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Sugiyama Y, Reed DA, Herrmann D, Lovicu FJ, Robinson ML, Timpson P, Masai I. Fibroblast growth factor-induced lens fiber cell elongation is driven by the stepwise activity of Rho and Rac. Development 2024; 151:dev202123. [PMID: 38240393 PMCID: PMC10911273 DOI: 10.1242/dev.202123] [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: 06/27/2023] [Accepted: 01/09/2024] [Indexed: 01/30/2024]
Abstract
The spheroidal shape of the eye lens is crucial for precise light focusing onto the retina. This shape is determined by concentrically aligned, convexly elongated lens fiber cells along the anterior and posterior axis of the lens. Upon differentiation at the lens equator, the fiber cells increase in height as their apical and basal tips migrate towards the anterior and posterior poles, respectively. The forces driving this elongation and migration remain unclear. We found that, in the mouse lens, membrane protrusions or lamellipodia are observed only in the maturing fibers undergoing cell curve conversion, indicating that lamellipodium formation is not the primary driver of earlier fiber migration. We demonstrated that elevated levels of fibroblast growth factor (FGF) suppressed the extension of Rac-dependent protrusions, suggesting changes in the activity of FGF controlling Rac activity, switching to lamellipodium-driven migration. Inhibitors of ROCK, myosin and actin reduced the height of both early and later fibers, indicating that elongation of these fibers relies on actomyosin contractility. Consistent with this, active RhoA was detected throughout these fibers. Given that FGF promotes fiber elongation, we propose that it does so through regulation of Rho activity.
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Affiliation(s)
- Yuki Sugiyama
- Developmental Neurobiology Unit, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa 904-0495, Japan
- Save Sight Institute, The University of Sydney, Sydney, NSW 2000, Australia
| | - Daniel A. Reed
- Cancer Ecosystems Program, The Garvan Institute of Medical Research & The Kinghorn Cancer Centre, St Vincent's Clinical School, Faculty of Medicine, UNSW Sydney, Sydney, NSW 2010, Australia
| | - David Herrmann
- Cancer Ecosystems Program, The Garvan Institute of Medical Research & The Kinghorn Cancer Centre, St Vincent's Clinical School, Faculty of Medicine, UNSW Sydney, Sydney, NSW 2010, Australia
| | - Frank J. Lovicu
- Save Sight Institute, The University of Sydney, Sydney, NSW 2000, Australia
- Molecular and Cellular Biomedicine, School of Medical Sciences, The University of Sydney, Sydney, NSW 2006, Australia
| | - Michael L. Robinson
- Department of Biology and Center for Visual Sciences, Miami University, Oxford, OH 45056, USA
| | - Paul Timpson
- Cancer Ecosystems Program, The Garvan Institute of Medical Research & The Kinghorn Cancer Centre, St Vincent's Clinical School, Faculty of Medicine, UNSW Sydney, Sydney, NSW 2010, Australia
| | - Ichiro Masai
- Developmental Neurobiology Unit, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa 904-0495, Japan
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2
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Sugiyama Y, Reed DA, Herrmann D, Lovicu FJ, Robinson ML, Timpson P, Masai I. Fibroblast Growth Factor-induced lens fiber cell elongation is driven by the stepwise activity of Rho and Rac. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.03.569812. [PMID: 38106159 PMCID: PMC10723307 DOI: 10.1101/2023.12.03.569812] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2023]
Abstract
The spheroidal shape of the eye lens is critical for precise light focusing onto the retina. This shape is determined by concentrically aligned, convexly elongated lens fiber cells along the anterior and posterior axis of the lens. Upon differentiation at the lens equator, the fiber cells increase in height as their apical and basal tips migrate towards the anterior and posterior poles, respectively. The forces driving this elongation and migration remain unclear. We found that membrane protrusions or lamellipodia are observed only in the maturing fibers undergoing cell curve conversion, indicating lamellipodium is not the primary driver of earlier fiber migration. We demonstrated that elevated levels of fibroblast growth factor (FGF) suppressed the extension of Rac-dependent protrusions, suggesting changes in the activity of FGF controling Rac activity, switching to lamellipodium-driven migration. Inhibitors of ROCK, myosin, and actin reduced the height of both early and later fibers, indicating elongation of these fibers relies on actomyosin contractility. Consistently, active RhoA was detected throughout these fibers. Given that FGF promotes fiber elongation, we propose it to do so through regulation of Rho activity.
