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Albano GA, Hackam AS. Repurposing development genes for axonal regeneration following injury: Examining the roles of Wnt signaling. Front Cell Dev Biol 2024; 12:1417928. [PMID: 38882059 PMCID: PMC11176474 DOI: 10.3389/fcell.2024.1417928] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2024] [Accepted: 05/13/2024] [Indexed: 06/18/2024] Open
Abstract
In this review, we explore the connections between developmental embryology and axonal regeneration. Genes that regulate embryogenesis and central nervous system (CNS) development are discussed for their therapeutic potential to induce axonal and cellular regeneration in adult tissues after neuronal injury. Despite substantial differences in the tissue environment in the developing CNS compared with the injured CNS, recent studies have identified multiple molecular pathways that promote axonal growth in both scenarios. We describe various molecular cues and signaling pathways involved in neural development, with an emphasis on the versatile Wnt signaling pathway. We discuss the capacity of developmental factors to initiate axonal regrowth in adult neural tissue within the challenging environment of the injured CNS. Our discussion explores the roles of Wnt signaling and also examines the potential of other embryonic genes including Pax, BMP, Ephrin, SOX, CNTF, PTEN, mTOR and STAT3 to contribute to axonal regeneration in various CNS injury model systems, including spinal cord and optic crush injuries in mice, Xenopus and zebrafish. Additionally, we describe potential contributions of Müller glia redifferentiation to neuronal regeneration after injury. Therefore, this review provides a comprehensive summary of the state of the field, and highlights promising research directions for the potential therapeutic applications of specific embryologic molecular pathways in axonal regeneration in adults.
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Affiliation(s)
- Gabrielle A Albano
- Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL, United States
| | - Abigail S Hackam
- Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL, United States
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2
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Kim JM, Min KW, Kim YJ, Smits R, Basler K, Kim JW. Wnt/β-Catenin Signaling Pathway Is Necessary for the Specification but Not the Maintenance of the Mouse Retinal Pigment Epithelium. Mol Cells 2023; 46:441-450. [PMID: 37190767 PMCID: PMC10336276 DOI: 10.14348/molcells.2023.0029] [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: 02/06/2023] [Accepted: 03/19/2023] [Indexed: 05/17/2023] Open
Abstract
β-Catenin (Ctnnb1) has been shown to play critical roles in the development and maintenance of epithelial cells, including the retinal pigment epithelium (RPE). Ctnnb1 is not only a component of intercellular junctions in the epithelium, it also functions as a transcriptional regulator in the Wnt signaling pathway. To identify which of its functional modalities is critically involved in mouse RPE development and maintenance, we varied Ctnnb1 gene content and activity in mouse RPE lineage cells and tested their impacts on mouse eye development. We found that a Ctnnb1 double mutant (Ctnnb1dm), which exhibits impaired transcriptional activity, could not replace Ctnnb1 in the RPE, whereas Ctnnb1Y654E, which has reduced affinity for the junctions, could do so. Expression of the constitutively active Ctnnb1∆ex3 mutant also suppressed the development of RPE, instead facilitating a ciliary cell fate. However, the post-mitotic or mature RPE was insensitive to the loss, inactivation, or constitutive activation of Ctnnb1. Collectively, our results suggest that Ctnnb1 should be maintained within an optimal range to specify RPE through transcriptional regulation of Wnt target genes in the optic neuroepithelium.
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Affiliation(s)
- Jong-Myeong Kim
- Department of Biological Sciences and KAIST Stem Cell Center, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Korea
| | - Kwang Wook Min
- Department of Biological Sciences and KAIST Stem Cell Center, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Korea
| | - You-Joung Kim
- Department of Biological Sciences and KAIST Stem Cell Center, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Korea
| | - Ron Smits
- Department of Gastroenterology and Hepatology, Erasmus MC-University Medical Center, 3015 GD Rotterdam, The Netherlands
| | - Konrad Basler
- Department of Molecular Life Sciences, University of Zurich, CH-8057 Zurich, Switzerland
| | - Jin Woo Kim
- Department of Biological Sciences and KAIST Stem Cell Center, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Korea
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Theerakittayakorn K, Thi Nguyen H, Musika J, Kunkanjanawan H, Imsoonthornruksa S, Somredngan S, Ketudat-Cairns M, Parnpai R. Differentiation Induction of Human Stem Cells for Corneal Epithelial Regeneration. Int J Mol Sci 2020; 21:E7834. [PMID: 33105778 PMCID: PMC7660084 DOI: 10.3390/ijms21217834] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Revised: 10/16/2020] [Accepted: 10/17/2020] [Indexed: 12/13/2022] Open
Abstract
Deficiency of corneal epithelium causes vision impairment or blindness in severe cases. Transplantation of corneal epithelial cells is an effective treatment but the availability of the tissue source for those cells is inadequate. Stem cells can be induced to differentiate to corneal epithelial cells and used in the treatment. Multipotent stem cells (mesenchymal stem cells) and pluripotent stem cells (embryonic stem cells and induced pluripotent stem cells) are promising cells to address the problem. Various protocols have been developed to induce differentiation of the stem cells into corneal epithelial cells. The feasibility and efficacy of both human stem cells and animal stem cells have been investigated for corneal epithelium regeneration. However, some physiological aspects of animal stem cells are different from those of human stem cells, the protocols suited for animal stem cells might not be suitable for human stem cells. Therefore, in this review, only the investigations of corneal epithelial differentiation of human stem cells are taken into account. The available protocols for inducing the differentiation of human stem cells into corneal epithelial cells are gathered and compared. Also, the pathways involving in the differentiation are provided to elucidate the relevant mechanisms.
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Affiliation(s)
- Kasem Theerakittayakorn
- Embryo Technology and Stem Cell Research Center, School of Biotechnology, Institute of Agricultural Technology, Suranaree University of Technology, Nakhon Ratchasima 30000, Thailand; (K.T.); (H.T.N.); (J.M.); (S.I.); (S.S.); (M.K.-C.)
| | - Hong Thi Nguyen
- Embryo Technology and Stem Cell Research Center, School of Biotechnology, Institute of Agricultural Technology, Suranaree University of Technology, Nakhon Ratchasima 30000, Thailand; (K.T.); (H.T.N.); (J.M.); (S.I.); (S.S.); (M.K.-C.)
| | - Jidapa Musika
- Embryo Technology and Stem Cell Research Center, School of Biotechnology, Institute of Agricultural Technology, Suranaree University of Technology, Nakhon Ratchasima 30000, Thailand; (K.T.); (H.T.N.); (J.M.); (S.I.); (S.S.); (M.K.-C.)
| | - Hataiwan Kunkanjanawan
- Medeze Research and Development Co., Ltd. 28/9 Moo 8, Phutthamonthon Sai 4 Rd., Krathum Lom, Sam Phran, Nakhon Pathom 73220, Thailand;
| | - Sumeth Imsoonthornruksa
- Embryo Technology and Stem Cell Research Center, School of Biotechnology, Institute of Agricultural Technology, Suranaree University of Technology, Nakhon Ratchasima 30000, Thailand; (K.T.); (H.T.N.); (J.M.); (S.I.); (S.S.); (M.K.-C.)
| | - Sirilak Somredngan
- Embryo Technology and Stem Cell Research Center, School of Biotechnology, Institute of Agricultural Technology, Suranaree University of Technology, Nakhon Ratchasima 30000, Thailand; (K.T.); (H.T.N.); (J.M.); (S.I.); (S.S.); (M.K.-C.)
| | - Mariena Ketudat-Cairns
- Embryo Technology and Stem Cell Research Center, School of Biotechnology, Institute of Agricultural Technology, Suranaree University of Technology, Nakhon Ratchasima 30000, Thailand; (K.T.); (H.T.N.); (J.M.); (S.I.); (S.S.); (M.K.-C.)
| | - Rangsun Parnpai
- Embryo Technology and Stem Cell Research Center, School of Biotechnology, Institute of Agricultural Technology, Suranaree University of Technology, Nakhon Ratchasima 30000, Thailand; (K.T.); (H.T.N.); (J.M.); (S.I.); (S.S.); (M.K.-C.)
