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Giannone AA, Sellitto C, Rosati B, McKinnon D, White TW. Single-Cell RNA Sequencing Analysis of the Early Postnatal Mouse Lens Epithelium. Invest Ophthalmol Vis Sci 2023; 64:37. [PMID: 37870847 PMCID: PMC10599162 DOI: 10.1167/iovs.64.13.37] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Accepted: 10/06/2023] [Indexed: 10/24/2023] Open
Abstract
Purpose The lens epithelium maintains the overall health of the organ. We used single-cell RNA sequencing (scRNA-seq) technology to assess transcriptional heterogeneity between cells in the postnatal day 2 (P2) epithelium and identify distinct epithelial cell subtypes. Analysis of these data was used to better understand lens growth, differentiation, and homeostasis on P2. Methods scRNA-seq on P2 mouse lenses was performed using the 10x Genomics Chromium Single Cell 3' Kit (v3.1) and short-read Illumina sequencing. Sequence alignment and preprocessing of data were conducted using 10x Genomics Cell Ranger software. Seurat was employed for preprocessing, quality control, dimensionality reduction, and cell clustering, and Monocle was utilized for trajectory analysis to understand the developmental progression of the lens cells. CellChat and GO analyses were used to explore cell-cell communication networks and signaling interactions. Results Lens epithelial cells (LECs) were divided into seven subclusters, classified by specific gene markers. The expression of crystallin, cell-cycle, and metabolic genes was not uniform, indicating distinct functional roles of LECs. Trajectory analysis predicted a bifurcation of differentiating and cycling cells from an Igfbp5+ progenitor pool. We also identified heterogeneity in signaling molecules and pathways, suggesting that cycling and progenitor subclusters have prominent roles in coordinating crosstalk. Conclusions scRNA-seq corroborated many known markers of epithelial differentiation and proliferation while providing further insight into the pathways and genes directing these processes. Interestingly, we demonstrated that the developing epithelium can be divided into distinct subpopulations. These clusters reflect the transcriptionally diverse roles of the epithelium in proliferation, signaling, and maintenance.
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Affiliation(s)
- Adrienne A. Giannone
- Department of Physiology and Biophysics, Stony Brook University School of Medicine, Stony Brook University, Stony Brook, New York, United States
| | - Caterina Sellitto
- Department of Physiology and Biophysics, Stony Brook University School of Medicine, Stony Brook University, Stony Brook, New York, United States
| | - Barbara Rosati
- Department of Physiology and Biophysics, Stony Brook University School of Medicine, Stony Brook University, Stony Brook, New York, United States
- Veterans Affairs Medical Center, Northport, New York, United States
| | - David McKinnon
- Department of Neurobiology and Behavior, Stony Brook University School of Medicine, Stony Brook University, Stony Brook, New York, United States
| | - Thomas W. White
- Department of Physiology and Biophysics, Stony Brook University School of Medicine, Stony Brook University, Stony Brook, New York, United States
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Wang Z, Gletten RB, Schey KL. Spatially Resolved Proteomics Reveals Lens Suture-Related Cell-Cell Junctional Protein Distributions. Invest Ophthalmol Vis Sci 2023; 64:28. [PMID: 37603353 PMCID: PMC10445239 DOI: 10.1167/iovs.64.11.28] [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: 05/17/2023] [Accepted: 07/31/2023] [Indexed: 08/22/2023] Open
Abstract
Purpose Lens transparency relies on the precise organization of lens fiber cells. The formation of the highly ordered lens architecture results from not only cell-cell adhesion along the lateral interfaces, but also from proper organization of fiber cells tips at lens sutures. Little is known about the cell adhesion between fiber tips at the sutures. The purpose of this study is to map suture-specific protein distributions. Methods Tissue sections were obtained from fresh frozen bovine lenses and washes were performed to remove soluble proteins and to retain membrane and membrane associated proteins. Imaging mass spectrometry (IMS) combined with on-tissue trypsin digestion was used to visualize protein spatial distributions. Sutures and adjacent regions were captured by laser capture microdissection and samples were digested by trypsin. Proteins were analyzed by liquid chromatography tandem MS and quantified by label-free quantification. Protein spatial distributions were confirmed by immunofluorescence. Results IMS results showed enrichment of adherens junction proteins cadherin-2 and armadillo repeat gene deleted in velo-cardio-facial syndrome (ARVCF) in both anterior and posterior sutures of bovine lenses. Liquid chromatography tandem MS confirmed higher expression of cadherin-2 and ARVCF and other adherens junction proteins including catenin α2 (CTNNA2) and catenin β1 (CTNNB1) in sutures. In contrast, IMS indicated low expression of gap junction protein connexin 50 and connexin 46 in the suture regions. The localization of cadherin-2 and connexin 50 was confirmed by immunofluorescence. Conclusions The complementary expression of adherens junction proteins and gap junction proteins in lens suture regions implicates adherens junctions in fiber cell tip adhesion and in maintaining the integrity of the lens.
