1
|
Shen S, Zhang Y. Restoration of corneal epithelial barrier function: A possible target for corneal neovascularization. Ocul Surf 2024; 34:38-49. [PMID: 38901546 DOI: 10.1016/j.jtos.2024.06.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2024] [Revised: 06/10/2024] [Accepted: 06/11/2024] [Indexed: 06/22/2024]
Abstract
Corneal neovascularization (CoNV) is the second leading common cause of vision impairment worldwide and is a blinding pathological alteration brought on by ocular trauma, infection, and other factors. There are some limitations in the treatment of CoNV, hence it's critical to look into novel therapeutic targets. The corneal epithelial barrier, which is the initial barrier of the ocular surface, is an important structure that shields the eye from changes in the internal environment or invasion by the external environment. This study sought to collate evidence on the regulation of corneal epithelial barrier injury on the activation of vascular endothelial cells (VECs), basement membrane (BM) degradation, differentiation, migration, and proliferation of VECs, vascular maturation and stability, and other key processes in CoNV, so as to provide a novel concept for CoNV therapy targeting corneal epithelial barrier repair.
Collapse
Affiliation(s)
- Sitong Shen
- Department of Ophthalmology, The Second Hospital of Jilin University, 218 Ziqiang Street, Nanguan District, Changchun, Jilin Province, 130041, China
| | - Yan Zhang
- Department of Ophthalmology, The Second Hospital of Jilin University, 218 Ziqiang Street, Nanguan District, Changchun, Jilin Province, 130041, China; Department of Ophthalmology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200080, China.
| |
Collapse
|
2
|
Volatier T, Cursiefen C, Notara M. Current Advances in Corneal Stromal Stem Cell Biology and Therapeutic Applications. Cells 2024; 13:163. [PMID: 38247854 PMCID: PMC10814767 DOI: 10.3390/cells13020163] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Revised: 01/08/2024] [Accepted: 01/12/2024] [Indexed: 01/23/2024] Open
Abstract
Corneal stromal stem cells (CSSCs) are of particular interest in regenerative ophthalmology, offering a new therapeutic target for corneal injuries and diseases. This review provides a comprehensive examination of CSSCs, exploring their anatomy, functions, and role in maintaining corneal integrity. Molecular markers, wound healing mechanisms, and potential therapeutic applications are discussed. Global corneal blindness, especially in more resource-limited regions, underscores the need for innovative solutions. Challenges posed by corneal defects, emphasizing the urgent need for advanced therapeutic interventions, are discussed. The review places a spotlight on exosome therapy as a potential therapy. CSSC-derived exosomes exhibit significant potential for modulating inflammation, promoting tissue repair, and addressing corneal transparency. Additionally, the rejuvenation potential of CSSCs through epigenetic reprogramming adds to the evolving regenerative landscape. The imperative for clinical trials and human studies to seamlessly integrate these strategies into practice is emphasized. This points towards a future where CSSC-based therapies, particularly leveraging exosomes, play a central role in diversifying ophthalmic regenerative medicine.
Collapse
Affiliation(s)
- Thomas Volatier
- Department of Ophthalmology, Faculty of Medicine, University Hospital Cologne, University of Cologne, 50937 Cologne, Germany
| | - Claus Cursiefen
- Department of Ophthalmology, Faculty of Medicine, University Hospital Cologne, University of Cologne, 50937 Cologne, Germany
- Cologne Excellence Cluster for Cellular Stress Responses Aging-Associated Diseases (CECAD), University of Cologne, Joseph-Stelzmann-Strasse 26, 50931 Cologne, Germany
- Center for Molecular Medicine Cologne (CMMC), Faculty of Medicine, University Hospital Cologne, University of Cologne, 50931 Cologne, Germany
| | - Maria Notara
- Department of Ophthalmology, Faculty of Medicine, University Hospital Cologne, University of Cologne, 50937 Cologne, Germany
- Center for Molecular Medicine Cologne (CMMC), Faculty of Medicine, University Hospital Cologne, University of Cologne, 50931 Cologne, Germany
| |
Collapse
|
3
|
Kaur S, Sohnen P, Swamynathan S, Du Y, Espana EM, Swamynathan SK. Molecular nature of ocular surface barrier function, diseases that affect it, and its relevance for ocular drug delivery. Ocul Surf 2023; 30:3-13. [PMID: 37543173 PMCID: PMC10837323 DOI: 10.1016/j.jtos.2023.08.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2023] [Revised: 08/01/2023] [Accepted: 08/02/2023] [Indexed: 08/07/2023]
Abstract
The structural and functional integrity of the ocular surface, a continuous epithelial structure comprised of the cornea, the conjunctiva, and the ductal surface of the lacrimal as well as meibomian glands, is crucial for proper vision. The ocular surface barrier function (OSBF), sum of the different types of protective mechanisms that exist at the ocular surface, is essential to protect the rest of the eye from vision-threatening physical, chemical, and biological insults. OSBF helps maintain the immune privileged nature of the cornea and the aqueous humor by preventing entry of infectious agents, allergens, and noxious chemicals. Disruption of OSBF exposes the dense nerve endings of the cornea to these stimuli, resulting in discomfort and pain. This review summarizes the status of our knowledge related to the molecular nature of OSBF, describes the effect of different ocular surface disorders on OSBF, and examines the relevance of this knowledge for ocular drug delivery.
Collapse
Affiliation(s)
- Satinder Kaur
- Department of Ophthalmology, Morsani College of Medicine, University of South Florida, 12901 Bruce B. Downs Blvd., Room 2114, Tampa, FL 33612. USA
| | - Peri Sohnen
- Department of Ophthalmology, Morsani College of Medicine, University of South Florida, 12901 Bruce B. Downs Blvd., Room 2114, Tampa, FL 33612. USA
| | - Sudha Swamynathan
- Department of Ophthalmology, Morsani College of Medicine, University of South Florida, 12901 Bruce B. Downs Blvd., Room 2114, Tampa, FL 33612. USA
| | - Yiqin Du
- Department of Ophthalmology, Morsani College of Medicine, University of South Florida, 12901 Bruce B. Downs Blvd., Room 2114, Tampa, FL 33612. USA
| | - Edgar M Espana
- Department of Ophthalmology, Morsani College of Medicine, University of South Florida, 12901 Bruce B. Downs Blvd., Room 2114, Tampa, FL 33612. USA
| | - Shivalingappa K Swamynathan
- Department of Ophthalmology, Morsani College of Medicine, University of South Florida, 12901 Bruce B. Downs Blvd., Room 2114, Tampa, FL 33612. USA.
| |
Collapse
|
4
|
Swamynathan SK, Swamynathan S. Corneal epithelial development and homeostasis. Differentiation 2023; 132:4-14. [PMID: 36870804 PMCID: PMC10363238 DOI: 10.1016/j.diff.2023.02.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Revised: 01/27/2023] [Accepted: 02/20/2023] [Indexed: 03/06/2023]
Abstract
The corneal epithelium (CE), the most anterior cellular structure of the eye, is a self-renewing stratified squamous tissue that protects the rest of the eye from external elements. Each cell in this exquisite three-dimensional structure needs to have proper polarity and positional awareness for the CE to serve as a transparent, refractive, and protective tissue. Recent studies have begun to elucidate the molecular and cellular events involved in the embryonic development, post-natal maturation, and homeostasis of the CE, and how they are regulated by a well-coordinated network of transcription factors. This review summarizes the status of related knowledge and aims to provide insight into the pathophysiology of disorders caused by disruption of CE development, and/or homeostasis.