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Kobayashi Y, Hayashi R, Shibata S, Quantock AJ, Nishida K. Ocular surface ectoderm instigated by WNT inhibition and BMP4. Stem Cell Res 2020; 46:101868. [PMID: 32603880 PMCID: PMC7347012 DOI: 10.1016/j.scr.2020.101868] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Revised: 03/27/2020] [Accepted: 05/20/2020] [Indexed: 12/13/2022] Open
Abstract
We sought to elucidate how and when the ocular surface ectoderm commits to its differentiation into the corneal epithelium in eye development from human induced pluripotent stem cells (hiPSCs) under the influence of WNT signaling and the actions of BMP4. These signals are key drivers ocular surface ectodermal cell fate determination. It was discovered that secreted frizzled related protein-2 (SFRP2) and Dickkopf1 (DKK1), which are expressed in neural ectoderm, are both influential in the differentiation of hiPSCs, where they act as canonical WNT antagonists. BMP4, moreover, was found to simultaneously initiate non-neural ectodermal differentiation into a corneal epithelial lineage. Combined treatment of hiPSCs with exogenous BMP4 aligned to WNT inhibition for the initial four days of differentiation increased the ocular surface ectodermal cell population and induced a corneal epithelial phenotype. Specification of a surface ectodermal lineage and its fate is thus determined by a fine balance of BMP4 exposure and WNT inhibition in the very earliest stages of human eye development.
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Affiliation(s)
- Yuki Kobayashi
- Department of Ophthalmology, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan; Department of Stem Cells and Applied Medicine, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Ryuhei Hayashi
- Department of Ophthalmology, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan; Department of Stem Cells and Applied Medicine, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan.
| | - Shun Shibata
- Department of Stem Cells and Applied Medicine, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan; Research and Development Division, ROHTO Pharmaceutical Co Ltd, Osaka, Osaka 544-8666, Japan
| | - Andrew J Quantock
- Structural Biophysics Group, School of Optometry and Vision Sciences, College of Biomedical and Life Sciences, Cardiff University, Cardiff, CF24 4HQ Wales, UK
| | - Kohji Nishida
- Department of Ophthalmology, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan; Integrated Frontier Research for Medical Science Division, Institute for Open and Transdisciplinary Research Initiatives (OTRI), Osaka University, Suita, Osaka 565-0871, Japan
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5
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Vallée A, Vallée JN, Guillevin R, Lecarpentier Y. Riluzole: a therapeutic strategy in Alzheimer's disease by targeting the WNT/β-catenin pathway. Aging (Albany NY) 2020; 12:3095-3113. [PMID: 32035419 PMCID: PMC7041777 DOI: 10.18632/aging.102830] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Accepted: 01/27/2020] [Indexed: 12/17/2022]
Abstract
Alzheimer's disease (AD) is a neurodegenerative disease, where the etiology remains unclear. AD is characterized by amyloid-(Aβ) protein aggregation and neurofibrillary plaques deposits. Oxidative stress and chronic inflammation have been suggested as causes of AD. Glutamatergic pathway dysregulation is also mainly associated with AD process. In AD, the canonical WNT/β-catenin pathway is downregulated. Downregulation of WNT/β-catenin, by activation of GSK-3β-induced Aβ, and inactivation of PI3K/Akt pathway involve oxidative stress in AD. The downregulation of the WNT/β-catenin pathway decreases the activity of EAAT2, the glutamate receptors, and leads to neuronal death. In AD, oxidative stress, neuroinflammation and glutamatergic pathway operate in a vicious circle driven by the dysregulation of the WNT/β-catenin pathway. Riluzole is a glutamate modulator and used as treatment in amyotrophic lateral sclerosis. Recent findings have highlighted its use in AD and its potential increase power on the WNT pathway. Nevertheless, the mechanism by which Riluzole can operate in AD remains unclear and should be better determine. The focus of our review is to highlight the potential action of Riluzole in AD by targeting the canonical WNT/β-catenin pathway to modulate glutamatergic pathway, oxidative stress and neuroinflammation.
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Affiliation(s)
- Alexandre Vallée
- DACTIM-MIS, Laboratory of Mathematics and Applications (LMA), University of Poitiers, CHU de Poitiers, Poitiers, France
| | - Jean-Noël Vallée
- CHU Amiens Picardie, University of Picardie Jules Verne (UPJV), Amiens, France.,Laboratory of Mathematics and Applications (LMA), University of Poitiers, Poitiers, France
| | - Rémy Guillevin
- DACTIM-MIS, Laboratory of Mathematics and Applications (LMA), University of Poitiers, CHU de Poitiers, Poitiers, France
| | - Yves Lecarpentier
- Centre de Recherche Clinique, Grand Hôpital de l'Est Francilien (GHEF), Meaux, France
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Vallée A, Lecarpentier Y, Vallée R, Guillevin R, Vallée JN. Circadian Rhythms in Exudative Age-Related Macular Degeneration: The Key Role of the Canonical WNT/β-Catenin Pathway. Int J Mol Sci 2020; 21:ijms21030820. [PMID: 32012797 PMCID: PMC7037737 DOI: 10.3390/ijms21030820] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 01/23/2020] [Accepted: 01/27/2020] [Indexed: 02/07/2023] Open
Abstract
Age-related macular degeneration (AMD) is considered as the main worldwide cause of blindness in elderly adults. Exudative AMD type represents 10 to 15% of macular degeneration cases, but is the main cause of vision loss and blindness. Circadian rhythm changes are associated with aging and could further accelerate it. However, the link between circadian rhythms and exudative AMD is not fully understood. Some evidence suggests that dysregulation of circadian functions could be manifestations of diseases or could be risk factors for the development of disease in elderly adults. Biological rhythms are complex systems interacting with the environment and control several physiological pathways. Recent findings have shown that the dysregulation of circadian rhythms is correlated with exudative AMD. One of the main pathways involved in exudative AMD is the canonical WNT/β-catenin pathway. Circadian clocks have a main role in some tissues by driving the circadian expression of genes involved in physiological and metabolic functions. In exudative AMD, the increase of the canonical WNT/β-catenin pathway is enhanced by the dysregulation of circadian rhythms. Exudative AMD progression is associated with major metabolic reprogramming, initiated by aberrant WNT/β-catenin pathway, of aerobic glycolysis. This review focuses on the interest of circadian rhythm dysregulation in exudative AMD through the aberrant upregulation of the canonical WNT/β-catenin pathway.
