Molecular Genetics and Biochemistry, Tel Aviv University, Ramat Aviv, Tel Aviv 69978, Israel
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29
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Kiselev Y, Eriksen TE, Forsdahl S, Nguyen LHT, Mikkola I. 3T3 cell lines stably expressing Pax6 or Pax6(5a)--a new tool used for identification of common and isoform specific target genes. PLoS One 2012; 7:e31915. [PMID: 22384097 PMCID: PMC3285655 DOI: 10.1371/journal.pone.0031915] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2011] [Accepted: 01/19/2012] [Indexed: 12/03/2022] Open
Abstract
Pax6 and Pax6(5a) are two isoforms of the evolutionary conserved Pax6 gene often co-expressed in specific stochiometric relationship in the brain and the eye during development. The Pax6(5a) protein differs from Pax6 by having a 14 amino acid insert in the paired domain, causing the two proteins to have different DNA binding specificities. Difference in functions during development is proven by the fact that mutations in the 14 amino acid insertion for Pax6(5a) give a slightly different eye phenotype than the one described for Pax6. Whereas quite many Pax6 target genes have been published during the last years, few Pax6(5a) specific target genes have been reported on. However, target genes identified by Pax6 knockout studies can probably be Pax6(5a) targets as well, since this isoform also will be affected by the knockout. In order to identify new Pax6 target genes, and to try to distinguish between genes regulated by Pax6 and Pax6(5a), we generated FlpIn-3T3 cell lines stably expressing Pax6 or Pax6(5a). RNA was harvested from these cell lines and used in gene expression microarrays where we identified a number of genes differentially regulated by Pax6 and Pax6(5a). A majority of these were associated with the extracellular region. By qPCR we verified that Ncam1, Ngef, Sphk1, Dkk3 and Crtap are Pax6(5a) specific target genes, while Tgfbi, Vegfa, EphB2, Klk8 and Edn1 were confirmed as Pax6 specific target genes. Nbl1, Ngfb and seven genes encoding different glycosyl transferases appeared to be regulated by both. Direct binding to the promoters of Crtap, Ctgf, Edn1, Dkk3, Pdgfb and Ngef was verified by ChIP. Furthermore, a change in morphology of the stably transfected Pax6 and Pax6(5a) cells was observed, and the Pax6 expressing cells were shown to have increased proliferation and migration capacities.
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Affiliation(s)
| | | | | | | | - Ingvild Mikkola
- Research Group of Pharmacology, Department of Pharmacy, University of Tromsø, Tromsø, Norway
- * E-mail:
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30
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Kuznetsova AV, Grigoryan EN, Aleksandrova MA. Human adult retinal pigment epithelial cells as potential cell source for retina recovery. ACTA ACUST UNITED AC 2011. [DOI: 10.1134/s1990519x11050075] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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31
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Chanas SA, Collinson JM, Ramaesh T, Dorà N, Kleinjan DA, Hill RE, West JD. Effects of elevated Pax6 expression and genetic background on mouse eye development. Invest Ophthalmol Vis Sci 2009; 50:4045-59. [PMID: 19387074 PMCID: PMC2763115 DOI: 10.1167/iovs.07-1630] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE To analyze the effects of Pax6 overexpression and its interaction with genetic background on eye development. METHODS Histologic features of eyes from hemizygous PAX77(+/-) transgenic (high Pax6 gene dose) and wild-type mice were compared on different genetic backgrounds. Experimental PAX77(+/-)<-->wild-type and control wild-type<-->wild-type chimeras were analyzed to investigate the causes of abnormal eye development in PAX77(+/-) mice. RESULTS PAX77(+/-) mice showed an overlapping but distinct spectrum of eye abnormalities to Pax6(+/-) heterozygotes (low Pax6 dose). Some previously reported PAX77(+/-) eye abnormalities did not occur on all three genetic backgrounds examined. Several types of eye abnormalities occurred in the experimental PAX77(+/-)<-->wild-type chimeras, and they occurred more frequently in chimeras with higher contributions of PAX77(+/-) cells. Groups of RPE cells intruded into the optic nerve sheath, indicating that the boundary between the retina and optic nerve may be displaced. Both PAX77(+/-) and wild-type cells were involved in this ingression and in retinal folds, suggesting that neither effect was cell-autonomous. Cell-autonomous effects included failure of PAX77(+/-) and wild-type cells to mix normally and overrepresentation of PAX77(+/-) in the lens epithelium and RPE. CONCLUSIONS The extent of PAX77(+/-) eye abnormalities depended on PAX77(+/-) genotype, genetic background, and stochastic variation. Chimera analysis identified two types of cell-autonomous effects of the PAX77(+/-) genotype. Abnormal cell mixing between PAX77(+/-) and wild-type cells suggests altered expression of cell surface adhesion molecules. Some phenotypic differences between PAX77(+/-)<-->wild-type and Pax6(+/-)<-->wild-type chimeras may reflect differences in the levels of PAX77(+/-) and Pax6(+/-) contributions to chimeric lenses.
