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Liu H, Qi B, Liu G, Duan H, Li Z, Shi Z, Chen Y, Chu WK, Zhou Q, Zhang BN. RAD21 deficiency drives corneal to scleral differentiation fate switching via upregulating WNT9B. iScience 2024; 27:109875. [PMID: 38774716 PMCID: PMC11107359 DOI: 10.1016/j.isci.2024.109875] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2023] [Revised: 02/28/2024] [Accepted: 04/29/2024] [Indexed: 05/24/2024] Open
Abstract
The cornea and sclera are distinct adjacent tissues, yet their stromal cells originate from common neural crest cells (NCCs). Sclerocornea is a disease characterized by an indistinguishable boundary between the cornea and sclera. Previously, we identified a RAD21 mutation in a sclerocornea pedigree. Here, we investigated the impacts of RAD21 on NCC activities during eye development. RAD21 deficiency caused upregulation of PCDHGC3. Both RAD21 knockdown and PCDHGC3 upregulation disrupted the migration of NCCs. Transcriptome analysis indicated that WNT9B had 190.9-fold higher expression in scleral stroma than in corneal stroma. WNT9B was also significantly upregulated by both RAD21 knockdown and PCDHGC3 overexpression, and knock down of WNT9B rescued the differentiation and migration of NCCs with RAD21 deficiency. Consistently, overexpressing wnt9b in Xenopus tropicalis led to ocular developmental abnormalities. In summary, WNT9B is a determinant factor during NCC differentiation into corneal keratocytes or scleral stromal cells and is affected by RAD21 expression.
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Affiliation(s)
- Hongyan Liu
- Shandong First Medical University and Shandong Academy of Medical Sciences, Jinan, Shandong, China
- Eye Institute of Shandong First Medical University, Qingdao Eye Hospital of Shandong First Medical University, Qingdao, China
- School of Ophthalmology, Shandong First Medical University, Qingdao, China
| | - Benxiang Qi
- Eye Institute of Shandong First Medical University, Qingdao Eye Hospital of Shandong First Medical University, Qingdao, China
- School of Ophthalmology, Shandong First Medical University, Qingdao, China
- State Key Laboratory Cultivation Base, Shandong Provincial Key Laboratory of Ophthalmology, Qingdao, China
| | - Guanghui Liu
- Department of Chemical Biology, School of Life Sciences, Guangdong Provincial Key Laboratory of Cell Microenvironment and Disease Research, Shenzhen Key Laboratory of Cell Microenvironment, Southern University of Science and Technology, Shenzhen, China
| | - Haoyun Duan
- Eye Institute of Shandong First Medical University, Qingdao Eye Hospital of Shandong First Medical University, Qingdao, China
- School of Ophthalmology, Shandong First Medical University, Qingdao, China
- State Key Laboratory Cultivation Base, Shandong Provincial Key Laboratory of Ophthalmology, Qingdao, China
| | - Zongyi Li
- Eye Institute of Shandong First Medical University, Qingdao Eye Hospital of Shandong First Medical University, Qingdao, China
- School of Ophthalmology, Shandong First Medical University, Qingdao, China
- State Key Laboratory Cultivation Base, Shandong Provincial Key Laboratory of Ophthalmology, Qingdao, China
| | - Zhaoying Shi
- Department of Chemical Biology, School of Life Sciences, Guangdong Provincial Key Laboratory of Cell Microenvironment and Disease Research, Shenzhen Key Laboratory of Cell Microenvironment, Southern University of Science and Technology, Shenzhen, China
| | - Yonglong Chen
- Department of Chemical Biology, School of Life Sciences, Guangdong Provincial Key Laboratory of Cell Microenvironment and Disease Research, Shenzhen Key Laboratory of Cell Microenvironment, Southern University of Science and Technology, Shenzhen, China
| | - Wai Kit Chu
- Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Hong Kong, China
| | - Qingjun Zhou
- Eye Institute of Shandong First Medical University, Qingdao Eye Hospital of Shandong First Medical University, Qingdao, China
- School of Ophthalmology, Shandong First Medical University, Qingdao, China
- State Key Laboratory Cultivation Base, Shandong Provincial Key Laboratory of Ophthalmology, Qingdao, China
| | - Bi Ning Zhang
- Eye Institute of Shandong First Medical University, Qingdao Eye Hospital of Shandong First Medical University, Qingdao, China
- School of Ophthalmology, Shandong First Medical University, Qingdao, China
- State Key Laboratory Cultivation Base, Shandong Provincial Key Laboratory of Ophthalmology, Qingdao, China
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Dorgau B, Collin J, Rozanska A, Zerti D, Unsworth A, Crosier M, Hussain R, Coxhead J, Dhanaseelan T, Patel A, Sowden JC, FitzPatrick DR, Queen R, Lako M. Single-cell analyses reveal transient retinal progenitor cells in the ciliary margin of developing human retina. Nat Commun 2024; 15:3567. [PMID: 38670973 PMCID: PMC11053058 DOI: 10.1038/s41467-024-47933-x] [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: 07/11/2023] [Accepted: 04/12/2024] [Indexed: 04/28/2024] Open