Collapse
Affiliation(s)
| | - Sudha Swamynathan
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA, 15213, USA
| |
Collapse
|
5
|
Sunny SS, Lachova J, Dupacova N, Kozmik Z. Multiple roles of Pax6 in postnatal cornea development. Dev Biol 2022; 491:1-12. [PMID: 36049534 DOI: 10.1016/j.ydbio.2022.08.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2022] [Revised: 08/20/2022] [Accepted: 08/23/2022] [Indexed: 11/19/2022]
Abstract
Mammalian corneal development is a multistep process, including formation of the corneal epithelium (CE), endothelium and stroma during embryogenesis, followed by postnatal stratification of the epithelial layers and continuous renewal of the epithelium to replace the outermost corneal cells. Here, we employed the Cre-loxP system to conditionally deplete Pax6 proteins in two domains of ocular cells, i.e., the ocular surface epithelium (cornea, limbus and conjunctiva) (OSE) or postnatal CE via K14-cre or Aldh3-cre, respectively. Earlier and broader inactivation of Pax6 in the OSE resulted in thickened OSE with CE and limbal cells adopting the conjunctival keratin expression pattern. More restricted depletion of Pax6 in postnatal CE resulted in an abnormal cornea marked by reduced epithelial thickness despite increased epithelial cell proliferation. Immunofluorescence studies revealed loss of intermediate filament Cytokeratin 12 and diffused expression of adherens junction components, together with reduced tight junction protein, Zonula occludens-1. Furthermore, the expression of Cytokeratin 14, a basal cell marker in apical layers, indicates impaired differentiation of CE cells. Collectively, our data demonstrate that Pax6 is essential for maintaining proper differentiation and strong intercellular adhesion in postnatal CE cells, whereas limbal Pax6 is required to prevent the outgrowth of conjunctival cells to the cornea.
Collapse
Affiliation(s)
- Sweetu Susan Sunny
- Laboratory of Transcriptional Regulation, Institute of Molecular Genetics of the Czech Academy of Sciences, Videnska 1083, Praha 4, 142 20, Czech Republic
| | - Jitka Lachova
- Laboratory of Transcriptional Regulation, Institute of Molecular Genetics of the Czech Academy of Sciences, Videnska 1083, Praha 4, 142 20, Czech Republic
| | - Naoko Dupacova
- Laboratory of Transcriptional Regulation, Institute of Molecular Genetics of the Czech Academy of Sciences, Videnska 1083, Praha 4, 142 20, Czech Republic
| | - Zbynek Kozmik
- Laboratory of Transcriptional Regulation, Institute of Molecular Genetics of the Czech Academy of Sciences, Videnska 1083, Praha 4, 142 20, Czech Republic.
| |
Collapse
|
6
|
Dou S, Wang Q, Qi X, Zhang B, Jiang H, Chen S, Duan H, Lu Y, Dong J, Cao Y, Xie L, Zhou Q, Shi W. Molecular identity of human limbal heterogeneity involved in corneal homeostasis and privilege. Ocul Surf 2021; 21:206-220. [PMID: 33964410 DOI: 10.1016/j.jtos.2021.04.010] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Revised: 04/10/2021] [Accepted: 04/24/2021] [Indexed: 12/20/2022]
Abstract
PURPOSE The corneal limbus maintains the homeostasis, immune and angiogenic privilege of cornea. This study aimed to depict the landscape of human limbal tissues by single-cell RNA sequencing (scRNA-seq). METHODS Single cells of human limbus collected from donor corneas were subjected to 10x scRNA-seq, followed by clustering cell types through the t-distributed stochastic neighbor embedding (t-SNE) and unbiased computational informatic analysis. Immunofluorescent staining was performed using human corneas to validate the analysis results. RESULTS 47,627 cells acquired from six human limbal tissues were collected and subjected to scRNA-seq. 14 distinct clusters were identified and 8 cell types were annotated with representative markers. In-depth dissection revealed three limbal epithelial cell subtypes and refined the X-Y-Z hypothesis of corneal epithelial maintenance. We further unveiled two cell states with higher stemness (TP63+ and CCL20+ cells), and two other differentiated cell states (GPHA2+ and KRT6B + cells) in homeostatic limbal stem/progenitor cells (LSPCs) that differ in transcriptional profiles. Cell-cell communication analysis revealed the central role of LSPCs and their bidirectional regulation with various niche cells. Moreover, comparative analysis between limbus and skin deciphered the pivotal contribution of limbal immune cells, vascular and lymphatic endothelial cells to corneal immune and angiogenic privilege. CONCLUSIONS The human limbus atlas provided valuable resources and foundations for understanding corneal biology, disease and potential interventions.
