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Stehle IF, Imventarza JA, Woerz F, Hoffmann F, Boldt K, Beyer T, Quinn PM, Ueffing M. Human CRB1 and CRB2 form homo- and heteromeric protein complexes in the retina. Life Sci Alliance 2024; 7:e202302440. [PMID: 38570189 PMCID: PMC10992996 DOI: 10.26508/lsa.202302440] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Revised: 03/26/2024] [Accepted: 03/26/2024] [Indexed: 04/05/2024] Open
Abstract
Crumbs homolog 1 (CRB1) is one of the key genes linked to retinitis pigmentosa and Leber congenital amaurosis, which are characterized by a high clinical heterogeneity. The Crumbs family member CRB2 has a similar protein structure to CRB1, and in zebrafish, Crb2 has been shown to interact through the extracellular domain. Here, we show that CRB1 and CRB2 co-localize in the human retina and human iPSC-derived retinal organoids. In retina-specific pull-downs, CRB1 was enriched in CRB2 samples, supporting a CRB1-CRB2 interaction. Furthermore, novel interactors of the crumbs complex were identified, representing a retina-derived protein interaction network. Using co-immunoprecipitation, we further demonstrate that human canonical CRB1 interacts with CRB1 and CRB2, but not with CRB3, which lacks an extracellular domain. Next, we explored how missense mutations in the extracellular domain affect CRB1-CRB2 interactions. We observed no or a mild loss of CRB1-CRB2 interaction, when interrogating various CRB1 or CRB2 missense mutants in vitro. Taken together, our results show a stable interaction of human canonical CRB2 and CRB1 in the retina.
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Affiliation(s)
- Isabel F Stehle
- https://ror.org/03a1kwz48 Institute for Ophthalmic Research, Eberhard Karls University Tübingen, Tübingen, Germany
| | - Joel A Imventarza
- Department of Ophthalmology, Vagelos College of Physicians & Surgeons, Columbia University; New York, NY, USA
| | - Franziska Woerz
- https://ror.org/03a1kwz48 Institute for Ophthalmic Research, Eberhard Karls University Tübingen, Tübingen, Germany
| | - Felix Hoffmann
- https://ror.org/03a1kwz48 Institute for Ophthalmic Research, Eberhard Karls University Tübingen, Tübingen, Germany
| | - Karsten Boldt
- https://ror.org/03a1kwz48 Institute for Ophthalmic Research, Eberhard Karls University Tübingen, Tübingen, Germany
| | - Tina Beyer
- https://ror.org/03a1kwz48 Institute for Ophthalmic Research, Eberhard Karls University Tübingen, Tübingen, Germany
| | - Peter Mj Quinn
- Department of Ophthalmology, Vagelos College of Physicians & Surgeons, Columbia University; New York, NY, USA
| | - Marius Ueffing
- https://ror.org/03a1kwz48 Institute for Ophthalmic Research, Eberhard Karls University Tübingen, Tübingen, Germany
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2
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Zhou X, Zhao L, Wang C, Sun W, Jia B, Li D, Fu J. Diverse functions and pathogenetic role of Crumbs in retinopathy. Cell Commun Signal 2024; 22:290. [PMID: 38802833 PMCID: PMC11129452 DOI: 10.1186/s12964-024-01673-z] [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: 02/13/2024] [Accepted: 05/20/2024] [Indexed: 05/29/2024] Open
Abstract
The Crumbs protein (CRB) family plays a crucial role in maintaining the apical-basal polarity and integrity of embryonic epithelia. The family comprises different isoforms in different animals and possesses diverse structural, localization, and functional characteristics. Mutations in the human CRB1 or CRB2 gene may lead to a broad spectrum of retinal dystrophies. Various CRB-associated experimental models have recently provided mechanistic insights into human CRB-associated retinopathies. The knowledge obtained from these models corroborates the importance of CRB in retinal development and maintenance. Therefore, complete elucidation of these models can provide excellent therapeutic prospects for human CRB-associated retinopathies. In this review, we summarize the current animal models and human-derived models of different CRB family members and describe the main characteristics of their retinal phenotypes.