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Affiliation(s)
- Alexandre Vallée
- DACTIM-MIS, Laboratory of Mathematics and Applications (LMA), UMR CNRS 7348, University of Poitiers, CHU de Poitiers, 86021 Poitiers, France
| | - Yves Lecarpentier
- Centre de Recherche Clinique, Grand Hôpital de l'Est Francilien (GHEF), 77100 Meaux, France
| | - Rodolphe Vallée
- University Hospital Group of Paris-Seine-Saint-Denis, APHP, University of Paris-13 Sorbonne Paris-Cité, 93000 Paris, France
| | - Rémy Guillevin
- DACTIM-MIS, Laboratory of Mathematics and Applications (LMA), UMR CNRS 7348, University of Poitiers, CHU de Poitiers, 86021 Poitiers, France
| | - Jean-Noël Vallée
- CHU Amiens Picardie, University of Picardie Jules Verne (UPJV), 80000 Amiens, France
- Laboratory of Mathematics and Applications (LMA), UMR CNRS 7348, University of Poitiers, 86021 Poitiers, France
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7
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Zhao Y, Zheng D, Cvekl A. Profiling of chromatin accessibility and identification of general cis-regulatory mechanisms that control two ocular lens differentiation pathways. Epigenetics Chromatin 2019; 12:27. [PMID: 31053165 PMCID: PMC6498704 DOI: 10.1186/s13072-019-0272-y] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2019] [Accepted: 04/23/2019] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND Promoters and enhancers are cis-regulatory DNA sequences that control specificity and quantity of transcription. Both are rich on clusters of cis-acting sites that interact with sequence-specific DNA-binding transcription factors (TFs). At the level of chromatin, these regions display increased nuclease sensitivity, reduced nucleosome density, including nucleosome-free regions, and specific combinations of posttranslational modifications of core histone proteins. Together, "open" and "closed" chromatins represent transcriptionally active and repressed states of individual genes, respectively. Cellular differentiation is marked by changes in local chromatin structure. Lens morphogenesis, regulated by TF Pax6, includes differentiation of epithelial precursor cells into lens fibers in parallel with differentiation of epithelial precursors into the mature lens epithelium. RESULTS Using ATAC-seq, we investigated dynamics of chromatin changes during mouse lens fibers and epithelium differentiation. Tissue-specific features of these processes are demonstrated via comparative studies of embryonic stem cells, forebrain, and liver chromatins. Unbiased analysis reveals cis-regulatory logic of lens differentiation through known (e.g., AP-1, Ets, Hsf4, Maf, and Pax6 sites) and novel (e.g., CTCF, Tead, and NF1) motifs. Twenty-six DNA-binding TFs, recognizing these cis-motifs, are markedly up-regulated in differentiating lens fibers. As specific examples, our ATAC-seq data uncovered both the regulatory regions and TF binding motifs in Foxe3, Prox1, and Mip loci that are consistent with previous, though incomplete, experimental data. A cross-examination of Pax6 binding with ATAC-seq data demonstrated that Pax6 bound to both open (H3K27ac and P300-enriched) and closed chromatin domains in lens and forebrain. CONCLUSIONS Our study has generated the first lens chromatin accessibility maps that support a general model of stage-specific chromatin changes associated with transcriptional activities of batteries of genes required for lens fiber cell formation. Analysis of active (or open) promoters and enhancers reveals important cis-DNA motifs that establish the molecular foundation for temporally and spatially regulated gene expression in lens. Together, our data and models open new avenues for the field to conduct mechanistic studies of transcriptional control regions, reconstruction of gene regulatory networks that govern lens morphogenesis, and identification of cataract-causing mutations in noncoding sequences.
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Affiliation(s)
- Yilin Zhao
- The Departments of Genetics, Albert Einstein College of Medicine, Bronx, NY 10461 USA
| | - Deyou Zheng
- The Departments of Genetics, Albert Einstein College of Medicine, Bronx, NY 10461 USA
- Neurology and Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461 USA
| | - Ales Cvekl
- The Departments of Genetics, Albert Einstein College of Medicine, Bronx, NY 10461 USA
- Ophthalmology and Visual Sciences, Albert Einstein College of Medicine, Bronx, NY 10461 USA
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Quintana-Urzainqui I, Kozić Z, Mitra S, Tian T, Manuel M, Mason JO, Price DJ. Tissue-Specific Actions of Pax6 on Proliferation and Differentiation Balance in Developing Forebrain Are Foxg1 Dependent. iScience 2018; 10:171-191. [PMID: 30529950 PMCID: PMC6287089 DOI: 10.1016/j.isci.2018.11.031] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Revised: 10/02/2018] [Accepted: 11/16/2018] [Indexed: 12/12/2022] Open
Abstract
Differences in the growth and maturation of diverse forebrain tissues depend on region-specific transcriptional regulation. Individual transcription factors act simultaneously in multiple regions that develop very differently, raising questions about the extent to which their actions vary regionally. We found that the transcription factor Pax6 affects the transcriptomes and the balance between proliferation and differentiation in opposite directions in the diencephalon versus cerebral cortex. We tested several possible mechanisms to explain Pax6's tissue-specific actions and found that the presence of the transcription factor Foxg1 in the cortex but not in the diencephalon was most influential. We found that Foxg1 is responsible for many of the differences in cell cycle gene expression between the diencephalon and cortex and, in cortex lacking Foxg1, Pax6's action on the balance of proliferation versus differentiation becomes diencephalon like. Our findings reveal a mechanism for generating regional forebrain diversity in which one transcription factor completely reverses the actions of another.
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Affiliation(s)
- Idoia Quintana-Urzainqui
- Simons Initiative for the Developing Brain, Hugh Robson Building, George Square, Edinburgh EH8 9XD, UK.
| | - Zrinko Kozić
- Simons Initiative for the Developing Brain, Hugh Robson Building, George Square, Edinburgh EH8 9XD, UK
| | - Soham Mitra
- Simons Initiative for the Developing Brain, Hugh Robson Building, George Square, Edinburgh EH8 9XD, UK
| | - Tian Tian
- Simons Initiative for the Developing Brain, Hugh Robson Building, George Square, Edinburgh EH8 9XD, UK
| | - Martine Manuel
- Simons Initiative for the Developing Brain, Hugh Robson Building, George Square, Edinburgh EH8 9XD, UK
| | - John O Mason
- Simons Initiative for the Developing Brain, Hugh Robson Building, George Square, Edinburgh EH8 9XD, UK
| | - David J Price
- Simons Initiative for the Developing Brain, Hugh Robson Building, George Square, Edinburgh EH8 9XD, UK
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Abstract
In this review, we compare and contrast the three different forms of vertebrate lens regeneration: Wolffian lens regeneration, cornea-lens regeneration, and lens regeneration from lens epithelial cells. An examination of the diverse cellular origins of these lenses, their unique phylogenetic distribution, and the underlying molecular mechanisms, suggests that these different forms of lens regeneration evolved independently and utilize neither conserved nor convergent mechanisms to regulate these processes.
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Affiliation(s)
- Jonathan J Henry
- Department of Cell and Developmental Biology, University of Illinois, Urbana, IL
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10
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Wang Y, Mahesh P, Wang Y, Novo SG, Shihan MH, Hayward-Piatkovskyi B, Duncan MK. Spatiotemporal dynamics of canonical Wnt signaling during embryonic eye development and posterior capsular opacification (PCO). Exp Eye Res 2018; 175:148-158. [PMID: 29932883 DOI: 10.1016/j.exer.2018.06.020] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2018] [Revised: 06/14/2018] [Accepted: 06/18/2018] [Indexed: 02/07/2023]
Abstract
The appropriate spatial and temporal regulation of canonical Wnt signaling is vital for eye development. However, the literature often conflicts on the distribution of canonical Wnt signaling in the eye. Here, using a sensitive mouse transgenic reporter line, we report a detailed re-evaluation of the spatiotemporal dynamics of canonical Wnt signaling in the developing eye. Canonical Wnt activity was dynamic in the optic vesicle and later in the retina, while it was absent from the ectodermal precursors of the lens and corneal epithelium. However, later in corneal development, canonical Wnt reporter activity was detected in corneal stroma and endothelium precursors as they form from the neural crest, although this was lost around birth. Interestingly, while no canonical Wnt signaling was detected in the corneal limbus or basal cells at any developmental stage, it was robust in adult corneal wing and squamous epithelial cells. While canonical Wnt reporter activity was also absent from the postnatal lens, upon lens injury intended to model cataract surgery, it upregulated within 12 h in remnant lens epithelial cells, and co-localized with alpha smooth muscle actin in fibrotic lens epithelial cells from 48 h post-surgery onward. This pattern correlated with downregulation of the inhibitor of canonical Wnt signaling, Dkk3. These data demonstrate that canonical Wnt signaling is dynamic within the developing eye and upregulates in lens epithelial cells in response to lens injury. As canonical Wnt signaling can collaborate with TGFβ to drive fibrosis in other systems, these data offer the first evidence in a lens-injury model that canonical Wnt may synergize with TGFβ signaling to drive fibrotic posterior capsular opacification (PCO).
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Affiliation(s)
- Yichen Wang
- Department of Biological Sciences, University of Delaware, Newark, DE 19716, United States
| | - Priyha Mahesh
- Department of Biological Sciences, University of Delaware, Newark, DE 19716, United States
| | - Yan Wang
- Department of Biological Sciences, University of Delaware, Newark, DE 19716, United States
| | - Samuel G Novo
- Department of Biological Sciences, University of Delaware, Newark, DE 19716, United States
| | - Mahbubul H Shihan
- Department of Biological Sciences, University of Delaware, Newark, DE 19716, United States
| | | | - Melinda K Duncan
- Department of Biological Sciences, University of Delaware, Newark, DE 19716, United States.
