1
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Scott H, Dong L, Stevenson A, MacDonald AI, Srinivasan S, Massimi P, Banks L, Martin PE, Johnstone SR, Graham SV. The human discs large protein 1 interacts with and maintains connexin 43 at the plasma membrane in keratinocytes. J Cell Sci 2023; 136:jcs259984. [PMID: 37288673 PMCID: PMC10309592 DOI: 10.1242/jcs.259984] [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: 03/08/2022] [Accepted: 04/21/2023] [Indexed: 05/10/2023] Open
Abstract
Gap junction channels, composed of connexins, allow direct cell-to-cell communication. Connexin 43 (Cx43; also known as GJA1) is widely expressed in tissues, including the epidermis. In a previous study of human papillomavirus-positive cervical epithelial tumour cells, we identified Cx43 as a binding partner of the human homologue of Drosophila Discs large (Dlg1; also known as SAP97). Dlg1 is a member of the membrane associated-guanylate kinase (MAGUK) scaffolding protein family, which is known to control cell shape and polarity. Here, we show that Cx43 also interacts with Dlg1 in uninfected keratinocytes in vitro and in keratinocytes, dermal cells and adipocytes in normal human epidermis in vivo. Depletion of Dlg1 in keratinocytes did not alter Cx43 transcription but was associated with a reduction in Cx43 protein levels. Reduced Dlg1 levels in keratinocytes resulted in a reduction in Cx43 at the plasma membrane with a concomitant reduction in gap junctional intercellular communication and relocation of Cx43 to the Golgi compartment. Our data suggest a key role for Dlg1 in maintaining Cx43 at the plasma membrane in keratinocytes.
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Affiliation(s)
- Harry Scott
- MRC-University of Glasgow Centre for Virus Research, School of Infection and Immunity, College of Medical Veterinary and Life Sciences, University of Glasgow, Garscube Estate, Glasgow G61 1QH, UK
| | - Li Dong
- MRC-University of Glasgow Centre for Virus Research, School of Infection and Immunity, College of Medical Veterinary and Life Sciences, University of Glasgow, Garscube Estate, Glasgow G61 1QH, UK
| | - Andrew Stevenson
- MRC-University of Glasgow Centre for Virus Research, School of Infection and Immunity, College of Medical Veterinary and Life Sciences, University of Glasgow, Garscube Estate, Glasgow G61 1QH, UK
| | - Alasdair I. MacDonald
- MRC-University of Glasgow Centre for Virus Research, School of Infection and Immunity, College of Medical Veterinary and Life Sciences, University of Glasgow, Garscube Estate, Glasgow G61 1QH, UK
| | - Sharmila Srinivasan
- Translation Research Platform for Veterinary Biologicals, Chennai, Tamil Nadu, India
| | - Paola Massimi
- International Centre for Genetic Engineering and Biotechnology, Trieste, Italy
| | - Lawrence Banks
- International Centre for Genetic Engineering and Biotechnology, Trieste, Italy
| | - Patricia E. Martin
- Department of Biological and Biomedical Sciences, School of Health and Life Sciences, Glasgow Caledonian University, Glasgow G4 0BA, UK
| | - Scott R. Johnstone
- Fralin Biomedical Research Institute at Virginia Tech Carilion, Center for Vascular and Heart Research, Virginia Tech, Roanoke VA 24016, USA
| | - Sheila V. Graham
- MRC-University of Glasgow Centre for Virus Research, School of Infection and Immunity, College of Medical Veterinary and Life Sciences, University of Glasgow, Garscube Estate, Glasgow G61 1QH, UK
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2
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Castillo-Azofeifa D, Wald T, Reyes EA, Gallagher A, Schanin J, Vlachos S, Lamarche-Vane N, Bomidi C, Blutt S, Estes MK, Nystul T, Klein OD. A DLG1-ARHGAP31-CDC42 axis is essential for the intestinal stem cell response to fluctuating niche Wnt signaling. Cell Stem Cell 2023; 30:188-206.e6. [PMID: 36640764 PMCID: PMC9922544 DOI: 10.1016/j.stem.2022.12.008] [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: 03/14/2022] [Revised: 10/13/2022] [Accepted: 12/12/2022] [Indexed: 01/15/2023]
Abstract
A central factor in the maintenance of tissue integrity is the response of stem cells to variations in the levels of niche signals. In the gut, intestinal stem cells (ISCs) depend on Wnt ligands for self-renewal and proliferation. Transient increases in Wnt signaling promote regeneration after injury or in inflammatory bowel diseases, whereas constitutive activation of this pathway leads to colorectal cancer. Here, we report that Discs large 1 (Dlg1), although dispensable for polarity and cellular turnover during intestinal homeostasis, is required for ISC survival in the context of increased Wnt signaling. RNA sequencing (RNA-seq) and genetic mouse models demonstrated that DLG1 regulates the cellular response to increased canonical Wnt ligands. This occurs via the transcriptional regulation of Arhgap31, a GTPase-activating protein that deactivates CDC42, an effector of the non-canonical Wnt pathway. These findings reveal a DLG1-ARHGAP31-CDC42 axis that is essential for the ISC response to increased niche Wnt signaling.
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Affiliation(s)
- David Castillo-Azofeifa
- Department of Orofacial Sciences and Program in Craniofacial Biology, University of California, San Francisco, San Francisco, CA, USA; Department of Regenerative Medicine, Genentech, Inc., South San Francisco, CA, USA
| | - Tomas Wald
- Department of Orofacial Sciences and Program in Craniofacial Biology, University of California, San Francisco, San Francisco, CA, USA
| | - Efren A Reyes
- Department of Orofacial Sciences and Program in Craniofacial Biology, University of California, San Francisco, San Francisco, CA, USA; Department of Pharmaceutical Chemistry and TETRAD Program, University of California, San Francisco, San Francisco, CA, USA
| | - Aaron Gallagher
- Department of Orofacial Sciences and Program in Craniofacial Biology, University of California, San Francisco, San Francisco, CA, USA
| | - Julia Schanin
- Department of Orofacial Sciences and Program in Craniofacial Biology, University of California, San Francisco, San Francisco, CA, USA
| | - Stephanie Vlachos
- Department of Anatomy, University of California, San Francisco, San Francisco, CA, USA
| | - Nathalie Lamarche-Vane
- Cancer Research Program, Research Institute of the McGill University Health Centre, Montréal, QC, Canada; Department of Anatomy and Cell Biology, McGill University, Montréal, QC, Canada
| | - Carolyn Bomidi
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX, USA
| | - Sarah Blutt
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX, USA
| | - Mary K Estes
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX, USA
| | - Todd Nystul
- Department of Anatomy, University of California, San Francisco, San Francisco, CA, USA
| | - Ophir D Klein
- Department of Orofacial Sciences and Program in Craniofacial Biology, University of California, San Francisco, San Francisco, CA, USA; Department of Pediatrics and Institute for Human Genetics, University of California, San Francisco, San Francisco, CA, USA; Department of Pediatrics, Cedars-Sinai Medical Center, Los Angeles, CA, USA.