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Affiliation(s)
- Simon A. Chanas
- Division of Reproductive and Developmental Sciences, Genes and Development Group, University of Edinburgh, Edinburgh, Scotland, United Kingdom
| | - J. Martin Collinson
- School of Medical Sciences, College of Life Sciences and Medicine, University of Aberdeen, Institute of Medical Sciences, Aberdeen, Scotland, United Kingdom
| | - Thaya Ramaesh
- Division of Reproductive and Developmental Sciences, Genes and Development Group, University of Edinburgh, Edinburgh, Scotland, United Kingdom
- Department of Clinical and Surgical Sciences, Ophthalmology Section, University of Edinburgh, Princess Alexandra Eye Pavilion, Royal Infirmary of Edinburgh, Edinburgh, Scotland, United Kingdom
| | - Natalie Dorà
- School of Medical Sciences, College of Life Sciences and Medicine, University of Aberdeen, Institute of Medical Sciences, Aberdeen, Scotland, United Kingdom
| | - Dirk A. Kleinjan
- Medical and Developmental Genetics Section, MRC Human Genetics Unit, Edinburgh, Scotland, United Kingdom
| | - Robert E. Hill
- Medical and Developmental Genetics Section, MRC Human Genetics Unit, Edinburgh, Scotland, United Kingdom
| | - John D. West
- Division of Reproductive and Developmental Sciences, Genes and Development Group, University of Edinburgh, Edinburgh, Scotland, United Kingdom
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Davis N, Yoffe C, Raviv S, Antes R, Berger J, Holzmann S, Stoykova A, Overbeek PA, Tamm ER, Ashery-Padan R. Pax6 dosage requirements in iris and ciliary body differentiation. Dev Biol 2009; 333:132-42. [DOI: 10.1016/j.ydbio.2009.06.023] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2009] [Revised: 06/18/2009] [Accepted: 06/22/2009] [Indexed: 11/15/2022]
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Mascarenhas JB, Young KP, Littlejohn EL, Yoo BK, Salgia R, Lang D. PAX6 is expressed in pancreatic cancer and actively participates in cancer progression through activation of the MET tyrosine kinase receptor gene. J Biol Chem 2009; 284:27524-32. [PMID: 19651775 DOI: 10.1074/jbc.m109.047209] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Tumors of the exocrine pancreas have a poor prognosis. Several proteins are overexpressed in this cancer type, including the MET tyrosine kinase receptor and the transcription factor PAX6. In this report, we find that PAX6(5a), an alternately spliced variant form of PAX6, is expressed in pancreatic carcinoma cell lines at higher levels than the canonical PAX6 protein. Both protein forms of PAX6 bind directly to an enhancer element in the MET promoter and activate the expression of the MET gene. In addition, inhibition of PAX6 transcripts leads to a decline in cell growth and survival, differentiation, and a concurrent reduction of MET protein expression. These data support a model for a neoplastic pathway, where expression of a transcription factor from development activates the MET receptor, a protein that has been directly linked to protumorigenic processes of resisting apoptosis, tumor growth, invasion, and metastasis.
