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McNamara NA, Gallup M, Porco TC. Establishing PAX6 as a biomarker to detect early loss of ocular phenotype in human patients with Sjögren's syndrome. Invest Ophthalmol Vis Sci 2014; 55:7079-84. [PMID: 25228544 DOI: 10.1167/iovs.14-14828] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
PURPOSE Sjögren's syndrome (SS) is a common autoimmune disease that can cause aqueous-deficient dry eye and the aberrant differentiation of ocular mucosal epithelial cells toward a lineage that is pathologically keratinized and skin-like. PAX6 is the master regulator of corneal lineage commitment. Recently, we showed a functional role for PAX6 in preventing ocular surface damage induced by the proinflammatory cytokine, IL-1β, in a mouse model of SS. Here, we examine PAX6's potential as a clinical biomarker that predicts ocular surface disease in SS patients. METHODS Impression cytology specimens isolated from the bulbar conjunctiva of control (n = 43) and SS patients (n = 43) were used to evaluate the relative abundance of PAX6, IL-1β, and pathologic keratinization marker, small proline-rich protein (SPRR1B) by TaqMan qPCR. Transcript expression was examined relative to clinical data, including the ocular staining score (OSS), tear breakup time (TBUT), Schirmer tear test, serum autoantibody results, and the labial salivary gland focus score. RESULTS PAX6 expression was significantly reduced in SS patients (P = 0.010, Wilcoxon rank sum test), and highly correlated with OSS (Spearman ρ = 0.239, 95% CI 0.02-0.43; P = 0.027). The extent to which PAX6 predicted SPRR1B was largely dependent on IL-1β expression (R(2) = 0.28, P < 0.01) and elevated IL-1β predicted reduced TBUT (R(2) = 0.24, P = 0.035), low tear secretion (R(2) = 0.30, P = 0.011), and focus score (R(2) = 0.21, P = 0.002). CONCLUSIONS Downregulation of PAX6 in SS patients was highly associated with ocular surface damage and largely dependent on the level of inflammation. Restoration of PAX6 may provide a clinical approach to manage dry eye in SS patients.
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Affiliation(s)
- Nancy A McNamara
- Francis I. Proctor Foundation, University of California San Francisco, San Francisco, California, United States
| | - Marianne Gallup
- Francis I. Proctor Foundation, University of California San Francisco, San Francisco, California, United States
| | - Travis C Porco
- Francis I. Proctor Foundation, University of California San Francisco, San Francisco, California, United States Department of Ophthalmology, University of California San Francisco, San Francisco, California, United States Department of Epidemiology and Biostatistics, University of California San Francisco, San Francisco, California, United States
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Brzeszczynska J, Samuel K, Greenhough S, Ramaesh K, Dhillon B, Hay DC, Ross JA. Differentiation and molecular profiling of human embryonic stem cell-derived corneal epithelial cells. Int J Mol Med 2014; 33:1597-606. [PMID: 24676408 DOI: 10.3892/ijmm.2014.1714] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2014] [Accepted: 02/14/2014] [Indexed: 11/06/2022] Open
Abstract
It has been suggested that the isolation of scalable populations of limbal stem cells may lead to radical changes in ocular therapy. In particular, the derivation and transplantation of corneal stem cells from these populations may result in therapies providing clinical normality of the diseased or damaged cornea. Although feasible in theory, the lack of donor material in sufficient quantity and quality currently limits such a strategy. A potential scalable source of corneal cells could be derived from pluripotent stem cells (PSCs). We developed an in vitro and serum-free corneal differentiation model which displays significant promise. Our stepwise differentiation model was designed with reference to development and gave rise to cells which displayed similarities to epithelial progenitor cells which can be specified to cells displaying a corneal epithelial phenotype. We believe our approach is novel, provides a robust model of human development and in the future, may facilitate the generation of corneal epithelial cells that are suitable for clinical use. Additionally, we demonstrate that following continued cell culture, stem cell-derived corneal epithelial cells undergo transdifferentiation and exhibit squamous metaplasia and therefore, also offer an in vitro model of disease.
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Affiliation(s)
- J Brzeszczynska
- Tissue Injury and Repair Group, MRC Centre for Regenerative Medicine, Chancellor's Building, University of Edinburgh, Edinburgh EH16 4SB, Scotland, UK
| | - K Samuel
- SNBTS Cellular Therapy Group, MRC Centre for Regenerative Medicine, Chancellor's Building, University of Edinburgh, Edinburgh EH16 4SB, Scotland, UK
| | - S Greenhough
- Pluripotent Stem Cell Hepatocyte Development Group, MRC Centre for Regenerative Medicine, Chancellor's Building, University of Edinburgh, Edinburgh EH16 4SB, Scotland, UK
| | - K Ramaesh
- Tennent Institute of Ophthalmology, Gartnavel General Hospital, Glasgow G12 0YN, Scotland, UK
| | - B Dhillon
- Department of Clinical and Surgical Sciences, Ophthalmology Section, Princess Alexandra Eye Pavilion, Royal Infirmary of Edinburgh, Edinburgh EH3 9HA, Scotland, UK
| | - D C Hay
- Pluripotent Stem Cell Hepatocyte Development Group, MRC Centre for Regenerative Medicine, Chancellor's Building, University of Edinburgh, Edinburgh EH16 4SB, Scotland, UK
| | - J A Ross
- Tissue Injury and Repair Group, MRC Centre for Regenerative Medicine, Chancellor's Building, University of Edinburgh, Edinburgh EH16 4SB, Scotland, UK
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Ng GY, Yeh LK, Zhang Y, Liu H, Feng GS, Kao WWY, Liu CY. Role of SH2-containing tyrosine phosphatase Shp2 in mouse corneal epithelial stratification. Invest Ophthalmol Vis Sci 2013; 54:7933-42. [PMID: 24204042 DOI: 10.1167/iovs.13-12646] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
PURPOSE Shp2 protein tyrosine phosphatase mediates a wide variety of receptor tyrosine kinases (RTK) cell signaling. Herein, we investigate the role of Shp2 in corneal morphogenesis and homeostasis. METHODS Shp2 was conditionally knocked out (Shp2(cko)) in Krt14-rtTA;tet-O-Cre;Shp2(f/f) triple transgenic mice administrated with doxycycline (Dox) from postnatal day 1 (P1) to P10, P15, and P25, respectively. In addition, corneal epithelial debridement was performed in adult (P42) mice treated with or without Dox for 8 days (from P42-P50). Mouse eyes were then subjected to histology and immunohistochemistry. RESULTS Shp2(cko) revealed impaired stratification of conjunctival and corneal epithelia during morphogenesis. Likewise, Shp2(cko) failed to restore epithelial stratification after a corneal epithelial wound in adult Shp2(cko). At the cellular level, the ratio of proliferating cell nuclear antigen (PCNA-positive)/total basal cells remained unchanged, but cells in G2/M (survivin-positive) phase was significantly increased in Shp2(cko) as compared with those in the control littermate. Interestingly, deltaN-p63 (ΔNp63) expression and the asymmetric division of the basal cells were coincidentally dampened in Shp2(cko). Transmission electron microscopic study showed that desmosome and hemidesmosome densities were reduced in the corneal epithelium of Shp2(cko). Immunohistochemistry also demonstrated that expression of E-cadherin/β-catenin junction and laminin-β1 was extensively downregulated in Shp2(cko). On the other hand, corneal epithelium lacking Shp2 remained positive for K14, Pax-6, and keratin 12 (K12), suggesting that Shp2 was dispensable for the corneal epithelial-type differentiation. CONCLUSIONS These data argued that Shp2 deficiency predominantly impacted p63-dependent cell division and cell adhesive ability, which resulted in the impairment of stratification during corneal epithelial development and wound healing.
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Affiliation(s)
- Gracia Y Ng
- Edith J. Crawley Vision Research Center/Department of Ophthalmology, College of Medicine, University of Cincinnati, Cincinnati, Ohio
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Chen YT, Chen FYT, Vijmasi T, Stephens DN, Gallup M, McNamara NA. Pax6 downregulation mediates abnormal lineage commitment of the ocular surface epithelium in aqueous-deficient dry eye disease. PLoS One 2013; 8:e77286. [PMID: 24143217 PMCID: PMC3797128 DOI: 10.1371/journal.pone.0077286] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2013] [Accepted: 08/31/2013] [Indexed: 11/23/2022] Open
Abstract
Keratinizing squamous metaplasia (SQM) of the ocular surface is a blinding consequence of systemic autoimmune disease and there is no cure. Ocular SQM is traditionally viewed as an adaptive tissue response during chronic keratoconjunctivitis sicca (KCS) that provokes pathological keratinization of the corneal epithelium and fibrosis of the corneal stroma. Recently, we established the autoimmune regulator-knockout (Aire KO) mouse as a model of autoimmune KCS and identified an essential role for autoreactive CD4+ T cells in SQM pathogenesis. In subsequent studies, we noted the down-regulation of paired box gene 6 (Pax6) in both human patients with chronic KCS associated with Sjögren’s syndrome and Aire KO mice. Pax6 encodes a pleiotropic transcription factor guiding eye morphogenesis during development. While the postnatal function of Pax6 is largely unknown, we hypothesized that its role in maintaining ocular surface homeostasis was disrupted in the inflamed eye and that loss of Pax6 played a functional role in the initiation and progression of SQM. Adoptive transfer of autoreactive T cells from Aire KO mice to immunodeficient recipients confirmed CD4+ T cells as the principal downstream effectors promoting Pax6 downregulation in Aire KO mice. CD4+ T cells required local signaling via Interleukin-1 receptor (IL-1R1) to provoke Pax6 loss, which prompted a switch from corneal-specific cytokeratin, CK12, to epidermal-specific CK10. The functional role of Pax6 loss in SQM pathogenesis was indicated by the reversal of SQM and restoration of ocular surface homeostasis following forced expression of Pax6 in corneal epithelial cells using adenovirus. Thus, tissue-restricted restoration of Pax6 prevented aberrant epidermal-lineage commitment suggesting adjuvant Pax6 gene therapy may represent a novel therapeutic approach to prevent SQM in patients with chronic inflammatory diseases of the ocular surface.