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3
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Cvekl A, Camerino MJ. Generation of Lens Progenitor Cells and Lentoid Bodies from Pluripotent Stem Cells: Novel Tools for Human Lens Development and Ocular Disease Etiology. Cells 2022; 11:cells11213516. [PMID: 36359912 PMCID: PMC9658148 DOI: 10.3390/cells11213516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Revised: 10/31/2022] [Accepted: 11/02/2022] [Indexed: 11/09/2022] Open
Abstract
In vitro differentiation of human pluripotent stem cells (hPSCs) into specialized tissues and organs represents a powerful approach to gain insight into those cellular and molecular mechanisms regulating human development. Although normal embryonic eye development is a complex process, generation of ocular organoids and specific ocular tissues from pluripotent stem cells has provided invaluable insights into the formation of lineage-committed progenitor cell populations, signal transduction pathways, and self-organization principles. This review provides a comprehensive summary of recent advances in generation of adenohypophyseal, olfactory, and lens placodes, lens progenitor cells and three-dimensional (3D) primitive lenses, "lentoid bodies", and "micro-lenses". These cells are produced alone or "community-grown" with other ocular tissues. Lentoid bodies/micro-lenses generated from human patients carrying mutations in crystallin genes demonstrate proof-of-principle that these cells are suitable for mechanistic studies of cataractogenesis. Taken together, current and emerging advanced in vitro differentiation methods pave the road to understand molecular mechanisms of cataract formation caused by the entire spectrum of mutations in DNA-binding regulatory genes, such as PAX6, SOX2, FOXE3, MAF, PITX3, and HSF4, individual crystallins, and other genes such as BFSP1, BFSP2, EPHA2, GJA3, GJA8, LIM2, MIP, and TDRD7 represented in human cataract patients.
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Affiliation(s)
- Aleš Cvekl
- Departments Ophthalmology and Visual Sciences, Albert Einstein College of Medicine, Bronx, NY 10461, USA
- Department of Genetics, Albert Einstein College of Medicine, Bronx, NY 10461, USA
- Correspondence: ; Tel.: +1-718-430-3217; Fax: +1-718-430-8778
| | - Michael John Camerino
- Departments Ophthalmology and Visual Sciences, Albert Einstein College of Medicine, Bronx, NY 10461, USA
- Department of Genetics, Albert Einstein College of Medicine, Bronx, NY 10461, USA
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Murugan S, Cheng C. Roles of Eph-Ephrin Signaling in the Eye Lens Cataractogenesis, Biomechanics, and Homeostasis. Front Cell Dev Biol 2022; 10:852236. [PMID: 35295853 PMCID: PMC8918484 DOI: 10.3389/fcell.2022.852236] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Accepted: 02/04/2022] [Indexed: 01/26/2023] Open
Abstract
The eye lens is responsible for fine focusing of light onto the retina, and its function relies on tissue transparency and biomechanical properties. Recent studies have demonstrated the importance of Eph-ephrin signaling for the maintenance of life-long lens homeostasis. The binding of Eph receptor tyrosine kinases to ephrin ligands leads to a bidirectional signaling pathway that controls many cellular processes. In particular, dysfunction of the receptor EphA2 or the ligand ephrin-A5 lead to a variety of congenital and age-related cataracts, defined as any opacity in the lens, in human patients. In addition, a wealth of animal studies reveal the unique and overlapping functions of EphA2 and ephrin-A5 in lens cell shape, cell organization and patterning, and overall tissue optical and biomechanical properties. Significant differences in lens phenotypes of mouse models with disrupted EphA2 or ephrin-A5 signaling indicate that genetic modifiers likely affect cataract phenotypes and progression, suggesting a possible reason for the variability of human cataracts due to Eph-ephrin dysfunction. This review summarizes the roles of EphA2 and ephrin-A5 in the lens and suggests future avenues of study.
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Saito Y, Desai RR, Muthuswamy SK. Reinterpreting polarity and cancer: The changing landscape from tumor suppression to tumor promotion. Biochim Biophys Acta Rev Cancer 2018; 1869:103-116. [DOI: 10.1016/j.bbcan.2017.12.001] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2017] [Accepted: 12/08/2017] [Indexed: 12/21/2022]
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Ghosh A, Ramagopal UA, Bonanno JB, Brenowitz M, Almo SC. Structures of the L27 Domain of Disc Large Homologue 1 Protein Illustrate a Self-Assembly Module. Biochemistry 2018; 57:1293-1305. [PMID: 29261291 DOI: 10.1021/acs.biochem.7b01074] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Disc large 1 (Dlg1) proteins, members of the MAGUK protein family, are linked to cell polarity via their participation in multiprotein assemblies. At their N-termini, Dlg1 proteins contain a L27 domain. Typically, the L27 domains participate in the formation of obligate hetero-oligomers with the L27 domains from their cognate partners. Among the MAGUKs, Dlg1 proteins exist as homo-oligomers, and the oligomerization is solely dependent on the L27 domain. Here we provide biochemical and structural evidence of homodimerization via the L27 domain of Dlg1 from Drosophila melanogaster. The structure reveals that the core of the dimer is formed by a distinctive six-helix assembly, involving all three conserved helices from each subunit (monomer). The homodimer interface is extended by the C-terminal tail of the L27 domain of Dlg1, which forms a two-stranded antiparallel β-sheet. The structure reconciles and provides a structural context for a large body of available mutational data. From our analyses, we conclude that the observed L27 homodimerization is most likely a feature unique to the Dlg1 orthologs within the MAGUK family.