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Shimizu N, Watanabe H, Kubota J, Wu J, Saito R, Yokoi T, Era T, Iwatsubo T, Watanabe T, Nishina S, Azuma N, Katada T, Nishina H. Pax6-5a Promotes Neuronal Differentiation of Murine Embryonic Stem Cells. Biol Pharm Bull 2009; 32:999-1003. [DOI: 10.1248/bpb.32.999] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Nao Shimizu
- Department of Developmental and Regenerative Biology, Medical Research Institute, Tokyo Medical and Dental University
- Department of Physiological Chemistry, Graduate School of Pharmaceutical Sciences, University of Tokyo
| | - Hajime Watanabe
- Center for Integrative Bioscience, Okazaki National Research Institutes
| | - Junko Kubota
- Department of Physiological Chemistry, Graduate School of Pharmaceutical Sciences, University of Tokyo
| | - Jinzhan Wu
- Department of Developmental and Regenerative Biology, Medical Research Institute, Tokyo Medical and Dental University
- Department of Physiological Chemistry, Graduate School of Pharmaceutical Sciences, University of Tokyo
| | - Ryota Saito
- Department of Developmental and Regenerative Biology, Medical Research Institute, Tokyo Medical and Dental University
- Department of Physiological Chemistry, Graduate School of Pharmaceutical Sciences, University of Tokyo
| | - Tadashi Yokoi
- Department of Developmental and Regenerative Biology, Medical Research Institute, Tokyo Medical and Dental University
- Department of Ophthalmology, National Center for Child Health and Development
| | - Takumi Era
- Department of Organogenesis, Institute of Molecular Embryology and Genetics, Kumamoto University
| | - Takeshi Iwatsubo
- Department of Neuropathology and Neuroscience, Graduate School of Pharmaceutical Sciences, University of Tokyo
| | - Takashi Watanabe
- Department of Laboratory Medicine, Kyorin University School of Medicine
| | - Sachiko Nishina
- Department of Ophthalmology, National Center for Child Health and Development
| | - Noriyuki Azuma
- Department of Ophthalmology, National Center for Child Health and Development
| | - Toshiaki Katada
- Department of Physiological Chemistry, Graduate School of Pharmaceutical Sciences, University of Tokyo
| | - Hiroshi Nishina
- Department of Developmental and Regenerative Biology, Medical Research Institute, Tokyo Medical and Dental University
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35
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The Evolution of Alternative Splicing in the Pax Family: The View from the Basal Chordate Amphioxus. J Mol Evol 2008; 66:605-20. [DOI: 10.1007/s00239-008-9113-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2008] [Revised: 04/16/2008] [Accepted: 04/22/2008] [Indexed: 10/22/2022]
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Kim J, Lauderdale JD. Overexpression of pairedless Pax6 in the retina disrupts corneal development and affects lens cell survival. Dev Biol 2008; 313:434-54. [DOI: 10.1016/j.ydbio.2007.10.043] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2006] [Revised: 10/23/2007] [Accepted: 10/26/2007] [Indexed: 12/12/2022]
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37
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Katyal S, Gao Z, Liu RZ, Godbout R. Evolutionary conservation of alternative splicing in chicken. Cytogenet Genome Res 2007; 117:146-57. [PMID: 17675855 PMCID: PMC3726401 DOI: 10.1159/000103175] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2006] [Accepted: 09/13/2006] [Indexed: 12/21/2022] Open
Abstract
Alternative splicing represents a source of great diversity for regulating protein expression and function. It has been estimated that one-third to two-thirds of mammalian genes are alternatively spliced. With the sequencing of the chicken genome and analysis of transcripts expressed in chicken tissues, we are now in a position to address evolutionary conservation of alternative splicing events in chicken and mammals. Here, we compare chicken and mammalian transcript sequences of 41 alternatively-spliced genes and 50 frequently accessed genes. Our results support a high frequency of splicing events in chicken, similar to that observed in mammals.