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Affiliation(s)
- Ying Ting Chen
- Francis I. Proctor Foundation, University of California San Francisco, San Francisco, California, United States of America
| | - Feeling Y. T. Chen
- Francis I. Proctor Foundation, University of California San Francisco, San Francisco, California, United States of America
| | - Trinka Vijmasi
- Francis I. Proctor Foundation, University of California San Francisco, San Francisco, California, United States of America
| | - Denise N. Stephens
- Francis I. Proctor Foundation, University of California San Francisco, San Francisco, California, United States of America
| | - Marianne Gallup
- Francis I. Proctor Foundation, University of California San Francisco, San Francisco, California, United States of America
| | - Nancy A. McNamara
- Francis I. Proctor Foundation, University of California San Francisco, San Francisco, California, United States of America
- Departments of Anatomy and Ophthalmology, University of California San Francisco, San Francisco, California, United States of America
- School of Optometry and Vision Science Graduate Group, University of California, Berkeley, California, United States of America
- * E-mail:
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Douvaras P, Mort RL, Edwards D, Ramaesh K, Dhillon B, Morley SD, Hill RE, West JD. Increased corneal epithelial turnover contributes to abnormal homeostasis in the Pax6(+/-) mouse model of aniridia. PLoS One 2013; 8:e71117. [PMID: 23967157 PMCID: PMC3742784 DOI: 10.1371/journal.pone.0071117] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2013] [Accepted: 06/24/2013] [Indexed: 01/09/2023] Open
Abstract
We aimed to test previous predictions that limbal epithelial stem cells (LESCs) are quantitatively deficient or qualitatively defective in Pax6+/− mice and decline with age in wild-type (WT) mice. Consistent with previous studies, corneal epithelial stripe patterns coarsened with age in WT mosaics. Mosaic patterns were also coarser in Pax6+/− mosaics than WT at 15 weeks but not at 3 weeks, which excludes a developmental explanation and strengthens the prediction that Pax6+/− mice have a LESC-deficiency. To investigate how Pax6 genotype and age affected corneal homeostasis, we compared corneal epithelial cell turnover and label-retaining cells (LRCs; putative LESCs) in Pax6+/− and WT mice at 15 and 30 weeks. Limbal BrdU-LRC numbers were not reduced in the older WT mice, so this analysis failed to support the predicted age-related decline in slow-cycling LESC numbers in WT corneas. Similarly, limbal BrdU-LRC numbers were not reduced in Pax6+/− heterozygotes but BrdU-LRCs were also present in Pax6+/− corneas. It seems likely that Pax6+/− LRCs are not exclusively stem cells and some may be terminally differentiated CD31-positive blood vessel cells, which invade the Pax6+/− cornea. It was not, therefore, possible to use this approach to test the prediction that Pax6+/− corneas had fewer LESCs than WT. However, short-term BrdU labelling showed that basal to suprabasal movement (leading to cell loss) occurred more rapidly in Pax6+/− than WT mice. This implies that epithelial cell loss is higher in Pax6+/− mice. If increased corneal epithelial cell loss exceeds the cell production capacity it could cause corneal homeostasis to become unstable, resulting in progressive corneal deterioration. Although it remains unclear whether Pax6+/− mice have LESC-deficiency, we suggest that features of corneal deterioration, that are often taken as evidence of LESC-deficiency, might occur in the absence of stem cell deficiency if corneal homeostasis is destabilised by excessive cell loss.
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Affiliation(s)
- Panagiotis Douvaras
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom
| | - Richard L. Mort
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom
| | - Dominic Edwards
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom
| | - Kanna Ramaesh
- Tennent Institute of Ophthalmology, Gartnaval General Hospital, Glasgow, United Kingdom
| | - Baljean Dhillon
- School of Clinical Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Steven D. Morley
- Division of Health Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Robert E. Hill
- Medical Research Council Human Genetics Unit, Medical Research Council Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, United Kingdom
| | - John D. West
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom
- * E-mail:
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Elso C, Lu X, Weisner PA, Thompson HL, Skinner A, Carver E, Stubbs L. A reciprocal translocation dissects roles of Pax6 alternative promoters and upstream regulatory elements in the development of pancreas, brain, and eye. Genesis 2013; 51:630-46. [PMID: 23798316 DOI: 10.1002/dvg.22409] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2013] [Revised: 05/28/2013] [Accepted: 06/12/2013] [Indexed: 12/23/2022]
Abstract
Pax6 encodes a transcription factor with key roles in the development of the pancreas, central nervous system, and eye. Gene expression is orchestrated by several alternative promoters and enhancer elements that are distributed over several hundred kilobases. Here, we describe a reciprocal translocation, called 1Gso, which disrupts the integrity of transcripts arising from the 5'-most promoter, P0, and separates downstream promoters from enhancers active in pancreas and eye. Despite this fact, 1Gso animals exhibit none of the dominant Pax6 phenotypes, and the translocation complements recessive brain and craniofacial phenotypes. However, 1Gso fails to complement Pax6 recessive effects in lacrimal gland, conjunctiva, lens, and pancreas. The 1Gso animals also express a corneal phenotype that is related to but distinct from that expressed by Pax6 null mutants, and an abnormal density and organization of retinal ganglion cell axons; these phenotypes may be related to a modest upregulation of Pax6 expression from downstream promoters that we observed during development. Our investigation maps the activities of Pax6 alternative promoters including a novel one in developing tissues, confirms the phenotypic consequences of upstream enhancer disruption, and limits the likely effects of the P0 transcript null mutation to recessive abnormalities in the pancreas and specific structures of the eye.
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Affiliation(s)
- Colleen Elso
- Genome Biology Division, Lawrence Livermore National Laboratory, Livermore, California
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57
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Ocular surface development and gene expression. J Ophthalmol 2013; 2013:103947. [PMID: 23533700 PMCID: PMC3595720 DOI: 10.1155/2013/103947] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2012] [Accepted: 01/16/2013] [Indexed: 01/10/2023] Open
Abstract
The ocular surface-a continuous epithelial surface with regional specializations including the surface and glandular epithelia of the cornea, conjunctiva, and lacrimal and meibomian glands connected by the overlying tear film-plays a central role in vision. Molecular and cellular events involved in embryonic development, postnatal maturation, and maintenance of the ocular surface are precisely regulated at the level of gene expression by a well-coordinated network of transcription factors. A thorough appreciation of the biological characteristics of the ocular surface in terms of its gene expression profiles and their regulation provides us with a valuable insight into the pathophysiology of various blinding disorders that disrupt the normal development, maturation, and/or maintenance of the ocular surface. This paper summarizes the current status of our knowledge related to the ocular surface development and gene expression and the contribution of different transcription factors to this process.
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Blanco-Kelly F, Villaverde-Montero C, Lorda-Sánchez I, Millán JM, Trujillo-Tiebas MJ, Ayuso C. Guidelines for genetic study of aniridia. ACTA ACUST UNITED AC 2012; 88:145-52. [PMID: 23597644 DOI: 10.1016/j.oftal.2012.07.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2011] [Revised: 04/24/2012] [Accepted: 07/10/2012] [Indexed: 10/27/2022]
Abstract
INTRODUCTION Aniridia is a panocular disorder which occurs in 1/50,000 to 1/100,000 live births and can appear either in isolated form or in the context of a syndrome. Isolated aniridia is inherited as an autosomal dominant condition and is caused by mutations of the PAX6 gene. A variety of techniques and methodologies within molecular genetics and cytogenetics are used to study these mutations. OBJECTIVE To identify the different aspects of this disease and to provide a guide for proper genetic diagnosis leading to improved clinical management of the disease. DEVELOPMENT Aniridia is an autosomal dominant disease that primarily affects the iris, though it can impact most of the ocular structures. The disease is mainly caused by mutations in the PAX6 gene located on chromosome 11p13 which encodes a transcription factor that is involved in the development of the eye. Genetic analysis of aniridia is complex and requires the use of both molecular genetics and cytogenetics techniques. These procedures are indicated in all cases of aniridia. It is important bear certain clinical and technical aspects in mind prior to starting analysis or providing genetic counseling for patients and their families. CONCLUSIONS The use of molecular genetic techniques in the genetic diagnosis of aniridia enables patients and their families to receive better clinical management.
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Affiliation(s)
- F Blanco-Kelly
- Servicio de Genética, Instituto de Investigación Sanitaria, Fundación Jiménez Díaz, Madrid, Spain.
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Kenchegowda D, Harvey SAK, Swamynathan S, Lathrop KL, Swamynathan SK. Critical role of Klf5 in regulating gene expression during post-eyelid opening maturation of mouse corneas. PLoS One 2012; 7:e44771. [PMID: 23024760 PMCID: PMC3443110 DOI: 10.1371/journal.pone.0044771] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2012] [Accepted: 08/07/2012] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Klf5 plays an important role in maturation and maintenance of the mouse ocular surface. Here, we quantify WT and Klf5-conditional null (Klf5CN) corneal gene expression, identify Klf5-target genes and compare them with the previously identified Klf4-target genes to understand the molecular basis for non-redundant functions of Klf4 and Klf5 in the cornea. METHODOLOGY/PRINCIPAL FINDINGS Postnatal day-11 (PN11) and PN56 WT and Klf5CN corneal transcriptomes were quantified by microarrays to compare gene expression in maturing WT corneas, identify Klf5-target genes, and compare corneal Klf4- and Klf5-target genes. Whole-mount corneal immunofluorescent staining was employed to examine CD45+ cell influx and neovascularization. Effect of Klf5 on expression of desmosomal components was studied by immunofluorescent staining and transient co-transfection assays. Expression of 714 and 753 genes was increased, and 299 and 210 genes decreased in PN11 and PN56 Klf5CN corneas, respectively, with 366 concordant increases and 72 concordant decreases. PN56 Klf5CN corneas shared 241 increases and 98 decreases with those previously described in Klf4CN corneas. Xenobiotic metabolism related pathways were enriched among genes decreased in Klf5CN corneas. Expression of angiogenesis and immune response-related genes was elevated, consistent with neovascularization and CD45+ cell influx in Klf5CN corneas. Expression of 1574 genes was increased and 1915 genes decreased in WT PN56 compared with PN11 corneas. Expression of ECM-associated genes decreased, while that of solute carrier family members increased in WT PN56 compared with PN11 corneas. Dsg1a, Dsg1b and Dsp were down-regulated in Klf5CN corneas and their corresponding promoter activities were stimulated by Klf5 in transient co-transfection assays. CONCLUSIONS/SIGNIFICANCE Differences between PN11 and PN56 corneal Klf5-target genes reveal dynamic changes in functions of Klf5 during corneal maturation. Klf5 contributes to corneal epithelial homeostasis by regulating the expression of desmosomal components. Klf4- and Klf5-target genes are largely distinct, consistent with their non-redundant roles in the mouse cornea.
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Affiliation(s)
- Doreswamy Kenchegowda
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Stephen A. K. Harvey
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Sudha Swamynathan
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Kira L. Lathrop
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Shivalingappa K. Swamynathan
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
- Department of Cell Biology and Physiology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
- McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
- * E-mail:
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Ordonez P, Di Girolamo N. Limbal epithelial stem cells: role of the niche microenvironment. Stem Cells 2012; 30:100-7. [PMID: 22131201 DOI: 10.1002/stem.794] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The cornea contains a reservoir of self-regenerating epithelial cells that are essential for maintaining its transparency and good vision. The study of stem cells in this functionally important organ has grown over the past four decades, partly due to the ease with which this tissue is visualized, its accessibility with minimally invasive instruments, and the fact that its stem cells are segregated within a transitional zone between two functionally diverse epithelia. While human, animal, and ex vivo models have been instrumental in progressing the corneal stem cell field, there is still much to be discovered about this exquisitely sensitive window for sight. This review will provide an overview of the human cornea, where its stem cells reside and how components of the microenvironment including extracellular matrix proteins and their integrin receptors are thought to govern corneal stem cell homeostasis.