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11
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Vallée A, Lecarpentier Y, Guillevin R, Vallée JN. Aerobic Glycolysis Hypothesis Through WNT/Beta-Catenin Pathway in Exudative Age-Related Macular Degeneration. J Mol Neurosci 2017; 62:368-379. [PMID: 28689265 DOI: 10.1007/s12031-017-0947-4] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2017] [Accepted: 06/28/2017] [Indexed: 12/18/2022]
Abstract
Exudative age-related macular degeneration (AMD) is characterized by molecular mechanisms responsible for the initiation of choroidal neovascularization (CNV). Inflammatory processes are associated with upregulation of the canonical WNT/beta-catenin pathway in exudative AMD. We focus this review on the link between WNT/beta-catenin pathway activation and neovascular progression in exudative AMD through activation of aerobic glycolysis for production of angiogenic factors. Increased WNT/beta-catenin pathway involves hexokinase 2 (HK2) and pyruvate kinase M2 (PKM2). WNT/beta-catenin pathway stimulates PI3K/Akt pathway and then HIF-1alpha which activates glycolytic enzymes: glucose transporter (Glut), pyruvate dehydrogenase kinase 1 (PDK1), lactate dehydrogenase A (LDH-A), and monocarboxylate lactate transporter (MCT-1). This phenomenon is called aerobic glycolysis or the Warburg effect. Consequently, phosphorylation of PDK-1 inhibits the pyruvate dehydrogenase complex (PDH). Thus, a large part of pyruvate cannot be converted into acetyl-CoA in mitochondria and only a part of acetyl-CoA can enter the tricarboxylic acid cycle. Cytosolic pyruvate is converted into lactate through the action of LDH-A. In exudative AMD, high level of cytosolic lactate is correlated with increase of VEGF expression, the angiogenic factor of CNV. Photoreceptors in retina cells can metabolize glucose through aerobic glycolysis to protect them against oxidative damage, as cancer cells do.
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Affiliation(s)
- Alexandre Vallée
- Experimental and Clinical Neurosciences Laboratory, INSERM U1084, University of Poitiers, Poitiers, France.
- Laboratoire de Mathématiques et Applications (LMA), UMR CNRS 7348, Université de Poitiers, 11 Boulevard Marie et Pierre Curie, Poitiers, France.
| | | | - Rémy Guillevin
- DACTIM, Laboratoire de Mathématiques et Applications, Université de Poitiers et CHU de Poitiers, UMR CNRS 7348, SP2MI Futuroscope, Chasseneuil-du-Poitou, France
| | - Jean-Noël Vallée
- Laboratoire de Mathématiques et Applications (LMA), UMR CNRS 7348, Université de Poitiers, 11 Boulevard Marie et Pierre Curie, Poitiers, France
- CHU Amiens Picardie, Université Picardie Jules Verne (UPJV), Amiens, France
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The Gene Regulatory Network of Lens Induction Is Wired through Meis-Dependent Shadow Enhancers of Pax6. PLoS Genet 2016; 12:e1006441. [PMID: 27918583 PMCID: PMC5137874 DOI: 10.1371/journal.pgen.1006441] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Accepted: 10/21/2016] [Indexed: 01/03/2023] Open
Abstract
Lens induction is a classical developmental model allowing investigation of cell specification, spatiotemporal control of gene expression, as well as how transcription factors are integrated into highly complex gene regulatory networks (GRNs). Pax6 represents a key node in the gene regulatory network governing mammalian lens induction. Meis1 and Meis2 homeoproteins are considered as essential upstream regulators of Pax6 during lens morphogenesis based on their interaction with the ectoderm enhancer (EE) located upstream of Pax6 transcription start site. Despite this generally accepted regulatory pathway, Meis1-, Meis2- and EE-deficient mice have surprisingly mild eye phenotypes at placodal stage of lens development. Here, we show that simultaneous deletion of Meis1 and Meis2 in presumptive lens ectoderm results in arrested lens development in the pre-placodal stage, and neither lens placode nor lens is formed. We found that in the presumptive lens ectoderm of Meis1/Meis2 deficient embryos Pax6 expression is absent. We demonstrate using chromatin immunoprecipitation (ChIP) that in addition to EE, Meis homeoproteins bind to a remote, ultraconserved SIMO enhancer of Pax6. We further show, using in vivo gene reporter analyses, that the lens-specific activity of SIMO enhancer is dependent on the presence of three Meis binding sites, phylogenetically conserved from man to zebrafish. Genetic ablation of EE and SIMO enhancers demostrates their requirement for lens induction and uncovers an apparent redundancy at early stages of lens development. These findings identify a genetic requirement for Meis1 and Meis2 during the early steps of mammalian eye development. Moreover, they reveal an apparent robustness in the gene regulatory mechanism whereby two independent "shadow enhancers" maintain critical levels of a dosage-sensitive gene, Pax6, during lens induction.
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Fujimura N. WNT/β-Catenin Signaling in Vertebrate Eye Development. Front Cell Dev Biol 2016; 4:138. [PMID: 27965955 PMCID: PMC5127792 DOI: 10.3389/fcell.2016.00138] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2016] [Accepted: 11/09/2016] [Indexed: 01/04/2023] Open
Abstract
The vertebrate eye is a highly specialized sensory organ, which is derived from the anterior neural plate, head surface ectoderm, and neural crest-derived mesenchyme. The single central eye field, generated from the anterior neural plate, divides to give rise to the optic vesicle, which evaginates toward the head surface ectoderm. Subsequently, the surface ectoderm, in conjunction with the optic vesicle invaginates to form the lens vesicle and double-layered optic cup, respectively. This complex process is controlled by transcription factors and several intracellular and extracellular signaling pathways including WNT/β-catenin signaling. This signaling pathway plays an essential role in multiple developmental processes and has a profound effect on cell proliferation and cell fate determination. During eye development, the activity of WNT/β-catenin signaling is tightly controlled. Faulty regulation of WNT/β-catenin signaling results in multiple ocular malformations due to defects in the process of cell fate determination and differentiation. This mini-review summarizes recent findings on the role of WNT/β-catenin signaling in eye development. Whilst this mini-review focuses on loss-of-function and gain-of-function mutants of WNT/β-catenin signaling components, it also highlights some important aspects of β-catenin-independent WNT signaling in the eye development at later stages.
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Affiliation(s)
- Naoko Fujimura
- Laboratory of Eye Biology, BIOCEV Division, Institute of Molecular Genetics Prague, Czechia
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14
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Bunt J, Lim JWC, Zhao L, Mason S, Richards LJ. PAX6 does not regulate Nfia and Nfib expression during neocortical development. Sci Rep 2015; 5:10668. [PMID: 26021864 PMCID: PMC4448127 DOI: 10.1038/srep10668] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2014] [Accepted: 04/24/2015] [Indexed: 12/20/2022] Open
Abstract
The Nuclear factor I (NFI) family of transcription factors regulates proliferation and differentiation throughout the developing central nervous system. In the developing telencephalon of humans and mice, reduced Nfi expression is associated with agenesis of the corpus callosum and other neurodevelopmental defects. Currently, little is known about how Nfi expression is regulated during early telencephalic development. PAX6, a transcription factor important for telencephalic development, has been proposed as an upstream regulator of Nfi expression in the neocortex. Here we demonstrate that, in the developing neocortex of mice, NFIA and NFIB are endogenously expressed in gradients with high caudo-medial to low rostro-lateral expression and are most highly expressed in the cortical plate. We found that this expression pattern deviates from that of PAX6, suggesting that PAX6 does not drive Nfi expression. This is supported by in vitro reporter assays showing that PAX6 over-expression does not regulate Nfi promoter activity. Similarly, we also found that in the Pax6 Small Eye mutant, no changes in Nfi mRNA or protein expression are observed in the neocortical ventricular zone where PAX6 and the NFIs are expressed. Together these data demonstrate that in mice, PAX6 is not a transcriptional activator of Nfi expression during neocortical development.