Abstract
The emergence of retinal progenitor cells and differentiation to various retinal cell types represent fundamental processes during retinal development. Herein, we provide a comprehensive single cell characterisation of transcriptional and chromatin accessibility changes that underline retinal progenitor cell specification and differentiation over the course of human retinal development up to midgestation. Our lineage trajectory data demonstrate the presence of early retinal progenitors, which transit to late, and further to transient neurogenic progenitors, that give rise to all the retinal neurons. Combining single cell RNA-Seq with spatial transcriptomics of early eye samples, we demonstrate the transient presence of early retinal progenitors in the ciliary margin zone with decreasing occurrence from 8 post-conception week of human development. In retinal progenitor cells, we identified a significant enrichment for transcriptional enhanced associate domain transcription factor binding motifs, which when inhibited led to loss of cycling progenitors and retinal identity in pluripotent stem cell derived organoids.
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Affiliation(s)
- Birthe Dorgau
- Biosciences Institute, Newcastle University, Newcastle, UK
| | - Joseph Collin
- Biosciences Institute, Newcastle University, Newcastle, UK
| | - Agata Rozanska
- Biosciences Institute, Newcastle University, Newcastle, UK
| | - Darin Zerti
- Biosciences Institute, Newcastle University, Newcastle, UK
- Department of Biotechnological and Applied Clinical Sciences, University of L'Aquila, L'Aquila, Italy
| | | | - Moira Crosier
- Biosciences Institute, Newcastle University, Newcastle, UK
| | | | | | | | - Aara Patel
- UCL Great Ormond Street Institute of Child Health and NIHR Great Ormond Street Hospital Biomedical Research Centre, University College London, London, UK
| | - Jane C Sowden
- UCL Great Ormond Street Institute of Child Health and NIHR Great Ormond Street Hospital Biomedical Research Centre, University College London, London, UK
| | - David R FitzPatrick
- MRC Human Genetics Unit, Institute of Genetics and Cancer, University of Edinburgh, Edinburgh, UK
| | - Rachel Queen
- Biosciences Institute, Newcastle University, Newcastle, UK.
| | - Majlinda Lako
- Biosciences Institute, Newcastle University, Newcastle, UK.
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Garis M, Meyer MD, Lwigale P. Expression of Nephronectin in the Descemet's membrane of mouse corneas during development and adult homeostasis. Exp Eye Res 2024; 240:109797. [PMID: 38246333 DOI: 10.1016/j.exer.2024.109797] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2023] [Revised: 01/15/2024] [Accepted: 01/18/2024] [Indexed: 01/23/2024]
Abstract
Nephronectin (Npnt) is an extracellular matrix (ECM) protein with pleiotropic functions during organogenesis, disease, and homeostasis. Although the ECM plays a crucial role during development and homeostasis of the adult cornea, little is known about the expression of Npnt in the mammalian cornea. Here, we investigated the expression of Npnt during early embryonic and postnatal development, and in adult mouse corneas. We combined ultrastructural and immunohistochemical analyses to study the early formation of the Descemet's membrane and how the expression of Npnt relates to key basement membrane proteins. Our section in situ hybridization and immunohistochemical analyses revealed that Npnt mRNA is expressed by the nascent corneal endothelial cells at embryonic day (E) 14.5, whereas the protein is localized in the adjacent extracellular matrix. These expression patterns were maintained in the corneal endothelium and Descemet's membrane throughout development and in adult corneas. Ultrastructural analysis revealed discontinuous electron dense regions of protein aggregates at E18.5 that was separated from the endothelial layer by an electron lucent space. At birth (postnatal day, P0), the Descemet's membrane was a single layer, which continuously thickened throughout P4, P8, P10, and P14. Npnt was localized to the Descemet's membrane by E18.5 and overlapped with Collagens IV and VIII, Laminin, and Perlecan. However, the proteins subsequently shifted and formed distinct layers in the adult cornea, whereby Npnt localized between two Collagen VIII bands and anterior to Collagen IV but overlapped with Laminin and Perlecan. Combined, our results reveal the expression of Npnt in the mouse cornea and define its spatiotemporal localization relative to key basement membrane proteins during the formation of the Descemet's membrane and in the adult cornea. Understanding the spatiotemporal expression of Npnt is important for future studies to elucidate its function in the mammalian cornea.