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Affiliation(s)
- Zhen Wang
- Department of Biochemistry and Mass Spectrometry Research Center, Vanderbilt University School of Medicine, Nashville, Tennessee, United States
| | - Romell B. Gletten
- Department of Biochemistry and Mass Spectrometry Research Center, Vanderbilt University School of Medicine, Nashville, Tennessee, United States
| | - Kevin L. Schey
- Department of Biochemistry and Mass Spectrometry Research Center, Vanderbilt University School of Medicine, Nashville, Tennessee, United States
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3
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Pan Q, Lu K, Luo J, Jiang Y, Xia B, Chen L, Wang M, Dai R, Chen T. Japanese medaka Olpax6.1 mutant as a potential model for spondylo-ocular syndrome. Funct Integr Genomics 2023; 23:168. [PMID: 37204625 DOI: 10.1007/s10142-023-01090-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Revised: 05/03/2023] [Accepted: 05/05/2023] [Indexed: 05/20/2023]
Abstract
pax6 is a canonic master gene for eye formation. Knockout of pax6 affects the development of craniofacial skeleton and eye in mice. Whether pax6 affects the development of spinal bone has not been reported yet. In the present study, we used CRISPR/Cas9 system to generate Olpax6.1 mutant in Japanese medaka. Phenotype analysis showed that ocular mutation caused by the Olpax6.1 mutation occurred in the homozygous mutant. The phenotype of heterozygotes is not significantly different from that of wild-type. In addition, knockout Olpax6.1 resulted in severe curvature of the spine in the homozygous F2 generation. Comparative transcriptome analysis and qRT-PCR revealed that the defective Olpax6.1 protein caused a decrease in the expression level of sp7, col10a1a, and bglap, while the expression level of xylt2 did not change significantly. The functional enrichment of differentially expressed genes (DEGs) using the Kyoto Encyclopedia of Genes and Genomes database showed that the DEGs between Olpax6.1 mutation and wild-type were enriched in p53 signaling pathway, extracellular matrix (ECM) -receptor interaction, et al. Our results indicated that the defective Olpax6.1 protein results in the reduction of sp7 expression level and the activation of p53 signaling pathway, which leads to a decrease in the expression of genes encoding ECM protein, such as collagen protein family and bone gamma-carboxyglutamate protein, which further inhibits bone development. Based on the phenotype and molecular mechanism of ocular mutation and spinal curvature induced by Olpax6.1 knockout, we believe that the Olpax6.1-/- mutant could be a potential model for the study of spondylo-ocular syndrome.