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Affiliation(s)
- S Katyal
- Department of Oncology, University of Alberta, Cross Cancer Institute, Edmonton, Alberta, Canada
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Lakowski J, Majumder A, Lauderdale JD. Mechanisms controlling Pax6 isoform expression in the retina have been conserved between teleosts and mammals. Dev Biol 2007; 307:498-520. [PMID: 17509554 DOI: 10.1016/j.ydbio.2007.04.015] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2006] [Revised: 03/16/2007] [Accepted: 04/12/2007] [Indexed: 11/26/2022]
Abstract
The Pax6 gene plays several roles in retinal development, including control of cell proliferation, maintenance of the retinogenic potential of progenitor cells, and cell fate specification. Emerging evidence suggests that these different aspects of Pax6 gene function are mediated by different isoforms of the Pax6 protein; however, relatively little is known about the spatiotemporal expression of Pax6 isoforms in the vertebrate retina. Using bacterial artificial chromosome (BAC) technology, we modified a zebrafish Pax6a BAC such that we could distinguish paired-containing Pax6a transcripts from paired-less Pax6a transcripts. In the zebrafish, the spatial and temporal onset of expression of these transcripts suggests that the paired-less isoform is involved in the cell fate decision leading to the generation of amacrine cells; however, because of limitations associated with transient transgenic analysis, it was not feasible to establish whether this promoter was active in all amacrine cells or in a specific population of amacrine cells. By making mice transgenic for the zebrafish Pax6a BAC reporter transgene, we were able to show that paired-containing and paired-less Pax6a transcripts were differentially expressed in amacrine subpopulations. Our study also directly demonstrates the functional conservation of the regulatory mechanisms governing Pax6 transcription in teleosts and mammals.
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Affiliation(s)
- Jörn Lakowski
- Department of Cellular Biology, The University of Georgia, Athens, GA 30602, USA
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Xu S, Sunderland ME, Coles BL, Kam A, Holowacz T, Ashery-Padan R, Marquardt T, McInnes RR, van der Kooy D. The proliferation and expansion of retinal stem cells require functional Pax6. Dev Biol 2007; 304:713-21. [PMID: 17316600 PMCID: PMC1950846 DOI: 10.1016/j.ydbio.2007.01.021] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2006] [Revised: 01/10/2007] [Accepted: 01/11/2007] [Indexed: 10/23/2022]
Abstract
Retinal stem cells (RSCs) exist as rare pigmented ciliary epithelial cells in adult mammalian eyes. We hypothesized that RSCs are at the top of the retinal cell lineage. Thus, genes expressed early in embryonic development to establish the retinal field in forebrain neuroectoderm may play important roles in RSCs. Pax6, a paired domain and homeodomain-containing transcription factor, is one of the earliest genes expressed in the eye field and is considered a master control gene for retinal and eye development. Here, we demonstrate that Pax6 is enriched in RSCs. Inactivation of Pax6 in vivo results in loss of competent RSCs as assayed by the failure to form clonal RSC spheres from the optic vesicles of conventional Pax6 knockout embryos and from the ciliary epithelial cells of adult Pax6 conditional knockout mice. In vitro clonal inactivation of Pax6 in adult RSCs results in a serious proliferation defect, suggesting that Pax6 is required for the proliferation and expansion of RSCs.