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Affiliation(s)
- Yuki Sugiyama
- Developmental Neurobiology Unit, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa 904-0495, Japan
- Save Sight Institute, The University of Sydney, Sydney, NSW 2000, Australia
| | - Daniel A. Reed
- Cancer Ecosystems Program, The Garvan Institute of Medical Research & The Kinghorn Cancer Centre, St Vincent’s Clinical School, Faculty of Medicine, UNSW Sydney, Sydney, NSW 2010, Australia
| | - David Herrmann
- Cancer Ecosystems Program, The Garvan Institute of Medical Research & The Kinghorn Cancer Centre, St Vincent’s Clinical School, Faculty of Medicine, UNSW Sydney, Sydney, NSW 2010, Australia
| | - Frank J. Lovicu
- Save Sight Institute, The University of Sydney, Sydney, NSW 2000, Australia
- Molecular and Cellular Biomedicine, School of Medical Sciences, The University of Sydney, Sydney, NSW 2006, Australia
| | - Michael L. Robinson
- Department of Biology and Center for Visual Sciences, Miami University, Oxford, OH, USA
| | - Paul Timpson
- Cancer Ecosystems Program, The Garvan Institute of Medical Research & The Kinghorn Cancer Centre, St Vincent’s Clinical School, Faculty of Medicine, UNSW Sydney, Sydney, NSW 2010, Australia
| | - Ichiro Masai
- Developmental Neurobiology Unit, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa 904-0495, Japan
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3
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Zhao M, Mei T, Shang B, Zou B, Lian Q, Xu W, Wu K, Lai Y, Liu C, Wei L, Zhu J, Zhang K, Liu Y, Zhao L. Defect of LSS Disrupts Lens Development in Cataractogenesis. Front Cell Dev Biol 2021; 9:788422. [PMID: 34926465 PMCID: PMC8675080 DOI: 10.3389/fcell.2021.788422] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2021] [Accepted: 10/29/2021] [Indexed: 11/24/2022] Open
Abstract
Congenital cataract is one of the leading causes of blindness in children worldwide. About one-third of congenital cataracts are caused by genetic defects. LSS, which encodes lanosterol synthase, is a causal gene for congenital cataracts. LSS is critical in preventing abnormal protein aggregation of various cataract-causing mutant crystallins; however, its roles in lens development remain largely unknown. In our study, we generated a mouse model harboring Lss G589S mutation, which is homologous to cataract-causing G588S mutation in human LSS. LssG589S/G589S mice exhibited neonatal lethality at postal day 0 (P0), whereas these mice showed severe opacity in eye lens. Also, we found that cataract was formed at E17.5 after we examined the opacity of embryonic lens from E13.5 to E18.5. Moreover, disrupted lens differentiation occurred at E14.5 prior to formation of the opacity of eye lens, shown as delayed differentiation of lens secondary fiber and disordered lens fiber organization. In addition, RNA-seq analysis indicated that cholesterol synthesis signaling pathways were significantly downregulated. Overall, our findings provide clear evidence that a mouse model harboring a homozygous Lss G589S mutation can recapitulate human congenital cataract. Our study points out that LSS functions as a critical determinant of lens development, which will contribute to better understanding LSS defects in cataractogenesis and developing therapies for cataracts.