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Affiliation(s)
- Xuebin Zhou
- Department of Ophthalmology, The Second Hospital of Jilin University, Changchun, 130000, China
| | - Liangliang Zhao
- Department of Ophthalmology, The Second Hospital of Jilin University, Changchun, 130000, China
| | - Chenguang Wang
- Department of Ophthalmology, The Second Hospital of Jilin University, Changchun, 130000, China
| | - Wei Sun
- College of Basic Medical Sciences, Jilin University, Changchun, 130000, China
| | - Bo Jia
- Department of Ophthalmology, The Second Hospital of Jilin University, Changchun, 130000, China
| | - Dan Li
- Department of Ophthalmology, The Second Hospital of Jilin University, Changchun, 130000, China
| | - Jinling Fu
- Department of Ophthalmology, The Second Hospital of Jilin University, Changchun, 130000, China.
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3
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Sharkova M, Aparicio G, Mouzaaber C, Zolessi FR, Hocking JC. Photoreceptor calyceal processes accompany the developing outer segment, adopting a stable length despite a dynamic core. J Cell Sci 2024; 137:jcs261721. [PMID: 38477343 PMCID: PMC11058337 DOI: 10.1242/jcs.261721] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2023] [Accepted: 03/04/2024] [Indexed: 03/14/2024] Open
Abstract
Vertebrate photoreceptors detect light through a large cilium-based outer segment, which is filled with photopigment-laden membranous discs. Surrounding the base of the outer segment are microvilli-like calyceal processes (CPs). Although CP disruption has been associated with altered outer segment morphology and photoreceptor degeneration, the role of the CPs remains elusive. Here, we used zebrafish as a model to characterize CPs. We quantified CP parameters and report a strong disparity in outer segment coverage between photoreceptor subtypes. CP length is stable across light and dark conditions, yet heat-shock inducible expression of tagged actin revealed rapid turnover of the CP actin core. Detailed imaging of the embryonic retina uncovered substantial remodeling of the developing photoreceptor apical surface, including a transition from dynamic tangential processes to vertically oriented CPs immediately prior to outer segment formation. Remarkably, we also found a direct connection between apical extensions of the Müller glia and retinal pigment epithelium, arranged as bundles around the ultraviolet sensitive cones. In summary, our data characterize the structure, development and surrounding environment of photoreceptor microvilli in the zebrafish retina.
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Affiliation(s)
- Maria Sharkova
- Department of Cell Biology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Gonzalo Aparicio
- Sección Biología Celular, Facultad de Ciencias, Universidad de la República, 11400, Uruguay
- Institut Pasteur Montevideo, Uruguay
| | - Constantin Mouzaaber
- Department of Cell Biology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Flavio R. Zolessi
- Sección Biología Celular, Facultad de Ciencias, Universidad de la República, 11400, Uruguay
- Institut Pasteur Montevideo, Uruguay
| | - Jennifer C. Hocking
- Department of Cell Biology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
- Division of Anatomy, Department of Surgery, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada
- Department of Medical Genetics, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
- Women and Children's Health Research Institute, University of Alberta, Edmonton, Alberta, Canada
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4
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Liu N, Zhang P, Xue M, Zhang M, Huang Z, Xu C, Meng Y, Fan Y, Liu W, Zhang F, Chen P, Zhou Y. Hypolipidemic Effect of Rice Bran Oil Extract Tocotrienol in High-Fat Diet-Induced Hyperlipidemia Zebrafish (Danio Rerio) Induced by High-Fat Diet. Int J Mol Sci 2024; 25:2954. [PMID: 38474201 DOI: 10.3390/ijms25052954] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2024] [Revised: 02/23/2024] [Accepted: 02/24/2024] [Indexed: 03/14/2024] Open
Abstract