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Affiliation(s)
- Paula Ordonez
- Inflammation and Infection Research Centre, School of Medical Sciences, University of New South Wales, Sydney, New South Wales, Australia
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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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Edén U, Fagerholm P, Danyali R, Lagali N. Pathologic epithelial and anterior corneal nerve morphology in early-stage congenital aniridic keratopathy. Ophthalmology 2012; 119:1803-10. [PMID: 22512983 DOI: 10.1016/j.ophtha.2012.02.043] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2011] [Revised: 02/27/2012] [Accepted: 02/27/2012] [Indexed: 12/13/2022] Open
Abstract
OBJECTIVE To document the clinical and morphologic corneal findings in the early stages of congenital aniridic keratopathy in Swedish families. DESIGN Prospective, observational, comparative case series. PARTICIPANTS A total of 16 eyes of 16 subjects with congenital aniridic keratopathy and a clear central cornea, and 6 eyes from 6 healthy controls (unaffected relatives). Nine of the 16 eyes with aniridia came from 5 families with a documented familial history of aniridia. METHODS Detailed ophthalmic examinations included best spectacle-corrected visual acuity (BSCVA), tear film production, tear break-up time (BUT), corneal touch sensitivity, intraocular pressure measurement, ultrasound pachymetry, slit-lamp biomicroscopy, and laser scanning in vivo confocal microscopy (IVCM). MAIN OUTCOME MEASURES Confirmed stage of aniridic keratopathy, clinical parameters of cornea and tear film (visual acuity, sensitivity, corneal thickness, tear production, and BUT), and the morphologic status of corneal epithelium, sub-basal nerves, and limbal palisades of Vogt. RESULTS In early-stage aniridic keratopathy, BSCVA and tear BUT were reduced relative to controls (P < 0.001 for both), and corneal thickness was increased (P=0.01). Inflammatory dendritic cells were present in the central epithelium in aniridia, with significantly increased density relative to controls (P = 0.001). Discrete focal opacities in the basal epithelial region were present in 5 of 11 aniridia cases with an otherwise clear cornea. Opacities were associated with dendritic cells and harbored structures presumed to be goblet cells. Sub-basal nerves were extremely dense in 3 aniridia cases, and a prominent whorl pattern of nerves and epithelial cells was observed in 1 case. Normal limbal palisade morphology was absent in aniridia but present in controls. CONCLUSIONS Early-stage aniridic keratopathy is characterized by the development of focal opacities in the basal epithelium, altered sub-basal nerves, infiltration of the central epithelium by dendritic cells, tear film instability, and increased corneal thickness and degradation of limbal palisade architecture. These findings may help to elucidate the pathogenesis of aniridic keratopathy.
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Affiliation(s)
- Ulla Edén
- Department of Ophthalmology, Institute for Clinical and Experimental Medicine, Faculty of Health Sciences, Linköping University, Linköping, Sweden.
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Mort RL, Douvaras P, Morley SD, Dorà N, Hill RE, Collinson JM, West JD. Stem cells and corneal epithelial maintenance: insights from the mouse and other animal models. Results Probl Cell Differ 2012; 55:357-94. [PMID: 22918816 PMCID: PMC3471528 DOI: 10.1007/978-3-642-30406-4_19] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Maintenance of the corneal epithelium is essential for vision and is a dynamic process incorporating constant cell production, movement and loss. Although cell-based therapies involving the transplantation of putative stem cells are well advanced for the treatment of human corneal defects, the scientific understanding of these interventions is poor. No definitive marker that discriminates stem cells that maintain the corneal epithelium from the surrounding tissue has been discovered and the identity of these elusive cells is, therefore, hotly debated. The key elements of corneal epithelial maintenance have long been recognised but it is still not known how this dynamic balance is co-ordinated during normal homeostasis to ensure the corneal epithelium is maintained at a uniform thickness. Most indirect experimental evidence supports the limbal epithelial stem cell (LESC) hypothesis, which proposes that the adult corneal epithelium is maintained by stem cells located in the limbus at the corneal periphery. However, this has been challenged recently by the corneal epithelial stem cell (CESC) hypothesis, which proposes that during normal homeostasis the mouse corneal epithelium is maintained by stem cells located throughout the basal corneal epithelium with LESCs only contributing during wound healing. In this chapter we review experimental studies, mostly based on animal work, that provide insights into how stem cells maintain the normal corneal epithelium and consider the merits of the alternative LESC and CESC hypotheses. Finally, we highlight some recent research on other stem cell systems and consider how this could influence future research directions for identifying the stem cells that maintain the corneal epithelium.
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Mort RL, Bentley AJ, Martin FL, Collinson JM, Douvaras P, Hill RE, Morley SD, Fullwood NJ, West JD. Effects of aberrant Pax6 gene dosage on mouse corneal pathophysiology and corneal epithelial homeostasis. PLoS One 2011; 6:e28895. [PMID: 22220198 PMCID: PMC3248408 DOI: 10.1371/journal.pone.0028895] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2011] [Accepted: 11/16/2011] [Indexed: 11/18/2022] Open
Abstract
Background Altered dosage of the transcription factor PAX6 causes multiple human eye pathophysiologies. PAX6+/− heterozygotes suffer from aniridia and aniridia-related keratopathy (ARK), a corneal deterioration that probably involves a limbal epithelial stem cell (LESC) deficiency. Heterozygous Pax6+/Sey-Neu (Pax6+/−) mice recapitulate the human disease and are a good model of ARK. Corneal pathologies also occur in other mouse Pax6 mutants and in PAX77Tg/− transgenics, which over-express Pax6 and model human PAX6 duplication. Methodology/Principal Findings We used electron microscopy to investigate ocular defects in Pax6+/− heterozygotes (low Pax6 levels) and PAX77Tg/− transgenics (high Pax6 levels). As well as the well-documented epithelial defects, aberrant Pax6 dosage had profound effects on the corneal stroma and endothelium in both genotypes, including cellular vacuolation, similar to that reported for human macular corneal dystrophy. We used mosaic expression of an X-linked LacZ transgene in X-inactivation mosaic female (XLacZTg/−) mice to investigate corneal epithelial maintenance by LESC clones in Pax6+/− and PAX77Tg/− mosaic mice. PAX77Tg/− mosaics, over-expressing Pax6, produced normal corneal epithelial radial striped patterns (despite other corneal defects), suggesting that centripetal cell movement was unaffected. Moderately disrupted patterns in Pax6+/− mosaics were corrected by introducing the PAX77 transgene (in Pax6+/−, PAX77Tg/− mosaics). Pax6Leca4/+, XLacZTg/− mosaic mice (heterozygous for the Pax6Leca4 missense mutation) showed more severely disrupted mosaic patterns. Corrected corneal epithelial stripe numbers (an indirect estimate of active LESC clone numbers) declined with age (between 15 and 30 weeks) in wild-type XLacZTg/− mosaics. In contrast, corrected stripe numbers were already low at 15 weeks in Pax6+/− and PAX77Tg/− mosaic corneas, suggesting Pax6 under- and over-expression both affect LESC clones. Conclusions/Significance Pax6+/− and PAX77Tg/− genotypes have only relatively minor effects on LESC clone numbers but cause more severe corneal endothelial and stromal defects. This should prompt further investigations of the pathophysiology underlying human aniridia and ARK.
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Affiliation(s)
- Richard L. Mort
- Division of Reproductive and Developmental Sciences, University of Edinburgh, Edinburgh, United Kingdom
- Medical Research Council Human Genetics Unit, Medical Research Council Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, United Kingdom
| | - Adam J. Bentley
- Division of Biomedical and Life Sciences, Lancaster University, Lancaster, United Kingdom
| | - Francis L. Martin
- Centre for Biophotonics, Lancaster University, Lancaster, United Kingdom
| | - J. Martin Collinson
- Institute of Medical Sciences, University of Aberdeen, Aberdeen, United Kingdom
| | - Panagiotis Douvaras
- Division of Reproductive and Developmental Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Robert E. Hill
- Medical Research Council Human Genetics Unit, Medical Research Council Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, United Kingdom
| | - Steven D. Morley
- School of Clinical Sciences & Community Health, University of Edinburgh, Edinburgh, United Kingdom
| | - Nigel J. Fullwood
- Division of Biomedical and Life Sciences, Lancaster University, Lancaster, United Kingdom
| | - John D. West
- Division of Reproductive and Developmental Sciences, University of Edinburgh, Edinburgh, United Kingdom
- * E-mail:
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Abstract
Pax6 encodes a highly conserved transcriptional regulator with two DNA-binding motifs, a paired domain and a paired-like homeodomain. Humans carrying PAX6 loss-of-function mutations suffer from abnormal development of the eyes (congenital aniridia) and brain. Small eye mice carrying Pax6 loss-of-function mutations provide a good model for these human conditions. Their analysis has demonstrated the critical importance of this transcription factor in multiple cell types and at several key stages of forebrain development. In the forebrain, Pax6 is critical for the establishment of the pallial-subpallial boundary, which separates dorsal (future cerebral cortex) and ventral (future striatum) telencephalic regions. Levels of Pax6 expression are critically important for cortical progenitor proliferation and its presence in a rostro-lateral(high) to caudo-medial(low) gradient in the cortex is necessary to establish rostro-lateral identities. Furthermore, axon guidance is disrupted in Pax6⁻/⁻ mutants: the majority of thalamocortical axons fail to enter the ventral telencephalon and those that do are unable to innervate their cortical targets. The extent to which the effects of Pax6 later in development are secondary to its effects in early patterning and proliferation remains largely unknown. This is likely to be clarified by future studies on the molecular mechanisms of action of Pax6 and, in particular, the identification of its downstream target genes. Such studies should also help generate an increasingly coherent understanding of how this pleiotropic transcription factor becomes involved in so many facets of neural development.
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Affiliation(s)
- Petrina A Georgala
- Genes and Development Group, Centre for Integrative Physiology, University of Edinburgh, Edinburgh EH89XD, United Kingdom.
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Douvaras P, Webb S, Whitaker DA, Dorà N, Hill RE, Dorin JR, West JD. Rare corneal clones in mice suggest an age-related decrease of stem cell activity and support the limbal epithelial stem cell hypothesis. Stem Cell Res 2011; 8:109-19. [PMID: 22099025 DOI: 10.1016/j.scr.2011.08.007] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/21/2010] [Revised: 08/05/2011] [Accepted: 08/27/2011] [Indexed: 01/10/2023] Open
Abstract
The anterior ocular surface comprises the cornea, conjunctiva and a narrow intermediate region called the limbus. It is widely accepted that the corneal epithelium is maintained by stem cells but different hypotheses propose that the stem cells that maintain the mouse corneal epithelium during normal homeostasis are located either in the basal limbal epithelium or throughout the basal corneal epithelium. There are no specific markers to help test these alternatives and new methods are required to distinguish between them. We observed that KRT5(LacZ/-) transgenic mice produced rare β-galactosidase (β-gal)-positive radial stripes in the corneal epithelium. These stripes are likely to be clonal lineages of cells derived from stem cells, so they provide a lineage marker for actively proliferating stem cells. The distributions of the β-gal-positive radial stripes suggested they extended centripetally from the limbus, supporting the limbal epithelial stem cell (LESC) hypothesis. Stripe frequency declined between 15 and 30 weeks, which predicts a reduction in stem cell function with age. Pax6(+/-), KRT5(LacZ/-) corneas had small patches rather than stripes, which confirms that corneal maintenance is abnormal in Pax6(+/-) mice.