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Affiliation(s)
- Agnidipta Ghosh
- Department of Biochemistry, Albert Einstein College of Medicine , Bronx, New York 10461, United States
| | - Udupi A Ramagopal
- Biological Sciences Division, Poornaprajna Institute of Scientific Research , Sadashivanagar, Bangalore 560080, India
| | - Jeffrey B Bonanno
- Department of Biochemistry, Albert Einstein College of Medicine , Bronx, New York 10461, United States
| | - Michael Brenowitz
- Department of Biochemistry, Albert Einstein College of Medicine , Bronx, New York 10461, United States
| | - Steven C Almo
- Department of Biochemistry, Albert Einstein College of Medicine , Bronx, New York 10461, United States
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7
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Maddala R, Rao PV. Switching of α-Catenin From Epithelial to Neuronal Type During Lens Epithelial Cell Differentiation. Invest Ophthalmol Vis Sci 2017; 58:3445-3455. [PMID: 28692740 PMCID: PMC5505122 DOI: 10.1167/iovs.17-21539] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Purpose Ocular lens fiber cell elongation, differentiation, and compaction are associated with extensive reorganization of cell adhesive interactions and cytoskeleton; however, our knowledge of proteins critical to these events is still evolving. This study characterizes the distribution pattern of neuronal-specific α-catenin (αN-catenin) and its interaction with the N-cadherin–associated adherens junctions (AJs) and their stability in the mouse lens fibers. Methods Expression and distribution of αN-catenin in developing mouse and adult human lenses was determined by RT-PCR, immunoblot, and immunofluorescence analyses. Characterization of αN-catenin and N-cadherin interacting proteins and colocalization analyses were performed using immunoprecipitation, mass spectrometry, and confocal imaging. Effects of periaxin deficiency on the stability of lens fiber cell AJs were evaluated using perixin-null mice. Results αN-catenin exhibits discrete distribution to lens fibers in both mouse and human lenses, undergoing a robust up-regulation during fiber cell differentiation and maturation. Epithelial-specific α-catenin (αE-catenin), in contrast, distributes primarily to the lens epithelium. αN-catenin and N-cadherin reciprocally coimmunoprecipitate and colocalize along with β-catenin, actin, spectrin, vinculin, Armadillo repeat protein deleted in velo-cardio-facial syndrome homolog, periaxin, and ankyrin-B in lens fibers. Fiber cells from periaxin-null mouse lenses revealed disrupted N-cadherin/αN-catenin–based AJs. Conclusions These results suggest that the discrete shift in α-catenin expression from αE-catenin to αN-catenin subtype that occurs during lens epithelial cell differentiation may play a key role in fiber cell cytoarchitecture by regulating the assembly and stability of N-cadherin–based AJs. This study also provides evidence for the importance of the fiber cell–specific cytoskeletal interacting periaxin, in the stability of N-cadherin/αN-catenin–based AJs in lens fibers.
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Affiliation(s)
- Rupalatha Maddala
- Department of Ophthalmology, Duke University School of Medicine, Durham, North Carolina, United States
| | - Ponugoti Vasantha Rao
- Department of Ophthalmology, Duke University School of Medicine, Durham, North Carolina, United States 2Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, North Carolina, United States
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8
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Logan CM, Rajakaruna S, Bowen C, Radice GL, Robinson ML, Menko AS. N-cadherin regulates signaling mechanisms required for lens fiber cell elongation and lens morphogenesis. Dev Biol 2017; 428:118-134. [PMID: 28552735 DOI: 10.1016/j.ydbio.2017.05.022] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2017] [Revised: 05/15/2017] [Accepted: 05/15/2017] [Indexed: 12/14/2022]
Abstract
Tissue development and regeneration involve high-ordered morphogenetic processes that are governed by elements of the cytoskeleton in conjunction with cell adhesion molecules. Such processes are particularly important in the lens whose structure dictates its function. Studies of our lens-specific N-cadherin conditional knockout mouse (N-cadcKO) revealed an essential role for N-cadherin in the migration of the apical tips of differentiating lens fiber cells along the apical surfaces of the epithelium, a region termed the Epithelial Fiber Interface (EFI), that is necessary for normal fiber cell elongation and the morphogenesis. Studies of the N-cadcKO lens suggest that N-cadherin function in fiber cell morphogenesis is linked to the activation of Rac1 and myosin II, both signaling pathways central to the regulation of cell motility including determining the directionality of cellular movement. The absence of N-cadherin did not disrupt lateral contacts between fiber cells during development, and the maintenance of Aquaporin-0 and increased expression of EphA2 at cell-cell interfaces suggests that these molecules may function in this role. E-cadherin was maintained in newly differentiating fiber cells without interfering with expression of lens-specific differentiation proteins but was not able to replace N-cadherin function in these cells. The dependence of migration of the fiber cell apical domains along the EFI for lens morphogenesis on N-cadherin provides new insight into the process of tissue development.
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Affiliation(s)
- Caitlin M Logan
- Thomas Jefferson University, Pathology Anatomy and Cell Biology, Philadelphia, PA, United States
| | - Suren Rajakaruna
- Thomas Jefferson University, Pathology Anatomy and Cell Biology, Philadelphia, PA, United States
| | - Caitlin Bowen
- Thomas Jefferson University, Pathology Anatomy and Cell Biology, Philadelphia, PA, United States
| | - Glenn L Radice
- Thomas Jefferson University, Pathology Anatomy and Cell Biology, Philadelphia, PA, United States
| | - Michael L Robinson
- Department of Biology, Cell Molecular and Structural Biology Graduate Program, Miami University, Oxford, OH, United States
| | - A Sue Menko
- Thomas Jefferson University, Pathology Anatomy and Cell Biology, Philadelphia, PA, United States.