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Affiliation(s)
- Minglei Zhao
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, China
| | - Tingfang Mei
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, China.,Guangdong Province Key Laboratory of Brain Function and Disease, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
| | - Bizhi Shang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, China
| | - Bin Zou
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, China
| | - Qing Lian
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, China.,Dongguan Guangming Ophthalmic Hospital, Dongguan, China
| | - Wenchang Xu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, China
| | - Keling Wu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, China
| | - Yuhua Lai
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, China
| | - Chujun Liu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, China
| | - Lai Wei
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, China
| | - Jie Zhu
- Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, China
| | - Kang Zhang
- Center for Biomedicine and Innovations, Faculty of Medicine, Macau University of Science and Technology and University Hospital, Macau, China
| | - Yizhi Liu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, China.,Guangzhou Regenerative Medicine and Health Guangdong Laboratory, Guangzhou, China.,Research Unit of Ocular Development and Regeneration, Chinese Academy of Medical Sciences, Guangzhou, China
| | - Ling Zhao
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, China
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4
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Biswas S, Son A, Yu Q, Zhou R, Lo WK. Breakdown of interlocking domains may contribute to formation of membranous globules and lens opacity in ephrin-A5(-/-) mice. Exp Eye Res 2015; 145:130-139. [PMID: 26643403 DOI: 10.1016/j.exer.2015.11.017] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2015] [Revised: 11/05/2015] [Accepted: 11/24/2015] [Indexed: 01/17/2023]
Abstract
Ephrin-A5, a ligand of the Eph family of receptor tyrosine kinases, plays a key role in lens fiber cell packing and cell-cell adhesion, with approximately 87% of ephrin-A5(-/-) mice develop nuclear cataracts. Here, we investigated the extensive formation of light-scattering globules associated with breakdown of interlocking protrusions during lens opacification in ephrin-A5(-/-) mice. Lenses from wild-type (WT) and ephrin-A5(-/-) mice between 2 and 21 weeks old were studied with light and electron microscopy, immunofluorescence labeling, freeze-fracture TEM and filipin cytochemistry for membrane cholesterol detection. Lens opacities with various densities were first observed in ephrin-A5(-/-) mice at around 60 days old. Dense cataracts in the mutant lenses were seen primarily in the nuclear region surrounded by transparent cortices from all eyes examined. We confirmed that a majority of nuclear cataracts were dislocated posteriorly and ruptured the thinner posterior lens capsule. SEM analysis indicated that numerous interlocking protrusions and wavy ridge-and-valley membrane surfaces in deep cortical and nuclear fibers did not cause lens opacity in both transparent ephrin-A5(-/-) and WT mice. In contrast, abundant isolated membranous globules of approximately 1000 nm in size were distributed randomly along the intact fiber cells during early stage of all ephrin-A5(-/-) cataracts examined. A further examination using both SEM and TEM revealed that isolated globules were generated from the disintegrated interlocking protrusions originally located along the corners of hexagonal fiber cells. Freeze-fracture TEM further revealed the association of square-array aquaporin junctions with both isolated globules and interlocking membrane domains. This study reports for the first time that disrupted interlocking protrusions are the source of numerous large membranous globules that contribute to light scattering and nuclear cataracts in the ephrin-A5(-/-) mice. Our results further suggest that dissociations of N-cadherin and adherens junctions in the associated interlocking domains may result in the formation of isolated globules and nuclear opacities in the ephrin-A5(-/-) mice.
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Affiliation(s)
- Sondip Biswas
- Department of Neurobiology, Morehouse School of Medicine, Atlanta, GA, USA
| | - Alexander Son
- Department of Chemical Biology, College of Pharmacy, Rutgers University, Piscataway, NJ, USA
| | - Qili Yu
- Department of Chemical Biology, College of Pharmacy, Rutgers University, Piscataway, NJ, USA
| | - Renping Zhou
- Department of Chemical Biology, College of Pharmacy, Rutgers University, Piscataway, NJ, USA.
| | - Woo-Kuen Lo
- Department of Neurobiology, Morehouse School of Medicine, Atlanta, GA, USA.
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5
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Bassnett S, Shi Y, Vrensen GFJM. Biological glass: structural determinants of eye lens transparency. Philos Trans R Soc Lond B Biol Sci 2011; 366:1250-64. [PMID: 21402584 PMCID: PMC3061108 DOI: 10.1098/rstb.2010.0302] [Citation(s) in RCA: 228] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
The purpose of the lens is to project a sharply focused, undistorted image of the visual surround onto the neural retina. The first pre-requisite, therefore, is that the tissue should be transparent. Despite the presence of remarkably high levels of protein, the lens cytosol remains transparent as a result of short-range-order interactions between the proteins. At a cellular level, the programmed elimination of nuclei and other light-scattering organelles from cells located within the pupillary space contributes directly to tissue transparency. Scattering at the cell borders is minimized by the close apposition of lens fibre cells facilitated by a plethora of adhesive proteins, some expressed only in the lens. Similarly, refractive index matching between lens membranes and cytosol is believed to minimize scatter. Refractive index matching between the cytoplasm of adjacent cells is achieved through the formation of cellular fusions that allow the intermingling of proteins. Together, these structural adaptations serve to minimize light scatter and enable this living, cellular structure to function as 'biological glass'.