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Affiliation(s)
- Qihua Pan
- Fisheries College of Jimei University, Key Laboratory of Healthy Mariculture for the East China Sea, Ministry of Agriculture and Rural Affairs, Engineering Research Center of the Modern Technology for Eel Industry, Ministry of Education, Xiamen, 361021, Fujian, China
- College of Fisheries, Huazhong Agricultural University, Wuhan, 430070, Hubei, China
| | - Ke Lu
- College of Fisheries, Huazhong Agricultural University, Wuhan, 430070, Hubei, China
| | - Junzhi Luo
- College of Fisheries, Huazhong Agricultural University, Wuhan, 430070, Hubei, China
| | - Yuewen Jiang
- College of Fisheries, Huazhong Agricultural University, Wuhan, 430070, Hubei, China
| | - Bilin Xia
- College of Fisheries, Huazhong Agricultural University, Wuhan, 430070, Hubei, China
| | - Lei Chen
- Fisheries College of Jimei University, Key Laboratory of Healthy Mariculture for the East China Sea, Ministry of Agriculture and Rural Affairs, Engineering Research Center of the Modern Technology for Eel Industry, Ministry of Education, Xiamen, 361021, Fujian, China
| | - Mengyang Wang
- Fisheries College of Jimei University, Key Laboratory of Healthy Mariculture for the East China Sea, Ministry of Agriculture and Rural Affairs, Engineering Research Center of the Modern Technology for Eel Industry, Ministry of Education, Xiamen, 361021, Fujian, China
| | - Ronggui Dai
- Fisheries College of Jimei University, Key Laboratory of Healthy Mariculture for the East China Sea, Ministry of Agriculture and Rural Affairs, Engineering Research Center of the Modern Technology for Eel Industry, Ministry of Education, Xiamen, 361021, Fujian, China
| | - Tiansheng Chen
- Fisheries College of Jimei University, Key Laboratory of Healthy Mariculture for the East China Sea, Ministry of Agriculture and Rural Affairs, Engineering Research Center of the Modern Technology for Eel Industry, Ministry of Education, Xiamen, 361021, Fujian, China.
- College of Fisheries, Huazhong Agricultural University, Wuhan, 430070, Hubei, China.
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4
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Zhou Z, Qu J, He L, Peng H, Chen P, Zhou Y. α6-Integrin alternative splicing: distinct cytoplasmic variants in stem cell fate specification and niche interaction. Stem Cell Res Ther 2018; 9:122. [PMID: 29720266 PMCID: PMC5930856 DOI: 10.1186/s13287-018-0868-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
α6-Integrin subunit (also known as CD49f) is a stemness signature that has been found on the plasma membrane of more than 30 stem cell populations. A growing body of studies have focused on the critical role of α6-containing integrins (α6β1 and α6β4) in the regulation of stem cell properties, lineage-specific differentiation, and niche interaction. α6-Integrin subunit can be alternatively spliced at the post-transcriptional level, giving rise to divergent isoforms which differ in the cytoplasmic and/or extracellular domains. The cytoplasmic domain of integrins is an important functional part of integrin-mediated signals. Structural changes in the cytoplasmic domain of α6 provide an efficient means for the regulation of stem cell responses to biochemical stimuli and/or biophysical cues in the stem cell niche, thus impacting stem cell fate determination. In this review, we summarize the current knowledge on the structural variants of the α6-integrin subunit and spatiotemporal expression of α6 cytoplasmic variants in embryonic and adult stem/progenitor cells. We highlight the roles of α6 cytoplasmic variants in stem cell fate decision and niche interaction, and discuss the potential mechanisms involved. Understanding of the distinct functions of α6 splicing variants in stem cell biology may inform the rational design of novel stem cell-based therapies for a range of human diseases.
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Affiliation(s)
- Zijing Zhou
- Department of Medicine, Division of Pulmonary, Allergy and Critical Care Medicine, University of Alabama at Birmingham, Tinsley Harrison Tower 437B, 1900 University Blvd, Birmingham, AL, 35294, USA.,Department of Respiratory Medicine, The Second Xiangya Hospital, Central-South University, Changsha, 410011, Hunan, China
| | - Jing Qu
- Department of Medicine, Division of Pulmonary, Allergy and Critical Care Medicine, University of Alabama at Birmingham, Tinsley Harrison Tower 437B, 1900 University Blvd, Birmingham, AL, 35294, USA
| | - Li He
- Department of Medicine, Division of Pulmonary, Allergy and Critical Care Medicine, University of Alabama at Birmingham, Tinsley Harrison Tower 437B, 1900 University Blvd, Birmingham, AL, 35294, USA
| | - Hong Peng
- Department of Respiratory Medicine, The Second Xiangya Hospital, Central-South University, Changsha, 410011, Hunan, China
| | - Ping Chen
- Department of Respiratory Medicine, The Second Xiangya Hospital, Central-South University, Changsha, 410011, Hunan, China
| | - Yong Zhou
- Department of Medicine, Division of Pulmonary, Allergy and Critical Care Medicine, University of Alabama at Birmingham, Tinsley Harrison Tower 437B, 1900 University Blvd, Birmingham, AL, 35294, USA.