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9
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Lee S, Shatadal S, Griep AE. Dlg-1 Interacts With and Regulates the Activities of Fibroblast Growth Factor Receptors and EphA2 in the Mouse Lens. Invest Ophthalmol Vis Sci 2016; 57:707-18. [PMID: 26906157 PMCID: PMC4771194 DOI: 10.1167/iovs.15-17727] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
PURPOSE We previously showed that Discs large-1 (Dlg-1) regulates lens fiber cell structure and the fibroblast growth factor receptor (Fgfr) signaling pathway, a pathway required for fiber cell differentiation. Herein, we investigated the mechanism through which Dlg-1 regulates Fgfr signaling. METHODS Immunofluorescence was used to measure levels of Fgfr1, Fgfr2, and activated Fgfr signaling intermediates, pErk and pAkt, in control and Dlg-1-deficient lenses that were haplodeficient for Fgfr1 or Fgfr2. Immunoblotting was used to measure levels of N-cadherin, EphA2, β-catenin, and tyrosine-phosphorylated EphA2, Fgfr1, Fgfr2, and Fgfr3 in cytoskeletal-associated and cytosolic fractions of control and Dlg-1-deficient lenses. Complex formation between Dlg-1, N-cadherin, β-catenin, Fgfr1, Fgfr2, Fgfr3, and EphA2 was assessed by coimmunoprecipitation. RESULTS Lenses deficient for Dlg-1 and haplodeficient for Fgfr1 or Fgfr2 showed increased levels of Fgfr2 or Fgfr1, respectively. Levels of pErk and pAkt correlated with the level of Fgfr2. N-cadherin was reduced in the cytoskeletal-associated fraction and increased in the cytosolic fraction of Dlg-1-deficient lenses. Dlg-1 complexed with β-catenin, EphA2, Fgfr1, Fgfr2, and Fgfr3. EphA2 complexed with N-cadherin, β-catenin, Fgfr1, Fgfr2, and Fgfr3. Levels of these interactions were altered in Dlg-1-deficient lenses. Loss of Dlg-1 led to changes in Fgfr1, Fgfr2, Fgfr3, and EphA2 levels and to greater changes in the levels of their activation. CONCLUSIONS Dlg-1 complexes with and regulates the activities of EphA2, Fgfr1, Fgfr2, and Fgfr3. As EphA2 contains a Psd95/Dlg/ZO-1 (PDZ) binding motif, whereas Fgfrs do not, we propose that the PDZ protein, Dlg-1, modulates Fgfr signaling through regulation of EphA2.
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10
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Lan Y, Zhang N, Liu H, Xu J, Jiang R. Golgb1 regulates protein glycosylation and is crucial for mammalian palate development. Development 2016; 143:2344-55. [PMID: 27226319 DOI: 10.1242/dev.134577] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Accepted: 05/09/2016] [Indexed: 12/14/2022]
Abstract
Cleft palate is a common major birth defect for which currently known causes account for less than 30% of pathology in humans. In this study, we carried out mutagenesis screening in mice to identify new regulators of palatogenesis. Through genetic linkage mapping and whole-exome sequencing, we identified a loss-of-function mutation in the Golgb1 gene that co-segregated with cleft palate in a new mutant mouse line. Golgb1 is a ubiquitously expressed large coiled-coil protein, also known as giantin, that is localized at the Golgi membrane. Using CRISPR/Cas9-mediated genome editing, we generated and analyzed developmental defects in mice carrying additional Golgb1 loss-of-function mutations, which supported a crucial requirement for Golgb1 in palate development. Through maxillary explant culture assays, we demonstrate that the Golgb1 mutant embryos have intrinsic defects in palatal shelf elevation. Just prior to the developmental stage of palatal shelf elevation in wild-type littermates, Golgb1 mutant embryos exhibit increased cell density, reduced hyaluronan accumulation and impaired protein glycosylation in the palatal mesenchyme. Together, these results demonstrate that, although it is a ubiquitously expressed Golgi-associated protein, Golgb1 has specific functions in protein glycosylation and tissue morphogenesis.
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Affiliation(s)
- Yu Lan
- Division of Plastic Surgery, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA Division of Developmental Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
| | - Nian Zhang
- Division of Developmental Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
| | - Han Liu
- Division of Developmental Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
| | - Jingyue Xu
- Division of Developmental Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
| | - Rulang Jiang
- Division of Plastic Surgery, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA Division of Developmental Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
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11
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Intrinsic and extrinsic regulatory mechanisms are required to form and maintain a lens of the correct size and shape. Exp Eye Res 2016; 156:34-40. [PMID: 27109030 DOI: 10.1016/j.exer.2016.04.009] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Revised: 04/13/2016] [Accepted: 04/16/2016] [Indexed: 02/04/2023]
Abstract
Understanding how tissues and organs acquire and maintain an appropriate size and shape remains one of the most challenging areas in developmental biology. The eye lens represents an excellent system to provide insights into regulatory mechanisms because in addition to its relative simplicity in cellular composition (being made up of only two forms of cells, epithelial and fiber cells), these cells must become organized to generate the precise spheroidal arrangement that delivers normal lens function. Epithelial and fiber cells also represent spatially distinct proliferation and differentiation compartments, respectively, and an ongoing balance between these domains must be tightly regulated so that the lens achieves and maintains appropriate dimensions during growth and ageing. Recent research indicates that reciprocal inductive interactions mediated by Wnt-Frizzled and Notch-Jagged signaling pathways are important for maintaining and organizing these compartments. The Hippo-Yap pathway has also been implicated in maintaining the epithelial progenitor compartment and regulating growth processes. Thus, whilst some molecules and mechanisms have been identified, further work in this important area is needed to provide a clearer understanding of how lens size and shape is regulated.
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12
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Cheng C, Nowak RB, Fowler VM. The lens actin filament cytoskeleton: Diverse structures for complex functions. Exp Eye Res 2016; 156:58-71. [PMID: 26971460 DOI: 10.1016/j.exer.2016.03.005] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2015] [Revised: 03/01/2016] [Accepted: 03/07/2016] [Indexed: 01/05/2023]
Abstract
The eye lens is a transparent and avascular organ in the front of the eye that is responsible for focusing light onto the retina in order to transmit a clear image. A monolayer of epithelial cells covers the anterior hemisphere of the lens, and the bulk of the lens is made up of elongated and differentiated fiber cells. Lens fiber cells are very long and thin cells that are supported by sophisticated cytoskeletal networks, including actin filaments at cell junctions and the spectrin-actin network of the membrane skeleton. In this review, we highlight the proteins that regulate diverse actin filament networks in the lens and discuss how these actin cytoskeletal structures assemble and function in epithelial and fiber cells. We then discuss methods that have been used to study actin in the lens and unanswered questions that can be addressed with novel techniques.