In recent years, the potent influence of tocotrienol (T3) on diminishing blood glucose and lipid concentrations in both Mus musculus (rats) and Homo sapiens (humans) has been established. However, the comprehensive exploration of tocotrienol's hypolipidemic impact and the corresponding mechanisms in aquatic species remains inadequate. In this study, we established a zebrafish model of a type 2 diabetes mellitus (T2DM) model through high-fat diet administration to zebrafish. In the T2DM zebrafish, the thickness of ocular vascular walls significantly increased compared to the control group, which was mitigated after treatment with T3. Additionally, our findings demonstrate the regulatory effect of T3 on lipid metabolism, leading to the reduced synthesis and storage of adipose tissue in zebrafish. We validated the expression patterns of genes relevant to these processes using RT-qPCR. In the T2DM model, there was an almost two-fold upregulation in pparγ and cyp7a1 mRNA levels, coupled with a significant downregulation in cpt1a mRNA (p < 0.01) compared to the control group. The ELISA revealed that the protein expression levels of Pparγ and Rxrα exhibited a two-fold elevation in the T2DM group relative to the control. In the T3-treated group, Pparγ and Rxrα protein expression levels consistently exhibited a two-fold decrease compared to the model group. Lipid metabolomics showed that T3 could affect the metabolic pathways of zebrafish lipid regulation, including lipid synthesis and decomposition. We provided experimental evidence that T3 could mitigate lipid accumulation in our zebrafish T2DM model. Elucidating the lipid-lowering effects of T3 could help to minimize the detrimental impacts of overfeeding in aquaculture.
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Affiliation(s)
- Naicheng Liu
- Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan 430223, China
| | - Peng Zhang
- Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan 430223, China
| | - Mingyang Xue
- Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan 430223, China
| | - Mengwei Zhang
- Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan 430223, China
| | - Zhenyu Huang
- Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan 430223, China
| | - Chen Xu
- Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan 430223, China
| | - Yan Meng
- Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan 430223, China
| | - Yuding Fan
- Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan 430223, China
| | - Wei Liu
- Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan 430223, China
| | - Feixiang Zhang
- Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan 430223, China
- College of Fisheries and Life, Shanghai Ocean University, Shanghai 201306, China
| | - Peng Chen
- Institute of Fishery Research of Xinjiang Uygur Autonenous Region, Urumqi 830099, China
| | - Yong Zhou
- Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan 430223, China
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5
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Zhang L, Wei X. Stepwise modulation of apical orientational cell adhesions for vertebrate neurulation. Biol Rev Camb Philos Soc 2023; 98:2271-2283. [PMID: 37534608 DOI: 10.1111/brv.13006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2022] [Revised: 07/05/2023] [Accepted: 07/25/2023] [Indexed: 08/04/2023]
Abstract
Neurulation transforms the neuroectoderm into the neural tube. This transformation relies on reorganising the configurational relationships between the orientations of intrinsic polarities of neighbouring cells. These orientational intercellular relationships are established, maintained, and modulated by orientational cell adhesions (OCAs). Here, using zebrafish (Danio rerio) neurulation as a major model, we propose a new perspective on how OCAs contribute to the parallel, antiparallel, and opposing intercellular relationships that underlie the neural plate-keel-rod-tube transformation, a stepwise process of cell aggregation followed by cord hollowing. We also discuss how OCAs in neurulation may be regulated by various adhesion molecules, including cadherins, Eph/Ephrins, Claudins, Occludins, Crumbs, Na+ /K+ -ATPase, and integrins. By comparing neurulation among species, we reveal that antiparallel OCAs represent a conserved mechanism for the fusion of the neural tube. Throughout, we highlight some outstanding questions regarding OCAs in neurulation. Answers to these questions will help us understand better the mechanisms of tubulogenesis of many tissues.