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Affiliation(s)
- Steven Bassnett
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St Louis, MO, USA
| | - Yanrong Shi
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St Louis, MO, USA
| | - Gijs F. J. M. Vrensen
- Department of Ophthalmology, Leiden University Medical Center, Leiden, The Netherlands
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6
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A developmental defect in astrocytes inhibits programmed regression of the hyaloid vasculature in the mammalian eye. Eur J Cell Biol 2011; 90:440-8. [PMID: 21354650 DOI: 10.1016/j.ejcb.2011.01.003] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2010] [Revised: 01/07/2011] [Accepted: 01/09/2011] [Indexed: 11/21/2022] Open
Abstract
Previously we reported the novel observation that astrocytes ensheath the persistent hyaloid artery, both in the Nuc1 spontaneous mutant rat, and in human PFV (persistent fetal vasculature) disease (Developmental Dynamics 234:36-47, 2005). We now show that astrocytes isolated from both the optic nerve and retina of Nuc1 rats migrate faster than wild type astrocytes. Aquaporin 4 (AQP4), the major water channel in astrocytes, has been shown to be important in astrocyte migration. We demonstrate that AQP4 expression is elevated in the astrocytes in PFV conditions, and we hypothesize that this causes the cells to migrate abnormally into the vitreous where they ensheath the hyaloid artery. This abnormal association of astrocytes with the hyaloid artery may impede the normal macrophage-mediated remodeling and regression of the hyaloid system.
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7
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Rivera C, Yamben IF, Shatadal S, Waldof M, Robinson ML, Griep AE. Cell-autonomous requirements for Dlg-1 for lens epithelial cell structure and fiber cell morphogenesis. Dev Dyn 2009; 238:2292-308. [PMID: 19623611 DOI: 10.1002/dvdy.22036] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Cell polarity and adhesion are thought to be key determinants in organismal development. In Drosophila, discs large (dlg) has emerged as an important regulator of epithelial cell proliferation, adhesion, and polarity. Herein, we investigated the role of the mouse homolog of dlg (Dlg-1) in the development of the mouse ocular lens. Tissue-specific ablation of Dlg-1 throughout the lens early in lens development led to an expansion and disorganization of the epithelium that correlated with changes in the distribution of adhesion and polarity factors. In the fiber cells, differentiation defects were observed. These included alterations in cell structure and the disposition of cell adhesion/cytoskeletal factors, delay in denucleation, and reduced levels of alpha-catenin, pERK1/2, and MIP26. These fiber cell defects were recapitulated when Dlg-1 was disrupted only in fiber cells. These results suggest that Dlg-1 acts in a cell autonomous manner to regulate epithelial cell structure and fiber cell differentiation.
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Affiliation(s)
- Charlene Rivera
- Department of Anatomy, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin 53706, USA
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8
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Sugiyama Y, Akimoto K, Robinson ML, Ohno S, Quinlan RA. A cell polarity protein aPKClambda is required for eye lens formation and growth. Dev Biol 2009; 336:246-56. [PMID: 19835853 PMCID: PMC2806522 DOI: 10.1016/j.ydbio.2009.10.010] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2009] [Revised: 10/03/2009] [Accepted: 10/05/2009] [Indexed: 11/28/2022]
Abstract
The organisation of individual cells into a functional three-dimensional tissue is still a major question in developmental biology. Modulation of epithelial cell shape is a critical driving force in forming tissues. This is well illustrated in the eye lens where epithelial cells elongate extensively during their differentiation into fibre cells. It is at the lens equator that epithelial cells elongate along their apical–basal axis. During this process the elongating epithelial cells and their earliest fibre cell derivatives remain anchored at their apical tips, forming a discrete region or modiolus, which we term the lens fulcrum. How this is achieved has received scant attention and is little understood. Here, we show that conditional depletion of aPKCλ, a central effector of the PAR polarity complex, disrupts the apical junctions in elongating epithelial cells so that the lens fulcrum fails to form. This results in disorganised fibre cell alignment that then causes cataract. Interestingly, aPKCλ depletion also promotes epithelial–mesenchymal transition of the lens epithelial cells, reducing their proliferation, leading ultimately to a small lens and microphthalmia. These observations indicate that aPKCλ, a regulator of polarity and apical junctions, is required for development of a lens that is the correct size and shape.