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Affiliation(s)
- Catherine Cheng
- Department of Cell and Molecular Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Roberta B Nowak
- Department of Cell and Molecular Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Velia M Fowler
- Department of Cell and Molecular Biology, The Scripps Research Institute, La Jolla, CA 92037, USA.
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14
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Cvekl A, Ashery-Padan R. The cellular and molecular mechanisms of vertebrate lens development. Development 2014; 141:4432-47. [PMID: 25406393 PMCID: PMC4302924 DOI: 10.1242/dev.107953] [Citation(s) in RCA: 150] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The ocular lens is a model system for understanding important aspects of embryonic development, such as cell specification and the spatiotemporally controlled formation of a three-dimensional structure. The lens, which is characterized by transparency, refraction and elasticity, is composed of a bulk mass of fiber cells attached to a sheet of lens epithelium. Although lens induction has been studied for over 100 years, recent findings have revealed a myriad of extracellular signaling pathways and gene regulatory networks, integrated and executed by the transcription factor Pax6, that are required for lens formation in vertebrates. This Review summarizes recent progress in the field, emphasizing the interplay between the diverse regulatory mechanisms employed to form lens progenitor and precursor cells and highlighting novel opportunities to fill gaps in our understanding of lens tissue morphogenesis.
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Affiliation(s)
- Aleš Cvekl
- Department of Genetics, Albert Einstein College of Medicine, Bronx, NY 10461, USA Department of Ophthalmology and Visual Sciences, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Ruth Ashery-Padan
- Sackler School of Medicine and Sagol School of Neuroscience, Tel-Aviv University, 69978 Ramat Aviv, Tel Aviv, Israel
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15
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Chaffee BR, Shang F, Chang ML, Clement TM, Eddy EM, Wagner BD, Nakahara M, Nagata S, Robinson ML, Taylor A. Nuclear removal during terminal lens fiber cell differentiation requires CDK1 activity: appropriating mitosis-related nuclear disassembly. Development 2014; 141:3388-98. [PMID: 25139855 DOI: 10.1242/dev.106005] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Lens epithelial cells and early lens fiber cells contain the typical complement of intracellular organelles. However, as lens fiber cells mature they must destroy their organelles, including nuclei, in a process that has remained enigmatic for over a century, but which is crucial for the formation of the organelle-free zone in the center of the lens that assures clarity and function to transmit light. Nuclear degradation in lens fiber cells requires the nuclease DNase IIβ (DLAD) but the mechanism by which DLAD gains access to nuclear DNA remains unknown. In eukaryotic cells, cyclin-dependent kinase 1 (CDK1), in combination with either activator cyclins A or B, stimulates mitotic entry, in part, by phosphorylating the nuclear lamin proteins leading to the disassembly of the nuclear lamina and subsequent nuclear envelope breakdown. Although most post-mitotic cells lack CDK1 and cyclins, lens fiber cells maintain these proteins. Here, we show that loss of CDK1 from the lens inhibited the phosphorylation of nuclear lamins A and C, prevented the entry of DLAD into the nucleus, and resulted in abnormal retention of nuclei. In the presence of CDK1, a single focus of the phosphonuclear mitotic apparatus is observed, but it is not focused in CDK1-deficient lenses. CDK1 deficiency inhibited mitosis, but did not prevent DNA replication, resulting in an overall reduction of lens epithelial cells, with the remaining cells possessing an abnormally large nucleus. These observations suggest that CDK1-dependent phosphorylations required for the initiation of nuclear membrane disassembly during mitosis are adapted for removal of nuclei during fiber cell differentiation.
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Affiliation(s)
- Blake R Chaffee
- Department of Biology, Miami University, Oxford, OH 45056, USA
| | - Fu Shang
- Laboratory for Nutrition and Vision Research, Human Nutrition Research Center on Aging, Nutrition &Vision Res-USDA-HNRCA, Tufts University, Boston 02111, MA, USA
| | - Min-Lee Chang
- Laboratory for Nutrition and Vision Research, Human Nutrition Research Center on Aging, Nutrition &Vision Res-USDA-HNRCA, Tufts University, Boston 02111, MA, USA
| | - Tracy M Clement
- National Institute of Environmental Health Sciences, NIH, Research Triangle Park, NC 27709, USA
| | - Edward M Eddy
- National Institute of Environmental Health Sciences, NIH, Research Triangle Park, NC 27709, USA
| | - Brad D Wagner
- Department of Biology, Miami University, Oxford, OH 45056, USA
| | - Masaki Nakahara
- Department of Molecular and Cellular Physiology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Shigekazu Nagata
- Department of Medical Chemistry, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | | | - Allen Taylor
- Laboratory for Nutrition and Vision Research, Human Nutrition Research Center on Aging, Nutrition &Vision Res-USDA-HNRCA, Tufts University, Boston 02111, MA, USA Department of Biological Chemistry, Weizmann Institute of Science, Rehovot, Israel
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16
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Saadaoui M, Machicoane M, di Pietro F, Etoc F, Echard A, Morin X. Dlg1 controls planar spindle orientation in the neuroepithelium through direct interaction with LGN. ACTA ACUST UNITED AC 2014; 206:707-17. [PMID: 25202028 PMCID: PMC4164945 DOI: 10.1083/jcb.201405060] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Dlg1 recruits LGN to the cortex of cells in the chick neuroepithelium and may provide instructive cues that drive planar spindle orientation. Oriented cell divisions are necessary for the development of epithelial structures. Mitotic spindle orientation requires the precise localization of force generators at the cell cortex via the evolutionarily conserved LGN complex. However, polarity cues acting upstream of this complex in vivo in the vertebrate epithelia remain unknown. In this paper, we show that Dlg1 is localized at the basolateral cell cortex during mitosis and is necessary for planar spindle orientation in the chick neuroepithelium. Live imaging revealed that Dlg1 is required for directed spindle movements during metaphase. Mechanistically, we show that direct interaction between Dlg1 and LGN promotes cortical localization of the LGN complex. Furthermore, in human cells dividing on adhesive micropatterns, homogenously localized Dlg1 recruited LGN to the mitotic cortex and was also necessary for proper spindle orientation. We propose that Dlg1 acts primarily to recruit LGN to the cortex and that Dlg1 localization may additionally provide instructive cues for spindle orientation.