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5
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Samuelsson AR, Belvindrah R, Wu C, Müller U, Halfter W. β1-Integrin Signaling is Essential for Lens Fiber Survival. GENE REGULATION AND SYSTEMS BIOLOGY 2017. [DOI: 10.1177/117762500700100016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Integrins have been proposed to play a major role in lens morphogenesis. To determine the role of β1-integrin and its down-stream signaling partner, integrin linked kinase (ILK), in lens morphogenesis, eyes of WT mice and mice with a nestin-linked conditional knockout of β1-integrin or ILK were analyzed for defects in lens development. Mice, lacking the genes encoding the p1-integrin subunit ( Itgb1) or ILK ( Ilk), showed a perinatal degeneration of the lens. Early signs of lens degeneration included vacuolization, random distribution of lens cell nuclei, disrupted fiber morphology and attenuation and separation of the lens capsule. The phenotype became progressively more severe during the first postnatal week eventually leading to the complete loss of the lens. A more severe phenotype was observed in ILK mutants at similar stages. Eyes from embryonic day 13 β1-integrin-mutant embryos showed no obvious signs of lens degeneration, indicating that mutant lens develops normally until peri-recombination. Our findings suggest that β1-integrins and ILK cooperate to control lens cell survival and link lens fibers to the surrounding extracellular matrix. The assembly and integrity of the lens capsule also appears to be reliant on integrin signaling within lens fibers. Extrapolation of these results indicates a novel role of integrins in lens cell-cell adhesions as well as a potential role in the pathogenesis of congenital cataracts.
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Affiliation(s)
- Andrew R. Samuelsson
- Department of Neurobiology, University of Pittsburgh, 1402 E Biological Science Tower, Pittsburgh PA 15261
| | - Richard Belvindrah
- Department of Cell Biology and Institute for Childhood and Neglected Disease, Scripps Research Institute, La Jolla, CA 92037
| | - Chuanyue Wu
- Department of Pathology, 707 Scaife Hall, University of Pittsburgh, Pittsburgh PA 15261
| | - Uli Müller
- Department of Cell Biology and Institute for Childhood and Neglected Disease, Scripps Research Institute, La Jolla, CA 92037
| | - Willi Halfter
- Department of Neurobiology, University of Pittsburgh, 1402 E Biological Science Tower, Pittsburgh PA 15261
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6
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Zhang Y, Fan J, Ho JWK, Hu T, Kneeland SC, Fan X, Xi Q, Sellarole MA, de Vries WN, Lu W, Lachke SA, Lang RA, John SWM, Maas RL. Crim1 regulates integrin signaling in murine lens development. Development 2015; 143:356-66. [PMID: 26681494 PMCID: PMC4725338 DOI: 10.1242/dev.125591] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Accepted: 12/07/2015] [Indexed: 12/19/2022]
Abstract
The developing lens is a powerful system for investigating the molecular basis of inductive tissue interactions and for studying cataract, the leading cause of blindness. The formation of tightly controlled cell-cell adhesions and cell-matrix junctions between lens epithelial (LE) cells, between lens fiber (LF) cells, and between these two cell populations enables the vertebrate lens to adopt a highly ordered structure and acquire optical transparency. Adhesion molecules are thought to maintain this ordered structure, but little is known about their identity or interactions. Cysteine-rich motor neuron 1 (Crim1), a type I transmembrane protein, is strongly expressed in the developing lens and its mutation causes ocular disease in both mice and humans. How Crim1 regulates lens morphogenesis is not understood. We identified a novel ENU-induced hypomorphic allele of Crim1, Crim1glcr11, which in the homozygous state causes cataract and microphthalmia. Using this and two other mutant alleles, Crim1null and Crim1cko, we show that the lens defects in Crim1 mouse mutants originate from defective LE cell polarity, proliferation and cell adhesion. Crim1 adhesive function is likely to be required for interactions both between LE cells and between LE and LF cells. We show that Crim1 acts in LE cells, where it colocalizes with and regulates the levels of active β1 integrin and of phosphorylated FAK and ERK. The RGD and transmembrane motifs of Crim1 are required for regulating FAK phosphorylation. These results identify an important function for Crim1 in the regulation of integrin- and FAK-mediated LE cell adhesion during lens development. Summary: Crim1, a type I transmembrane protein, acts in lens epithelial cells where it colocalizes with and regulates the levels of active β1 integrin to control cell adhesion during mouse lens morphogenesis.