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Affiliation(s)
- Yuki Sugiyama
- School of Biological and Biomedical Sciences, University of Durham, Durham, UK
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9
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Joy A, Currie MS, Donohue ST, Al-Ghoul KJ. Aberrant basal fiber end migration underlies structural malformations in a streptozotocin-induced diabetic rat model. Exp Eye Res 2009; 89:344-57. [PMID: 19358842 DOI: 10.1016/j.exer.2009.03.022] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2008] [Revised: 02/17/2009] [Accepted: 03/27/2009] [Indexed: 11/27/2022]
Abstract
This study characterized early structural changes at posterior fiber ends in the crystalline lens after diabetic induction. Wistar rats (n = 49), randomized into one naïve control group and four experimental groups, were rendered diabetic via streptozotocin injection. Animals were euthanized at 1 week intervals, blood glucose levels recorded and lenses were evaluated grossly, by SEM and by confocal microscopy. Scoring Indices were developed to assess structural alterations and for statistical correlations between the scores and the duration of hyperglycemic exposure as well as blood glucose levels. Average blood glucose levels increased progressively from 98.5 mg/dL (controls) to 331.4 mg/dL (4 weeks). Diabetic lenses displayed abnormal suture sub-branches and opacity formation beginning late in the first week post-injection and rapidly progressing in severity through four weeks. SEM analyses showed gradual elongation of fiber ends and filopodia which comprised a disorganized configuration and a loss of recognizable migration patterns. Structural alterations culminated in foci of fiber degeneration by the third to fourth weeks. The F-actin distribution at basal fiber ends was significantly altered as compared to naïve controls. Cadherin distribution was altered as compared to controls, but largely at later time points. The grading system clearly shows increased structural compromise with elevated blood glucose levels in streptozotocin-induced diabetes. Further, although the initial rise in blood glucose levels was associated with pathological changes, their progression depended to a larger extent on continued hyperglycemic exposure. The data suggests that hyperglycemia initially disrupts fiber end migration, resulting in structural alterations and eventual fiber degeneration.
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Affiliation(s)
- Anita Joy
- Department of Anatomy & Cell Biology, Rush University Medical Center, 600 S. Paulina St, Chicago, IL 60612, USA
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10
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Loss of ephrin-A5 function disrupts lens fiber cell packing and leads to cataract. Proc Natl Acad Sci U S A 2008; 105:16620-5. [PMID: 18948590 DOI: 10.1073/pnas.0808987105] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Cell-cell interactions organize lens fiber cells into highly ordered structures to maintain transparency. However, signals regulating such interactions have not been well characterized. We report here that ephrin-A5, a ligand of the Eph receptor tyrosine kinases, plays a key role in lens fiber cell shape and cell-cell interactions. Lens fiber cells in mice lacking ephrin-A5 function appear rounded and irregular in cross-section, in contrast to their normal hexagonal appearance in WT lenses. Cataracts eventually develop in 87% of ephrin-A5 KO mice. We further demonstrate that ephrin-A5 interacts with the EphA2 receptor to regulate the adherens junction complex by enhancing recruitment of beta-catenin to N-cadherin. These results indicate that the Eph receptors and their ligands are critical regulators of lens development and maintenance.
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11
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Rao PV. The pulling, pushing and fusing of lens fibers: a role for Rho GTPases. Cell Adh Migr 2008; 2:170-3. [PMID: 19262112 DOI: 10.4161/cam.2.3.6495] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Lens development and differentiation are intricate and complex processes characterized by distinct molecular and morphological changes. The growth of a transparent lens involves proliferation of the epithelial cells and their subsequent differentiation into secondary fiber cells. Prior to differentiation, epithelial cells at the lens equator exit from the cell cycle and elongate into long, ribbon-like cells. Fiber cell elongation takes place bidirectionally as fiber tips migrate both anteriorly and posteriorly along the apical surface of the epithelium and inner surface of the capsule, respectively. The differentiating fiber cells move inward from the periphery to the center of the lens on a continuous basis as the lens grows throughout life. Finally, when fiber cells reach the center or suture line, their basal and apical tips detach from the epithelium and capsule, respectively, and interlock with cells from the opposite direction of the lens and form the suture line. Further, symmetric packing of fiber cells and degradation of most of the cellular organelle during fiber cell terminal differentiation are crucial for lens transparency. These sequential events are presumed to depend on cytoskeletal dynamics and cell adhesive interactions; however, our knowledge of regulation of lens fiber cell cytosketal reorganization, cell adhesive interactions and mechanotransduction, and their role in lens morphogenesis and function is limited at present. Recent biochemical and molecular studies have targeted cytoskeletal signaling proteins, including Rho GTPases, Abl kinase interacting proteins, cell adhesion molecules, myosin II, Src kinase and phosphoinositide 3-kinase in the developing chicken and mouse lens and characterized components of the fiber cell basal membrane complex. These studies have begun to unravel the vital role of cytoskeletal proteins and their regulatory pathways in control of lens morphogenesis, fiber cell elongation, migration, differentiation, survival and mechanical properties.