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Affiliation(s)
- Lili Zhang
- Department of Psychology, Dalian Medical University, 9 South LvShun Road, Dalian, 116044, China
| | - Xiangyun Wei
- Departments of Ophthalmology, Developmental Biology, and Microbiology & Molecular Genetics, University of Pittsburgh, 3501 Fifth Avenue, Pittsburgh, PA, 15213, USA
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6
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Buck TM, Quinn PMJ, Pellissier LP, Mulder AA, Jongejan A, Lu X, Boon N, Koot D, Almushattat H, Arendzen CH, Vos RM, Bradley EJ, Freund C, Mikkers HMM, Boon CJF, Moerland PD, Baas F, Koster AJ, Neefjes J, Berlin I, Jost CR, Wijnholds J. CRB1 is required for recycling by RAB11A+ vesicles in human retinal organoids. Stem Cell Reports 2023; 18:1793-1810. [PMID: 37541258 PMCID: PMC10545476 DOI: 10.1016/j.stemcr.2023.07.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Revised: 07/03/2023] [Accepted: 07/04/2023] [Indexed: 08/06/2023] Open
Abstract
CRB1 gene mutations can cause early- or late-onset retinitis pigmentosa, Leber congenital amaurosis, or maculopathy. Recapitulating human CRB1 phenotypes in animal models has proven challenging, necessitating the development of alternatives. We generated human induced pluripotent stem cell (iPSC)-derived retinal organoids of patients with retinitis pigmentosa caused by biallelic CRB1 mutations and evaluated them against autologous gene-corrected hiPSCs and hiPSCs from healthy individuals. Patient organoids show decreased levels of CRB1 and NOTCH1 expression at the retinal outer limiting membrane. Proximity ligation assays show that human CRB1 and NOTCH1 can interact via their extracellular domains. CRB1 patient organoids feature increased levels of WDFY1+ vesicles, fewer RAB11A+ recycling endosomes, decreased VPS35 retromer complex components, and more degradative endolysosomal compartments relative to isogenic control organoids. Taken together, our data demonstrate that patient-derived retinal organoids enable modeling of retinal degeneration and highlight the importance of CRB1 in early endosome maturation receptor recycling in the retina.
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Affiliation(s)
- Thilo M Buck
- Department of Ophthalmology, Leiden University Medical Center (LUMC), Leiden 2333 ZA, the Netherlands
| | - Peter M J Quinn
- Department of Ophthalmology, Leiden University Medical Center (LUMC), Leiden 2333 ZA, the Netherlands
| | - Lucie P Pellissier
- Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences (KNAW), Amsterdam 1105 BA, the Netherlands
| | - Aat A Mulder
- Department of Cell & Chemical Biology, Leiden University Medical Center (LUMC), Leiden 2300 RC, the Netherlands
| | - Aldo Jongejan
- Bioinformatics Laboratory, Epidemiology & Data Science, Amsterdam University Medical Centers, Amsterdam 1105 AZ, the Netherlands
| | - Xuefei Lu
- Department of Ophthalmology, Leiden University Medical Center (LUMC), Leiden 2333 ZA, the Netherlands
| | - Nanda Boon
- Department of Ophthalmology, Leiden University Medical Center (LUMC), Leiden 2333 ZA, the Netherlands
| | - Daniëlle Koot
- Department of Ophthalmology, Leiden University Medical Center (LUMC), Leiden 2333 ZA, the Netherlands
| | - Hind Almushattat
- Department of Ophthalmology, Leiden University Medical Center (LUMC), Leiden 2333 ZA, the Netherlands
| | | | - Rogier M Vos
- Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences (KNAW), Amsterdam 1105 BA, the Netherlands
| | - Edward J Bradley
- Department of Genome Analysis, Amsterdam University Medical Centers, Amsterdam 1105 AZ, the Netherlands
| | - Christian Freund
- Leiden University Medical Center hiPSC Hotel, Leiden 2333 ZA, the Netherlands
| | - Harald M M Mikkers