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Affiliation(s)
- Ying Zhang
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115, USA
| | - Jieqing Fan
- Department of Developmental Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
| | - Joshua W K Ho
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115, USA Center for Biomedical Informatics, Harvard Medical School, Boston, MA 02115, USA Victor Chang Cardiac Research Institute, and The University of New South Wales, Sydney, New South Wales 2010, Australia
| | - Tommy Hu
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115, USA
| | - Stephen C Kneeland
- Howard Hughes Medical Institute and The Jackson Laboratory, 600 Main Street, Bar Harbor, ME 04609, USA
| | - Xueping Fan
- Renal Section, Department of Medicine, Boston University Medical Center, Boston, MA 02118, USA
| | - Qiongchao Xi
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115, USA
| | - Michael A Sellarole
- Victor Chang Cardiac Research Institute, and The University of New South Wales, Sydney, New South Wales 2010, Australia
| | - Wilhelmine N de Vries
- Victor Chang Cardiac Research Institute, and The University of New South Wales, Sydney, New South Wales 2010, Australia
| | - Weining Lu
- Renal Section, Department of Medicine, Boston University Medical Center, Boston, MA 02118, USA
| | - Salil A Lachke
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115, USA Department of Biological Sciences, University of Delaware, Newark, DE 19716, USA
| | - Richard A Lang
- Department of Developmental Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
| | - Simon W M John
- Victor Chang Cardiac Research Institute, and The University of New South Wales, Sydney, New South Wales 2010, Australia
| | - Richard L Maas
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115, USA
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7
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Abstract
BACKGROUND Calcium is considered an important factor in the development of both osteoporosis and cataract. This study evaluated the association between osteoporosis and cataracts. OBJECTIVE To evaluate the prevalence of osteoporosis among patients undergoing cataract surgery, and the association between the two. PATIENTS AND METHODS This was a retrospective observational case-control study, conducted in the Central District of Clalit Health Services (a district of the largest health maintenance organization in Israel). All Clalit members in the district older than 50 years who underwent cataract surgery from 2000 to 2007 (n=12,984) and 25,968 age- and sex-matched controls comprised the sample. Electronic medical records of all patients in the study were reviewed. The main outcome measure was the prevalence of osteoporosis and the odds ratio of having osteoporosis among cataract patients compared with controls. RESULTS Demographically, 41.8% were men with a mean age of 68.7 ± 8.2 years. A logistic regression model for osteoporosis showed that age, female sex, higher socioeconomic class, smoking, chronic renal failure, hyperthyroidism, rheumatoid arthritis, inflammatory bowel diseases, and cataract are all associated with increased prevalence of osteoporosis. Obesity is a protective factor for osteoporosis. In all age-groups, osteoporosis was more prevalent in cataract patients than in the control group. CONCLUSION Among other well-known risk factors, osteoporosis is associated with the presence of cataracts. Common pathophysiological associations with both conditions, such as calcium imbalance, hormonal abnormalities, and shared genetic predisposition, are discussed.
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Affiliation(s)
- Arie Y Nemet
- Department of Ophthalmology, Meir Medical Center, Kfar Saba, Israel
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8
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Martinez G, de Iongh R. The lens epithelium in ocular health and disease. Int J Biochem Cell Biol 2010; 42:1945-63. [PMID: 20883819 DOI: 10.1016/j.biocel.2010.09.012] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2010] [Revised: 09/19/2010] [Accepted: 09/20/2010] [Indexed: 01/11/2023]
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9
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Walker J, Menko AS. Integrins in lens development and disease. Exp Eye Res 2008; 88:216-25. [PMID: 18671967 DOI: 10.1016/j.exer.2008.06.020] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2008] [Revised: 06/19/2008] [Accepted: 06/23/2008] [Indexed: 11/26/2022]
Abstract
Integrins are the major cell surface receptors for proteins in the extracellular matrix. These receptors form major cell signaling centers that are bidirectional, communicating messages between the cell and its environment. They are a large receptor family, with members well-known to regulate cellular processes essential to both development and disease. In this review we examine the literature regarding integrins in the lens. Here we cover integrin function in lens cell differentiation, in the development of the lens and in protection of the lens epithelial cell phenotype. In addition, we analyze the role of integrins in the progression of lens fibrotic diseases, focusing particularly on integrin regulation of TGFbeta signaling pathways in posterior capsule opacification (PCO) and anterior subcapsular cataract (ASC).