Collapse
Affiliation(s)
- Shengqian Dou
- State Key Laboratory Cultivation Base, Shandong Provincial Key Laboratory of Ophthalmology, Shandong Eye Institute, Shandong First Medical University & Shandong Academy of Medical Sciences, Qingdao, China; Qingdao Eye Hospital of Shandong First Medical University, Qingdao, China
| | - Qun Wang
- State Key Laboratory Cultivation Base, Shandong Provincial Key Laboratory of Ophthalmology, Shandong Eye Institute, Shandong First Medical University & Shandong Academy of Medical Sciences, Qingdao, China; Qingdao Eye Hospital of Shandong First Medical University, Qingdao, China
| | - Xia Qi
- State Key Laboratory Cultivation Base, Shandong Provincial Key Laboratory of Ophthalmology, Shandong Eye Institute, Shandong First Medical University & Shandong Academy of Medical Sciences, Qingdao, China; Qingdao Eye Hospital of Shandong First Medical University, Qingdao, China
| | - Bin Zhang
- State Key Laboratory Cultivation Base, Shandong Provincial Key Laboratory of Ophthalmology, Shandong Eye Institute, Shandong First Medical University & Shandong Academy of Medical Sciences, Qingdao, China; Qingdao Eye Hospital of Shandong First Medical University, Qingdao, China
| | - Hui Jiang
- State Key Laboratory Cultivation Base, Shandong Provincial Key Laboratory of Ophthalmology, Shandong Eye Institute, Shandong First Medical University & Shandong Academy of Medical Sciences, Qingdao, China; Qingdao Eye Hospital of Shandong First Medical University, Qingdao, China
| | - Shengwen Chen
- State Key Laboratory Cultivation Base, Shandong Provincial Key Laboratory of Ophthalmology, Shandong Eye Institute, Shandong First Medical University & Shandong Academy of Medical Sciences, Qingdao, China; Qingdao Eye Hospital of Shandong First Medical University, Qingdao, China
| | - Haoyun Duan
- State Key Laboratory Cultivation Base, Shandong Provincial Key Laboratory of Ophthalmology, Shandong Eye Institute, Shandong First Medical University & Shandong Academy of Medical Sciences, Qingdao, China; Qingdao Eye Hospital of Shandong First Medical University, Qingdao, China
| | - Yao Lu
- OE Biotech Co., Ltd, Shanghai, Shanghai, China
| | | | - Yihai Cao
- Department of Microbiology, Tumor, and Cell Biology, Karolinska Institute, Stockholm, Sweden
| | - Lixin Xie
- State Key Laboratory Cultivation Base, Shandong Provincial Key Laboratory of Ophthalmology, Shandong Eye Institute, Shandong First Medical University & Shandong Academy of Medical Sciences, Qingdao, China; Qingdao Eye Hospital of Shandong First Medical University, Qingdao, China
| | - Qingjun Zhou
- State Key Laboratory Cultivation Base, Shandong Provincial Key Laboratory of Ophthalmology, Shandong Eye Institute, Shandong First Medical University & Shandong Academy of Medical Sciences, Qingdao, China; Qingdao Eye Hospital of Shandong First Medical University, Qingdao, China.
| | - Weiyun Shi
- State Key Laboratory Cultivation Base, Shandong Provincial Key Laboratory of Ophthalmology, Shandong Eye Institute, Shandong First Medical University & Shandong Academy of Medical Sciences, Qingdao, China; Qingdao Eye Hospital of Shandong First Medical University, Qingdao, China; Eye Hospital of Shandong First Medical University, Jinan, China.
| |
Collapse
|
7
|
Tiwari A, Swamynathan S, Campbell G, Jhanji V, Swamynathan SK. BMP6 Regulates Corneal Epithelial Cell Stratification by Coordinating Their Proliferation and Differentiation and Is Upregulated in Pterygium. Invest Ophthalmol Vis Sci 2021; 61:46. [PMID: 32845956 PMCID: PMC7452852 DOI: 10.1167/iovs.61.10.46] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Purpose Proper balance between cell proliferation and differentiation is essential for corneal epithelial (CE) stratification and homeostasis. Although bone morphogenetic protein-6 (BMP6) is known to be expressed in the CE for over 25 years, its function in this tissue remains unknown. Here, we test the hypothesis that BMP6 promotes CE cell stratification and homeostasis by regulating their proliferation and differentiation. Methods We employed postnatal day-12 (PN-12), PN-14, PN-20, and PN-90 mouse eyes; human corneal limbal epithelial (HCLE) cells; and ocular surface fibrovascular disease pterygium tissues to evaluate the role of BMP6 in CE proliferation, differentiation, and pathology by RT-qPCR, immunoblots, and/or immunofluorescent staining. Cell proliferation was quantified by immunostaining for Ki67. Results Coincident with the mouse CE stratification between PN-12 and PN-20, BMP6 was significantly upregulated and the BMP6 antagonist Noggin downregulated. Mature CE retained high BMP6 and low Noggin expression at PN-90. BMP6 and its receptors BMPR1A and BMPR2 were upregulated during in vitro stratification of HCLE cells. Consistent with its anti-proliferative role, exogenous BMP6 suppressed HCLE cell proliferation, downregulated cyclin-D1 and cyclin-D2, and upregulated cell-cycle inhibitors Krüppel-like factor 4 (KLF4) and p21. BMP6 also upregulated the desmosomal cadherins desmoplakin and desmoglein in HCLE cells, consistent with its pro-differentiation role. Human pterygium displayed significant upregulation of BMP6 coupled with downregulation of Noggin and cell-cycle suppressors KLF4 and p21. Conclusions BMP6 coordinates CE stratification and homeostasis by regulating their proliferation and differentiation. BMP6 is significantly upregulated in human pterygium concurrent with downregulation of Noggin, KLF4, and p21.
Collapse
Affiliation(s)
- Anil Tiwari
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States
| | - Sudha Swamynathan
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States
| | - Gregory Campbell
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States
| | - Vishal Jhanji
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States
| | - Shivalingappa K Swamynathan
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States.,Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States.,Fox Center for Vision Restoration, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States.,McGowan Institute of Regenerative Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
| |
Collapse
|
8
|
Efraim Y, Chen FYT, Stashko C, Cheong KN, Gaylord E, McNamara N, Knox SM. Alterations in corneal biomechanics underlie early stages of autoimmune-mediated dry eye disease. J Autoimmun 2020; 114:102500. [PMID: 32565048 PMCID: PMC8269964 DOI: 10.1016/j.jaut.2020.102500] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2020] [Revised: 05/25/2020] [Accepted: 05/25/2020] [Indexed: 12/11/2022]
Abstract
Autoimmune-mediated dry eye disease is a pathological feature of multiple disorders including Sjögren's syndrome, lupus and rheumatoid arthritis that has a life-long, detrimental impact on vision and overall quality of life. Although late stage disease outcomes such as epithelial barrier dysfunction, reduced corneal innervation and chronic inflammation have been well characterized in both human patients and mouse models, there is little to no understanding of early pathological processes. Moreover, the mechanisms underlying the loss of cornea homeostasis and disease progression are unknown. Here, we utilize the autoimmune regulatory (Aire)-deficient mouse model of autoimmune-mediated dry eye disease in combination with genome wide transcriptomics, high-resolution imaging and atomic force microscopy to reveal a potential extracellular matrix (ECM)-biomechanical-based mechanism driving cellular and morphological changes at early disease onset. Early disease in the Aire-deficient mouse model is associated with a mild reduction in tear production and moderate immune cell infiltration, allowing for interrogation of cellular, molecular and biomechanical changes largely independent of chronic inflammation. Using these tools, we demonstrate for the first time that the emergence of autoimmune-mediated dry eye disease is associated with an alteration in the biomechanical properties of the cornea. We reveal a dramatic disruption of the synthesis and organization of the extracellular matrix as well as degradation of the epithelial basement membrane during early disease. Notably, we provide evidence that the nerve supply to the cornea is severely reduced at early disease stages and that this is independent of basement membrane destruction or significant immune cell infiltration. Furthermore, diseased corneas display spatial heterogeneity in mechanical, structural and compositional changes, with the limbal compartment often exhibiting the opposite response compared to the central cornea. Despite these differences, however, epithelial hyperplasia is apparent in both compartments, possibly driven by increased activation of IL-1R1 and YAP signaling pathways. Thus, we reveal novel perturbations in corneal biomechanics, matrix organization and cell behavior during the early phase of dry eye that may underlie disease development and progression, presenting new potential targets for therapeutic intervention.