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Affiliation(s)
- Jens Bunt
- Queensland Brain Institute, The University of Queensland, Brisbane, 4072, Australia
| | - Jonathan W C Lim
- Queensland Brain Institute, The University of Queensland, Brisbane, 4072, Australia
| | - Lu Zhao
- Queensland Brain Institute, The University of Queensland, Brisbane, 4072, Australia
| | - Sharon Mason
- Queensland Brain Institute, The University of Queensland, Brisbane, 4072, Australia
| | - Linda J Richards
- 1] Queensland Brain Institute, The University of Queensland, Brisbane, 4072, Australia [2] The School of Biomedical Sciences, The University of Queensland, Brisbane, 4072, Australia
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Carpenter AC, Smith AN, Wagner H, Cohen-Tayar Y, Rao S, Wallace V, Ashery-Padan R, Lang RA. Wnt ligands from the embryonic surface ectoderm regulate 'bimetallic strip' optic cup morphogenesis in mouse. Development 2015; 142:972-82. [PMID: 25715397 PMCID: PMC4352985 DOI: 10.1242/dev.120022] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The Wnt/β-catenin response pathway is central to many developmental processes. Here, we assessed the role of Wnt signaling in early eye development using the mouse as a model system. We showed that the surface ectoderm region that includes the lens placode expressed 12 out of 19 possible Wnt ligands. When these activities were suppressed by conditional deletion of wntless (Le-cre; Wlsfl/fl) there were dramatic consequences that included a saucer-shaped optic cup, ventral coloboma, and a deficiency of periocular mesenchyme. This phenotype shared features with that produced when the Wnt/β-catenin pathway co-receptor Lrp6 is mutated or when retinoic acid (RA) signaling in the eye is compromised. Consistent with this, microarray and cell fate marker analysis identified a series of expression changes in genes known to be regulated by RA or by the Wnt/β-catenin pathway. Using pathway reporters, we showed that Wnt ligands from the surface ectoderm directly or indirectly elicit a Wnt/β-catenin response in retinal pigment epithelium (RPE) progenitors near the optic cup rim. In Le-cre; Wlsfl/fl mice, the numbers of RPE cells are reduced and this can explain, using the principle of the bimetallic strip, the curvature of the optic cup. These data thus establish a novel hypothesis to explain how differential cell numbers in a bilayered epithelium can lead to shape change. Summary: During optic cup morphogenesis, Wnt ligands expressed in the surface ectoderm control cell proliferation in the retinal pigmented epithelium, and thus influence bending of the neural retina.
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Affiliation(s)
- April C Carpenter
- Visual Systems Group, Abrahamson Pediatric Eye Institute, Division of Pediatric Ophthalmology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
| | - April N Smith
- Visual Systems Group, Abrahamson Pediatric Eye Institute, Division of Pediatric Ophthalmology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
| | - Heidi Wagner
- Visual Systems Group, Abrahamson Pediatric Eye Institute, Division of Pediatric Ophthalmology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
| | - Yamit Cohen-Tayar
- Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine and Sagol School of Neuroscience, Tel-Aviv University, Ramat Aviv, Tel Aviv 6997801, Israel
| | - Sujata Rao
- Visual Systems Group, Abrahamson Pediatric Eye Institute, Division of Pediatric Ophthalmology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
| | - Valerie Wallace
- Vision Science Research Program, Toronto Western Research Institute, University Health Network, Toronto, Ontario M5T 2S8, Canada Department of Ophthalmology and Vision Science, University of Toronto, Toronto, Ontario M5T 2S8, Canada
| | - Ruth Ashery-Padan
- Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine and Sagol School of Neuroscience, Tel-Aviv University, Ramat Aviv, Tel Aviv 6997801, Israel
| | - Richard A Lang
- Visual Systems Group, Abrahamson Pediatric Eye Institute, Division of Pediatric Ophthalmology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA Division of Developmental Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA Department of Ophthalmology, College of Medicine, University of Cincinnati, Cincinnati, OH 45229, USA
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16
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Anchan RM, Lachke SA, Gerami-Naini B, Lindsey J, Ng N, Naber C, Nickerson M, Cavallesco R, Rowan S, Eaton JL, Xi Q, Maas RL. Pax6- and Six3-mediated induction of lens cell fate in mouse and human ES cells. PLoS One 2014; 9:e115106. [PMID: 25517354 PMCID: PMC4269389 DOI: 10.1371/journal.pone.0115106] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Accepted: 11/18/2014] [Indexed: 11/19/2022] Open
Abstract
Embryonic stem (ES) cells provide a potentially useful in vitro model for the study of in vivo tissue differentiation. We used mouse and human ES cells to investigate whether the lens regulatory genes Pax6 and Six3 could induce lens cell fate in vitro. To help assess the onset of lens differentiation, we derived a new mES cell line (Pax6-GFP mES) that expresses a GFP reporter under the control of the Pax6 P0 promoter and lens ectoderm enhancer. Pax6 or Six3 expression vectors were introduced into mES or hES cells by transfection or lentiviral infection and the differentiating ES cells analyzed for lens marker expression. Transfection of mES cells with Pax6 or Six3 but not with other genes induced the expression of lens cell markers and up-regulated GFP reporter expression in Pax6-GFP mES cells by 3 days post-transfection. By 7 days post-transfection, mES cell cultures exhibited a>10-fold increase over controls in the number of colonies expressing γA-crystallin, a lens fiber cell differentiation marker. RT-PCR and immunostaining revealed induction of additional lens epithelial or fiber cell differentiation markers including Foxe3, Prox1, α- and β-crystallins, and Tdrd7. Moreover, γA-crystallin- or Prox1-expressing lentoid bodies formed by 30 days in culture. In hES cells, Pax6 or Six3 lentiviral vectors also induced lens marker expression. mES cells that express lens markers reside close to but are distinct from the Pax6 or Six3 transduced cells, suggesting that the latter induce nearby undifferentiated ES cells to adopt a lens fate by non-cell autonomous mechanisms. In sum, we describe a novel mES cell GFP reporter line that is useful for monitoring induction of lens fate, and demonstrate that Pax6 or Six3 is sufficient to induce ES cells to adopt a lens fate, potentially via non-cell autonomous mechanisms. These findings should facilitate investigations of lens development.
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Affiliation(s)
- Raymond M. Anchan
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, 02115, United States of America
- Division of Reproductive Endocrinology and Infertility, Department of Obstetrics, Gynecology and Reproductive Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, 02115, United States of America
| | - Salil A. Lachke
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, 02115, United States of America
- Department of Biological Sciences, Center for Bioinformatics and Computational Biology, University of Delaware, Newark, Delaware, 9716, United States of America
| | - Behzad Gerami-Naini
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, 02115, United States of America
- Division of Reproductive Endocrinology and Infertility, Department of Obstetrics, Gynecology and Reproductive Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, 02115, United States of America
| | - Jennifer Lindsey
- Division of Reproductive Endocrinology and Infertility, Department of Obstetrics, Gynecology and Reproductive Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, 02115, United States of America
| | - Nicholas Ng
- Division of Reproductive Endocrinology and Infertility, Department of Obstetrics, Gynecology and Reproductive Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, 02115, United States of America
| | - Catherine Naber
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, 02115, United States of America
| | - Michael Nickerson
- Division of Reproductive Endocrinology and Infertility, Department of Obstetrics, Gynecology and Reproductive Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, 02115, United States of America
| | - Resy Cavallesco
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, 02115, United States of America
| | - Sheldon Rowan
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, 02115, United States of America
| | - Jennifer L. Eaton
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, 02115, United States of America
| | - Qiongchao Xi
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, 02115, United States of America
| | - Richard L. Maas
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, 02115, United States of America
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17
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Cantù C, Zimmerli D, Hausmann G, Valenta T, Moor A, Aguet M, Basler K. Pax6-dependent, but β-catenin-independent, function of Bcl9 proteins in mouse lens development. Genes Dev 2014; 28:1879-84. [PMID: 25184676 PMCID: PMC4197948 DOI: 10.1101/gad.246140.114] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Bcl9 and Bcl9l (Bcl9/9l) encode Wnt signaling components that mediate the interaction between β-catenin and Pygo. Cantù et al. find that Bcl9/9l contribute in a Pygo-dependent, but β-catenin-independent, fashion to eye lens formation. Pax6, the master regulator of eye differentiation, directly activates Bcl9 and Bcl9l transcription. Bcl9 and Bcl9l (Bcl9/9l) encode Wnt signaling components that mediate the interaction between β-catenin and Pygopus (Pygo) via two evolutionarily conserved domains, HD1 and HD2, respectively. We generated mouse strains lacking these domains to probe the β-catenin-dependent and β-catenin-independent roles of Bcl9/9l and Pygo during mouse development. While lens development is critically dependent on the presence of the HD1 domain, it is not affected by the lack of the HD2 domain, indicating that Bcl9/9l act in this context in a β-catenin-independent manner. Furthermore, we uncover a new regulatory circuit in which Pax6, the master regulator of eye development, directly activates Bcl9/9l transcription.