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Affiliation(s)
- Panagiotis Douvaras
- Division of Reproductive and Developmental Sciences, Genes and Development Group, University of Edinburgh, Edinburgh EH8 9XD, Scotland, UK
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Gupta D, Harvey SAK, Kaminski N, Swamynathan SK. Mouse conjunctival forniceal gene expression during postnatal development and its regulation by Kruppel-like factor 4. Invest Ophthalmol Vis Sci 2011; 52:4951-62. [PMID: 21398290 DOI: 10.1167/iovs.10-7068] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
PURPOSE To identify the changes in postnatal mouse conjunctival forniceal gene expression and their regulation by Klf4 during the eye-opening stage when the goblet cells first appear. METHODS Laser microdissection (LMD) was used to collect conjunctival forniceal cells from postnatal (PN) day 9, PN14 and PN20 wild-type (WT), and PN14 Klf4-conditional null (Klf4CN) mice, in which goblet cells are absent, developing, present, and missing, respectively. Microarrays were used to compare gene expression among these groups. Expression of selected genes was validated by quantitative RT-PCR, and spatiotemporal expression was assessed by in situ hybridization. RESULTS This study identified 668, 251, 1160, and 139 transcripts that were increased and 492, 377, 1419, and 57 transcripts that were decreased between PN9 and PN14, PN14 and PN20, PN9 and PN20, and PN14 WT and Klf4CN conjunctiva, respectively. Transcripts encoding transcription factors Spdef, FoxA1, and FoxA3 that regulate goblet cell development in other mucosal epithelia, and epithelium-specific Ets (ESE) transcription factor family members were increased during conjunctival development. Components of pathways related to the mesenchymal-epithelial transition, glycoprotein biosynthesis, mucosal immunity, signaling, and endocytic and neural regulation were increased during conjunctival development. Conjunctival Klf4 target genes differed significantly from the previously identified corneal Klf4 target genes, implying tissue-dependent regulatory targets for Klf4. CONCLUSIONS The changes in gene expression accompanying mouse conjunctival development were identified, and the role of Klf4 in this process was determined. This study provides new probes for examining conjunctival development and function and reveals that the gene regulatory network necessary for goblet cell development is conserved across different mucosal epithelia.
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Affiliation(s)
- Divya Gupta
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Eye and Ear Institute, 203 Lothrop Street, Pittsburgh PA 15213, USA
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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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Coutinho P, Pavlou S, Bhatia S, Chalmers KJ, Kleinjan DA, van Heyningen V. Discovery and assessment of conserved Pax6 target genes and enhancers. Genome Res 2011; 21:1349-59. [PMID: 21617155 DOI: 10.1101/gr.124115.111] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The characterization of transcriptional networks (TNs) is essential for understanding complex biological phenomena such as development, disease, and evolution. In this study, we have designed and implemented a procedure that combines in silico target screens with zebrafish and mouse validation, in order to identify cis-elements and genes directly regulated by Pax6. We chose Pax6 as the paradigm because of its crucial roles in organogenesis and human disease. We identified over 600 putative Pax6 binding sites and more than 200 predicted direct target genes, conserved in evolution from zebrafish to human and to mouse. This was accomplished using hidden Markov models (HMMs) generated from experimentally validated Pax6 binding sites. A small sample of genes, expressed in the neural lineage, was chosen from the predictions for RNA in situ validation using zebrafish and mouse models. Validation of DNA binding to some predicted cis-elements was also carried out using chromatin immunoprecipitation (ChIP) and zebrafish reporter transgenic studies. The results show that this combined procedure is a highly efficient tool to investigate the architecture of TNs and constitutes a useful complementary resource to ChIP and expression data sets because of its inherent spatiotemporal independence. We have identified several novel direct targets, including some putative disease genes, among them Foxp2; these will allow further dissection of Pax6 function in development and disease.
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Affiliation(s)
- Pedro Coutinho
- Medical Research Council (MRC) Human Genetics Unit, Western General Hospital, Edinburgh EH4 2XU, UK.
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Kenchegowda D, Swamynathan S, Gupta D, Wan H, Whitsett J, Swamynathan SK. Conditional disruption of mouse Klf5 results in defective eyelids with malformed meibomian glands, abnormal cornea and loss of conjunctival goblet cells. Dev Biol 2011; 356:5-18. [PMID: 21600198 DOI: 10.1016/j.ydbio.2011.05.005] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2010] [Revised: 04/05/2011] [Accepted: 05/03/2011] [Indexed: 01/05/2023]
Abstract
Members of the Krüppel-like family of transcription factors regulate diverse developmental processes in various organs. Previously, we have demonstrated the role of Klf4 in the mouse ocular surface. Herein, we determined the role of the structurally related Klf5, using Klf5-conditional null (Klf5CN) mice derived by mating Klf5-LoxP and Le-Cre mice. Klf5 mRNA was detected as early as embryonic day 12 (E12) in the cornea, conjunctiva and eyelids, wherein its expression increased during development. Though the embryonic eye morphogenesis was unaltered in the Klf5CN mice, postnatal maturation was defective, resulting in smaller eyes with swollen eyelids that failed to separate properly. Klf5CN palpebral epidermis was hyperplastic with 7-9 layers of keratinocytes, compared with 2-3 in the wild type (WT). Klf5CN eyelid hair follicles and sebaceous glands were significantly enlarged, and the meibomian glands malformed. Klf5CN lacrimal glands displayed increased vasculature and large number of infiltrating cells. Klf5CN corneas were translucent, thicker with defective epithelial basement membrane and hypercellular stroma. Klf5CN conjunctiva lacked goblet cells, demonstrating that Klf5 is required for conjunctival goblet cell development. The number of Ki67-positive mitotic cells was more than doubled, consistent with the increased number of Klf5CN ocular surface epithelial cells. Co-ablation of Klf4 and Klf5 resulted in a more severe ocular surface phenotype compared with Klf4CN or Klf5CN, demonstrating that Klf4 and Klf5 share few if any, redundant functions. Thus, Klf5CN mice provide a useful model for investigating ocular surface pathologies involving meibomian gland dysfunction, blepharitis, corneal or conjunctival defects.
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Swamynathan S, Kenchegowda D, Piatigorsky J, Swamynathan S. Regulation of corneal epithelial barrier function by Kruppel-like transcription factor 4. Invest Ophthalmol Vis Sci 2011; 52:1762-9. [PMID: 21051695 DOI: 10.1167/iovs.10-6134] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Previously, the authors showed that Klf4-conditional null (Klf4CN) corneas display epithelial fragility. Here, they investigated the mechanism by which Klf4 regulates corneal epithelial barrier function. METHODS Klf4CN mice were generated by breeding Le-Cre with Klf4-LoxP mice. Fluorescein staining was used to test the corneal barrier function. RT-PCR, immunoblots, and immunofluorescence were used to detect the expression of cell junctional proteins. The effect of Klf4 on promoter activities was measured by transient cotransfection assays. Trans-epithelial electrical resistance (TEER) was used to measure the barrier-forming ability of control or anti-KLF4 siRNA-treated cells. RESULTS Increased fluorescein staining and decreased tight junction protein Tjp1 expression demonstrated that the Klf4CN corneal epithelial barrier function is defective. Expression of desmosomal components Dsp, Dsg-1a, and Dsg-1b was downregulated in the Klf4CN corneas, and their corresponding promoter activities were upregulated by Klf4 in transient cotransfection assays. Hemidesmosomal α3- and β4-integrin levels were not affected even though there were fewer hemidesmosomes in the Klf4CN corneas. The basement membrane components laminin-α5, -α3, -β3, and -β1-1 were downregulated, suggesting that the disrupted basement membrane is responsible for fewer hemidesmosomes in the Klf4CN cornea. Tight junction proteins OCLN1 and TJP1were downregulated in anti-KLF4 siRNA-treated cells, which failed to develop epithelial barrier function as measured by TEER. CONCLUSIONS Klf4 contributes to corneal epithelial barrier function by upregulating the expression of functionally related subsets of cell junctional proteins and basement membrane components.
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Affiliation(s)
- Sudha Swamynathan
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
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Isoform- and dose-sensitive feedback interactions between paired box 6 gene and delta-catenin in cell differentiation and death. Exp Cell Res 2010; 316:1070-81. [PMID: 20074565 DOI: 10.1016/j.yexcr.2010.01.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2009] [Revised: 12/17/2009] [Accepted: 01/04/2010] [Indexed: 12/11/2022]
Abstract
Pax6, a mammalian homolog of the Drosophila paired box gene family member expressed in stem and progenitor cells, resides at the top of the genetic hierarchy in controlling cell fates and morphogenesis. While Pax6 activation can lead to mitotic arrest, premature neurogenesis, and apoptosis, the underlying molecular mechanisms have not been resolved. Here we report that either Pax6(+5a) or Pax6(-5a) was sufficient to promote, whereas their knockdown reduced the expression of delta-catenin (CTNND2), a neural specific member of the armadillo/beta-catenin superfamily. Pax6(+5a) elicited stronger effects on delta-catenin than Pax6(-5a). Inducible Pax6(+5a) expression demonstrated a biphasic and dose-dependent regulation of delta-catenin expression and cell fates. A moderate upregulation of Pax6(+5a) promoted delta-catenin expression and induced neurite-like cellular protrusions, but increasing expression of Pax6(+5a) reversed these processes. Furthermore, sustained high expression of Pax6(+5a) triggered apoptosis as determined by the reduction of phospho-Bad, Bcl-2, survivin and procaspases, as well as the increases in Bax and cleaved poly(ADP-ribose) polymerase. Importantly, re-introducing delta-catenin by ectopic expression elicited a feedback suppression on Pax6(+5a) expression and reduced Pax6(+5a) induced apoptosis. Therefore, delta-catenin expression is not only controlled by Pax6, but it also provides a feedback suppression mechanism for their functional interactions with important implications in cellular morphogenesis, apoptosis, and cancer.
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Murphy MJ, Polok BK, Schorderet DF, Cleary ML. Essential role for Pbx1 in corneal morphogenesis. Invest Ophthalmol Vis Sci 2009; 51:795-803. [PMID: 19797217 DOI: 10.1167/iovs.08-3327] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
PURPOSE The Pbx TALE (three-amino-acid loop extension) homeodomain proteins interact with class 1 Hox proteins, which are master regulators of cell fate decisions. This study was performed to elucidate the role of the Pbx1 TALE protein in the corneal epithelium of mice. METHODS Pbx1(f/f) mice were crossed with mice containing Cre recombinase under the control of the K14 promoter. Subsequently, the eyes of these mice were dissected and prepared for histologic or molecular analysis. RESULTS Tissue-specific deletion of Pbx1 in the corneal epithelium of mice resulted in corneal dystrophy and clouding that was apparent in newborns and progressively worsened with age. Thickening of the cornea epithelium was accompanied by stromal infiltration with atypical basal cells, severe disorganization of stromal collagen matrix, and loss of corneal barrier function. High epithelial cell turnover was associated with perturbed expression of developmental regulators and aberrant differentiation, suggesting an important function for Pbx1 in determining corneal identity. CONCLUSIONS These studies establish an essential role of the Pbx1 proto-oncogene in corneal morphogenesis.