Collapse
Affiliation(s)
- Yael Efraim
- Program in Craniofacial Biology, Department of Cell & Tissue Biology, University of California San Francisco, San Francisco, CA, 94143, USA
| | - Feeling Yu Ting Chen
- Program in Craniofacial Biology, Department of Cell & Tissue Biology, University of California San Francisco, San Francisco, CA, 94143, USA
| | - Connor Stashko
- Center for Bioengineering and Tissue Regeneration, Department of Surgery, University of California San Francisco, San Francisco, CA, 94143, USA
| | - Ka Neng Cheong
- Program in Craniofacial Biology, Department of Cell & Tissue Biology, University of California San Francisco, San Francisco, CA, 94143, USA
| | - Eliza Gaylord
- Program in Craniofacial Biology, Department of Cell & Tissue Biology, University of California San Francisco, San Francisco, CA, 94143, USA
| | - Nancy McNamara
- School of Optometry and Vision Science Graduate Program, University of California, Berkeley, CA, 94720, USA; Department of Anatomy, University of California San Francisco, San Francisco, CA, 94143, USA.
| | - Sarah M Knox
- Program in Craniofacial Biology, Department of Cell & Tissue Biology, University of California San Francisco, San Francisco, CA, 94143, USA.
| |
Collapse
|
9
|
Ortiz-Melo MT, Garcia-Murillo MJ, Salazar-Rojas VM, Campos JE, Castro-Muñozledo F. Transcriptional profiles along cell programming into corneal epithelial differentiation. Exp Eye Res 2020; 202:108302. [PMID: 33098888 DOI: 10.1016/j.exer.2020.108302] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Revised: 09/23/2020] [Accepted: 10/12/2020] [Indexed: 12/15/2022]
Abstract
Using the rabbit corneal epithelial cell line RCE1(5T5) as a model, we analyzed three differentiation stages, distinguished on basis to the growth state of cultured cells and after studying the expression of transcription factors such as Oct4, Pax6 and ΔNp63α, selected differentiation markers, and signaling or epigenetic markers such as Notch receptors and Prdm3. Namely, proliferative non-differentiated cells, committed cells, and cells that constitute a stratified epithelium with a limbal epithelial-like structure. RNAseq based transcriptome analysis showed that 4891 genes were differentially expressed among these stages displaying distinctive gene signatures: proliferative cells had 1278 genes as gene signature, and seem to be early epithelial progenitors with an Oct4+, KLF4+, Myc+, ΔNp63α+, ABCG2+, Vimentin+, Zeb1+, VANGL1+, Krt3-, Krt12- phenotype. Committed cells had a gene signature with 417 genes and displayed markers indicative of the beginning of corneal differentiation, and genes characteristic of proliferative cells; we found the possible participation of Six3 and Six4 transcription factors along this stage. The third stage matches with a stratified corneal epithelium (gene signature comprising 979 genes) and is typified by an increase in the expression of WNT10A and NOTCH 2 and 3 signaling and Cux1 transcription factor, besides Pax6, KLF4 or Sox9. The differentiated cells express about 50% of the genes that belong to the Epidermal Differentiation Complex (EDC). Analysis of the differences between corneal epithelium and epidermis could be crucial to understand the regulatory mechanisms that lead to the expression of the differentiated phenotype.
Collapse
Affiliation(s)
- María Teresa Ortiz-Melo
- Department of Cell Biology, Centro de Investigación y de Estudios Avanzados del IPN, Apdo. Postal 14-740. México City, 07000, Mexico; Unidad de Biotecnología y Prototipos, Facultad de Estudios Superiores Iztacala, Universidad Nacional Autónoma de México, Ap. Postal 314, 54000, Tlalnepantla, Edo. de México, Mexico; Posgrado en Ciencias Biológicas, Universidad Nacional Autónoma de México. Unidad de Posgrado, Edificio A, 1° Piso, Circuito de Posgrados, Ciudad Universitaria, Coyoacán, C.P. 04510, Ciudad de México, Mexico
| | - Maria Jimena Garcia-Murillo
- Department of Cell Biology, Centro de Investigación y de Estudios Avanzados del IPN, Apdo. Postal 14-740. México City, 07000, Mexico
| | - Víctor Manuel Salazar-Rojas
- Unidad de Biotecnología y Prototipos, Facultad de Estudios Superiores Iztacala, Universidad Nacional Autónoma de México, Ap. Postal 314, 54000, Tlalnepantla, Edo. de México, Mexico
| | - Jorge E Campos
- Unidad de Biotecnología y Prototipos, Facultad de Estudios Superiores Iztacala, Universidad Nacional Autónoma de México, Ap. Postal 314, 54000, Tlalnepantla, Edo. de México, Mexico
| | - Federico Castro-Muñozledo
- Department of Cell Biology, Centro de Investigación y de Estudios Avanzados del IPN, Apdo. Postal 14-740. México City, 07000, Mexico.
| |
Collapse
|
10
|
Tiwari A, Swamynathan S, Jhanji V, Swamynathan SK. KLF4 Coordinates Corneal Epithelial Apical-Basal Polarity and Plane of Cell Division and Is Downregulated in Ocular Surface Squamous Neoplasia. Invest Ophthalmol Vis Sci 2020; 61:15. [PMID: 32396634 PMCID: PMC7409308 DOI: 10.1167/iovs.61.5.15] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Purpose Previously, we demonstrated that Krüppel-like factor 4 (KLF4) promotes corneal epithelial (CE) homeostasis by suppressing epithelial-mesenchymal transition (EMT) and TGF-β signaling. As TGF-β affects epithelial apicobasal polarity (ABP) and plane of division, we investigated the role of KLF4 in these processes. Methods Klf4 was ablated in adult ternary transgenic Klf4Δ/ΔCE (Klf4LoxP/LoxP/Krt12rtTA/rtTA/Tet-O-Cre) mouse CE using doxycycline chow. ABP and plane of division markers’ expression in Klf4Δ/ΔCE and human ocular surface squamous neoplasia (OSSN) tissues relative to controls was evaluated by quantitative PCR, immunoblots, and/or immunofluorescent staining. Results Klf4Δ/ΔCE CE cells displayed downregulation of apical Pals1 and Crumbs1, apicolateral Par3, and basolateral Scribble, as well as upregulation of Rho family GTPase Cdc42, suggesting disruption of ABP. Phalloidin staining revealed that the Klf4Δ/ΔCE CE actin cytoskeleton is disrupted. Klf4Δ/ΔCE cells favored vertical plane of division within 67.5° to 90° of the CE basement membrane (39% and 47% of the dividing cells relative to 23% and 26% in the control based on phospho-histone-H3 and survivin, respectively), resulting in more dividing cells within the Klf4Δ/ΔCE CE as reported previously. KLF4 was downregulated in human OSSN tissues that displayed EMT and downregulation of PAR3, PALS1, and SCRIB, consistent with a protective role for KLF4. Conclusions By demonstrating that Klf4 ablation affects CE expression of ABP markers and Cdc42, cytoskeletal actin organization, and the plane of cell division and that KLF4 is downregulated in OSSN tissues that display EMT and lack ABP, these results elucidate the key integrative role of KLF4 in coordinating CE cell polarity and plane of division, loss of which results in OSSN.