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Affiliation(s)
- Matthew Garis
- Department of Biosciences, Rice University, Houston, TX, 77019, USA
| | - Matthew D Meyer
- Shared Equipment Authority, Rice University, Houston, TX, 77019, USA
| | - Peter Lwigale
- Department of Biosciences, Rice University, Houston, TX, 77019, USA.
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Shah R, Amador C, Chun ST, Ghiam S, Saghizadeh M, Kramerov AA, Ljubimov AV. Non-canonical Wnt signaling in the eye. Prog Retin Eye Res 2023; 95:101149. [PMID: 36443219 PMCID: PMC10209355 DOI: 10.1016/j.preteyeres.2022.101149] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2022] [Revised: 11/12/2022] [Accepted: 11/17/2022] [Indexed: 11/27/2022]
Abstract
Wnt signaling comprises a group of complex signal transduction pathways that play critical roles in cell proliferation, differentiation, and apoptosis during development, as well as in stem cell maintenance and adult tissue homeostasis. Wnt pathways are classified into two major groups, canonical (β-catenin-dependent) or non-canonical (β-catenin-independent). Most previous studies in the eye have focused on canonical Wnt signaling, and the role of non-canonical signaling remains poorly understood. Additionally, the crosstalk between canonical and non-canonical Wnt signaling in the eye has hardly been explored. In this review, we present an overview of available data on ocular non-canonical Wnt signaling, including developmental and functional aspects in different eye compartments. We also discuss important changes of this signaling in various ocular conditions, such as keratoconus, aniridia-related keratopathy, diabetes, age-related macular degeneration, optic nerve damage, pathological angiogenesis, and abnormalities in the trabecular meshwork and conjunctival cells, and limbal stem cell deficiency.
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Affiliation(s)
- Ruchi Shah
- Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, CA, USA; Regenerative Medicine Institute Eye Program, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Cynthia Amador
- Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, CA, USA; Regenerative Medicine Institute Eye Program, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Steven T Chun
- Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, CA, USA; Regenerative Medicine Institute Eye Program, Cedars-Sinai Medical Center, Los Angeles, CA, USA; University of California Los Angeles, Los Angeles, CA, USA
| | - Sean Ghiam
- Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, CA, USA; Regenerative Medicine Institute Eye Program, Cedars-Sinai Medical Center, Los Angeles, CA, USA; Sackler School of Medicine, New York State/American Program of Tel Aviv University, Tel Aviv, Israel
| | - Mehrnoosh Saghizadeh
- Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, CA, USA; Regenerative Medicine Institute Eye Program, Cedars-Sinai Medical Center, Los Angeles, CA, USA; David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, USA
| | - Andrei A Kramerov
- Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, CA, USA; Regenerative Medicine Institute Eye Program, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Alexander V Ljubimov
- Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, CA, USA; Regenerative Medicine Institute Eye Program, Cedars-Sinai Medical Center, Los Angeles, CA, USA; David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, USA; Neurosurgery, Cedars-Sinai Medical Center, Los Angeles, CA, USA.
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5
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BMP3 inhibits TGFβ2-mediated myofibroblast differentiation during wound healing of the embryonic cornea. NPJ Regen Med 2022; 7:36. [PMID: 35879352 PMCID: PMC9314337 DOI: 10.1038/s41536-022-00232-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Accepted: 07/06/2022] [Indexed: 11/29/2022] Open
Abstract
Often acute damage to the cornea initiates drastic tissue remodeling, resulting in fibrotic scarring that disrupts light transmission and precedes vision impairment. Very little is known about the factors that can mitigate fibrosis and promote scar-free cornea wound healing. We previously described transient myofibroblast differentiation during non-fibrotic repair in an embryonic cornea injury model. Here, we sought to elucidate the mechanistic regulation of myofibroblast differentiation during embryonic cornea wound healing. We found that alpha-smooth muscle actin (αSMA)-positive myofibroblasts are superficial and their presence inversely correlates with wound closure. Expression of TGFβ2 and nuclear localization of pSMAD2 were elevated during myofibroblast induction. BMP3 and BMP7 were localized in the corneal epithelium and corresponded with pSMAD1/5/8 activation and absence of myofibroblasts in the healing stroma. In vitro analyses with corneal fibroblasts revealed that BMP3 inhibits the persistence of TGFβ2-induced myofibroblasts by promoting disassembly of focal adhesions and αSMA fibers. This was confirmed by the expression of vinculin and pFAK. Together, these data highlight a mechanism to inhibit myofibroblast persistence during cornea wound repair.