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Affiliation(s)
- Claudio Cantù
- Institute of Molecular Life Sciences, University of Zurich, 8057 Zurich, Switzerland
| | - Dario Zimmerli
- Institute of Molecular Life Sciences, University of Zurich, 8057 Zurich, Switzerland
| | - George Hausmann
- Institute of Molecular Life Sciences, University of Zurich, 8057 Zurich, Switzerland
| | - Tomas Valenta
- Institute of Molecular Life Sciences, University of Zurich, 8057 Zurich, Switzerland
| | - Andreas Moor
- Swiss Institute for Experimental Cancer Research, Ecole Polytechnique Fédérale de Lausanne, School of Life Sciences, 1011 Lausanne, Switzerland
| | - Michel Aguet
- Swiss Institute for Experimental Cancer Research, Ecole Polytechnique Fédérale de Lausanne, School of Life Sciences, 1011 Lausanne, Switzerland
| | - Konrad Basler
- Institute of Molecular Life Sciences, University of Zurich, 8057 Zurich, Switzerland;
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18
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Forsdahl S, Kiselev Y, Hogseth R, Mjelle JE, Mikkola I. Pax6 regulates the expression of Dkk3 in murine and human cell lines, and altered responses to Wnt signaling are shown in FlpIn-3T3 cells stably expressing either the Pax6 or the Pax6(5a) isoform. PLoS One 2014; 9:e102559. [PMID: 25029272 PMCID: PMC4100929 DOI: 10.1371/journal.pone.0102559] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2014] [Accepted: 06/19/2014] [Indexed: 02/07/2023] Open
Abstract
Pax6 is a transcription factor important for early embryo development. It is expressed in several cancer cell lines and tumors. In glioblastoma, PAX6 has been shown to function as a tumor suppressor. Dickkopf 3 (Dkk3) is well established as a tumor suppressor in several tumor types, but not much is known about the regulation of its expression. We have previously found that Pax6 and Pax6(5a) increase the expression of the Dkk3 gene in two stably transfected mouse fibroblast cell lines. In this study the molecular mechanism behind this regulation is looked at. Western blot and reverse transcriptase quantitative PCR (RT-qPCR) confirmed higher level of Dkk3 expression in both Pax6 and Pax6(5a) expressing cell lines compared to the control cell line. By the use of bioinformatics and electrophoretic mobility shift assay (EMSA) we have mapped a functional Pax6 binding site in the mouse Dkk3 promoter. The minimal Dkk3 promoter fragment required for transcriptional activation by Pax6 and Pax6(5a) was a 200 bp region just upstream of the transcriptional start site. Mutation of the evolutionary conserved binding site in this region abrogated transcriptional activation and binding of Pax6/Pax6(5a) to the mouse Dkk3 promoter. Since the identified Pax6 binding site in this promoter is conserved, RT-qPCR and Western blot were used to look for regulation of Dkk3/REIC expression in human cell lines. Six of eight cell lines tested showed changes in Dkk3/REIC expression after PAX6 siRNA knockdown. Interestingly, we observed that the Pax6/Pax6(5a) expressing mouse fibroblast cell lines were less responsive to canonical Wnt pathway stimulation than the control cell line when TOP/FOP activity and the levels of active β-catenin and GSK3-β Ser9 phosphorylation were measured after LiCl stimulation.
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Affiliation(s)
- Siri Forsdahl
- Research Group of Pharmacology, Department of Pharmacy, UiT – The Artic University of Norway, Tromsoe, Norway
| | - Yury Kiselev
- Research Group of Pharmacology, Department of Pharmacy, UiT – The Artic University of Norway, Tromsoe, Norway
- Norwegian Translational Cancer Research Center, Department of Medical Biology, UiT – The Arctic University of Norway, Tromsoe, Norway
| | - Rune Hogseth
- Research Group of Pharmacology, Department of Pharmacy, UiT – The Artic University of Norway, Tromsoe, Norway
| | - Janne E. Mjelle
- Research Group of Pharmacology, Department of Pharmacy, UiT – The Artic University of Norway, Tromsoe, Norway
| | - Ingvild Mikkola
- Research Group of Pharmacology, Department of Pharmacy, UiT – The Artic University of Norway, Tromsoe, Norway
- * E-mail:
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19
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Antosova B, Smolikova J, Borkovcova R, Strnad H, Lachova J, Machon O, Kozmik Z. Ectopic activation of Wnt/β-catenin signaling in lens fiber cells results in cataract formation and aberrant fiber cell differentiation. PLoS One 2013; 8:e78279. [PMID: 24205179 PMCID: PMC3813504 DOI: 10.1371/journal.pone.0078279] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2013] [Accepted: 09/09/2013] [Indexed: 12/04/2022] Open
Abstract
The Wnt/β-catenin signaling pathway controls many processes during development, including cell proliferation, cell differentiation and tissue homeostasis, and its aberrant regulation has been linked to various pathologies. In this study we investigated the effect of ectopic activation of Wnt/β-catenin signaling during lens fiber cell differentiation. To activate Wnt/β-catenin signaling in lens fiber cells, the transgenic mouse referred to as αA-CLEF was generated, in which the transactivation domain of β-catenin was fused to the DNA-binding protein LEF1, and expression of the transgene was controlled by αA-crystallin promoter. Constitutive activation of Wnt/β-catenin signaling in lens fiber cells of αA-CLEF mice resulted in abnormal and delayed fiber cell differentiation. Moreover, adult αA-CLEF mice developed cataract, microphthalmia and manifested downregulated levels of γ-crystallins in lenses. We provide evidence of aberrant expression of cell cycle regulators in embryonic lenses of αA-CLEF transgenic mice resulting in the delay in cell cycle exit and in the shift of fiber cell differentiation to the central fiber cell compartment. Our results indicate that precise regulation of the Wnt/β-catenin signaling activity during later stages of lens development is essential for proper lens fiber cell differentiation and lens transparency.