Collapse
|
11
|
Wong HL, Poon SHL, Bu Y, Lo ACY, Jhanji V, Chan YK, Shih KC. A Systematic Review on Cornea Epithelial-Stromal Homeostasis. Ophthalmic Res 2020; 64:178-191. [PMID: 32474566 DOI: 10.1159/000509030] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Accepted: 05/29/2020] [Indexed: 11/19/2022]
Abstract
INTRODUCTION This review aims to summarise the role of different cells, genes, proteins and lipid in regulating cornea epithelial-stromal homeostasis. METHODS We performed an Entrez PubMed literature search using keywords "human," "cornea," "epithelial," "stromal," "homeostasis," "fibrosis response," and "pathogenesis" on 24th of September 2019, resulting in 35 papers, of which 18 were chosen after filtering for "English language" and "published within 10 years" as well as curation for relevance by the authors. RESULTS The 18 selected papers showed that corneal epithelial cells, fibroblasts and telocytes, together with genes such as Klf4, Pax6 and Id found in the cells, play important roles in achieving homeostasis to maintain corneal integrity and transparency. Proteins classified as pro-fibrotic ligands and anti-fibrotic ligands are responsible for regulating cornea stromal fibrosis and extracellular matrix deposition, thus regulators of scar formation during wound healing. Anti-inflammatory ligands and wound repairing ligands are critical in eliciting protective inflammation and promoting epithelial healing, respectively. Protein receptors located on cellular membrane play a role in maintaining intercellular connections as well as corneal hydration. DISCUSSION/CONCLUSION These studies prompt development of novel therapeutic strategies such as tear drops or ointments that target certain proteins to maintain corneal homeostasis. However, more in vitro and in vivo studies are required to prove the effectiveness of exogenous administration of molecules in improving healing outcome. Hence, future investigations of the molecular pathways highlighted in this review will reveal novel therapeutic tools such as gene or cell therapy to treat corneal diseases.
Collapse
Affiliation(s)
- Ho Lam Wong
- Department of Ophthalmology, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong, Hong Kong, China
| | - Stephanie Hiu Ling Poon
- Department of Ophthalmology, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong, Hong Kong, China
| | - Yashan Bu
- Department of Ophthalmology, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong, Hong Kong, China
| | - Amy Cheuk Yin Lo
- Department of Ophthalmology, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong, Hong Kong, China
| | - Vishal Jhanji
- Department of Ophthalmology, University of Pittsburgh Medical Centre, Pittsburgh, Pennsylvania, USA
| | - Yau Kei Chan
- Department of Ophthalmology, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong, Hong Kong, China
| | - Kendrick Co Shih
- Department of Ophthalmology, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong, Hong Kong, China,
| |
Collapse
|
12
|
Swamynathan SK, Wells A. Conjunctival goblet cells: Ocular surface functions, disorders that affect them, and the potential for their regeneration. Ocul Surf 2020; 18:19-26. [PMID: 31734511 PMCID: PMC7004882 DOI: 10.1016/j.jtos.2019.11.005] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Revised: 10/15/2019] [Accepted: 11/13/2019] [Indexed: 02/06/2023]
Abstract
Conjunctival goblet cells (CGCs) are specialized cells that produce and secrete soluble mucins to the tear film that bathes the ocular surface. CGC numbers and functions are affected in various ocular surface diseases including dry eye disease with diverse etiologies. In this review we will (i) summarize the important functions of CGCs in ocular surface health, (ii) describe the ocular surface diseases that affect CGC numbers and function, (iii) provide an update on recent research outcomes that elucidate CGC differentiation, gene expression and functions, and (iv) present evidence in support of the prediction that restoring CGC numbers and/or functions is a viable strategy for alleviating ocular surface disorders that impact the CGCs.
Collapse
Affiliation(s)
- Shivalingappa K Swamynathan
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA; McGowan Institute of Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA, USA; Fox Center for Vision Restoration, University of Pittsburgh, Pittsburgh, PA, USA; Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.
| | - Alan Wells
- McGowan Institute of Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA, USA; Department of Pathology, University of Pittsburgh, Pittsburgh, PA, USA; Pittsburgh Veterans Affairs Medical Center, Pittsburgh, PA, USA.
| |
Collapse
|
13
|
Agbo KC, Huang JZ, Ghaleb AM, Williams JL, Shroyer KR, Bialkowska AB, Yang VW. Loss of the Krüppel-like factor 4 tumor suppressor is associated with epithelial-mesenchymal transition in colorectal cancer. ACTA ACUST UNITED AC 2019; 5. [PMID: 32566755 PMCID: PMC7304562 DOI: 10.20517/2394-4722.2019.35] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Aim: Colorectal cancer (CRC) is the third leading cancer-related cause of death due to its propensity to metastasize. Epithelial-mesenchymal transition (EMT) is a multistep process important for invasion and metastasis of CRC. Krüppel-like factor 4 (KLF4) is a zinc finger transcription factor highly expressed in differentiated cells of the intestinal epithelium. KLF4 has been shown to play a tumor suppressor role during CRC tumorigenesis - its loss accelerates development and progression of cancer. The present study examined the relationship between KLF4 and markers of EMT in CRC. Methods: Immunofluorescence staining for KLF4 and EMT markers was performed on archived patient samples after colorectal cancer resection and on colonic tissues of mice with colitis-associated cancer. Results: We found that KLF4 expression is lost in tumor sections obtained from CRC patients and in those of mouse colon following azoxymethane and dextran sodium sulfate (AOM/DSS) treatment when compared to their respective normal appearing mucosa. Importantly, in CRC patient tumor sections, we observed a negative correlation between KLF4 levels and mesenchymal markers including TWIST, β-catenin, claudin-1, N-cadherin, and vimentin. Similarly, in tumor tissues from AOM/DSS-treated mice, KLF4 levels were negatively correlated with mesenchymal markers including SNAI2, β-catenin, and vimentin and positively correlated with the epithelial marker E-cadherin. Conclusion: These findings suggest that the loss of KLF4 expression is a potentially significant indicator of EMT in CRC.