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Affiliation(s)
- Janice Walker
- Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA
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10
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O'Connor MD, Wederell ED, de Iongh R, Lovicu FJ, McAvoy JW. Generation of transparency and cellular organization in lens explants. Exp Eye Res 2008; 86:734-45. [PMID: 18343368 DOI: 10.1016/j.exer.2008.01.020] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2007] [Revised: 01/02/2008] [Accepted: 01/29/2008] [Indexed: 10/22/2022]
Abstract
The lens grows via the proliferation and differentiation of lens epithelial cells into lens fibres. This differentiation process, thought to be controlled by factors present in the vitreous fluid, generates tightly-packed, parallel-aligned fibre cells that confer transparency to the lens. Using lens epithelial-cell explants we examined how explant orientation and growth factor treatment can affect cellular arrangement and explant transparency. Fibre cell differentiation was induced in lens explants by culturing cells with fibroblast growth factor (FGF) or bovine vitreous. Cell shape and arrangement was investigated using confocal microscopy, electron microscopy, immunofluorescence and in situ hybridization. Explant transparency was measured using light microscopy. Confocal microscopy demonstrated that explant orientation determined cellular arrangement, irrespective of the differentiation stimuli used. In explants where epithelial cells were confined between their normal basement membrane (the lens capsule) and the base of the culture dish, the cells became elongated, thin and parallel-aligned. In contrast, in explants cultured with cells directly exposed to the culture media the cells appeared to be shorter, globular and haphazardly arranged. FGF initiated the differentiation of most lens epithelial cells; however, abnormal cellular morphologies developed with subsequent culture of the cells. As a result, the transparency of these explants decreased with prolonged culture. Interestingly, explants cultured with vitreous (i) did not develop abnormal cellular morphologies, (ii) contained two distinct cell types (retained epithelial cells and newly differentiated fibre cells) and (iii) remained transparent throughout the lengthy culture period. In summary, we have developed a culture system that generates a transparent tissue with a cellular arrangement resembling that of the lens in vivo. We have shown that while FGF and vitreous initiate differentiation within this system, better maintenance of fibre cell integrity, more appropriate regulation of molecular events, and better maintenance of explant transparency was achieved in the presence of vitreous. This system offers an opportunity to further investigate the process of lens fibre cell differentiation as well as a means of better identifying the factors that contribute to the development of tissue transparency in vitro.
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Affiliation(s)
- Michael D O'Connor
- Save Sight Institute and Department of Clinical Ophthalmology & Eye Health, The University of Sydney, Sydney, NSW 2006, Australia.
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11
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Long AC, Agler A, Colitz CMH, Zhang J, Hayek MG, Failla ML, Bomser JA. Isolation and characterization of primary canine lens epithelial cells. Vet Ophthalmol 2008; 11:38-42. [DOI: 10.1111/j.1463-5224.2007.00599.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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12
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Simirskii VN, Wang Y, Duncan MK. Conditional deletion of beta1-integrin from the developing lens leads to loss of the lens epithelial phenotype. Dev Biol 2007; 306:658-68. [PMID: 17493607 PMCID: PMC1950782 DOI: 10.1016/j.ydbio.2007.04.004] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2007] [Revised: 04/03/2007] [Accepted: 04/05/2007] [Indexed: 10/23/2022]
Abstract
Beta1-integrins are cell surface receptors that participate in sensing the cell's external environment. We used the Cre-lox system to delete beta1-integrin in all lens cells as the lens vesicle transitions into the lens. Adult mice lacking beta1-integrin in the lens are microphthalmic due to apoptosis of the lens epithelium and neonatal disintegration of the lens fibers. The first morphological alterations in beta1-integrin null lenses are seen at 16.5 dpc when the epithelium becomes disorganized and begins to upregulate the fiber cell markers beta- and gamma-crystallins, the transcription factors cMaf and Prox1 and downregulate Pax6 levels demonstrating that beta1-integrin is essential to maintain the lens epithelial phenotype. Furthermore, beta1-integrin null lens epithelial cells upregulate the expression of alpha-smooth muscle actin and nuclear Smad4 and downregulate Smad6 suggesting that beta1-integrin may brake TGFbeta family signaling leading to epithelial-mesenchymal transitions in the lens. In contrast, beta1-integrin null lens epithelial cells show increased E-cadherin immunoreactivity which supports the proposed role of beta1-integrins in mediating complete EMT in response to TGFbeta family members. Thus, beta1-integrin is required to maintain the lens epithelial phenotype and block inappropriate activation of some aspects of the lens fiber cell differentiation program.