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6
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Ma J, Bi L, Spurlin J, Lwigale P. Nephronectin-Integrin α8 signaling is required for proper migration of periocular neural crest cells during chick corneal development. eLife 2022; 11:74307. [PMID: 35238772 PMCID: PMC8916771 DOI: 10.7554/elife.74307] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Accepted: 03/02/2022] [Indexed: 11/19/2022] Open
Abstract
During development, cells aggregate at tissue boundaries to form normal tissue architecture of organs. However, how cells are segregated into tissue precursors remains largely unknown. Cornea development is a perfect example of this process whereby neural crest cells aggregate in the periocular region prior to their migration and differentiation into corneal cells. Our recent RNA-seq analysis identified upregulation of nephronectin (Npnt) transcripts during early stages of corneal development where its function has not been investigated. We found that Npnt mRNA and protein are expressed by various ocular tissues, including the migratory periocular neural crest (pNC), which also express the integrin alpha 8 (Itgα8) receptor. Knockdown of either Npnt or Itgα8 attenuated cornea development, whereas overexpression of Npnt resulted in cornea thickening. Moreover, overexpression of Npnt variants lacking RGD-binding sites did not affect corneal thickness. Neither the knockdown nor augmentation of Npnt caused significant changes in cell proliferation, suggesting that Npnt directs pNC migration into the cornea. In vitro analyses showed that Npnt promotes pNC migration from explanted periocular mesenchyme, which requires Itgα8, focal adhesion kinase, and Rho kinase. Combined, these data suggest that Npnt augments cell migration into the presumptive cornea extracellular matrix by functioning as a substrate for Itgα8-positive pNC cells.
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Affiliation(s)
- Justin Ma
- Department of Biosciences, Rice University, Houston, United States
| | - Lian Bi
- Department of Biosciences, Rice University, Houston, United States
| | - James Spurlin
- Department of Biosciences, Rice University, Houston, United States
| | - Peter Lwigale
- Department of Biosciences, Rice University, Houston, United States
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Stanton CM, Findlay AS, Drake C, Mustafa MZ, Gautier P, McKie L, Jackson IJ, Vitart V. A Mouse Model of Brittle Cornea Syndrome caused by mutation in Zfp469. Dis Model Mech 2021; 14:272230. [PMID: 34368841 PMCID: PMC8476817 DOI: 10.1242/dmm.049175] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Accepted: 07/28/2021] [Indexed: 11/20/2022] Open
Abstract
Brittle cornea syndrome (BCS) is a rare recessive condition characterised by extreme thinning of the cornea and sclera. BCS results from loss-of-function mutations in the poorly understood genes ZNF469 or PRDM5. In order to determine the function of ZNF469 and to elucidate pathogenic mechanisms, we used genome editing to recapitulate a human ZNF469 BCS mutation in the orthologous mouse gene Zfp469. Ophthalmic phenotyping showed that homozygous Zfp469 mutation causes significant central and peripheral corneal thinning arising from reduced stromal thickness. Expression of key components of the corneal stroma in primary keratocytes from Zfp469BCS/BCS mice is affected, including decreased Col1a1 and Col1a2 expression. This alters the collagen type I/collagen type V ratio and results in collagen fibrils with smaller diameter and increased fibril density in homozygous mutant corneas, correlating with decreased biomechanical strength in the cornea. Cell-derived matrices generated by primary keratocytes show reduced deposition of collagen type I, offering an in vitro model for stromal dysfunction. Work remains to determine whether modulating ZNF469 activity will have therapeutic benefit in BCS or in conditions such as keratoconus in which the cornea thins progressively. This article has an associated First Person interview with the first author of the paper. Summary: A mouse model of brittle cornea syndrome was created to elucidate molecular mechanisms underlying the pathology of this rare connective tissue disorder in which extremely thin corneas rupture, causing irreversible blindness.