Collapse
Affiliation(s)
- Kimberley C Agbo
- Department of Medicine, Stony Brook University School of Medicine, Stony Brook, NY 11794, USA
| | - Jessie Z Huang
- Department of Medicine, Stony Brook University School of Medicine, Stony Brook, NY 11794, USA
| | - Amr M Ghaleb
- Department of Pathology, Stony Brook University School of Medicine, Stony Brook, NY 11794, USA
| | - Jennie L Williams
- Department of Family, Population and Preventive Medicine, Stony Brook, NY 11794, USA
| | - Kenneth R Shroyer
- Department of Pathology, Stony Brook University School of Medicine, Stony Brook, NY 11794, USA
| | - Agnieszka B Bialkowska
- Department of Medicine, Stony Brook University School of Medicine, Stony Brook, NY 11794, USA
| | - Vincent W Yang
- Department of Medicine, Stony Brook University School of Medicine, Stony Brook, NY 11794, USA.,Department of Physiology and Biophysics, Stony Brook University School of Medicine, Stony Brook, NY 11794, USA
| |
Collapse
|
14
|
Fujimoto S, Hayashi R, Hara S, Sasamoto Y, Harrington J, Tsujikawa M, Nishida K. KLF4 prevents epithelial to mesenchymal transition in human corneal epithelial cells via endogenous TGF-β2 suppression. Regen Ther 2019; 11:249-257. [PMID: 31538102 PMCID: PMC6745437 DOI: 10.1016/j.reth.2019.08.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2019] [Revised: 08/14/2019] [Accepted: 08/23/2019] [Indexed: 12/13/2022] Open
Abstract
Introduction Krüppel-like factor 4 (KLF4) is considered one of the Yamanaka factors, and recently, we and others have shown that KLF4 is one of the transcription factors essential for reprogramming non-human corneal epithelial cells (HCECs) into HCECs. Since epithelial to mesenchymal transition (EMT) suppression is vital for homeostasis of HCECs via regulation of transcription factors, in this study, we aimed to investigate whether KLF4 prevents EMT in HCECs and to elucidate the underlying mechanism within the canonical TGF-β signalling pathway, which is involved in corneal epithelial wound healing. Methods HCECs were collected from cadaver donors and cultivated. We generated KLF4-knockdown (KD) HCECs using siRNA transfection and analysed morphology, gene or protein expression, and endogenous TGF-β secretion. KLF4 was overexpressed using lentiviral KLF4 expression vectors and underwent protein expression analyses after TGF-β2 treatment. Results KLF4-KD HCECs showed a fibroblastic morphology, downregulation of the epithelial markers, keratin 12 and keratin 14, and upregulation of the mesenchymal markers, fibronectin 1, vimentin, N-cadherin, and SLUG. Although E-cadherin expression remained unchanged in KLF4-KD HCECs, immunocytochemical analysis showed that E-cadherin–positive adherens junctions decreased in KLF4-KD HCECs as well as the decreased total protein levels of E-cadherin analysed by immunoblotting. Moreover, within the TGF-β canonical signalling pathway, TGF-β2 secretion by HCECs increased up to 5 folds, and several TGF-β–associated markers (TGFB1, TGFB2, TGFBR1, and TGFBR2) were significantly upregulated up to 6 folds in the KLF4-KD HCECs. SMAD2/3, the main signal transduction molecules of the TGF-β signalling pathway, were found to be localised in the nucleus of KLF4-KD HCECs. When KLF4 was overexpressed, cultivated HCECs showed upregulation of epithelial markers, keratin 14 and E-cadherin, indicating the contributory role of KLF4 in the homeostasis of human corneal epithelium in vivo. In addition, KLF4 overexpression in HCECs resulted in decreased SMAD2 phosphorylation and altered nuclear localisation of SMAD2/3, even after TGF-β2 treatment. Conclusions These results show that KLF4 prevents EMT in HCECs and suggest a novel role of KLF4 as an endogenous TGF-β2 suppressor in the human corneal epithelium, thus highlighting the potential of KLF4 to prevent EMT and subsequent corneal fibrotic scar formation by attenuating TGF-β signalling. KLF4 inhibited EMT within corneal epithelia. TGF-β expression of human corneal epithelial cells is regulated by KLF4. KLF4 prevented phosphorylation and nuclear localisation of SMAD2. KLF4 may be an important transcription factor in wound healing.
Collapse
Affiliation(s)
- Satoko Fujimoto
- Department of Ophthalmology, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Ryuhei Hayashi
- Department of Ophthalmology, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka, 565-0871, Japan.,Department of Stem Cells and Applied Medicine, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Susumu Hara
- Department of Ophthalmology, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka, 565-0871, Japan.,Department of Stem Cells and Applied Medicine, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Yuzuru Sasamoto
- Department of Ophthalmology, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka, 565-0871, Japan.,Division of Genetics, Brigham & Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - Jodie Harrington
- Department of Stem Cells and Applied Medicine, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka, 565-0871, Japan.,Structural Biophysics Group, School of Optometry and Vision Sciences, College of Biomedical and Life Sciences, Cardiff University, Cardiff, CF24 4HQ, Wales, UK
| | - Motokazu Tsujikawa
- Department of Ophthalmology, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka, 565-0871, Japan.,Department of Biomedical Informatics, Osaka University Graduate School of Medicine, Division of Health Sciences, 2-2 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Kohji Nishida
- Department of Ophthalmology, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka, 565-0871, Japan
| |
Collapse
|
15
|
Tiwari A, Swamynathan S, Alexander N, Gnalian J, Tian S, Kinchington PR, Swamynathan SK. KLF4 Regulates Corneal Epithelial Cell Cycle Progression by Suppressing Canonical TGF-β Signaling and Upregulating CDK Inhibitors P16 and P27. Invest Ophthalmol Vis Sci 2019; 60:731-740. [PMID: 30786277 PMCID: PMC6383833 DOI: 10.1167/iovs.18-26423] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Purpose Krüppel-like factor 4 (KLF4) promotes corneal epithelial (CE) cell fate while suppressing mesenchymal properties. TGF-β plays a crucial role in cell differentiation and development, and if dysregulated, it induces epithelial-mesenchymal transition (EMT). As KLF4 and TGF-β regulate each other in a context-dependent manner, we evaluated the role of the crosstalk between KLF4 and TGF-β-signaling in CE homeostasis. Methods We used spatiotemporally regulated ablation of Klf4 within the adult mouse CE in ternary transgenic Klf4Δ/ΔCE (Klf4LoxP/LoxP/ Krt12rtTA/rtTA/ Tet-O-Cre) mice and short hairpin RNA (shRNA)-mediated knockdown or lentiviral vector-mediated overexpression of KLF4 in human corneal limbal epithelial (HCLE) cells to evaluate the crosstalk between KLF4 and TGF-β-signaling components. Expression of TGF-β signaling components and cyclin-dependent kinase (CDK) inhibitors was quantified by quantitative PCR, immunoblots, and/or immunofluorescent staining. Results CE-specific ablation of Klf4 resulted in (1) upregulation of TGF-β1, -β2, -βR1, and -βR2; (2) downregulation of inhibitory Smad7; (3) hyperphosphorylation of Smad2/3; (4) elevated nuclear localization of phospho-Smad2/3 and Smad4; and (5) downregulation of CDK inhibitors p16 and p27. Consistently, shRNA-mediated knockdown of KLF4 in HCLE cells resulted in upregulation of TGF-β1 and -β2, hyperphosphorylation and nuclear localization of SMAD2/3, downregulation of SMAD7, and elevated SMAD4 nuclear localization. Furthermore, overexpression of KLF4 in HCLE cells resulted in downregulation of TGF-β1, -βR1, and -βR2 and upregulation of SMAD7, p16, and p27. Conclusions Collectively, these results demonstrate that KLF4 regulates CE cell cycle progression by suppressing canonical TGF-β signaling and overcomes the undesirable concomitant decrease in TGF-β–dependent CDK inhibitors p16 and p27 expression by directly upregulating them.