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Affiliation(s)
- Mehdi Saadaoui
- Institut de Biologie de l'École Normale Supérieure, Ecole Normale Supérieure, F-75005 Paris, France Institut National de la Santé et de la Recherche Medicale, U1024, F-75005 Paris, France Centre National de la Recherche Scientifique, Unité Mixte de Recherche 8197, F-75005 Paris, France
| | - Mickaël Machicoane
- Membrane Traffic and Cell Division Laboratory, Institut Pasteur, F-75015 Paris, France Centre National de la Recherche Scientifique, Unité de Recherche Associée 2582, F-75015 Paris, France Cellule Pasteur-Université Pierre et Marie Curie, Université Pierre et Marie Curie, F-75015 Paris, France
| | - Florencia di Pietro
- Institut de Biologie de l'École Normale Supérieure, Ecole Normale Supérieure, F-75005 Paris, France Institut National de la Santé et de la Recherche Medicale, U1024, F-75005 Paris, France Centre National de la Recherche Scientifique, Unité Mixte de Recherche 8197, F-75005 Paris, France Institute of Doctoral Studies (IFD), Sorbonne Universités, Université Pierre et Marie Curie-Université Paris 6, F-75252 Paris, France
| | - Fred Etoc
- Institut de Biologie de l'École Normale Supérieure, Ecole Normale Supérieure, F-75005 Paris, France Institut National de la Santé et de la Recherche Medicale, U1024, F-75005 Paris, France Centre National de la Recherche Scientifique, Unité Mixte de Recherche 8197, F-75005 Paris, France
| | - Arnaud Echard
- Membrane Traffic and Cell Division Laboratory, Institut Pasteur, F-75015 Paris, France Centre National de la Recherche Scientifique, Unité de Recherche Associée 2582, F-75015 Paris, France
| | - Xavier Morin
- Institut de Biologie de l'École Normale Supérieure, Ecole Normale Supérieure, F-75005 Paris, France Institut National de la Santé et de la Recherche Medicale, U1024, F-75005 Paris, France Centre National de la Recherche Scientifique, Unité Mixte de Recherche 8197, F-75005 Paris, France
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17
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Lee S, Griep AE. Loss of Dlg-1 in the mouse lens impairs fibroblast growth factor receptor signaling. PLoS One 2014; 9:e97470. [PMID: 24824078 PMCID: PMC4019587 DOI: 10.1371/journal.pone.0097470] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2013] [Accepted: 04/20/2014] [Indexed: 01/21/2023] Open
Abstract
Coordination of cell proliferation, differentiation and survival is essential for normal development and maintenance of tissues in the adult organism. Growth factor receptor tyrosine kinase signaling pathways and planar cell polarity pathways are two regulators of many developmental processes. We have previously shown through analysis of mice conditionally null in the lens for the planar cell polarity gene (PCP), Dlg-1, that Dlg-1 is required for fiber differentiation. Herein, we asked if Dlg-1 is a regulator of the Fibroblast growth factor receptor (Fgfr) signaling pathway, which is known to be required for fiber cell differentiation. Western blot analysis of whole fiber cell extracts from control and Dlg-1 deficient lenses showed that levels of the Fgfr signaling intermediates pErk, pAkt, and pFrs2α, the Fgfr target, Erm, and the fiber cell specific protein, Mip26, were reduced in the Dlg-1 deficient fiber cells. The levels of Fgfr2 were decreased in Dlg-1 deficient lenses compared to controls. Conversely, levels of Fgfr1 in Dlg-1 deficient lenses were increased compared to controls. The changes in Fgfr levels were found to be specifically in the triton insoluble, cytoskeletal associated fraction of Dlg-1 deficient lenses. Immunofluorescent staining of lenses from E13.5 embryos showed that expression levels of pErk were reduced in the transition zone, a region of the lens that exhibits PCP, in the Dlg-1 deficient lenses as compared to controls. In control lenses, immunofluorescent staining for Fgfr2 was observed in the epithelium, transition zone and fibers. By E13.5, the intensity of staining for Fgfr2 was reduced in these regions of the Dlg-1 deficient lenses. Thus, loss of Dlg-1 in the lens impairs Fgfr signaling and leads to altered levels of Fgfrs, suggesting that Dlg-1 is a modulator of Fgfr signaling pathway at the level of the receptors and that Dlg-1 regulates fiber cell differentiation through its role in PCP.
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Affiliation(s)
- SungKyoung Lee
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Anne E. Griep
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
- * E-mail:
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18
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Kerr CL, Zaveri MA, Robinson ML, Williams T, West-Mays JA. AP-2α is required after lens vesicle formation to maintain lens integrity. Dev Dyn 2014; 243:1298-309. [PMID: 24753151 DOI: 10.1002/dvdy.24141] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2014] [Revised: 04/14/2014] [Accepted: 04/15/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Transcription factors are critical in regulating lens development. The AP-2 family of transcription factors functions in differentiation, cell growth and apoptosis, and in lens and eye development. AP-2α, in particular, is important in early lens development, and when conditionally deleted at the placode stage defective separation of the lens vesicle from the surface ectoderm results. AP-2α's role during later stages of lens development is unknown. To address this, the MLR10-Cre transgene was used to delete AP-2α from the lens epithelium beginning at embryonic day (E) 10.5. RESULTS The loss of AP-2α after lens vesicle separation resulted in morphological defects beginning at E18.5. By P4, a small highly vacuolated lens with a multilayered epithelium was evident in the MLR10-AP-2α mutants. Epithelial cells appeared elongated and expressed fiber cell specific βB1 and γ-crystallins. Epithelial cell polarity and lens cell adhesion was disrupted and accompanied by the misexpression of ZO-1, N-Cadherin, and β-catenin. Cell death was observed in the mutant lens epithelium between postnatal day (P) 14 and P30, and correlated with altered arrangements of cells within the epithelium. CONCLUSIONS Our findings demonstrate that AP-2α continues to be required after lens vesicle separation to maintain a normal lens epithelial cell phenotype and overall lens integrity and to ensure correct fiber cell differentiation.