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Affiliation(s)
- Mark J Murphy
- Department of Pathology, Stanford University School of Medicine, Stanford, California 94305, USA
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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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García-Villegas R, Escamilla J, Sánchez-Guzmán E, Pastén A, Hernández-Quintero M, Gómez-Flores E, Castro-Muñozledo F. Pax-6 is expressed early in the differentiation of a corneal epithelial model system. J Cell Physiol 2009; 220:348-56. [DOI: 10.1002/jcp.21771] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Chen Y, Carlson EC, Chen ZY, Hamik A, Jain MK, Dunwoodie SL, Yang YC. Conditional deletion of Cited2 results in defective corneal epithelial morphogenesis and maintenance. Dev Biol 2009; 334:243-52. [PMID: 19632219 DOI: 10.1016/j.ydbio.2009.07.028] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2009] [Revised: 07/16/2009] [Accepted: 07/17/2009] [Indexed: 12/23/2022]
Abstract
Cited2 is an important transcriptional cofactor involved in multiple organ development. Gene profile analysis has identified Cited2 as one of the transcription factors expressed at high levels in adult mouse cornea. To address the function of Cited2 in corneal morphogenesis, we deleted Cited2 in surface ectoderm derived ocular structures including cornea by crossing Cited2-floxed mice with Le-Cre transgenic mice. Cited2(flox/flox);Le-Cre(+) eyes invariably displayed corneal opacity and developed spontaneous corneal neovascularization at older age. Fewer layers of corneal epithelial cells and the absence of cytokeratin 12 (K12) expression featured Cited2 deficient postnatal and adult eyes. Cited2 deficient cornea exhibited impaired healing in response to corneal epithelial debridement by manifesting abnormal histology, lack of K12 expression and corneal neovascularization. Moreover, mechanistic studies suggest that Cited2 may play a role in corneal morphogenesis in part through modulating the expression of Pax6 and Klf4. Collectively, these findings demonstrate a novel function of Cited2 in postnatal corneal morphogenesis and maintenance. Our study will help better understand the molecular mechanisms involved in corneal biology, and more importantly, it may provide a valuable animal model for testing therapeutics in the treatment of corneal disorders, especially blindness as a result of corneal epithelial cell deficiency.
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Affiliation(s)
- Yu Chen
- Department of Biochemistry and Cancer Center, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
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Leiper LJ, Ou J, Walczysko P, Kucerova R, Lavery DN, West JD, Collinson JM. Control of patterns of corneal innervation by Pax6. Invest Ophthalmol Vis Sci 2008; 50:1122-8. [PMID: 19029029 DOI: 10.1167/iovs.08-2812] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Corneal nerves play essential roles in maintaining the ocular surface through provision of neurotrophic support, but genetic control of corneal innervation is poorly understood. The possibility of a neurotrophic failure in ocular surface disease associated with heterozygosity at the Pax6 locus (aniridia-related keratopathy [ARK]) was investigated. METHODS Patterns of corneal innervation were studied during development and aging in mice with different Pax6 dosages and in chimeras. Immunohistochemistry and ELISA-based assays were used to determine the molecular basis of defects seen in Pax6 mutants, and wound healing assays were performed. RESULTS In adults, the Pax6(+/-) epithelium was less densely innervated than the wild-type epithelium, and radial projection of epithelial nerves was disrupted. Neurotrophic support of the corneal epithelium appeared normal. Directed nerve projection correlated with patterns of epithelial cell migration in adult wild-types, but innervation defects observed in Pax6(+/-) mice were not fully corrected in wound healing or chimeric models where directed epithelial migration was restored. CONCLUSIONS Pax6 dosage nonautonomously controls robust directed radial projection of corneal neurons, and the guidance cues for growth cone guidance are not solely dependent on directed epithelial migration. There is little evidence that ARK represents neurotrophic keratitis.
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Affiliation(s)
- Lucy J Leiper
- School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen, United Kingdom
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Abstract
Aniridia is a rare panocular disorder affecting the cornea, anterior chamber, iris, lens, retina, macula and optic nerve. It occurs because of mutations in PAX6 on band p13 of chromosome 11. It is associated with a number of syndromes, including Wilm's tumour, bilateral sporadic aniridia, genitourinary abnormalities and mental retardation (WAGR) syndrome. PAX6 mutations result in alterations in corneal cytokeratin expression, cell adhesion and glycoconjugate expression. This, in addition to stem-cell deficiency, results in a fragile cornea and aniridia-associated keratopathy (AAK). It also results in abnormalities in the differentiation of the angle, resulting in glaucoma. Glaucoma may also develop as a result of progressive angle closure from synechiae. There is cataract development, and this is associated with a fragile lens capsule. The iris is deficient. The optic nerve and fovea are hypoplastic, and the retina may be prone to detachment. Aniridia is a profibrotic disorder, and as a result many interventions--including penetrating keratoplasty and filtration surgery--fail. The Boston keratoprosthesis may provide a more effective approach in the management of AAK. Guarded filtration surgery appears to be effective in glaucoma. Despite our increasing understanding of the genetics and pathology of this condition, effective treatment remains elusive.
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Affiliation(s)
- Helena Lee
- Department of Paediatric Ophthalmology, Children's University Hospital, Dublin, Ireland
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79
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Dorà N, Ou J, Kucerova R, Parisi I, West JD, Collinson JM. PAX6 dosage effects on corneal development, growth, and wound healing. Dev Dyn 2008; 237:1295-306. [PMID: 18386822 DOI: 10.1002/dvdy.21528] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
The requirement for correct dosage of the transcription factor Pax6 during corneal growth and development was investigated using the Pax6-overexpressing (PAX77) transgenic mouse. Transgenics had a microcornea phenotype due to failure of postnatal growth, associated with reduction in the number of cells layers in the corneal epithelium. Cell cycle progression was monitored using bromodeoxyuridine, p63, cyclin E, and phosphohistone-3 labeling: proliferation rates were higher in PAX77+ than wild-type, without a concomitant increase in apoptosis. Hence, failure of proliferation did not underlie microcornea. PAX77+ corneal epithelia had reduced levels of cytokeratin-12, and exhibited severe wound healing delay that, in contrast to Pax6+/- mice, could not be modulated by exogenous growth factors. PAX77+ lenses showed partial failure of lens fiber differentiation. The data demonstrate that anterior eye development is very sensitive to Pax6 dosage. Although there are similarities between the eye phenotype of Pax6 heterozygotes and overexpressing mice, there are also striking differences. Developmental
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Affiliation(s)
- Natalie Dorà
- School of Medical Sciences, University of Aberdeen, Institute of Medical Sciences, Foresterhill, Aberdeen, United Kingdom
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Abstract
The corneal epithelium is continuously renewed by a population of stem cells that reside in the corneoscleral junction, otherwise known as the limbus. These limbal epithelial stem cells (LESC) are imperative for corneal maintenance with deficiencies leading to in-growth of conjunctival cells, neovascularisation of the corneal stroma and eventual corneal opacity and visual loss. One such disease that has traditionally been thought to be due to LESC deficiency is aniridia, a pan-ocular congenital eye disease due to mutations in the PAX6 gene. Corneal changes or aniridia related keratopathy (ARK) seen in aniridia are typical of LESC deficiency. However, the pathophysiology behind ARK is still ill defined, with current theories suggesting it may be caused by a deficiency in the stem cell niche and adjacent corneal stroma, with altered wound healing responses also playing a role (Ramaesh et al, International Journal of Biochemistry & Cell Biology 37:547-557, 2005) or abnormal epidermal differentiation of LESC (Li et al., The Journal of Pathology 214:9, 2008). PAX6 is considered the master control gene for the eye and is required for normal eye development with expression continuing in the adult cornea, thus inferring a role for corneal repair and regeneration (Sivak et al., Developments in Biologicals 222:41-54, 2000). Studies of models of Pax6 deficiency, such as the small eyed (sey) mouse, should help to reveal the intrinsic and extrinsic mechanisms involved in normal LESC function.
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81
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Igarashi T, Shimmura S, Yoshida S, Tonogi M, Shinozaki N, Yamane GY. Isolation of oral epithelial progenitors using collagen IV. Oral Dis 2008; 14:413-8. [DOI: 10.1111/j.1601-0825.2007.01390.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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Manuel M, Pratt T, Liu M, Jeffery G, Price DJ. Overexpression of Pax6 results in microphthalmia, retinal dysplasia and defective retinal ganglion cell axon guidance. BMC DEVELOPMENTAL BIOLOGY 2008; 8:59. [PMID: 18507827 PMCID: PMC2422841 DOI: 10.1186/1471-213x-8-59] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/11/2007] [Accepted: 05/28/2008] [Indexed: 11/17/2022]
Abstract
Background The transcription factor Pax6 is expressed by many cell types in the developing eye. Eyes do not form in homozygous loss-of-function mouse mutants (Pax6Sey/Sey) and are abnormally small in Pax6Sey/+ mutants. Eyes are also abnormally small in PAX77 mice expressing multiple copies of human PAX6 in addition to endogenous Pax6; protein sequences are identical in the two species. The developmental events that lead to microphthalmia in PAX77 mice are not well-characterised, so it is not clear whether over- and under-expression of Pax6/PAX6 cause microphthalmia through similar mechanisms. Here, we examined the consequences of over-expression for the eye and its axonal connections. Results Eyes form in PAX77+/+ embryos but subsequently degenerate. At E12.5, we found no abnormalities in ocular morphology, retinal cell cycle parameters and the incidence of retinal cell death. From E14.5 on, we observed malformations of the optic disc. From E16.5 into postnatal life there is progressively more severe retinal dysplasia and microphthalmia. Analyses of patterns of gene expression indicated that PAX77+/+ retinae produce a normal range of cell types, including retinal ganglion cells (RGCs). At E14.5 and E16.5, quantitative RT-PCR with probes for a range of molecules associated with retinal development showed only one significant change: a slight reduction in levels of mRNA encoding the secreted morphogen Shh at E16.5. At E16.5, tract-tracing with carbocyanine dyes in PAX77+/+ embryos revealed errors in intraretinal navigation by RGC axons, a decrease in the number of RGC axons reaching the thalamus and an increase in the proportion of ipsilateral projections among those RGC axons that do reach the thalamus. A survey of embryos with different Pax6/PAX6 gene dosage (Pax6Sey/+, Pax6+/+, PAX77+ and PAX77+/+) showed that (1) the total number of RGC axons projected by the retina and (2) the proportions that are sorted into the ipsilateral and contralateral optic tracts at the optic chiasm vary differently with gene dosage. Increasing dosage increases the proportion projecting ipsilaterally regardless of the size of the total projection. Conclusion Pax6 overexpression does not obviously impair the initial formation of the eye and its major cell-types but prevents normal development of the retina from about E14.5, leading eventually to severe retinal degeneration in postnatal life. This sequence is different to that underlying microphthalmia in Pax6+/- heterozygotes, which is due primarily to defects in the initial stages of lens formation. Before the onset of severe retinal dysplasia, Pax6 overexpression causes defects of retinal axons, preventing their normal growth and navigation through the optic chiasm.
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Affiliation(s)
- Martine Manuel
- Genes and Development Group, Centres for Integrative Physiology and Neuroscience Research, Hugh Robson Building, George Square, University of Edinburgh, Edinburgh EH8 9XD, UK.