Collapse
Affiliation(s)
- Anil Tiwari
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States
| | - Sudha Swamynathan
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States
| | - Nicholas Alexander
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States
| | - John Gnalian
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States.,School of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
| | - Shenghe Tian
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States
| | - Paul R Kinchington
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States.,Department of Molecular Microbiology and Genetics, University of Pittsburgh, Pittsburgh, Pennsylvania, United States.,Fox Center for Vision Restoration, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States.,McGowan Institute of Regenerative Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
| | - Shivalingappa K Swamynathan
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States.,Fox Center for Vision Restoration, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States.,McGowan Institute of Regenerative Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, United States.,Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States
| |
Collapse
|
16
|
Sonam S, Srnak JA, Perry KJ, Henry JJ. Molecular markers for corneal epithelial cells in larval vs. adult Xenopus frogs. Exp Eye Res 2019; 184:107-125. [PMID: 30981716 DOI: 10.1016/j.exer.2019.04.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Accepted: 04/08/2019] [Indexed: 12/14/2022]
Abstract
Corneal Epithelial Stem Cells (CESCs) and their proliferative progeny, the Transit Amplifying Cells (TACs), are responsible for maintaining the integrity and transparency of the cornea. These stem cells (SCs) are widely used in corneal transplants and ocular surface reconstruction. Molecular markers are essential to identify, isolate and enrich for these cells, yet no definitive CESC marker has been established. An extensive literature survey shows variability in the expression of putative CESC markers among vertebrates; being attributed to species-specific variations, or other differences in developmental stages of these animals, approaches used in these studies and marker specificity. Here, we expanded the search for CESC markers using the amphibian model Xenopus laevis. In previous studies we found that long-term label retaining cells (suggestive of CESCs and TACs) are present throughout the larval basal corneal epithelium. In adult frogs, these cells become concentrated in the peripheral cornea (limbal region). Here, we used immunofluorescence to characterize the expression of nine proteins in the corneas of both Xenopus larvae and adults (post-metamorphic). We found that localization of some markers change between larval and adult stages. Markers such as p63, Keratin 19, and β1-integrin are restricted to basal corneal epithelial cells of the larvae. After metamorphosis their expression is found in basal and intermediate layer cells of the adult frog corneal epithelium. Another protein, Pax6 was expressed in the larval corneas, but surprisingly it was not detected in the adult corneal epithelium. For the first time we report that Tcf7l2 can be used as a marker to differentiate cornea vs. skin in frogs. Tcf7l2 is present only in the frog skin, which differs from reports indicating that the protein is expressed in the human cornea. Furthermore, we identified the transition between the inner, and the outer surface of the adult frog eyelid as a key boundary in terms of marker expression. Although these markers are useful to identify different regions and cellular layers of the frog corneal epithelium, none is unique to CESCs or TACs. Our results confirm that there is no single conserved CESC marker in vertebrates. This molecular characterization of the Xenopus cornea facilitates its use as a vertebrate model to understand the functions of key proteins in corneal homeostasis and wound repair.
Collapse
Affiliation(s)
- Surabhi Sonam
- Department of Cell and Developmental Biology, University of Illinois, 601 S. Goodwin Avenue, Urbana, IL, 61801, USA
| | - Jennifer A Srnak
- Department of Cell and Developmental Biology, University of Illinois, 601 S. Goodwin Avenue, Urbana, IL, 61801, USA
| | - Kimberly J Perry
- Department of Cell and Developmental Biology, University of Illinois, 601 S. Goodwin Avenue, Urbana, IL, 61801, USA
| | - Jonathan J Henry
- Department of Cell and Developmental Biology, University of Illinois, 601 S. Goodwin Avenue, Urbana, IL, 61801, USA.
| |
Collapse
|
17
|
Loughner CL, Tiwari A, Kenchegowda D, Swamynathan S, Swamynathan SK. Spatiotemporally Controlled Ablation of Klf5 Results in Dysregulated Epithelial Homeostasis in Adult Mouse Corneas. Invest Ophthalmol Vis Sci 2017; 58:4683-4693. [PMID: 28910443 PMCID: PMC5598321 DOI: 10.1167/iovs.17-22498] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Purpose Corneal epithelial (CE) homeostasis requires coordination between proliferation and differentiation. Here we examine the role of cell proliferation regulator Krüppel-like factor 5 (Klf5) in adult mouse CE homeostasis. Methods Klf5 was ablated in a spatiotemporally restricted manner by inducing Cre expression in 8-week-old ternary transgenic Klf5LoxP/LoxP/Krt12rtTA/rtTA/Tet-O-Cre (Klf5Δ/ΔCE) mouse CE by administering doxycycline via chow. Normal chow-fed ternary transgenic siblings served as controls. The control and Klf5Δ/ΔCE corneal (1) histology, (2) cell proliferation, and (3) Klf5-target gene expression were examined using (1) periodic acid Schiff reagent-stained sections, (2) Ki67 expression, and (3) quantitative PCR and immunostaining, respectively. The effect of KLF4, KLF5, and OCT1 on gastrokine-1 (GKN1) promoter activity was determined by transient transfection in human skin keratinocyte NCTC-2544 cells. Results Klf5 expression was decreased to 23% of the controls in Klf5Δ/ΔCE corneas, which displayed increased fluorescein uptake, downregulation of tight junction proteins Tjp1 and Gkn1, desmosomal Dsg1a, and basement membrane Lama3 and Lamb1, suggesting defective permeability barrier. In transient transfection assays, KLF5 and OCT1 synergistically stimulated GKN1 promoter activity. Klf5Δ/ΔCE CE displayed significantly fewer cell layers and Ki67+ proliferative cells coupled with significantly decreased cyclin-D1, and elevated phospho(Ser-10) p27/Kip1 expression. Expression of Krt12, E-cadherin, and β-catenin remained unaltered in Klf5Δ/ΔCE corneas. Conclusions Klf5 contributes to adult mouse CE homeostasis by promoting (1) permeability barrier function through upregulation of Tjp1, Gkn1, Dsg1a, Lama3, and Lamb1, and (2) basal cell proliferation through upregulation of cyclin-D1 and suppression of phospho(Ser-10) p27/Kip1, without significantly affecting the expression of epithelial markers Krt12, E-cadherin, and β-catenin.