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Affiliation(s)
- Christine L Kerr
- Department of Pathology and Molecular Medicine, McMaster University Health Science Centre, Hamilton, Ontario, Canada
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19
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Walch L. Emerging role of the scaffolding protein Dlg1 in vesicle trafficking. Traffic 2014; 14:964-73. [PMID: 23829493 DOI: 10.1111/tra.12089] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2013] [Revised: 07/02/2013] [Accepted: 07/06/2013] [Indexed: 01/23/2023]
Abstract
Discs large 1 (Dlg1) is a modular scaffolding protein implicated in the control of cell polarity through assembly of specific multiprotein complexes, including receptors, ion channels and signaling proteins, at specialized zones of the plasma membrane. Recent data have shown that in addition to these well-known interaction partners, Dlg1 may also recruit components of the vesicle trafficking machinery either to the plasma membrane or to transport vesicles. Here, we discuss Dlg1 function in vesicle formation, targeting, tethering and fusion, in both the exocytotic and endocytotic pathways. These pathways contribute to cell functions as major and diverse as glutamatergic activity in the neurons, membrane homeostasis in Schwann cell myelination, insulin stimulation of glucose transport in adipocytes, or endothelial secretion of the hemostatic protein, von Willebrand factor (VWF).
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Affiliation(s)
- Laurence Walch
- INSERM U698, Université Paris 7, Hemostasis, Bio-engineering and Cardiovascular Remodeling, CHU X. Bichat, Paris, France.
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20
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Yamben IF, Rachel RA, Shatadal S, Copeland NG, Jenkins NA, Warming S, Griep AE. Scrib is required for epithelial cell identity and prevents epithelial to mesenchymal transition in the mouse. Dev Biol 2013; 384:41-52. [PMID: 24095903 DOI: 10.1016/j.ydbio.2013.09.027] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2013] [Revised: 09/03/2013] [Accepted: 09/23/2013] [Indexed: 10/26/2022]
Abstract
The integrity and function of epithelial tissues depend on the establishment and maintenance of defining characteristics of epithelial cells, cell-cell adhesion and cell polarity. Disruption of these characteristics can lead to the loss of epithelial identity through a process called epithelial to mesenchymal transition (EMT), which can contribute to pathological conditions such as tissue fibrosis and invasive cancer. In invertebrates, the epithelial polarity gene scrib plays a critical role in establishing and maintaining cell adhesion and polarity. In this study we asked if the mouse homolog, Scrib, is required for establishment and/or maintenance of epithelial identity in vivo. To do so, we conditionally deleted Scrib in the head ectoderm tissue that gives rise to both the ocular lens and the corneal epithelium. Deletion of Scrib in the lens resulted in a change in epithelial cell shape from cuboidal to flattened and elongated. Early in the process, the cell adhesion protein, E-cadherin, and apical polarity protein, ZO-1, were downregulated and the myofibroblast protein, αSMA, was upregulated, suggesting EMT was occurring in the Scrib deficient lenses. Correlating temporally with the upregulation of αSMA, Smad3 and Smad4, TGFβ signaling intermediates, accumulated in the nucleus and Snail, a TGFβ target and transcriptional repressor of the gene encoding E-cadherin, was upregulated. Pax6, a lens epithelial transcription factor required to maintain lens epithelial cell identity also was downregulated. Loss of Scrib in the corneal epithelium also led to molecular changes consistent with EMT, suggesting that the effect of Scrib deficiency was not unique to the lens. Together, these data indicate that mammalian Scrib is required to maintain epithelial identity and that loss of Scrib can culminate in EMT, mediated, at least in part, through TGFβ signaling.
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Affiliation(s)
- Idella F Yamben
- Department of Cell and Regenerative Biology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI 53706, United States
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21
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Requirement for Dlgh-1 in planar cell polarity and skeletogenesis during vertebrate development. PLoS One 2013; 8:e54410. [PMID: 23349879 PMCID: PMC3551758 DOI: 10.1371/journal.pone.0054410] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2012] [Accepted: 12/13/2012] [Indexed: 01/20/2023] Open
Abstract
The development of specialized organs is tightly linked to the regulation of cell growth, orientation, migration and adhesion during embryogenesis. In addition, the directed movements of cells and their orientation within the plane of a tissue, termed planar cell polarity (PCP), appear to be crucial for the proper formation of the body plan. In Drosophila embryogenesis, Discs large (dlg) plays a critical role in apical-basal cell polarity, cell adhesion and cell proliferation. Craniofacial defects in mice carrying an insertional mutation in Dlgh-1 suggest that Dlgh-1 is required for vertebrate development. To determine what roles Dlgh-1 plays in vertebrate development, we generated mice carrying a null mutation in Dlgh-1. We found that deletion of Dlgh-1 caused open eyelids, open neural tube, and misorientation of cochlear hair cell stereociliary bundles, indicative of defects in planar cell polarity (PCP). Deletion of Dlgh-1 also caused skeletal defects throughout the embryo. These findings identify novel roles for Dlgh-1 in vertebrates that differ from its well-characterized roles in invertebrates and suggest that the Dlgh-1 null mouse may be a useful animal model to study certain human congenital birth defects.
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22
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Maddala R, Chauhan BK, Walker C, Zheng Y, Robinson ML, Lang RA, Rao PV. Rac1 GTPase-deficient mouse lens exhibits defects in shape, suture formation, fiber cell migration and survival. Dev Biol 2011; 360:30-43. [PMID: 21945075 DOI: 10.1016/j.ydbio.2011.09.004] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2011] [Accepted: 09/05/2011] [Indexed: 11/26/2022]
Abstract
Morphogenesis and shape of the ocular lens depend on epithelial cell elongation and differentiation into fiber cells, followed by the symmetric and compact organization of fiber cells within an enclosed extracellular matrix-enriched elastic capsule. The cellular mechanisms orchestrating these different events however, remain obscure. We investigated the role of the Rac1 GTPase in these processes by targeted deletion of expression using the conditional gene knockout (cKO) approach. Rac1 cKO mice were derived from two different Cre (Le-Cre and MLR-10) transgenic mice in which lens-specific Cre expression starts at embryonic day 8.75 and 10.5, respectively, in both the lens epithelium and fiber cells. The Le-Cre/Rac1 cKO mice exhibited an early-onset (E12.5) and severe lens phenotype compared to the MLR-10/Rac1 cKO (E15.5) mice. While the Le-Cre/Rac1 cKO lenses displayed delayed primary fiber cell elongation, lenses from both Rac1 cKO strains were characterized by abnormal shape, impaired secondary fiber cell migration, sutural defects and thinning of the posterior capsule which often led to rupture. Lens fiber cell N-cadherin/β-catenin/Rap1/Nectin-based cell-cell junction formation and WAVE-2/Abi-2/Nap1-regulated actin polymerization were impaired in the Rac1 deficient mice. Additionally, the Rac1 cKO lenses were characterized by a shortened epithelial sheet, reduced levels of extracellular matrix (ECM) proteins and increased apoptosis. Taken together, these data uncover the essential role of Rac1 GTPase activity in establishment and maintenance of lens shape, suture formation and capsule integrity, and in fiber cell migration, adhesion and survival, via regulation of actin cytoskeletal dynamics, cell adhesive interactions and ECM turnover.