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Affiliation(s)
- Barbora Antosova
- Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Prague, Czech Republic
- Department of Genetics and Microbiology, Faculty of Science, Charles University in Prague, Prague, Czech Republic
| | - Jana Smolikova
- Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - Romana Borkovcova
- Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - Hynek Strnad
- Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - Jitka Lachova
- Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - Ondrej Machon
- Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - Zbynek Kozmik
- Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Prague, Czech Republic
- * E-mail:
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Sugiyama Y, Shelley EJ, Wen L, Stump RJW, Shimono A, Lovicu FJ, McAvoy JW. Sfrp1 and Sfrp2 are not involved in Wnt/β-catenin signal silencing during lens induction but are required for maintenance of Wnt/β-catenin signaling in lens epithelial cells. Dev Biol 2013; 384:181-93. [PMID: 24140542 DOI: 10.1016/j.ydbio.2013.10.008] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2013] [Revised: 10/03/2013] [Accepted: 10/07/2013] [Indexed: 02/07/2023]
Abstract
During eye lens development, regulation of Wnt/β-catenin signaling is critical for two major processes: initially it must be silent in the lens placode for lens development to proceed, but subsequently it is required for maintenance of the lens epithelium. It is not known how these different phases of Wnt/β-catenin activity/inactivity are regulated. Secreted frizzled related protein-2 (Sfrp2), a putative Wnt-Fz antagonist, is expressed in lens placode and in lens epithelial cells and has been put forward as a candidate for regional Wnt/β-catenin pathway regulation. Here we show its closely-related isoform, Sfrp1, has a complimentary pattern of expression in the lens, being absent from the placode and epithelium but expressed in the fibers. As mice with single knockouts of Sfrp1 or Sfrp2 had no defects in lens formation, we examined lenses of Sfrp1 and Sfrp2 double knockout (DKO) mice and showed that they formed lens placode and subsequent lens structures. Consistent with this we did not observe ectopic TCF/Lef activity in lens placode of DKOs. This indicates that Sfrp1 and Sfrp2 individually, or together, do not constitute the putative negative regulator that blocks Wnt/β-catenin signaling during lens induction. In contrast, Sfrp1 and Sfrp2 appear to have a positive regulatory function because Wnt/β-catenin signaling in lens epithelial cells was reduced in Sfrp1 and Sfrp2 DKO mice. Lenses that formed in DKO mice were smaller than controls and exhibited a deficient epithelium. Thus Sfrps play a role in lens development, at least in part, by regulating aspects of Wnt/β-catenin signaling in lens epithelial cells.
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Affiliation(s)
- Yuki Sugiyama
- Save Sight Institute, The University of Sydney, Australia
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21
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Wolf L, Harrison W, Huang J, Xie Q, Xiao N, Sun J, Kong L, Lachke SA, Kuracha MR, Govindarajan V, Brindle PK, Ashery-Padan R, Beebe DC, Overbeek PA, Cvekl A. Histone posttranslational modifications and cell fate determination: lens induction requires the lysine acetyltransferases CBP and p300. Nucleic Acids Res 2013; 41:10199-214. [PMID: 24038357 PMCID: PMC3905850 DOI: 10.1093/nar/gkt824] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Lens induction is a classical embryologic model to study cell fate determination. It has been proposed earlier that specific changes in core histone modifications accompany the process of cell fate specification and determination. The lysine acetyltransferases CBP and p300 function as principal enzymes that modify core histones to facilitate specific gene expression. Herein, we performed conditional inactivation of both CBP and p300 in the ectodermal cells that give rise to the lens placode. Inactivation of both CBP and p300 resulted in the dramatic discontinuation of all aspects of lens specification and organogenesis, resulting in aphakia. The CBP/p300−/− ectodermal cells are viable and not prone to apoptosis. These cells showed reduced expression of Six3 and Sox2, while expression of Pax6 was not upregulated, indicating discontinuation of lens induction. Consequently, expression of αB- and αA-crystallins was not initiated. Mutant ectoderm exhibited markedly reduced levels of histone H3 K18 and K27 acetylation, subtly increased H3 K27me3 and unaltered overall levels of H3 K9ac and H3 K4me3. Our data demonstrate that CBP and p300 are required to establish lens cell-type identity during lens induction, and suggest that posttranslational histone modifications are integral to normal cell fate determination in the mammalian lens.
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Affiliation(s)
- Louise Wolf
- Department of Ophthalmology and Visual Sciences, Albert Einstein College of Medicine, Bronx, NY10461, USA, Department of Genetics, Albert Einstein College of Medicine, Bronx, NY10461, USA, Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030, USA, Departments of Ophthalmology and Visual Sciences, Washington University Saint Louis, Saint Louis, MO 63110, USA, Department of Biological Sciences, University of Delaware, Newark, DE 19716, USA, Center for Bioinformatics and Computational Biology, University of Delaware, Newark, DE 19716, USA, Department of Surgery, Creighton University, Omaha, NE 68178, USA, Department of Biochemistry, St. Jude Children's Research Hospital, Memphis, TN 38105, USA and Department of Human Molecular Genetics and Biochemistry, Sackler School of Medicine and Sagol School of Neuroscience, Tel Aviv University, Israel 69978
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22
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Henry JJ, Thomas AG, Hamilton PW, Moore L, Perry KJ. Cell signaling pathways in vertebrate lens regeneration. Curr Top Microbiol Immunol 2013; 367:75-98. [PMID: 23224710 DOI: 10.1007/82_2012_289] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/07/2023]
Abstract
Certain vertebrates are capable of regenerating parts of the eye, including the lens. Depending on the species, two principal forms of in vivo lens regeneration have been described wherein the new lens arises from either the pigmented epithelium of the dorsal iris or the cornea epithelium. These forms of lens regeneration are triggered by retinal factors present in the eye. Studies have begun to illuminate the nature of the signals that support lens regeneration. This review describes evidence for the involvement of specific signaling pathways in lens regeneration, including the FGF, retinoic acid, TGF-beta, Wnt, and Hedgehog pathways.
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Affiliation(s)
- Jonathan J Henry
- Department of Cell and Developmental Biology, University of Illinois, Urbana, IL 61801, USA.
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Jami A, Gadi J, Lee MJ, Kim EJ, Lee MJ, Jung HS, Kim HH, Lim SK. Pax6 expressed in osteocytes inhibits canonical Wnt signaling. Mol Cells 2013; 35:305-12. [PMID: 23529217 PMCID: PMC3887889 DOI: 10.1007/s10059-013-2310-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Revised: 02/22/2013] [Accepted: 02/22/2013] [Indexed: 01/10/2023] Open
Abstract
The transcription factor Pax6, which belongs to the paired box-containing gene family, regulates developmental processes, especially in the eyes, central nervous tissues and craniofacial structures. However, the role of Pax6 in bone has never been studied exclusively. Here we report that Pax6 is expressed at both the mRNA and protein level in the calvaria and long bones of adult mice as well as osteocyte-like MLOY4 cells and suppresses the canonical Wnt signaling pathway. Moreover, the expression levels of Pax6 were much higher in the calvaria than the long bones, and Pax6 was also expressed at E16 to E18 in both the calvaria and long bones. Knockdown of Pax6 in MLOY4 cells did not affect cell proliferation or survival; however, the expression of Sost, an osteocyte marker gene, was significantly decreased. In addition, the overexpression of Pax6 suppressed the canonical Wnt signaling pathway by enhancing the expression of Sost. Furthermore, we also demonstrated that Pax6 binds to the Sost promoter and that stimulation of Sost transcription by Pax6 was dependent on a specific Pax6-binding sequence within the promoter. In conclusion, the results of the present study suggest that Pax6 is expressed in bone and may play an important role in osteocyte differentiation by controlling canonical Wnt signaling.