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Affiliation(s)
- P Vasantha Rao
- Department of Ophthalmology, Duke University School of Medicine, Durham, North Carolina 27710, USA.
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12
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Expression and localisation of apical junctional complex proteins in lens epithelial cells. Exp Eye Res 2008; 87:64-70. [DOI: 10.1016/j.exer.2008.03.017] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2007] [Revised: 02/25/2008] [Accepted: 03/04/2008] [Indexed: 12/23/2022]
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13
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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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14
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Sinha D, Hose S, Zhang C, Neal R, Ghosh M, O'Brien TP, Sundin O, Goldberg MF, Robison WG, Russell P, Lo WK, Samuel Zigler J. A spontaneous mutation affects programmed cell death during development of the rat eye. Exp Eye Res 2005; 80:323-35. [PMID: 15721615 DOI: 10.1016/j.exer.2004.09.014] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2004] [Accepted: 09/29/2004] [Indexed: 12/30/2022]
Abstract
We have discovered a spontaneous mutation in the Sprague-Dawley rat with a novel eye phenotype that we have named Nuc1. The Nuc1 mutation behaves as a single semi-dominant locus with an intermediate phenotype in the heterozygotes. Heterozygotes exhibit nuclear cataracts. Homozygous Nuc1 rats are fully viable and have microphthalmia, retinal abnormalities and disruption of lens structure shortly before birth. The homozygous mutant shows no obvious pathology outside of the eye, indicating that the mutation is highly eye specific in its effects. An unusual feature of the mutation is that it prevents the normal programmed loss of nuclei from lens fiber cells, but does not affect the loss of other organelles. TUNEL, light, and electron microscopic studies show normal intact nuclei in lens fibers, in contrast to many other models with degenerate nuclei and unlike normal lenses where no such nuclei remain. The beaded filament protein, filensin, is down-regulated in fibers of Nuc1, while heat shock cognate 70 is up-regulated. Homozygous retinas are thicker than normal, and TUNEL labeling indicates roughly half the number of apoptotic cells compared to a wild-type retina. The transient layer of Chievitz persists in adult Nuc1 retina, indicative of delayed development. Hence, Nuc1 is a novel mutation that could be an eye-specific regulator of apoptosis.
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Affiliation(s)
- Debasish Sinha
- Department of Ophthalmology, School of Medicine, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD 21287, USA.
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15
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Straub BK, Boda J, Kuhn C, Schnoelzer M, Korf U, Kempf T, Spring H, Hatzfeld M, Franke WW. A novel cell-cell junction system: the cortex adhaerens mosaic of lens fiber cells. J Cell Sci 2004; 116:4985-95. [PMID: 14625392 DOI: 10.1242/jcs.00815] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The anucleate prismoid fiber cells of the eye lens are densely packed to form a tissue in which the plasma membranes and their associated cytoplasmic coat form a single giant cell-cell adhesive complex, the cortex adhaerens. Using biochemical and immunoprecipitation methods in various species (cow, pig, rat), in combination with immunolocalization microscopy, we have identified two different major kinds of cortical complex. In one, the transmembrane glycoproteins N-cadherin and cadherin-11 [which also occur in heterotypic ('mixed') complexes] are associated with alpha- and beta-catenin, plakoglobin (proportions variable among species), p120ctn and vinculin. The other complex contains ezrin, periplakin, periaxin and desmoyokin (and so is called the EPPD complex), usually together with moesin, spectrin(s) and plectin. In sections through lens fiber tissue, the short sides of the lens fiber hexagons appear to be enriched in the cadherin-based complexes, whereas the EPPD complexes also occur on the long sides. Moreover, high resolution double-label fluorescence microscopy has revealed, on the short sides, a finer, almost regular mosaicism of blocks comprising the cadherin-based, catenin-containing complexes, alternating with patches formed by the EPPD complexes. The latter, a new type of junctional plaque ensemble of proteins hitherto known only from certain other cell types, must be added to the list of major lens cortex proteins. We here discuss its possible functional importance for the maintenance of lens structure and functions, notably clear and sharp vision.