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Affiliation(s)
- Chloe M Stanton
- MRC Human Genetics Unit, Institute of Genetics & Cancer, The University of Edinburgh, Western General Hospital, Crewe Road, Edinburgh, EH4 2XU, UK
| | - Amy S Findlay
- MRC Human Genetics Unit, Institute of Genetics & Cancer, The University of Edinburgh, Western General Hospital, Crewe Road, Edinburgh, EH4 2XU, UK
| | - Camilla Drake
- MRC Human Genetics Unit, Institute of Genetics & Cancer, The University of Edinburgh, Western General Hospital, Crewe Road, Edinburgh, EH4 2XU, UK
| | - Mohammad Z Mustafa
- MRC Human Genetics Unit, Institute of Genetics & Cancer, The University of Edinburgh, Western General Hospital, Crewe Road, Edinburgh, EH4 2XU, UK
| | - Philippe Gautier
- MRC Human Genetics Unit, Institute of Genetics & Cancer, The University of Edinburgh, Western General Hospital, Crewe Road, Edinburgh, EH4 2XU, UK
| | - Lisa McKie
- MRC Human Genetics Unit, Institute of Genetics & Cancer, The University of Edinburgh, Western General Hospital, Crewe Road, Edinburgh, EH4 2XU, UK
| | - Ian J Jackson
- MRC Human Genetics Unit, Institute of Genetics & Cancer, The University of Edinburgh, Western General Hospital, Crewe Road, Edinburgh, EH4 2XU, UK
| | - Veronique Vitart
- MRC Human Genetics Unit, Institute of Genetics & Cancer, The University of Edinburgh, Western General Hospital, Crewe Road, Edinburgh, EH4 2XU, UK
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Bargagna‐Mohan P, Schultz G, Rheaume B, Trakhtenberg EF, Robson P, Pal‐Ghosh S, Stepp MA, Given KS, Macklin WB, Mohan R. Corneal nonmyelinating Schwann cells illuminated by single-cell transcriptomics and visualized by protein biomarkers. J Neurosci Res 2021; 99:731-749. [PMID: 33197966 PMCID: PMC7894186 DOI: 10.1002/jnr.24757] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Revised: 10/05/2020] [Accepted: 10/25/2020] [Indexed: 12/23/2022]
Abstract
The cornea is the most innervated tissue in the human body. Myelinated axons upon inserting into the peripheral corneal stroma lose their myelin sheaths and continue into the central cornea wrapped by only nonmyelinating corneal Schwann cells (nm-cSCs). This anatomical organization is believed to be important for central vision. Here we employed single-cell RNA sequencing (scRNA-seq), microscopy, and transgenics to characterize these nm-cSCs of the central cornea. Using principal component analysis, uniform manifold approximation and projection, and unsupervised hierarchal cell clustering of scRNA-seq data derived from central corneal cells of male rabbits, we successfully identified several clusters representing different corneal cell types, including a unique cell cluster representing nm-cSCs. To confirm protein expression of cSC genes, we performed cross-species validation, employing corneal whole-mount immunostaining with confocal microscopy in mouse corneas. The expression of several representative proteins of nm-cSCs were validated. As the proteolipid protein 1 (PLP1) gene was also expressed in nm-cSCs, we explored the Plp1-eGFP transgenic reporter mouse line to visualize cSCs. Specific and efficient eGFP expression was observed in cSCs in adult mice of different ages. Of several putative cornea-specific SC genes identified, Dickkopf-related protein 1 was shown to be present in nm-cSCs. Taken together, our findings, for the first time, identify important insights and tools toward the study nm-cSCs in isolated tissue and adult animals. We expect that our results will advance the future study of nm-cSCs in applications of nerve repair, and provide a resource for the study of corneal sensory function.