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Affiliation(s)
- Ajita Jami
- Division of Endocrinology, Department of Internal Medicine, Brain Korea 21 Project for Medical Sciences, Yonsei University College of Medicine, Seoul 120-752,
Korea
| | - Jogeswar Gadi
- Division of Endocrinology, Department of Internal Medicine, Brain Korea 21 Project for Medical Sciences, Yonsei University College of Medicine, Seoul 120-752,
Korea
| | - Min Jung Lee
- Division of Anatomy and Developmental Biology, Department of Oral Biology, Brain Korea 21 Project, Oral Science Research Center, College of Dentistry, Yonsei Center of Biotechnology, Yonsei University, Seoul 120-752,
Korea
| | - Eun Jin Kim
- Institute of Bio-Medical Sciences, Yonsei University, Seoul 120-752,
Korea
| | - Mi Jeong Lee
- Division of Endocrinology, Department of Internal Medicine, Brain Korea 21 Project for Medical Sciences, Yonsei University College of Medicine, Seoul 120-752,
Korea
| | - Han-Sung Jung
- Division of Anatomy and Developmental Biology, Department of Oral Biology, Brain Korea 21 Project, Oral Science Research Center, College of Dentistry, Yonsei Center of Biotechnology, Yonsei University, Seoul 120-752,
Korea
| | - Hong-Hee Kim
- Department of Cell and Developmental Biology, Brain Korea 21 Program and Dental Research Institute, Seoul National University, Seoul 110-749,
Korea
| | - Sung-Kil Lim
- Division of Endocrinology, Department of Internal Medicine, Brain Korea 21 Project for Medical Sciences, Yonsei University College of Medicine, Seoul 120-752,
Korea
- Institute of Bio-Medical Sciences, Yonsei University, Seoul 120-752,
Korea
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Pax6 interactions with chromatin and identification of its novel direct target genes in lens and forebrain. PLoS One 2013; 8:e54507. [PMID: 23342162 PMCID: PMC3544819 DOI: 10.1371/journal.pone.0054507] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2012] [Accepted: 12/12/2012] [Indexed: 01/22/2023] Open
Abstract
Pax6 encodes a specific DNA-binding transcription factor that regulates the development of multiple organs, including the eye, brain and pancreas. Previous studies have shown that Pax6 regulates the entire process of ocular lens development. In the developing forebrain, Pax6 is expressed in ventricular zone precursor cells and in specific populations of neurons; absence of Pax6 results in disrupted cell proliferation and cell fate specification in telencephalon. In the pancreas, Pax6 is essential for the differentiation of α-, β- and δ-islet cells. To elucidate molecular roles of Pax6, chromatin immunoprecipitation experiments combined with high-density oligonucleotide array hybridizations (ChIP-chip) were performed using three distinct sources of chromatin (lens, forebrain and β-cells). ChIP-chip studies, performed as biological triplicates, identified a total of 5,260 promoters occupied by Pax6. 1,001 (133) of these promoter regions were shared between at least two (three) distinct chromatin sources, respectively. In lens chromatin, 2,335 promoters were bound by Pax6. RNA expression profiling from Pax6+/− lenses combined with in vivo Pax6-binding data yielded 76 putative Pax6-direct targets, including the Gaa, Isl1, Kif1b, Mtmr2, Pcsk1n, and Snca genes. RNA and ChIP data were validated for all these genes. In lens cells, reporter assays established Kib1b and Snca as Pax6 activated and repressed genes, respectively. In situ hybridization revealed reduced expression of these genes in E14 cerebral cortex. Moreover, we examined differentially expressed transcripts between E9.5 wild type and Pax6−/− lens placodes that suggested Efnb2, Fat4, Has2, Nav1, and Trpm3 as novel Pax6-direct targets. Collectively, the present studies, through the identification of Pax6-direct target genes, provide novel insights into the molecular mechanisms of Pax6 gene control during mouse embryonic development. In addition, the present data demonstrate that Pax6 interacts preferentially with promoter regions in a tissue-specific fashion. Nevertheless, nearly 20% of the regions identified are accessible to Pax6 in multiple tissues.
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ZNRF3 promotes Wnt receptor turnover in an R-spondin-sensitive manner. Nature 2012; 485:195-200. [PMID: 22575959 DOI: 10.1038/nature11019] [Citation(s) in RCA: 669] [Impact Index Per Article: 55.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2011] [Accepted: 03/06/2012] [Indexed: 12/11/2022]
Abstract
R-spondin proteins strongly potentiate Wnt signalling and function as stem-cell growth factors. Despite the biological and therapeutic significance, the molecular mechanism of R-spondin action remains unclear. Here we show that the cell-surface transmembrane E3 ubiquitin ligase zinc and ring finger 3 (ZNRF3) and its homologue ring finger 43 (RNF43) are negative feedback regulators of Wnt signalling. ZNRF3 is associated with the Wnt receptor complex, and inhibits Wnt signalling by promoting the turnover of frizzled and LRP6. Inhibition of ZNRF3 enhances Wnt/β-catenin signalling and disrupts Wnt/planar cell polarity signalling in vivo. Notably, R-spondin mimics ZNRF3 inhibition by increasing the membrane level of Wnt receptors. Mechanistically, R-spondin interacts with the extracellular domain of ZNRF3 and induces the association between ZNRF3 and LGR4, which results in membrane clearance of ZNRF3. These data suggest that R-spondin enhances Wnt signalling by inhibiting ZNRF3. Our study provides new mechanistic insights into the regulation of Wnt receptor turnover, and reveals ZNRF3 as a tractable target for therapeutic exploration.
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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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Grocott T, Johnson S, Bailey AP, Streit A. Neural crest cells organize the eye via TGF-β and canonical Wnt signalling. Nat Commun 2011; 2:265. [PMID: 21468017 PMCID: PMC3104559 DOI: 10.1038/ncomms1269] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2010] [Accepted: 03/09/2011] [Indexed: 01/12/2023] Open
Abstract
In vertebrates, the lens and retina arise from different embryonic tissues raising the question of how they are aligned to form a functional eye. Neural crest cells are crucial for this process: in their absence, ectopic lenses develop far from the retina. Here we show, using the chick as a model system, that neural crest-derived transforming growth factor-βs activate both Smad3 and canonical Wnt signalling in the adjacent ectoderm to position the lens next to the retina. They do so by controlling Pax6 activity: although Smad3 may inhibit Pax6 protein function, its sustained downregulation requires transcriptional repression by Wnt-initiated β-catenin. We propose that the same neural crest-dependent signalling mechanism is used repeatedly to integrate different components of the eye and suggest a general role for the neural crest in coordinating central and peripheral parts of the sensory nervous system. In the developing eye, the lens and retina are derived from different embryonic tissues, and how these two structures develop next to each other is of interest. In this study, the authors show that transforming growth factor-β secreted by neural crest cells is critical for the positioning of the lens next to the retina.
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Affiliation(s)
- Timothy Grocott
- Department of Craniofacial Development, King's College London, Guy's Campus, London SE1 9RT, UK
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Davis J, Piatigorsky J. Overexpression of Pax6 in mouse cornea directly alters corneal epithelial cells: changes in immune function, vascularization, and differentiation. Invest Ophthalmol Vis Sci 2011; 52:4158-68. [PMID: 21447684 DOI: 10.1167/iovs.10-6726] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
PURPOSE To assess whether Pax6 functions directly in the cornea, a corneal-preferred promoter was used to overexpress Pax6 specifically in the cornea. METHODS Transgenic mice harboring a construct containing mouse Pax6 coding sequences fused downstream of the aldehyde dehydrogenase 3a1 (Aldh3a1) promoter were generated (Pax6 Tg). Pax6 expression was analyzed by Western blot and immunohistochemistry. Eye sections were stained with hematoxylin and eosin, Schiff reagent, and fluorescein, to assess morphologic changes, the presence of goblet cells, and barrier integrity, respectively. Gene expression changes in mildly affected Pax6 Tg corneas were compared to age-matched, wild-type (WT) corneas by microarray analysis and quantitative PCR. Promoter regulation of several differentially expressed genes was examined by monitoring luciferase activity of reporter constructs after cotransfection with Pax6 in COS7 cells. RESULTS Corneal overexpression of Pax6 produces an abnormal cornea with altered epithelial cell morphology, neovascularization, immune cell invasion, and a compromised barrier; the lens appeared normal. Major changes in expression of genes involved in immune function, vascularization, and epithelial differentiation occurred in corneas from Pax6 Tg versus WT mice. The keratin (K) profile was dramatically altered in the Pax6 Tg corneas, as were several components of the Wnt signaling pathway. In severely affected Pax6 Tg corneas, K12 was reduced, and Pax6 was redistributed into the cytoplasm. Promoters from the chitinase 3-like 3, Wnt inhibitory factor 1, and fms-related tyrosine kinase 1/soluble VEGF receptor genes were upregulated five-, seven-, and threefold, respectively, by Pax6 in transfected COS7 cells. CONCLUSIONS Pax6 functions directly to maintain normal, corneal epithelial cells.
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Affiliation(s)
- Janine Davis
- Laboratory of Molecular and Developmental Biology, National Eye Institute, National Institutes of Health, Bethesda, Maryland, USA.
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Liu W. Focus on molecules: Wnt8b: a suppressor of early eye and retinal progenitor formation. Exp Eye Res 2011; 101:113-4. [PMID: 21219900 DOI: 10.1016/j.exer.2010.12.015] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2010] [Accepted: 12/30/2010] [Indexed: 11/18/2022]
Affiliation(s)
- Wei Liu
- Department of Ophthalmology and Visual Sciences, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA.
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