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Affiliation(s)
- Beate K Straub
- Division of Cell Biology, German Cancer Research Center, Im Neuenheimer Feld 280, 69120 Heidelberg, Germany
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Zhou CJ, Lo WK. Association of clathrin, AP-2 adaptor and actin cytoskeleton with developing interlocking membrane domains of lens fibre cells. Exp Eye Res 2003; 77:423-32. [PMID: 12957142 DOI: 10.1016/s0014-4835(03)00171-4] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Interlocking membrane domains are specialized membrane interdigitations in the form of ball-and-sockets and protrusions between lens fibre cells of all species. They are believed to play a key role in maintaining fibre-fibre stability and are therefore, important for normal lens function. Here we report the specific association of the clathrin/AP-2 adaptor complex and the branching F-actin network with the development of interlocking domains in rats and several other species. By thin-section electron microscopy we consistently observed a layer of distinct coating (approximately 25-nm thick) on the concave membrane surface of small and intermediate-sized developing interlocking domains. These membrane coats remarkably resembled the clathrin-coat of endocytic vesicles in which clathrin and the AP-2 adaptor are involved in the induction of coated pit formation during receptor-mediated endocytosis. We hypothesize that the clathrin/AP-2 complex is directly involved in the induction of interlocking domains in fibre cells. By immunoconfocal microscopy, co-labelling of a dotted-pattern of clathrin and AP-2 adaptor antibodies was seen along the cortical fibre cells. Immunoblot analysis further confirmed that clathrin and AP-2 adaptor antibodies specifically stained a polypeptide band of 180 and 106kD, respectively, in the membrane fractions prepared separately from the outer and inner cortical fibres where interlocking domains are abundant but endocytic vesicles are absent. Immunoelectron microscopy showed that the clathrin antibody was localized along the interlocking membrane. In addition, branching actin filament networks were frequently observed within the cytoplasmic compartment of developing interlocking domains by TEM, in consistent with the findings by fluorescence and immunogold labelling of the F-actin antibody in the domains. These results demonstrate for the first time that the clathrin/AP-2 complex plays a new role for the formation of interlocking domains in lens fibre cells. Branching actin networks and possibly other cytoskeletal components are also associated with the development and maintenance of these interlocking domains. The coordinated 'pulling and pushing' actions generated by the clathrin/AP-2 complex and branching actin networks during interlocking domain formation are discussed.
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Affiliation(s)
- Cheng-Jing Zhou
- Department of Anatomy and Neurobiology, Morehouse School of Medicine, Atlanta, GA 30310, USA
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Masai I, Lele Z, Yamaguchi M, Komori A, Nakata A, Nishiwaki Y, Wada H, Tanaka H, Nojima Y, Hammerschmidt M, Wilson SW, Okamoto H. N-cadherin mediates retinal lamination, maintenance of forebrain compartments and patterning of retinal neurites. Development 2003; 130:2479-94. [PMID: 12702661 DOI: 10.1242/dev.00465] [Citation(s) in RCA: 231] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
The complex, yet highly ordered and predictable, structure of the neural retina is one of the most conserved features of the vertebrate central nervous system. In all vertebrate classes, retinal neurons are organized into laminae with each neuronal class adopting specific morphologies and patterns of connectivity. Using genetic analyses in zebrafish, we demonstrate that N-cadherin (Ncad) has several distinct and crucial functions during the establishment of retinal organization. Although the location of cell division is disorganized in embryos with reduced or no Ncad function, different classes of retinal neurons are generated. However, these neurons fail to organize into correct laminae, most probably owing to compromised adhesion between retinal cells. In addition, amacrine cells exhibit exuberant and misdirected outgrowth of neurites that contributes to severe disorganization of the inner plexiform layer. Retinal ganglion cells also exhibit defects in process outgrowth, with axons exhibiting fasciculation defects and adopting incorrect ipsilateral trajectories. At least some of these defects are likely to be due to a failure to maintain compartment boundaries between eye, optic nerve and brain. Although in vitro studies have implicated Fgf receptors in modulating the axon outgrowth promoting properties of Ncad, most aspects of the Ncad mutant phenotype are not phenocopied by treatments that block Fgf receptor function.
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Affiliation(s)
- Ichiro Masai
- Masai Initiative Research Unit, The Institute of Physical and Chemical Research (RIKEN), Hirosawa 2-1, Wako-shi, Saitama 351-0198, Japan.
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Abstract
Cytoplasmic proteins associated with adherens junctions were identified in the chicken ocular lens. The catenins, alpha, beta, and gamma, were present in epithelial and fiber cells, although their pattern of distribution changed with fiber cell differentiation. The sharp decline in alpha-catenin with fiber cell formation and the increasing Triton-insolubility of N-cadherin suggests that another subtype of alpha-catenin exists in the lens.