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Affiliation(s)
- Shunbin Xu
- Department of Medical Genetics and Microbiology, University of Toronto, ON M5S 1A8, Canada
| | | | - Brenda L.K. Coles
- Department of Medical Genetics and Microbiology, University of Toronto, ON M5S 1A8, Canada
| | - Angela Kam
- Department of Surgery, University of Toronto, ON M5S 1A8, Canada
| | - Tamara Holowacz
- Department of Medical Genetics and Microbiology, University of Toronto, ON M5S 1A8, Canada
| | | | - Till Marquardt
- Tel Aviv University, Tel Aviv, Israel
- The Salk Institute, La Jolla, USA
| | - Roderick R. McInnes
- Department of Medical Genetics and Microbiology, University of Toronto, ON M5S 1A8, Canada
- Max-Planck Institute, 37077 Gottingen, Germany
- Programs in Developmental Biology and Genetics, Research Institute, Hospital for Sick Children, Toronto, ON M5G 1X8, Canada
| | - Derek van der Kooy
- Department of Medical Genetics and Microbiology, University of Toronto, ON M5S 1A8, Canada
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Markitantova YV, Smirnova YA, Panova IG, Sukhikh GT, Zinov’eva RD, Mitashov VI. Analysis of expression of regulatory genes Pax6, Prox1, and Pitx2 in differentiating eye cells in human fetus. BIOL BULL+ 2006. [DOI: 10.1134/s1062359006040042] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Pinson J, Simpson TI, Mason JO, Price DJ. Positive autoregulation of the transcription factor Pax6 in response to increased levels of either of its major isoforms, Pax6 or Pax6(5a), in cultured cells. BMC DEVELOPMENTAL BIOLOGY 2006; 6:25. [PMID: 16725027 PMCID: PMC1489926 DOI: 10.1186/1471-213x-6-25] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/03/2006] [Accepted: 05/25/2006] [Indexed: 11/18/2022]
Abstract
Background Pax6 is a transcription factor essential for normal development of the eyes and nervous system. It has two major isoforms, Pax6 and Pax6(5a), and the ratios between their expression levels vary within narrow limits. We tested the effects of overexpressing either one or other isoform on endogenous Pax6 expression levels in Neuro2A and NIH3T3 cells. Results We found that both isoforms caused an up-regulation of endogenous Pax6 expression in cells with (Neuro2A) or without (NIH3T3) constitutive Pax6 expression. Western blots showed that cells stably transfected with constructs expressing either Pax6 or Pax6(5a) contained raised levels of both Pax6 and Pax6(5a). Quantitative RT-PCR confirmed an increase in levels of Pax6(5a) mRNA in cells containing Pax6-expressing constructs and an increase in levels of Pax6 mRNA in cells containing Pax6(5a)-expressing constructs. The fact that the introduction of constructs expressing only one isoform increased the cellular levels of not only that isoform but also the other indicates that activation of the endogenous Pax6 locus occurred. The ratio between the levels of the two isoforms was maintained close to physiological values. The overexpression of either isoform in neuroblastoma (Neuro2A) cell lines also promoted morphological change and an increase in β-III-tubulin expression, indicating an increase in neurogenesis. Conclusion Our results demonstrate that Pax6 can up-regulate production of Pax6 protein from an entire intact endogenous Pax6 locus in its genomic environment. This adds to previous studies showing that Pax6 can up-regulate reporter expression driven by isolated Pax6 regulatory elements. Furthermore, our results suggest that an important function of positive feedback might be to stabilise the relative levels of Pax6 and Pax6(5a).