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Affiliation(s)
- Paola Bargagna‐Mohan
- Department of NeuroscienceUniversity of Connecticut Health CenterFarmingtonCTUSA
| | - Gwendolyn Schultz
- Department of NeuroscienceUniversity of Connecticut Health CenterFarmingtonCTUSA
| | - Bruce Rheaume
- Department of NeuroscienceUniversity of Connecticut Health CenterFarmingtonCTUSA
| | | | - Paul Robson
- Department of Genetics & Genome SciencesUniversity of Connecticut Health CenterFarmingtonCTUSA
- The Jackson Laboratory for Genomic MedicineFarmingtonCTUSA
| | - Sonali Pal‐Ghosh
- Department of Anatomy and Regenerative BiologyGeorge Washington University Medical SchoolWashingtonDCUSA
| | - Mary Ann Stepp
- Department of Anatomy and Regenerative BiologyGeorge Washington University Medical SchoolWashingtonDCUSA
| | - Katherine S. Given
- Department of Cell and Developmental BiologyUniversity of Colorado School of MedicineAuroraCOUSA
| | - Wendy B. Macklin
- Department of Cell and Developmental BiologyUniversity of Colorado School of MedicineAuroraCOUSA
| | - Royce Mohan
- Department of NeuroscienceUniversity of Connecticut Health CenterFarmingtonCTUSA
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Babushkina A, Lwigale P. Periocular neural crest cell differentiation into corneal endothelium is influenced by signals in the nascent corneal environment. Dev Biol 2020; 465:119-129. [PMID: 32697973 PMCID: PMC7484247 DOI: 10.1016/j.ydbio.2020.06.012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Revised: 06/25/2020] [Accepted: 06/26/2020] [Indexed: 12/13/2022]
Abstract
During ocular development, periocular neural crest cells (pNC) migrate into the region between the lens and presumptive corneal epithelium to form the corneal endothelium and stromal keratocytes. Although defects in neural crest cell development are associated with ocular dysgenesis, very little is known about the molecular mechanisms involved in this process. This study focuses on the corneal endothelium, a monolayer of specialized cells that are essential for maintaining normal hydration and transparency of the cornea. In avians, corneal endothelial cells are first to be specified from the pNC during their migration into the presumptive corneal region. To investigate the signals required for formation of the corneal endothelium, we utilized orthotopic and heterotopic injections of dissociated quail pNC into chick ocular regions. We find that pNC are multipotent and that the nascent cornea is competent to induce differentiation of ectopically injected pNC into corneal endothelium. Injected pNC downregulate expression of multipotency transcription factors and upregulate genes that are consistent with ontogenesis of the chick corneal endothelium. Importantly, we showed that TGFβ2 is expressed by the nascent lens and the corneal endothelium, and that TGFβ signaling plays a critical role in changing the molecular signature of pNC in vitro. Collectively, our results demonstrate the significance of the ocular environmental cues towards pNC differentiation, and have potential implications for clinical application of stem cells in the anterior segment.
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Affiliation(s)
- Anna Babushkina
- BioSciences, Rice University, 6100 Main Street, Houston, TX, USA
| | - Peter Lwigale
- BioSciences, Rice University, 6100 Main Street, Houston, TX, USA.
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10
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Cell-independent matrix configuration in early corneal development. Exp Eye Res 2019; 187:107772. [PMID: 31445001 PMCID: PMC6892249 DOI: 10.1016/j.exer.2019.107772] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Revised: 08/01/2019] [Accepted: 08/20/2019] [Indexed: 01/01/2023]
Abstract
Mechanisms controlling the spatial configuration of the remarkably ordered collagen-rich extracellular matrix of the transparent cornea remain incompletely understood. We previously described the assembly of the emerging corneal matrix in the mid and late stages of embryogenesis and concluded that collagen fibril organisation was driven by cell-directed mechanisms. Here, the early stages of corneal morphogenesis were examined by serial block face scanning electron microscopy of embryonic chick corneas starting at embryonic day three (E3), followed by a Fourier transform analysis of three-dimensional datasets and theoretical considerations of factors that influence matrix formation. Eyes developing normally and eyes that had the lens surgically removed at E3 were studied. Uniformly thin collagen fibrils are deposited by surface ectoderm-derived corneal epithelium in the primary stroma of the developing chick cornea and form an acellular matrix with a striking micro-lamellar orthogonal arrangement. Fourier transform analysis supported this observation and indicated that adjacent micro-lamellae display a clockwise rotation of fibril orientation, depth-wise below the epithelium. We present a model which attempts to explain how, in the absence of cells in the primary stroma, collagen organisation might be influenced by cell-independent, intrinsic mechanisms, such as fibril axial charge derived from associated proteoglycans. On a supra-lamellar scale, fine cords of non-collagenous filamentous matrix were detected over large tissue volumes. These extend into the developing cornea from the epithelial basal lamina and appear to associate with the neural crest cells that migrate inwardly to form, first the corneal endothelium and then keratocytes which synthesise the mature, secondary corneal stroma. In a small number of experimental specimens, matrix cords were present even when periocular neural crest cell migration and corneal morphogenesis had been perturbed following removal of the lens at E3. Highly-ordered connective tissue appears early in development of the avian cornea. Cell-independent mechanisms may contribute to the organisation of collagen fibrils into an orthogonal array. Matrix cords from epithelium into stroma contact invading neural crest cells.
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