- Department of Cell & Chemical Biology, Leiden University Medical Center (LUMC), Leiden 2300 RC, the Netherlands; Leiden University Medical Center hiPSC Hotel, Leiden 2333 ZA, the Netherlands
| | - Camiel J F Boon
- Department of Ophthalmology, Leiden University Medical Center (LUMC), Leiden 2333 ZA, the Netherlands; Department of Ophthalmology, Amsterdam University Medical Centers, Academic Medical Center, University of Amsterdam, Amsterdam 1000 AE, the Netherlands
| | - Perry D Moerland
- Bioinformatics Laboratory, Epidemiology & Data Science, Amsterdam University Medical Centers, Amsterdam 1105 AZ, the Netherlands
| | - Frank Baas
- Department of Genome Analysis, Amsterdam University Medical Centers, Amsterdam 1105 AZ, the Netherlands; Department of Clinical Genetics/LDGA, Leiden University Medical Center, Leiden 2333 ZA, the Netherlands
| | - Abraham J Koster
- Department of Cell & Chemical Biology, Leiden University Medical Center (LUMC), Leiden 2300 RC, the Netherlands
| | - Jacques Neefjes
- Department of Cell & Chemical Biology, Leiden University Medical Center (LUMC), Leiden 2300 RC, the Netherlands
| | - Ilana Berlin
- Department of Cell & Chemical Biology, Leiden University Medical Center (LUMC), Leiden 2300 RC, the Netherlands
| | - Carolina R Jost
- Department of Cell & Chemical Biology, Leiden University Medical Center (LUMC), Leiden 2300 RC, the Netherlands
| | - Jan Wijnholds
- Department of Ophthalmology, Leiden University Medical Center (LUMC), Leiden 2333 ZA, the Netherlands; Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences (KNAW), Amsterdam 1105 BA, the Netherlands.
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7
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Owen N, Toms M, Tian Y, Toualbi L, Richardson R, Young R, Tracey‐White D, Dhami P, Beck S, Moosajee M. Loss of the crumbs cell polarity complex disrupts epigenetic transcriptional control and cell cycle progression in the developing retina. J Pathol 2023; 259:441-454. [PMID: 36656098 PMCID: PMC10601974 DOI: 10.1002/path.6056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Revised: 12/22/2022] [Accepted: 01/17/2023] [Indexed: 01/20/2023]
Abstract
The crumbs cell polarity complex plays a crucial role in apical-basal epithelial polarity, cellular adhesion, and morphogenesis. Homozygous variants in human CRB1 result in autosomal recessive Leber congenital amaurosis (LCA) and retinitis pigmentosa (RP), with no established genotype-phenotype correlation. The associated protein complexes have key functions in developmental pathways; however, the underlying disease mechanism remains unclear. Using the oko meduzym289/m289 (crb2a-/- ) zebrafish, we performed integrative transcriptomic (RNA-seq data) and methylomic [reduced representation bisulphite sequencing (RRBS)] analysis of whole retina to identify dysregulated genes and pathways. Delayed retinal cell specification was identified in both the crb2a-/- zebrafish and CRB1 patient-derived retinal organoids, highlighting the dysfunction of cell cycle modulation and epigenetic transcriptional control. Differential DNA methylation analysis revealed novel hypermethylated pathways involving biological adhesion, Hippo, and transforming growth factor β (TGFβ) signalling. By integrating gene expression with DNA methylation using functional epigenetic modules (FEM), we identified six key modules involving cell cycle control and disturbance of TGFβ, bone morphogenetic protein (BMP), Hippo, and SMAD protein signal transduction pathways, revealing significant interactome hotspots relevant to crb2a function and confirming the epigenetic control of gene regulation in early retinal development, which points to a novel mechanism underlying CRB1-retinopathies. © 2023 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.