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Affiliation(s)
- Rupalatha Maddala
- Department of Ophthalmology, Duke University School of Medicine, Durham, NC 27710, USA
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23
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Maddala R, Skiba NP, Lalane R, Sherman DL, Brophy PJ, Rao PV. Periaxin is required for hexagonal geometry and membrane organization of mature lens fibers. Dev Biol 2011; 357:179-90. [PMID: 21745462 PMCID: PMC3164832 DOI: 10.1016/j.ydbio.2011.06.036] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2011] [Revised: 06/14/2011] [Accepted: 06/14/2011] [Indexed: 01/06/2023]
Abstract
Transparency of the ocular lens depends on symmetric packing and membrane organization of highly elongated hexagonal fiber cells. These cells possess an extensive, well-ordered cortical cytoskeleton to maintain cell shape and to anchor membrane components. Periaxin (Prx), a PDZ domain protein involved in myelin sheath stabilization, is also a component of adhaerens plaques in lens fiber cells. Here we show that Prx is expressed in lens fibers and exhibits maturation dependent redistribution, clustering discretely at the tricellular junctions in mature fiber cells. Prx exists in a macromolecular complex with proteins involved in membrane organization including ankyrin-B, spectrin, NrCAM, filensin, ezrin and desmoyokin. Importantly, Prx knockout mouse lenses were found to be softer and more easily deformed than normal lenses, revealing disruptions in fiber cell hexagonal packing, membrane skeleton and membrane stability. These observations suggest a key role for Prx in maturation, packing, and membrane organization of lens fiber cells. Hence, there may be functional parallels between the roles of Prx in membrane stabilization of the myelin sheath and the lens fiber cell.
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Affiliation(s)
- Rupalatha Maddala
- Department of Ophthalmology, Duke University School of Medicine, NC. USA
| | - Nikolai P. Skiba
- Department of Ophthalmology, Duke University School of Medicine, NC. USA
| | - Robert Lalane
- Department of Ophthalmology, Duke University School of Medicine, NC. USA
| | - Diane L. Sherman
- Centre for Neuroregeneration, University of Edinburgh, Edinburgh, UK
| | - Peter J. Brophy
- Centre for Neuroregeneration, University of Edinburgh, Edinburgh, UK
| | - Ponugoti V. Rao
- Department of Ophthalmology, Duke University School of Medicine, NC. USA
- Department of Pharmacology and Cancer Biology, Duke University School of Medicine, NC. USA
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24
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Sugiyama Y, Lovicu FJ, McAvoy JW. Planar cell polarity in the mammalian eye lens. Organogenesis 2011; 7:191-201. [PMID: 22027540 DOI: 10.4161/org.7.3.18421] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
The major role of the eye lens is to transmit and focus images onto the retina. For this function, the lens needs to develop and maintain the correct shape, notably, the precise curvature and high-level order and organization of its elements. The lens is mainly comprised of highly elongated fiber cells with hexagonal cross-sectional profiles that facilitate regular packing. Collectively, they form concentrically arranged layers around the anterior-posterior polar axis, and their convex curvature contributes to the spheroidal shape of the lens. Although the lens has been a popular system for developmental studies, little is known about the mechanism(s) that underlies the development of its exquisite three-dimensional cellular architecture. In this review, we will describe our recent work, which shows how planar cell polarity (PCP) operates in lens and contributes to its morphogenesis. We believe that the lens will be a useful model system to study PCP in general and gain insights into mechanisms that generate high-level cellular order during development.
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25
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De Maria A, Shi Y, Luo X, Van Der Weyden L, Bassnett S. Cadm1 expression and function in the mouse lens. Invest Ophthalmol Vis Sci 2011; 52:2293-9. [PMID: 21217103 DOI: 10.1167/iovs.10-6677] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
PURPOSE The immunoglobulin superfamily member Cadm1 is a single-pass, type 1 membrane protein that mediates calcium-independent, cell-cell adhesion. Cadm1 has been implicated in tumor formation and synaptogenesis. A recent analysis of mouse lens cell membranes identified Cadm1 as a major constituent of the fiber cell membrane proteome. Here the authors examined the expression and function of Cadm1 in the mouse lens. METHODS Cadm1 expression was analyzed by Western blotting and immunofluorescence. The morphology of individual wild-type and Cadm1-null lens cells was visualized by confocal microscopy. RESULTS Cadm1 was present in epithelial and superficial fiber cells as a heavily glycosylated protein with an apparent molecular mass of ≈80 kDa. Analysis of proteins extracted from various strata of the lens indicated that Cadm1 was degraded during fiber cell differentiation, at approximately the same time as the lens organelles, an observation confirmed by confocal microscopy. In epithelial cells, Cadm1 was enriched in basolateral membranes, whereas, in fiber cells, expression was restricted to the lateral membranes. Lenses from Cadm1-null mice were of normal size and transparency. The three-dimensional morphology of the cells in the epithelial layer was unaltered in the absence of Cadm1. However, in contrast to wild-type lens fiber cells, Cadm1-null fiber cells had an irregular, highly undulating morphology. CONCLUSIONS Cadm1 is an abundant component of the lens fiber cell membrane. Although not essential for lens transparency, Cadm1 has an indispensable role in establishing and maintaining the characteristic three-dimensional architecture of the lens fiber cell mass.
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Affiliation(s)
- Alicia De Maria
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, Missouri, USA
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26
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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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