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Affiliation(s)
| | | | - Melinda K. Duncan
- *To whom all the correspondence should be addressed: Melinda K. Duncan, Department of Biological Sciences, University of Delaware, Newark, DE 19716, Telephone: (302) 831-0533, Fax: (302) 831-2281, E-mail address:
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13
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Abstract
Regulation of cell proliferation is a critical aspect of the development of multicellular organisms. The ocular lens is an excellent model system in which to unravel the mechanisms controlling cell proliferation during development. In recent years, several cell cycle regulators have been shown to be essential for maintaining normal patterns of lens cell proliferation. Additionally, many growth factor signaling pathways and cell adhesion factors have been shown to have the capacity to regulate lens cell proliferation. Given this complexity, understanding the cross talk between these many signaling pathways and how they are coordinated are important directions for the future.
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Affiliation(s)
- Anne E Griep
- Department of Anatomy, University of Wisconsin School of Medicine and Public Health, Madison, WI 53706, USA.
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14
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Rao PV, Maddala R. The role of the lens actin cytoskeleton in fiber cell elongation and differentiation. Semin Cell Dev Biol 2006; 17:698-711. [PMID: 17145190 PMCID: PMC1803076 DOI: 10.1016/j.semcdb.2006.10.011] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The vertebrate ocular lens is a fascinating and unique transparent tissue that grows continuously throughout life. During the process of differentiation into fiber cells, lens epithelial cells undergo dramatic morphological changes, membrane remodeling, polarization, transcriptional activation and elimination of cellular organelles including nuclei, concomitant with migration towards the lens interior. Most of these events are presumed to be influenced in large part, by dynamic reorganization of the cellular actin cytoskeleton and by intercellular and cell: extracellular matrix interactions. In light of recent and unprecedented advancement in our understanding of the mechanistic bases underlying regulation of actin cytoskeletal dynamics and the role of the actin cytoskeleton in cell function, this review attempts to summarize current knowledge regarding the role of the cellular actin cytoskeleton, in lens fiber cell elongation and differentiation, and regulation of actin cytoskeletal organization in the lens.
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Affiliation(s)
- P Vasantha Rao
- Departments of Ophthalmology, Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, NC, USA.
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15
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Wederell ED, de Iongh RU. Extracellular matrix and integrin signaling in lens development and cataract. Semin Cell Dev Biol 2006; 17:759-76. [PMID: 17134921 DOI: 10.1016/j.semcdb.2006.10.006] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
During development of the vertebrate lens there are dynamic interactions between the extracellular matrix (ECM) of the lens capsule and lens cells. Disruption of the ECM causes perturbation of lens development and cataract. Similarly, changes in cell signaling can result in abnormal ECM and cataract. Integrins are key mediators of ECM signals and recent studies have documented distinct repertoires of integrin expression during lens development, and in anterior subcapsular cataract (ASC) and posterior caspsule opacification (PCO). Increasingly, studies are being directed to investigating the signaling pathways that integrins modulate and have identified Src, focal adhesion kinase (FAK) and integrin-linked kinase (ILK) as downstream kinases that mediate proliferation, differentiation and morphological changes in the lens during development and cataract formation.