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83
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Swamynathan SK, Davis J, Piatigorsky J. Identification of candidate Klf4 target genes reveals the molecular basis of the diverse regulatory roles of Klf4 in the mouse cornea. Invest Ophthalmol Vis Sci 2008; 49:3360-70. [PMID: 18469187 DOI: 10.1167/iovs.08-1811] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
PURPOSE Krüppel-like factor 4 (Klf4) plays a crucial role in the development and maintenance of the mouse cornea. In the current study, wild-type (WT) and Klf4-conditional null (Klf4CN) corneal gene expression patterns were examined, to gain understanding of the molecular basis of the Klf4CN corneal phenotype. METHODS Expression of more than 22,000 genes in 10 WT and Klf4CN corneas was compared by microarrays, analyzed using BRB ArrayTools (National Cancer Institute, Bethesda, MD) and validated by Q-RT-PCR. Transient cotransfections were used to test whether Klf4 activates the aquaporin-3, Aldh3a1, and TKT promoters. RESULTS Scatterplot analysis identified 740 and 529 genes up- and downregulated by more than twofold, respectively, in the Klf4CN corneas. Cell cycle activators were upregulated, whereas the inhibitors were downregulated, consistent with the increased Klf4CN corneal epithelial cell proliferation. Desmosomal components were downregulated, consistent with the Klf4CN corneal epithelial fragility. Downregulation of aquaporin-3, detected by microarray, was confirmed by immunoblot and immunohistochemistry. Aquaporin-3 promoter activity was stimulated 7- to 10-fold by cotransfection with pCI-Klf4. The corneal crystallins Aldh3A1 and TKT were downregulated in the Klf4CN cornea, and their respective promoter activities were upregulated 16- and 9-fold by pCI-Klf4 in cotransfections. The expression of epidermal keratinocyte differentiation markers was affected in the Klf4CN cornea. Although the cornea-specific keratin-12 was downregulated, most other keratins were upregulated, suggesting hyperkeratosis. CONCLUSIONS Functionally diverse candidate Klf4 target genes were identified, revealing the molecular basis of the diverse aspects of the Klf4CN corneal phenotype. These results establish Klf4 as an important node in the genetic network of transcription factors regulating the corneal homeostasis.
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Affiliation(s)
- Shivalingappa K Swamynathan
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15213, USA.
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Ou J, Walczysko P, Kucerova R, Rajnicek AM, McCaig CD, Zhao M, Collinson JM. Chronic wound state exacerbated by oxidative stress in Pax6+/− aniridia-related keratopathy. J Pathol 2008; 215:421-30. [DOI: 10.1002/path.2371] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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Experimental transplantation of corneal epithelium-like cells induced by Pax6 gene transfection of mouse embryonic stem cells. Cornea 2008; 26:1220-7. [PMID: 18043180 DOI: 10.1097/ico.0b013e31814fa814] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
PURPOSE Corneal epithelial stem cells are deficient in cases of limbal disorders, leading to conjunctival epithelial ingrowth, vascularization, and eventually visual disturbance. We introduced the eye development-associated transcription factor pax6 to embryonic stem (ES) cells and tested whether pax6-transfected cells resembling purified corneal epithelial cells were applicable as a cell source for corneal transplantation. METHODS pax6 cDNA with green fluorescence protein was electrotransfected to ES cells and the cells were cultured with G418 for 14 days. They were characterized by reverse transcription-polymerase chain reaction and immunohistochemistry. The cells were transplanted onto experimentally damaged mouse corneas. Histologic reconstitution of the corneal epithelium was assessed. RESULTS pax6-transfected cells formed a monolayer of epithelium-like cells in vitro. They expressed cytokeratin12, a specific keratin of corneal epithelial cells, E-cadherin, and CD44, which are important adhesion molecules of corneal epithelial cells on the cell membrane. They accumulated to make a colony that gave a staining pattern of reticular configuration for cytokeratin 12, E-cadherin, and CD44. When the cells were transplanted onto damaged cornea, they have been kept alive on the cornea. CONCLUSIONS The purified corneal epithelium-like cells derived from ES cells transfected with pax6 gene adapted to the injured cornea and were kept alive on it. These results suggested application of ES cell-derived corneal epithelial cells for treating corneal injuries.
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86
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López-García JS, Rivas L, García-Lozano I, Murube J. Autologous Serum Eyedrops in the Treatment of Aniridic Keratopathy. Ophthalmology 2008; 115:262-7. [PMID: 17675158 DOI: 10.1016/j.ophtha.2007.03.087] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2006] [Revised: 03/30/2007] [Accepted: 03/30/2007] [Indexed: 11/27/2022] Open
Abstract
OBJECTIVE To study the effect of autologous serum eyedrop application in aniridic keratopathy. DESIGN Prospective, consecutive, comparative, interventional case series. PARTICIPANTS Twenty-six eyes from 13 patients (7 males and 6 females) with aniridic keratopathy treated with autologous serum eyedrops. METHODS All patients underwent a complete ophthalmic examination. The ocular surface examinations included corneal impression cytologic analysis and tear film evaluation. The eyes were divided into 4 groups according to the Mackman classification. Ocular surface photography was used to evaluate the corneal surface and tear film before treatment and every 2 or 3 days until serum drops were stopped. Tear films were evaluated by tear film break-up time (BUT) (normal, 10 seconds or more), Schirmer's test with anesthesia (normal, 10 mm/5 minutes or more), tear meniscus level (normal, 0.5 mm or more), and rose bengal and fluorescein staining pattern of the cornea. Impression cytologic analysis was carried out both before starting the serum eyedrops treatment and a few days after its finalization. MAIN OUTCOMES MEASURES Tear film production and stability, corneal epithelialization, and corneal epithelium squamous metaplasia. RESULTS There were no local side effects from autologous serum treatment. Clinical manifestations and slit-lamp findings were in relation to the severity of keratopathy. All patients showed a subjective improvement of keratopathy symptoms after the autologous serum applications. The corneal epithelialization, corneal epithelial cell squamous metaplasia, and tear stability improved significantly with the treatment, but visual acuity, regression of vascular pannus, and subepithelial scarring showed only slight improvement with treatment. CONCLUSIONS Autologous serum eyedrops improved the aniridic keratopathy in all patients, particularly in patients with light or moderate severity. In these patients, use of autologous serum eyedrops was superior to conventional therapy with substitute tears for improving the ocular surface and subjective comfort.
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87
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Zhang X, Tseng H. Basonuclin-null mutation impairs homeostasis and wound repair in mouse corneal epithelium. PLoS One 2007; 2:e1087. [PMID: 17971852 PMCID: PMC2034529 DOI: 10.1371/journal.pone.0001087] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2007] [Accepted: 10/04/2007] [Indexed: 01/08/2023] Open
Abstract
At least two cellular processes are required for corneal epithelium homeostasis and wound repair: cell proliferation and cell-cell adhesion. These processes are delicately balanced to ensure the maintenance of normal epithelial function. During wound healing, these processes must be reprogrammed in coordination to achieve a rapid re-epithelialization. Basonuclin (Bnc1) is a cell-type-specific transcription factor expressed mainly in the proliferative keratinocytes of stratified epithelium (e.g., corneal epithelium, epidermis and esophageal epithelium) and the gametogenic cells in testis and ovary. Our previous work suggested that basonuclin could regulate transcription of ribosomal RNA genes (rDNA) and genes involved in chromatin structure, transcription regulation, cell-cell junction/communication, ion-channels and intracelllular transportation. However, basonuclin's role in keratinocytes has not been demonstrated in vivo. Here we show that basonuclin-null mutation disrupts corneal epithelium homeostasis and delays wound healing by impairing cell proliferation. In basonuclin-null cornea epithelium, RNA polymerase I (Pol I) transcription is perturbed. This perturbation is unique because it affects transcripts from a subset of rDNA. Basonuclin-null mutation also perturbs RNA polymerase II (Pol II) transcripts from genes encoding chromatin structure proteins histone 3 and HMG2, transcription factor Gli2, gap-junction protein connexin 43 and adheren E-cadherin. In most cases, a concerted change in mRNA and protein level is observed. However, for E-cadherin, despite a notable increase in its mRNA level, its protein level was reduced. In conclusion, our study establishes basonuclin as a regulator of corneal epithelium homeostasis and maintenance. Basonuclin likely coordinates functions of a subset of ribosomal RNA genes (rDNA) and a group of protein coding genes in cellular processes critical for the regulation of cell proliferation.
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Affiliation(s)
- Xiaohong Zhang
- Department of Dermatology, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Hung Tseng
- Department of Dermatology, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- Cell and Developmental Biology, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- Center for Research on Reproduction and Women's Health, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
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Baharvand H, Ebrahimi M, Javadi MA. Comparison of characteristics of cultured limbal cells on denuded amniotic membrane and fresh conjunctival, limbal and corneal tissues. Dev Growth Differ 2007; 49:241-51. [PMID: 17394602 DOI: 10.1111/j.1440-169x.2007.00924.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
This study aimed to evaluate proposed molecular markers related to eye limbal stem cells (SC) and to identify novel associated genes. The expression of a set of genes potentially involved in stemness was assessed in freshly prepared limbal, corneal and conjunctival tissues. PAX6, AC133, K12 and OCT4 were detected in all the tissues and p63(+)/K3(-)/K12(+)/Nodal(+)/Cx43(+) were expressed in conjunctival, p63(-)/K3(+)/K12(+)/Nodal(-)/Cx43(+) in corneal, and p63(+)/K3(-)/K12(-)/Nodal(-)/Cx43(-) in limbal tissues. Limbal explants were cultured on human amniotic membrane for 21 days. The cells expressed p63 but not K3, K12, Nodal and Cx43, however, the expression of K3, K12 and Cx43 was detected, and p63 and the high BrdU-labeling index decreased with more culture. Ultrastructure analysis of the cultured cells showed typically immature organization of intracellular organelles and architecture. Our data suggest that limbal, corneal and conjunctival tissues are heterogeneous with some progenitors. Also, the expression of traditional SC markers may not be a reliable indicator of limbal SC and there is an increasing need to determine factor(s) involved in their stemness.
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Affiliation(s)
- Hossein Baharvand
- Department of Stem Cells, Royan Institute, PO Box 19395-4644, Tehran, Iran.
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Blixt A, Landgren H, Johansson BR, Carlsson P. Foxe3 is required for morphogenesis and differentiation of the anterior segment of the eye and is sensitive to Pax6 gene dosage. Dev Biol 2007; 302:218-29. [PMID: 17064680 DOI: 10.1016/j.ydbio.2006.09.021] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2006] [Revised: 09/08/2006] [Accepted: 09/11/2006] [Indexed: 11/19/2022]
Abstract
The dysgenetic lens (dyl) mouse mutant has mutations in Foxe3, which inactivate DNA binding by the encoded forkhead transcription factor. Here we confirm, by targeted inactivation, that Foxe3 mutations are responsible for the dyl phenotype, which include loss of lens epithelium; a small, cataractic lens; and failure of the lens to detach from the surface ectoderm. In contrast to a recent report of targeted Foxe3, we found no phenotypic difference between dyl and Foxe3(-/-) mutants when congenic strains were compared, and thus nothing that argues against Foxe3(dyl) being a null allele. In addition to the lens, most tissues of the anterior segment-iris, cornea, ciliary body and trabecular meshwork-are malformed or show differentiation defects. Many of these abnormalities, such as irido-corneal and irido-lenticular adherences, are present in a less severe form in mice heterozygous for the Foxe3 mutation, in spite of these having an intact lens epithelium. Early Foxe3 expression is highly sensitive to a halved Pax6 gene dosage and there is a striking phenotypic similarity between Pax6 and Foxe3 mutants. We therefore propose that many of the ocular malformations associated with Pax6 haploinsufficiency are consequences of a reduced expression of Foxe3.