Collapse
Affiliation(s)
- Chelsea L Loughner
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, United States
| | - Anil Tiwari
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, United States
| | - Doreswamy Kenchegowda
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, United States
| | - Sudha Swamynathan
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, United States
| | - Shivalingappa K Swamynathan
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, United States.,McGowan Institute of Regenerative Medicine, University of Pittsburgh, United States.,Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, United States.,Fox Center for Vision Restoration, University of Pittsburgh School of Medicine, Pittsburgh, United States
| |
Collapse
|
18
|
Tiwari A, Loughner CL, Swamynathan S, Swamynathan SK. KLF4 Plays an Essential Role in Corneal Epithelial Homeostasis by Promoting Epithelial Cell Fate and Suppressing Epithelial-Mesenchymal Transition. Invest Ophthalmol Vis Sci 2017; 58:2785-2795. [PMID: 28549095 PMCID: PMC5455171 DOI: 10.1167/iovs.17-21826] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Purpose The purpose of this study was to test the hypothesis that KLF4 promotes corneal epithelial (CE) cell fate by suppressing the epithelial–mesenchymal transition (EMT), using spatiotemporally regulated CE-specific ablation of Klf4 in Klf4Δ/ΔCE (Klf4LoxP/LoxP/Krt12rtTA/rtTA/Tet-O-Cre) mice. Methods CE-specific ablation of Klf4 was achieved by feeding Klf4Δ/ΔCE mice with doxycycline chow. The wild-type (WT; normal chow-fed littermates) and the Klf4Δ/ΔCE histology was compared by hematoxylin and eosin–stained sections; EMT marker expression was quantified by quantitative PCR, immunoblots, and immunofluorescent staining; and wound healing rate was measured by CE debridement using Algerbrush. KLF4 and EMT markers were quantified in human corneal limbal epithelial (HCLE) cells undergoing TGF-β1–induced EMT by quantitative PCR, immunoblots, and immunofluorescent staining. Results The epithelial markers E-cadherin, Krt12, claudin-3, and claudin-4 were down-regulated, whereas the mesenchymal markers vimentin, β-catenin, survivin, and cyclin-D1 and the EMT transcription factors Snail, Slug, Twist1, Twist2, Zeb1, and Zeb2 were up-regulated in the Klf4Δ/ΔCE corneas. The Klf4Δ/ΔCE cells migrated faster, filling 93% of the debrided area within 16 hours compared with 61% in the WT. After 7 days of wounding, the Klf4Δ/ΔCE cells that filled the gap failed to regain epithelial characteristics, as they displayed abnormal stratification; down-regulation of E-cadherin and Krt12; up-regulation of β-catenin, survivin, and cyclin-D1; and a 2.5-fold increase in the number of proliferative Ki67+ cells. WT CE cells at the migrating edge and the HCLE cells undergoing TGF-β1–induced EMT displayed significant down-regulation of KLF4. Conclusions Collectively, these results reveal that KLF4 plays an essential role in CE homeostasis by promoting epithelial cell fate and suppressing EMT.
Collapse
Affiliation(s)
- Anil Tiwari
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States
| | - Chelsea L Loughner
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States
| | - Sudha Swamynathan
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States
| | - Shivalingappa K Swamynathan
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States 2McGowan Institute of Regenerative Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, United States 3Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States 4Fox Center for Vision Restoration, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States
| |
Collapse
|
19
|
Swamynathan S, Delp EE, Harvey SAK, Loughner CL, Raju L, Swamynathan SK. Corneal Expression of SLURP-1 by Age, Sex, Genetic Strain, and Ocular Surface Health. Invest Ophthalmol Vis Sci 2016; 56:7888-96. [PMID: 26670825 DOI: 10.1167/iovs.15-18206] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
PURPOSE Although secreted Ly6/urokinase-type plasminogen activator receptor-related protein-1 (Slurp1) transcript is highly abundant in the mouse cornea, corresponding protein expression remains uncharacterized. Also, SLURP1 was undetected in previous tear proteomics studies, resulting in ambiguity about its baseline levels. Here, we examine mouse corneal Slurp1 expression in different sexes, age groups, strains, and health conditions, and quantify SLURP1 in human tears from healthy or inflamed ocular surfaces. METHODS Expression of Slurp1 in embryonic day-13 (E13), E16, postnatal day-1 (PN1), PN10, PN20, and PN70 Balb/C, FVBN, C57Bl/6, and DBA/2J mouse corneas, Klf4Δ/ΔCE corneas with corneal epithelial-specific ablation of Klf4, migrating cells in wild-type corneal epithelial wound edge, and in corneas exposed to pathogen-associated molecular patterns (PAMPs) poly(I:C), zymosan-A, or Pam3Csk4 was examined by QPCR, immunoblots, and immunofluorescent staining. Human SLURP1 levels were quantified by ELISA in tears from 34 men and women aged 18 to 80 years. RESULTS Expression of Slurp1, comparable in different strains and sexes, was low in E13, E16, PN1, and PN10 mouse corneas, and increased rapidly after eyelid opening in a Klf4-dependent manner. We found Slurp1 was downregulated in corneas exposed to PAMPs, and in migrating cells at the wound edge. Human SLURP1 expression, comparable in different sexes and age groups, was significantly decreased in tears from inflamed ocular surfaces (0.34%) than those from healthy individuals (0.77%). CONCLUSIONS These data describe the influence of age, sex, genetic background, and ocular surface health on mouse corneal expression of Slurp1, establish the baseline for human tear SLURP1 expression, and identify SLURP1 as a useful diagnostic and/or therapeutic target for inflammatory ocular surface disorders.
Collapse
Affiliation(s)
- Sudha Swamynathan
- Department of Ophthalmology University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States
| | - Emili E Delp
- Department of Ophthalmology University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States
| | - Stephen A K Harvey
- Department of Ophthalmology University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States
| | - Chelsea L Loughner
- Department of Ophthalmology University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States
| | - Leela Raju
- Department of Ophthalmology University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States
| | - Shivalingappa K Swamynathan
- Department of Ophthalmology University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States 2McGowan Institute of Regenerative Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, United States 3Department of Cell Biology, Un
| |
Collapse
|