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Affiliation(s)
- Jeni Pinson
- Genes and Development Group, Centre for Integrative Physiology, University of Edinburgh, Hugh Robson Building, George Square, Edinburgh EH8 9XD, UK
| | - T Ian Simpson
- Genes and Development Group, Centre for Integrative Physiology, University of Edinburgh, Hugh Robson Building, George Square, Edinburgh EH8 9XD, UK
| | - John O Mason
- Genes and Development Group, Centre for Integrative Physiology, University of Edinburgh, Hugh Robson Building, George Square, Edinburgh EH8 9XD, UK
| | - David J Price
- Genes and Development Group, Centre for Integrative Physiology, University of Edinburgh, Hugh Robson Building, George Square, Edinburgh EH8 9XD, UK
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Kim J, Lauderdale JD. Analysis of Pax6 expression using a BAC transgene reveals the presence of a paired-less isoform of Pax6 in the eye and olfactory bulb. Dev Biol 2006; 292:486-505. [PMID: 16464444 DOI: 10.1016/j.ydbio.2005.12.041] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2005] [Revised: 09/08/2005] [Accepted: 12/21/2005] [Indexed: 11/19/2022]
Abstract
Pax6, a member of the paired-family of transcription factors, exhibits restricted expression and essential functions in the developing eye, olfactory system, central nervous system, and pancreas. To understand Pax6 function, which critically depends on induction of proper expression levels during development, it is necessary to elucidate the molecular mechanisms governing Pax6 transcription. Although previous studies using classic transgenic approaches have provided a wealth of information about the distribution and types of regulatory elements involved in Pax6 regulation, genetic studies in both humans and mice indicate that these enhancers alone are not sufficient for fully regulated Pax6 expression. We report here our analysis of mice transgenic for a 160 kb mouse Pax6 BAC transgene, which was generated as a necessary first step towards testing the long-range control of Pax6 expression in vivo. We show that this BAC transgene replicates Pax6 expression in the eye. This is the first time that a reporter transgene has been expressed in a normal Pax6-like pattern in all of the tissues of the eye and defines an eye regulatory region within the Pax6 downstream regulatory region (DRR). Second, we show that this BAC transgene contains all of the cis regulatory elements required for normal Pax6 expression within the developing embryo, except for within the diencephalon and olfactory bulb. Third, we show that this transgene is subject to Pax6 autoregulation. Lastly, we identify, for the first time in mammals, an isoform of the Pax6 protein lacking the paired domain. This isoform is expressed in the developing olfactory bulb and eye. Over-expression of Pax6DeltaPD causes a microphthalmic phenotype in both Pax6(+/+) mice and Pax6(+/-) mice. These results demonstrate a role for Pax6DeltaPD in eye development, which appears to be different than that ascribed to either canonical Pax6 or Pax6(5a).
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Affiliation(s)
- Jiha Kim
- Department of Cellular Biology, The University of Georgia, Athens, GA 30602, USA
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Neveu MM, Holder GE, Sloper JJ, Jeffery G. Optic chiasm formation in humans is independent of foveal development. Eur J Neurosci 2006; 22:1825-9. [PMID: 16197526 DOI: 10.1111/j.1460-9568.2005.04364.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A failure of human foveal development only occurs in two genetically determined conditions; aniridia (Pax6 mutation) and albinism (tyrosinase mutation). The chiasmatic pathways from this region are disrupted in albinism and central retinal blood vessel patterns are abnormal. It is assumed that these three abnormalities have a common mechanism. Here we investigate whether similar abnormalities are present in subjects with aniridia. Using fundus photographs it is shown that abnormal blood vessel patterns are present in aniridia, but these significantly differ from those in albinos. Using electrophysiological techniques, abnormal hemispheric projections through the chiasm are demonstrated in albinos, but aniridics do not differ from normal subjects. These results demonstrate that although mutations in Pax6 and tyrosinase both affect central retinal development, they have a fundamentally different impact on the formation of the retinal vasculature and the projections from this region. This strongly suggests that separate mechanisms regulate the development of the central retina and decussation patterns at the optic chiasm.
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Affiliation(s)
- Magella M Neveu
- Institute of Ophthalmology, University College London, Bath Street, London EC1V 9EL, UK
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44
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Stanescu D, Iseli HP, Schwerdtfeger K, Ittner LM, Remé CE, Hafezi F. Continuous expression of the homeobox gene Pax6 in the ageing human retina. Eye (Lond) 2005; 21:90-3. [PMID: 16254589 DOI: 10.1038/sj.eye.6702166] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
PURPOSE In the past few years, the essential role of the homeobox gene Pax6 for eye development has been demonstrated unambiguously in a variety of species including humans. In humans, Pax6 mutations lead to a variety of ocular malformations of the anterior and posterior segment. However, little is known about PAX6 expression in the adult human retina. We have therefore investigated PAX6 levels and localization in the human retina at various ages. METHODS Adult human eyes of various ages (17-79 years) were obtained from the Zurich Eye Bank. PAX6 expression levels and patterns were analysed by Western blot analysis of total retinal protein and by immunohistochemistry on paraffin sections, respectively. RESULTS PAX6 expression in the retina was detected up to 79 years of donor age and was predominantly localized to the ganglion cell layer and the inner part of the inner nuclear layer. CONCLUSIONS PAX6 remains distinctly expressed throughout the lifespan of the human retina suggesting a role for PAX6 in the retina after completion of eye morphogenesis.