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Affiliation(s)
- Asa Blixt
- Dept of Cell and Molecular Biology, Göteborg University, 405 30 Göteborg, Sweden
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90
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Holm PC, Mader MT, Haubst N, Wizenmann A, Sigvardsson M, Götz M. Loss- and gain-of-function analyses reveal targets of Pax6 in the developing mouse telencephalon. Mol Cell Neurosci 2007; 34:99-119. [PMID: 17158062 DOI: 10.1016/j.mcn.2006.10.008] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2006] [Revised: 10/11/2006] [Accepted: 10/17/2006] [Indexed: 01/22/2023] Open
Abstract
Appropriate neurogenesis and patterning of the forebrain requires the transcription factor Pax6, yet it is largely unknown how Pax6 exerts its effects at the molecular level. To characterize Pax6-mediated regulation of gene expression during murine forebrain neurogenesis, we performed microarray analysis with tissue from the dorsal Pax6-dependent telencephalon and the ventral Pax6-negative telencephalon at the onset of neurogenesis (E12) and at mid-neurogenesis (E15) in wild-type and Pax6-deficient mutant littermates. In the Pax6-deficient cortex the expression levels of various transcription factors involved in neurogenesis (like Satb2, Nfia, AP-2gamma, NeuroD6, Ngn2, Tbr2, Bhlhb5) and the retinoic acid signalling molecule Rlbp1 were reduced. Regulation by Pax6 could be confirmed upon electroporation of a Pax6- and a dominant-negative Pax6-containing vector into embryonic cortex. Taken together, our data reveal novel insights into the molecular pathways regulated by Pax6 during cortical neurogenesis. Most intriguingly, this analysis revealed time- and region-specific differences in Pax6-mediated transcription, explaining the specific function of Pax6 at early and later stages of neurogenesis.
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Affiliation(s)
- Pontus C Holm
- Institute for Stem Cell Research, National Research Center for Environment and Health, Ingolstädter Landstrasse 1, D-85764 Neuherberg/Munich, Germany.
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Kucerova R, Ou J, Lawson D, Leiper LJ, Collinson JM. Cell surface glycoconjugate abnormalities and corneal epithelial wound healing in the pax6+/- mouse model of aniridia-related keratopathy. Invest Ophthalmol Vis Sci 2006; 47:5276-82. [PMID: 17122113 PMCID: PMC1876652 DOI: 10.1167/iovs.06-0581] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Congenital aniridia due to heterozygosity for Pax6 is associated with ocular surface disease, including keratopathy. This study investigated how defects in glycoconjugate component of the cell surface of Pax6+/- could cause the abnormal cellular migration phenotypes associated with the disease. METHODS Immunohistochemistry, lectin-based histochemistry, conventional staining techniques, and proteomic assays were performed on eyes and cultured corneal epithelial cells from wild-type and Pax6+/- littermates. Wild-type cells were manipulated in culture to replicate the glycoconjugate abnormalities found in Pax6 heterozygotes and determine the consequences for wound healing. RESULTS Multiple glycoconjugate defects were found in Pax6-mutant cells. Lectin cytochemistry of corneal epithelial cells suggested a partial failure of glycoprotein trafficking. Blocking cell surface carbohydrate moieties in wild-type corneal cells caused wound-healing delays similar to those seen in untreated Pax6+/- cells. CONCLUSIONS Alterations to the cell surface glycoconjugate signature of Pax6+/- corneal epithelia restrict the ability of cells to initiate migration in response to wounding. This underlies the observed wound-healing delay in cultured Pax6+/- epithelia.
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Affiliation(s)
- Romana Kucerova
- School of Medical Sciences, University of Aberdeen, Institute of Medical Sciences, Aberdeen, United Kingdom
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Curto GG, Lara JM, Parrilla M, Aijón J, Velasco A. Modifications of the retina neuronal populations of the heterozygous mutant small eye mouse, the Sey(Dey). Brain Res 2006; 1127:163-76. [PMID: 17113047 DOI: 10.1016/j.brainres.2006.10.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2006] [Revised: 10/02/2006] [Accepted: 10/03/2006] [Indexed: 10/23/2022]
Abstract
We analyzed the modifications of the retinal neurons in a heterozygous mutant small eye mouse, the Sey(Dey). This mouse presents a mutation in chromosome 2 which affects the gene Pax6 and other nearby genes, such as the Wt1 gene and the gene of the Reticulocalbin. The eyes of these animals do not have lenses and their retinas present important morphological alterations: in the anterior portion they are joined to the cornea, they are found detached from the pigment epithelium, they present folds that form rosettes in some zones and alteration of the lamination can be observed. The partial loss of the genes affected does not prevent the formation of the different layers of the retina, but does affect its thickness, principally of the plexiform layers; moreover, the internal limiting membrane is found disorganized. All the neuronal populations are present in the retina of these animals and express the same neurochemical markers as the control animals, but the number of Pax6(+) cells is notably reduced. In these retinas a marked disorganization of the distribution of the dendrites and axons is observed and a notable reduction in the axons of ganglion cells. These results suggest that, although it does not appear determinant in the differentiation of the distinct neuronal types of the retina, the partial lack of genes of the heterozygotes +/Sey(Dey) provokes important morphological and neurochemical modifications in the cytoarchitecture of the retina.
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Affiliation(s)
- Gloria González Curto
- Instituto de Neurociencias de Castilla y León, Departamento de Biología Celular, Universidad de Salamanca, 37007 Salamanca, Spain
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Kang LI, Wang Y, Suckow AT, Czymmek KJ, Cooke VG, Naik UP, Duncan MK. Deletion of JAM-A causes morphological defects in the corneal epithelium. Int J Biochem Cell Biol 2006; 39:576-85. [PMID: 17118692 DOI: 10.1016/j.biocel.2006.10.016] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2006] [Accepted: 10/11/2006] [Indexed: 11/30/2022]
Abstract
Junctional adhesion molecule-A (JAM-A, JAM-1, F11R) is an Ig domain containing transmembrane protein that has been proposed to function in diverse processes including platelet activation and adhesion, leukocyte transmigration, angiogenesis, epithelial cell shape and endothelial cell migration although its function in vivo is less well established. In the mouse eye, JAM-A protein expression is first detected at 12.5 dpc in the blood vessels of the tunica vasculosa, while it is first detected in both the corneal epithelium and lens between 13.5 and 14.5 dpc. In the corneal epithelium, JAM-A levels remain appreciable throughout life, while JAM-A immunostaining becomes stronger in the lens as the animals age. Both the cornea and lens of mice lacking an intact JAM-A gene are transparent until at least a year of age, although the cells of the JAM-A null corneal epithelium are irregularly shaped. In wild-type mice, JAM-A protein is found at the leading edge of repairing corneal epithelial wounds, however, corneal epithelial wound repair was qualitatively normal in JAM-A null animals. In summary, JAM-A is expressed in the corneal epithelium where it appears to regulate cell shape.
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MESH Headings
- Animals
- Base Sequence
- Cell Adhesion Molecules/deficiency
- Cell Adhesion Molecules/genetics
- Cell Adhesion Molecules/metabolism
- Cell Shape/genetics
- Cell Shape/physiology
- DNA Primers/genetics
- Epithelium, Corneal/abnormalities
- Epithelium, Corneal/cytology
- Epithelium, Corneal/embryology
- Epithelium, Corneal/metabolism
- Eye Proteins/genetics
- Eye Proteins/metabolism
- Female
- Gene Expression Regulation, Developmental
- Heterozygote
- Homeodomain Proteins/genetics
- Homeodomain Proteins/metabolism
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- PAX6 Transcription Factor
- Paired Box Transcription Factors/deficiency
- Paired Box Transcription Factors/genetics
- Paired Box Transcription Factors/metabolism
- Phenotype
- Pregnancy
- Receptors, Cell Surface/deficiency
- Receptors, Cell Surface/genetics
- Receptors, Cell Surface/metabolism
- Repressor Proteins/genetics
- Repressor Proteins/metabolism
- Wound Healing/physiology
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Affiliation(s)
- Liang I Kang
- Department of Biological Sciences, University of Delaware, Newark, DE 19716, USA
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94
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Swamynathan SK, Katz JP, Kaestner KH, Ashery-Padan R, Crawford MA, Piatigorsky J. Conditional deletion of the mouse Klf4 gene results in corneal epithelial fragility, stromal edema, and loss of conjunctival goblet cells. Mol Cell Biol 2006; 27:182-94. [PMID: 17060454 PMCID: PMC1800665 DOI: 10.1128/mcb.00846-06] [Citation(s) in RCA: 104] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The Krüppel-like transcription factor KLF4 is among the most highly expressed transcription factors in the mouse cornea (B. Norman, J. Davis, and J. Piatigorsky, Investig. Ophthalmol. Vis. Sci. 45:429-440, 2004). Here, we deleted the Klf4 gene selectively in the surface ectoderm-derived structures of the eye (cornea, conjunctiva, eyelids, and lens) by mating Klf4-LoxP mice (J. P. Katz, N. Perreault, B. G. Goldstein, C. S. Lee, P. A. Labosky, V. W. Yang, and K. H. Kaestner, Development 129:2619-2628, 2002) with Le-Cre mice (R. Ashery-Padan, T. Marquardt, X. Zhou, and P. Gruss, Genes Dev. 14:2701-2711, 2000). Klf4 conditional null (Klf4CN) embryos developed normally, and the adult mice were viable and fertile. Unlike the wild type, the Klf4CN cornea consisted of three to four epithelial cell layers; swollen, vacuolated basal epithelial and endothelial cells; and edematous stroma. The conjunctiva lacked goblet cells, and the anterior cortical lens was vacuolated in Klf4CN mice. Excessive cell sloughing resulted in fewer epithelial cell layers in spite of increased cell proliferation at the Klf4CN ocular surface. Expression of the keratin-12 and aquaporin-5 genes was downregulated, consistent with the Klf4CN corneal epithelial fragility and stromal edema, respectively. These observations provide new insights into the role of KLF4 in postnatal maturation and maintenance of the ocular surface and suggest that the Klf4CN mouse is a useful model for investigating ocular surface pathologies such as dry eye, Meesmann's dystrophy, and Steven's-Johnson syndrome.
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Affiliation(s)
- Shivalingappa K Swamynathan
- Laboratory of Molecular and Developmental Biology, National Eye Institute/NIH, 7 Memorial Drive, Room 129, Bethesda, MD 20892, USA.
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95
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Zaki PA, Collinson JM, Toraiwa J, Simpson TI, Price DJ, Quinn JC. Penetrance of eye defects in mice heterozygous for mutation of Gli3 is enhanced by heterozygous mutation of Pax6. BMC DEVELOPMENTAL BIOLOGY 2006; 6:46. [PMID: 17029624 PMCID: PMC1618390 DOI: 10.1186/1471-213x-6-46] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/13/2006] [Accepted: 10/09/2006] [Indexed: 11/17/2022]
Abstract
BACKGROUND Knowledge of the consequences of heterozygous mutations of developmentally important genes is important for understanding human genetic disorders. The Gli3 gene encodes a zinc finger transcription factor and homozygous loss-of-function mutations of Gli3 are lethal. Humans heterozygous for mutations in this gene suffer Greig cephalopolysyndactyly or Pallister-Hall syndromes, in which limb defects are prominent, and mice heterozygous for similar mutations have extra digits. Here we examined whether eye development, which is abnormal in mice lacking functional Gli3, is defective in Gli3+/- mice. RESULTS We showed that Gli3 is expressed in the developing eye but that Gli3+/- mice have only very subtle eye defects. We then generated mice compound heterozygous for mutations in both Gli3 and Pax6, which encodes another developmentally important transcription factor known to be crucial for eye development. Pax6+/-; Gli3+/- eyes were compared to the eyes of wild-type, Pax6+/- or Gli3+/- siblings. They exhibited a range of abnormalities of the retina, iris, lens and cornea that was more extensive than in single Gli3+/- or Pax6+/- mutants or than would be predicted by addition of their phenotypes. CONCLUSION These findings indicate that heterozygous mutations of Gli3 can impact on eye development. The importance of a normal Gli3 gene dosage becomes greater in the absence of a normal Pax6 gene dosage, suggesting that the two genes co-operate during eye morphogenesis.