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Affiliation(s)
- Nicholas Owen
- UCL Institute of OphthalmologyUniversity College LondonLondonUK
- The Francis Crick InstituteLondonUK
| | - Maria Toms
- UCL Institute of OphthalmologyUniversity College LondonLondonUK
- The Francis Crick InstituteLondonUK
| | - Yuan Tian
- Medical Genomics, UCL Cancer InstituteUniversity College LondonLondonUK
| | - Lyes Toualbi
- UCL Institute of OphthalmologyUniversity College LondonLondonUK
- The Francis Crick InstituteLondonUK
| | - Rose Richardson
- UCL Institute of OphthalmologyUniversity College LondonLondonUK
| | - Rodrigo Young
- UCL Institute of OphthalmologyUniversity College LondonLondonUK
| | | | - Pawan Dhami
- Medical Genomics, UCL Cancer InstituteUniversity College LondonLondonUK
| | - Stephan Beck
- Medical Genomics, UCL Cancer InstituteUniversity College LondonLondonUK
| | - Mariya Moosajee
- UCL Institute of OphthalmologyUniversity College LondonLondonUK
- The Francis Crick InstituteLondonUK
- Department of OphthalmologyGreat Ormond Street Hospital for Children NHS Foundation TrustLondonUK
- Department of GeneticsMoorfields Eye Hospital NHS Foundation TrustLondonUK
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8
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Zhang L, Wei X. Orientational cell adhesions (OCAs) for tissue morphogenesis. Trends Cell Biol 2022; 32:975-978. [PMID: 35934561 DOI: 10.1016/j.tcb.2022.07.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Revised: 07/08/2022] [Accepted: 07/11/2022] [Indexed: 01/21/2023]
Abstract
Distinct tissue architectures arise when cells are organized in specific orientations relative to neighboring cells. These orientational intercellular relationships are established and maintained by cell adhesions. We propose the concept of 'orientational cell adhesions' (OCAs) to couple cell orientations with cell adhesions, thus offering a new perspective to study tissue morphogenesis.
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Affiliation(s)
- Lili Zhang
- Department of Psychology, Dalian Medical University, Dalian, Liaoning Province, 116044, China
| | - Xiangyun Wei
- Departments of Ophthalmology, Developmental Biology, and Microbiology & Molecular Genetics, University of Pittsburgh, PA 15218, USA.
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9
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Apical-basal polarity and the control of epithelial form and function. Nat Rev Mol Cell Biol 2022; 23:559-577. [PMID: 35440694 DOI: 10.1038/s41580-022-00465-y] [Citation(s) in RCA: 89] [Impact Index Per Article: 44.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/11/2022] [Indexed: 02/02/2023]
Abstract
Epithelial cells are the most common cell type in all animals, forming the sheets and tubes that compose most organs and tissues. Apical-basal polarity is essential for epithelial cell form and function, as it determines the localization of the adhesion molecules that hold the cells together laterally and the occluding junctions that act as barriers to paracellular diffusion. Polarity must also target the secretion of specific cargoes to the apical, lateral or basal membranes and organize the cytoskeleton and internal architecture of the cell. Apical-basal polarity in many cells is established by conserved polarity factors that define the apical (Crumbs, Stardust/PALS1, aPKC, PAR-6 and CDC42), junctional (PAR-3) and lateral (Scribble, DLG, LGL, Yurt and RhoGAP19D) domains, although recent evidence indicates that not all epithelia polarize by the same mechanism. Research has begun to reveal the dynamic interactions between polarity factors and how they contribute to polarity establishment and maintenance. Elucidating these mechanisms is essential to better understand the roles of apical-basal polarity in morphogenesis and how defects in polarity contribute to diseases such as cancer.
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10
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Nahar A, Cho SH. Current perspectives in Leber congenital amaurosis type 8 mouse modeling. Dev Dyn 2022; 251:1094-1106. [PMID: 35150033 DOI: 10.1002/dvdy.462] [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: 09/03/2021] [Revised: 02/01/2022] [Accepted: 02/05/2022] [Indexed: 11/11/2022] Open
Abstract
Mutations in the CRB1 (Crumbs homolog 1) cause rare retinal diseases like retinitis pigmentosa type 12 (RP12) and Leber congenital amaurosis type 8 (LCA8). RP12 results in progressively worsening peripheral vision, whereas LCA8 causes severe visual impairment at birth or in early life. While several mouse models have been proposed for RP12, few replicate the full spectrum of human LCA8 pathology, such as disorganized retinal layering, abnormal retinal thickening, pigmentary defects, hyperreflective lesions, and severely attenuated electroretinogram responses at birth. Six models have been proposed utilizing the Cre-loxP system to delete candidate genes in specific retinal cell types and developmental stages. The model ablating Crb1 and its homolog Crb2 (using mRx-Cre) from the beginning of the eye development is the most complete as it shows blindness during the eye-opening stage, pigmentary defects in the RPE, ganglion cell layer heterotopia, disruption of retinal lamination, and acellular patches. LCA8 represents a unique type of retinal dystrophy among LCA subtypes, driven by dysfunctional retinal progenitor cells during eye development. In contrast, other LCA types and RP12 are caused by photoreceptor defects. Therefore, the most accurate LCA8-like mouse model must target both alleles of the Crb1 and Crb2 genes in the optic vesicle or earlier.