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Affiliation(s)
- D Stanescu
- Laboratory for retinal cell biology, Department of Ophthalmology, University Clinic Zurich, Frauenklinikstrasse, and Research Laboratory for Calcium Metabolism, Orthopedic University Hospital Balgrist, Zurich, Switzerland
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Abstract
The Optimedin gene, also known as Olfactomedin 3, encodes an olfactomedin domain-containing protein. There are two major splice variants of the Optimedin mRNA, Optimedin A and Optimedin B, transcribed from different promoters. The expression pattern of the Optimedin A variant in the eye and brain overlaps with that for Pax6, which encodes a protein containing the paired and homeobox DNA-binding domains. The Pax6 gene plays a critical role for the development of eyes, central nervous system, and endocrine glands. The proximal promoter of the Optimedin A variant contains a putative Pax6 binding site in position -86/-70. Pax6 binds this site through the paired domain in vitro as judged by electrophoretic mobility shift assay. Mutations in this site eliminate Pax6 binding as well as stimulation of the Optimedin promoter activity by Pax6 in transfection experiments. Pax6 occupies the binding site in the proximal promoter in vivo as demonstrated by the chromatin immunoprecipitation assay. Altogether these results identify the Optimedin gene as a downstream target regulated by Pax6. Although the function of optimedin is still not clear, it is suggested to be involved in cell-cell adhesion and cell attachment to the extracellular matrix. Pax6 regulation of Optimedin in the eye and brain may directly affect multiple developmental processes, including cell migration and axon growth.
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Affiliation(s)
- Oleg Grinchuk
- Section of Molecular Mechanisms of Glaucoma, Laboratory of Molecular and Developmental Biology, NEI, National Institutes of Health, Bethesda, Maryland 20892-0704, USA
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Azuma N, Tadokoro K, Asaka A, Yamada M, Yamaguchi Y, Handa H, Matsushima S, Watanabe T, Kida Y, Ogura T, Torii M, Shimamura K, Nakafuku M. Transdifferentiation of the retinal pigment epithelia to the neural retina by transfer of the Pax6 transcriptional factor. Hum Mol Genet 2005; 14:1059-68. [PMID: 15757974 DOI: 10.1093/hmg/ddi098] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
The Pax6 gene plays an important role in eye morphogenesis throughout the animal kingdom. The Pax6 gene and its homologue could form ectopic eyes by targeted expression in Drosophila and Xenopus. Thus, this gene is a master gene for the eye morphogenesis at least in these animals. In the early development of the vertebrate eye, Pax6 is required for the instruction of multipotential progenitor cells of the neural retina (NR). Primitive retinal pigment epithelial (RPE) cells are able to switch their phenotype and differentiate into NR under exogenous intervention, including treatment with fibroblast growth factors (FGFs), and surgical removal of endogenous NR. However, the molecular basis of phenotypic switching is still controversial. Here, we show that Pax6 alone is sufficient to induce transdifferentiation of ectopic NR from RPE cells without addition of FGFs or surgical manipulation. Pax6-mediated transdifferentiation can be induced even at later stages of development. Both in vivo and in vitro studies show that the Pax6 lies downstream of FGF signaling, highlighting the central roles of Pax6 in NR transdifferentiation. Our results provide an evidence of retinogenic potential of nearly mature RPE and a cue for new therapeutic approaches to regenerate functional NR in patients with a visual loss.
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Affiliation(s)
- Noriyuki Azuma
- Department of Ophthalmology, National Center for Child Health and Development, Tokyo 157-8535, Japan.
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