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Affiliation(s)
- Elizabeth D Wederell
- Department of Anatomy & Histology, Save Sight Institute, University of Sydney, NSW 2006, Australia
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Zinkevich NS, Bosenko DV, Link BA, Semina EV. laminin alpha 1 gene is essential for normal lens development in zebrafish. BMC DEVELOPMENTAL BIOLOGY 2006; 6:13. [PMID: 16522196 PMCID: PMC1450269 DOI: 10.1186/1471-213x-6-13] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/28/2005] [Accepted: 03/07/2006] [Indexed: 11/15/2022]
Abstract
Background Laminins represent major components of basement membranes and play various roles in embryonic and adult tissues. The functional laminin molecule consists of three chains, alpha, beta and gamma, encoded by separate genes. There are twelve different laminin genes identified in mammals to date that are highly homologous in their sequence but different in their tissue distribution. The laminin alpha -1 gene was shown to have the most restricted expression pattern with strong expression in ocular structures, particularly in the developing and mature lens. Results We identified the zebrafish lama1 gene encoding a 3075-amino acid protein (lama1) that possesses strong identity with the human LAMA1. Zebrafish lama1 transcripts were detected at all stages of embryo development with the highest levels of expression in the developing lens, somites, nervous and urogenital systems. Translation of the lama1 gene was inhibited using two non-overlapping morpholino oligomers that were complementary to sequences surrounding translation initiation. Morphant embryos exhibited an arrest in lens development and abnormalities in the body axis length and curvature. Conclusion These results underline the importance of the laminin alpha 1 for normal ocular development and provide a basis for further analysis of its developmental roles.
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Affiliation(s)
- Natalya S Zinkevich
- Department of Pediatrics, Medical College of Wisconsin, Milwaukee, WI 53226, USA
- Departments of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Dmitry V Bosenko
- Department of Pediatrics, Medical College of Wisconsin, Milwaukee, WI 53226, USA
- Departments of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Brian A Link
- Departments of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Elena V Semina
- Department of Pediatrics, Medical College of Wisconsin, Milwaukee, WI 53226, USA
- Departments of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, WI 53226, USA
- Departments of Human and Molecular Genetics Center, Medical College of Wisconsin, Milwaukee, WI 53226, USA
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de Iongh RU, Wederell E, Lovicu FJ, McAvoy JW. Transforming growth factor-beta-induced epithelial-mesenchymal transition in the lens: a model for cataract formation. Cells Tissues Organs 2005; 179:43-55. [PMID: 15942192 DOI: 10.1159/000084508] [Citation(s) in RCA: 204] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The vertebrate lens has a distinct polarity and structure that are regulated by growth factors resident in the ocular media. Fibroblast growth factors, in concert with other growth factors, are key regulators of lens fiber cell differentiation. While members of the transforming growth factor (TGFbeta) superfamily have also been implicated to play a role in lens fiber differentiation, inappropriate TGFbeta signaling in the anterior lens epithelial cells results in an epithelial-mesenchymal transition (EMT) that bears morphological and molecular resemblance to forms of human cataract, including anterior subcapsular (ASC) and posterior capsule opacification (PCO; also known as secondary cataract or after-cataract), which occurs after cataract surgery. Numerous in vitro and in vivo studies indicate that this TGFbeta-induced EMT is part of a wound healing response in lens epithelial cells and is characterized by induced expression of numerous extracellular matrix proteins (laminin, collagens I, III, tenascin, fibronectin, proteoglycans), intermediate filaments (desmin, alpha-smooth muscle actin) and various integrins (alpha2, alpha5, alpha7B), as well as the loss of epithelial genes [Pax6, Cx43, CP49, alpha-crystallin, E-cadherin, zonula occludens-1 protein (ZO-1)]. The signaling pathways involved in initiating the EMT seem to primarily involve the Smad-dependent pathway, whereby TGFbeta binding to specific high affinity cell surface receptors activates the receptor-Smad/Smad4 complex. Recent studies implicate other factors [such as fibroblast growth factor (FGFs), hepatocyte growth factor, integrins], present in the lens and ocular environment, in the pathogenesis of ASC and PCO. For example, FGF signaling can augment many of the effects of TGFbeta, and integrin signaling, possibly via ILK, appears to mediate some of the morphological features of EMT initiated by TGFbeta. Increasing attention is now being directed at the network of signaling pathways that effect the EMT in lens epithelial cells, with the aim of identifying potential therapeutic targets to inhibit cataract, particularly PCO, which remains a significant clinical problem in ophthalmology.
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Affiliation(s)
- R U de Iongh
- Department of Anatomy and Cell Biology, University of Melbourne, Parkville, Australia.
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