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Affiliation(s)
- M Bagchi
- Department of Anatomy/Cell Biology, Wayne State University, School of Medicine, Detroit, Michigan 48201, USA
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Batth BK, Tripathi R, Srinivas UK. Curcumin-induced differentiation of mouse embryonal carcinoma PCC4 cells. Differentiation 2001; 68:133-40. [PMID: 11686235 DOI: 10.1046/j.1432-0436.2001.680207.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Curcumin, a natural component of turmeric extracted from the rhizomes of Curcuma longa, is known to exhibit a number of biological properties. In the present study, curcumin, at low concentration, was shown to induce differentiation in embryonal carcinoma cell line PCC4. In response to curcumin, PCC4 cells ceased to proliferate and showed cell cycle arrest at G1 phase after 4 hours of treatment, followed by their differentiation which is characterized by increase of nuclear/cytoplasmic ratio. The expression of hsp 70 was also seen upon 8 h of curcumin treatment, and it remained constant up to 48 h. Differentiated cells also expressed a series of differentiation markers such as lamin A, well-established actin, and keratin cytoskeleton. We used mRNA differential display analysis to identify the genes that are regulated during curcumin-induced differentiation of PCC4 cells. We cloned and sequenced three partial cDNAs that were differentially expressed in normal and differentiated cells. Sequence comparison of one downregulated cDNA (Al) has shown homology to a gene present on mouse chromosome five, while the two upregulated cDNA (C1 and C7) are homologous to several mouse ESTs clones from organs of mesodermal origin. We have identified the full-length coding sequence of the Cl fragment with a putative amino acid sequence. Tissue-specific Northern with RNA from adult mouse organs with the C1 fragment alone showed hybridization with mRNA from several tissues, whereas the same Northern with only the coding sequence showed expression of C1 gene mainly in the adult kidney. Homology search revealed that C1 sequence is part of the 3' UTR and may be common to several genes expressed in many tissues. Thus, curcumin appears to differentiate embryonal carcinoma cell PCC4, and one of the upregulated genes seems to be expressed mainly in the adult kidney.
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Affiliation(s)
- B K Batth
- Centre for Cellular and Molecular Biology, Hyderabad, India
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Zolessi FR, Arruti C. Apical accumulation of MARCKS in neural plate cells during neurulation in the chick embryo. BMC DEVELOPMENTAL BIOLOGY 2001; 1:7. [PMID: 11329360 PMCID: PMC31341 DOI: 10.1186/1471-213x-1-7] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/20/2001] [Accepted: 04/24/2001] [Indexed: 11/15/2022]
Abstract
BACKGROUND The neural tube is formed by morphogenetic movements largely dependent on cytoskeletal dynamics. Actin and many of its associated proteins have been proposed as important mediators of neurulation. For instance, mice deficient in MARCKS, an actin cross-linking membrane-associated protein that is regulated by PKC and other kinases, present severe developmental defects, including failure of cranial neural tube closure. RESULTS To determine the distribution of MARCKS, and its possible relationships with actin during neurulation, chick embryos were transversely sectioned and double labeled with an anti-MARCKS polyclonal antibody and phalloidin. In the neural plate, MARCKS was found ubiquitously distributed at the periphery of the cells, being conspicuously accumulated in the apical cell region, in close proximity to the apical actin meshwork. This asymmetric distribution was particularly noticeable during the bending process. After the closure of the neural tube, the apically accumulated MARCKS disappeared, and this cell region became analogous to the other peripheral cell zones in its MARCKS content. Actin did not display analogous variations, remaining highly concentrated at the cell subapical territory. The transient apical accumulation of MARCKS was found throughout the neural tube axis. The analysis of another epithelial bending movement, during the formation of the lens vesicle, revealed an identical phenomenon. CONCLUSIONS MARCKS is transiently accumulated at the apical region of neural plate and lens placode cells during processes of bending. This asymmetric subcellular distribution of MARCKS starts before the onset of neural plate bending. These results suggest possible upstream regulatory actions of MARCKS on some functions of the actin subapical meshwork.
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Affiliation(s)
- Flavio R Zolessi
- Laboratorio de Cultivo de Tejidos, Sección Biología Celular, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay
| | - Cristina Arruti
- Laboratorio de Cultivo de Tejidos, Sección Biología Celular, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay
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