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Affiliation(s)
- Paulette A Zaki
- Genes and Development Group, University of Edinburgh, Hugh Robson Building, George Square, Edinburgh, EH8 9XD, UK
| | - J Martin Collinson
- School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Aberdeen AB25 2ZD, UK
| | - Junko Toraiwa
- Genes and Development Group, University of Edinburgh, Hugh Robson Building, George Square, Edinburgh, EH8 9XD, UK
| | - T Ian Simpson
- Genes and Development Group, University of Edinburgh, Hugh Robson Building, George Square, Edinburgh, EH8 9XD, UK
| | - David J Price
- Genes and Development Group, University of Edinburgh, Hugh Robson Building, George Square, Edinburgh, EH8 9XD, UK
| | - Jane C Quinn
- Genes and Development Group, University of Edinburgh, Hugh Robson Building, George Square, Edinburgh, EH8 9XD, UK
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96
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Leiper LJ, Walczysko P, Kucerova R, Ou J, Shanley LJ, Lawson D, Forrester JV, McCaig CD, Zhao M, Collinson JM. The roles of calcium signaling and ERK1/2 phosphorylation in a Pax6+/- mouse model of epithelial wound-healing delay. BMC Biol 2006; 4:27. [PMID: 16914058 PMCID: PMC1563477 DOI: 10.1186/1741-7007-4-27] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2006] [Accepted: 08/16/2006] [Indexed: 01/08/2023] Open
Abstract
Background Congenital aniridia caused by heterozygousity at the PAX6 locus is associated with ocular surface disease including keratopathy. It is not clear whether the keratopathy is a direct result of reduced PAX6 gene dosage in the cornea itself, or due to recurrent corneal trauma secondary to defects such as dry eye caused by loss of PAX6 in other tissues. We investigated the hypothesis that reducing Pax6 gene dosage leads to corneal wound-healing defects. and assayed the immediate molecular responses to wounding in wild-type and mutant corneal epithelial cells. Results Pax6+/- mouse corneal epithelia exhibited a 2-hour delay in their response to wounding, but subsequently the cells migrated normally to repair the wound. Both Pax6+/+ and Pax6+/- epithelia activated immediate wound-induced waves of intracellular calcium signaling. However, the intensity and speed of propagation of the calcium wave, mediated by release from intracellular stores, was reduced in Pax6+/- cells. Initiation and propagation of the calcium wave could be largely decoupled, and both phases of the calcium wave responses were required for wound healing. Wounded cells phosphorylated the extracellular signal-related kinases 1/2 (phospho-ERK1/2). ERK1/2 activation was shown to be required for rapid initiation of wound healing, but had only a minor effect on the rate of cell migration in a healing epithelial sheet. Addition of exogenous epidermal growth factor (EGF) to wounded Pax6+/- cells restored the calcium wave, increased ERK1/2 activation and restored the immediate healing response to wild-type levels. Conclusion The study links Pax6 deficiency to a previously overlooked wound-healing delay. It demonstrates that defective calcium signaling in Pax6+/- cells underlies this delay, and shows that it can be pharmacologically corrected. ERK1/2 phosphorylation is required for the rapid initiation of wound healing. A model is presented whereby minor abrasions, which are quickly healed in normal corneas, transiently persist in aniridic patients, compromising the corneal stroma.
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Affiliation(s)
- Lucy J Leiper
- School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Aberdeen AB25 2ZD, UK
| | - Petr Walczysko
- School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Aberdeen AB25 2ZD, UK
| | - Romana Kucerova
- School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Aberdeen AB25 2ZD, UK
| | - Jingxing Ou
- School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Aberdeen AB25 2ZD, UK
| | - Lynne J Shanley
- School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Aberdeen AB25 2ZD, UK
| | - Diane Lawson
- School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Aberdeen AB25 2ZD, UK
| | - John V Forrester
- School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Aberdeen AB25 2ZD, UK
| | - Colin D McCaig
- School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Aberdeen AB25 2ZD, UK
| | - Min Zhao
- School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Aberdeen AB25 2ZD, UK
| | - J Martin Collinson
- School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Aberdeen AB25 2ZD, UK
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97
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Mukhopadhyay M, Gorivodsky M, Shtrom S, Grinberg A, Niehrs C, Morasso MI, Westphal H. Dkk2 plays an essential role in the corneal fate of the ocular surface epithelium. Development 2006; 133:2149-54. [PMID: 16672341 DOI: 10.1242/dev.02381] [Citation(s) in RCA: 114] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The Dkk family of secreted cysteine-rich proteins regulates Wnt/beta-catenin signaling by interacting with the Wnt co-receptor Lrp5/6. Here, we show that Dkk2-mediated repression of the Wnt/beta-catenin pathway is essential to promote differentiation of the corneal epithelial progenitor cells into a non-keratinizing stratified epithelium. Complete transformation of the corneal epithelium into a stratified epithelium that expresses epidermal-specific differentiation markers and develops appendages such as hair follicles is achieved in the absence of the Dkk2 gene function. We show that Dkk2 is a key regulator of the corneal versus epidermal fate of the ocular surface epithelium.
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Affiliation(s)
- Mahua Mukhopadhyay
- Laboratory of Mammalian Genes and Development, National Institute of Child Health and Human Development, Bethesda, MD 20892, USA
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98
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Schlosser G. Induction and specification of cranial placodes. Dev Biol 2006; 294:303-51. [PMID: 16677629 DOI: 10.1016/j.ydbio.2006.03.009] [Citation(s) in RCA: 282] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2005] [Revised: 12/22/2005] [Accepted: 12/23/2005] [Indexed: 12/17/2022]
Abstract
Cranial placodes are specialized regions of the ectoderm, which give rise to various sensory ganglia and contribute to the pituitary gland and sensory organs of the vertebrate head. They include the adenohypophyseal, olfactory, lens, trigeminal, and profundal placodes, a series of epibranchial placodes, an otic placode, and a series of lateral line placodes. After a long period of neglect, recent years have seen a resurgence of interest in placode induction and specification. There is increasing evidence that all placodes despite their different developmental fates originate from a common panplacodal primordium around the neural plate. This common primordium is defined by the expression of transcription factors of the Six1/2, Six4/5, and Eya families, which later continue to be expressed in all placodes and appear to promote generic placodal properties such as proliferation, the capacity for morphogenetic movements, and neuronal differentiation. A large number of other transcription factors are expressed in subdomains of the panplacodal primordium and appear to contribute to the specification of particular subsets of placodes. This review first provides a brief overview of different cranial placodes and then synthesizes evidence for the common origin of all placodes from a panplacodal primordium. The role of various transcription factors for the development of the different placodes is addressed next, and it is discussed how individual placodes may be specified and compartmentalized within the panplacodal primordium. Finally, tissues and signals involved in placode induction are summarized with a special focus on induction of the panplacodal primordium itself (generic placode induction) and its relation to neural induction and neural crest induction. Integrating current data, new models of generic placode induction and of combinatorial placode specification are presented.
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Affiliation(s)
- Gerhard Schlosser
- Brain Research Institute, AG Roth, University of Bremen, FB2, 28334 Bremen, Germany.
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99
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Birger Y, Davis J, Furusawa T, Rand E, Piatigorsky J, Bustin M. A role for chromosomal protein HMGN1 in corneal maturation. Differentiation 2006; 74:19-29. [PMID: 16466397 PMCID: PMC3730489 DOI: 10.1111/j.1432-0436.2006.00054.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Corneal differentiation and maturation are associated with major changes in the expression levels of numerous genes, including those coding for the chromatin-binding high-mobility group (HMG) proteins. Here we report that HMGN1, a nucleosome-binding protein that alters the structure and activity of chromatin, affects the development of the corneal epithelium in mice. The corneal epithelium of Hmgn1(-/-) mice is thin, has a reduced number of cells, is poorly stratified, is depleted of suprabasal wing cells, and its most superficial cell layer blisters. In mature Hmgn1(-/-)mice, the basal cells retain the ovoid shape of immature cells, and rest directly on the basal membrane which is disorganized. Gene expression was modified in Hmgn1(-/-) corneas: glutathione-S-transferase (GST)alpha 4 and GST omega 1, epithelial layer-specific markers, were selectively reduced while E-cadherin and alpha-, beta-, and gamma-catenin, components of adherens junctions, were increased. Immunofluorescence analysis reveals a complete co-localization of HMGN1 and p 63 in small clusters of basal corneal epithelial cells of wild-type mice, and an absence of p 63 expressing cells in the central region of the Hmgn1(-/-) cornea. We suggest that interaction of HMGN1 with chromatin modulates the fidelity of gene expression and affects corneal development and maturation.
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Affiliation(s)
| | | | - Takashi Furusawa
- Protein Section, Laboratory of Metabolism, National Cancer Institute, Bethesda, MD 20892, USA, Tel: +1-301-496-5234
| | - Eyal Rand
- Protein Section, Laboratory of Metabolism, National Cancer Institute, Bethesda, MD 20892, USA, Tel: +1-301-496-5234
| | - Joram Piatigorsky
- Laboratory of Molecular and Developmental Biology, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA, Tel: +1-301-402-4343
| | - Michael Bustin
- Protein Section, Laboratory of Metabolism, National Cancer Institute, Bethesda, MD 20892, USA, Tel: +1-301-496-5234
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100
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Kriangkrai R, Chareonvit S, Yahagi K, Fujiwara M, Eto K, Iseki S. Study ofPax6 mutant rat revealed the association between upper incisor formation and midface formation. Dev Dyn 2006; 235:2134-43. [PMID: 16795023 DOI: 10.1002/dvdy.20875] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
In this study, we investigated the process of supernumerary upper incisor formation in the Pax6 mutant rat, rSey(2)/rSey(2), which exhibits a facial cleft between the medial nasal and maxillary processes. Histological investigation and epithelial labeling studies of wild type rat embryos indicated that the upper incisor develops by fusion of two primary dental placodes (PDPs) in the medial nasal process with a contribution from the epithelium of the maxillary process. In the rSey(2)/rSey(2) embryo, both PDPs are formed but they stay apart, then subsequently these PDPs independently develop into upper incisor tooth buds. In order to examine if the failure of the two placodes to fuse is due to the cleft between the maxillary and medial nasal processes, maxillary and medial nasal process fusion was inhibited with a barrier in wild type embryos. This resulted in the maintenance of the two distinct PDPs. These results demonstrate that fusion of the facial processes reduces the number of odontogenic placodes and is required to assemble all components at one site for rat upper incisor formation. The results also provide further insight into the mechanism of supernumerary incisor formation in human cleft lip conditions.
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Affiliation(s)
- Rungarun Kriangkrai
- Section of Molecular Craniofacial Embryology, Graduate School, Tokyo Medical and Dental University, Tokyo, Japan
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