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Affiliation(s)
- Ankur Nahar
- Thomas Jefferson University Sidney Kimmel Medical College, Philadelphia, Pennsylvania, USA
| | - Seo-Hee Cho
- Department of Medicine, Center for Translational Medicine, Thomas Jefferson University Sidney Kimmel Medical College, Philadelphia, Pennsylvania, USA
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11
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The Roles of Par3, Par6, and aPKC Polarity Proteins in Normal Neurodevelopment and in Neurodegenerative and Neuropsychiatric Disorders. J Neurosci 2022; 42:4774-4793. [PMID: 35705493 DOI: 10.1523/jneurosci.0059-22.2022] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Revised: 04/30/2022] [Accepted: 05/02/2022] [Indexed: 11/21/2022] Open
Abstract
Normal neural circuits and functions depend on proper neuronal differentiation, migration, synaptic plasticity, and maintenance. Abnormalities in these processes underlie various neurodevelopmental, neuropsychiatric, and neurodegenerative disorders. Neural development and maintenance are regulated by many proteins. Among them are Par3, Par6 (partitioning defective 3 and 6), and aPKC (atypical protein kinase C) families of evolutionarily conserved polarity proteins. These proteins perform versatile functions by forming tripartite or other combinations of protein complexes, which hereafter are collectively referred to as "Par complexes." In this review, we summarize the major findings on their biophysical and biochemical properties in cell polarization and signaling pathways. We next summarize their expression and localization in the nervous system as well as their versatile functions in various aspects of neurodevelopment, including neuroepithelial polarity, neurogenesis, neuronal migration, neurite differentiation, synaptic plasticity, and memory. These versatile functions rely on the fundamental roles of Par complexes in cell polarity in distinct cellular contexts. We also discuss how cell polarization may correlate with subcellular polarization in neurons. Finally, we review the involvement of Par complexes in neuropsychiatric and neurodegenerative disorders, such as schizophrenia and Alzheimer's disease. While emerging evidence indicates that Par complexes are essential for proper neural development and maintenance, many questions on their in vivo functions have yet to be answered. Thus, Par3, Par6, and aPKC continue to be important research topics to advance neuroscience.
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12
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Vasquez CG, de la Serna EL, Dunn AR. How cells tell up from down and stick together to construct multicellular tissues - interplay between apicobasal polarity and cell-cell adhesion. J Cell Sci 2021; 134:272658. [PMID: 34714332 DOI: 10.1242/jcs.248757] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Polarized epithelia define a topological inside and outside, and hence constitute a key evolutionary innovation that enabled the construction of complex multicellular animal life. Over time, this basic function has been elaborated upon to yield the complex architectures of many of the organs that make up the human body. The two processes necessary to yield a polarized epithelium, namely regulated adhesion between cells and the definition of the apicobasal (top-bottom) axis, have likewise undergone extensive evolutionary elaboration, resulting in multiple sophisticated protein complexes that contribute to both functions. Understanding how these components function in combination to yield the basic architecture of a polarized cell-cell junction remains a major challenge. In this Review, we introduce the main components of apicobasal polarity and cell-cell adhesion complexes, and outline what is known about their regulation and assembly in epithelia. In addition, we highlight studies that investigate the interdependence between these two networks. We conclude with an overview of strategies to address the largest and arguably most fundamental unresolved question in the field, namely how a polarized junction arises as the sum of its molecular parts.
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Affiliation(s)
- Claudia G Vasquez
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305, USA
| | - Eva L de la Serna
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305, USA
| | - Alexander R Dunn
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305, USA.,Biophysics Program, Stanford University, Stanford, CA 94305, USA.,Stanford Cardiovascular Institute, Stanford School of Medicine, Stanford, CA 94305, USA
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13
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Novales Flamarique I, Fujihara R, Yazawa R, Bolstad K, Gowen B, Yoshizaki G. Disrupted eye and head development in rainbow trout with reduced ultraviolet (sws1) opsin expression. J Comp Neurol 2021; 529:3013-3031. [PMID: 33778962 DOI: 10.1002/cne.25144] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2021] [Revised: 03/11/2021] [Accepted: 03/23/2021] [Indexed: 11/10/2022]
Abstract
Visual opsins are proteins expressed by retinal photoreceptors that capture light to begin the process of phototransduction. In vertebrates, the two types of photoreceptors (rods and cones) express one or multiple opsins and are distributed in variable patterns across the retina. Some cones form opsin retinal gradients, as in the mouse, whereas others form more demarcated opsin domains, as in the lattice-like mosaic retinas of teleost fishes. Reduced rod opsin (rh1) expression in mouse, zebrafish, and African clawed frog results in lack of photoreceptor outer segments (i.e., the cilium that houses the opsins) and, in the case of the mouse, to retinal degeneration. The effects of diminished cone opsin expression have only been studied in the mouse where knockout of the short-wavelength sensitive 1 (sws1) opsin leads to ventral retinal cones lacking outer segments, but no retinal degeneration. Here we show that, following CRISPR/Cas9 injections that targeted knockout of the sws1 opsin in rainbow trout, fish with diminished sws1 opsin expression exhibited a variety of developmental defects including head and eye malformations, underdeveloped outer retina, mislocalized opsin expression, cone degeneration, and mosaic irregularity. All photoreceptor types were affected even though sws1 is only expressed in the single cones of wild fish. Our results reveal unprecedented developmental defects associated with diminished cone opsin expression and suggest that visual opsin genes are involved in regulatory processes that precede photoreceptor differentiation.
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Affiliation(s)
- Iñigo Novales Flamarique
- Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, Canada.,Department of Biology, University of Victoria, Victoria, British Columbia, Canada
| | - Ryo Fujihara
- Department of Marine Biosciences, Tokyo University of Marine Science and Technology, Tokyo, Japan
| | - Ryosuke Yazawa
- Department of Marine Biosciences, Tokyo University of Marine Science and Technology, Tokyo, Japan
| | - Kennedy Bolstad
- Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Brent Gowen
- Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Goro Yoshizaki
- Department of Marine Biosciences, Tokyo University of Marine Science and Technology, Tokyo, Japan
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14
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Möller-Kerutt A, Rodriguez-Gatica JE, Wacker K, Bhatia R, Siebrasse JP, Boon N, Van Marck V, Boor P, Kubitscheck U, Wijnholds J, Pavenstädt H, Weide T. Crumbs2 Is an Essential Slit Diaphragm Protein of the Renal Filtration Barrier. J Am Soc Nephrol 2021; 32:1053-1070. [PMID: 33687977 PMCID: PMC8259666 DOI: 10.1681/asn.2020040501] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Accepted: 12/28/2020] [Indexed: 02/04/2023] Open
Abstract
BACKGROUND Crumbs2 is expressed at embryonic stages as well as in the retina, brain, and glomerular podocytes. Recent studies identified CRB2 mutations as a novel cause of steroid-resistant nephrotic syndrome (SRNS). METHODS To study the function of Crb2 at the renal filtration barrier, mice lacking Crb2 exclusively in podocytes were generated. Gene expression and histologic studies as well as transmission and scanning electron microscopy were used to analyze these Crb2podKO knockout mice and their littermate controls. Furthermore, high-resolution expansion microscopy was used to investigate Crb2 distribution in murine glomeruli. For pull-down experiments, live cell imaging, and transcriptome analyses, cell lines were applied that inducibly express fluorescent protein-tagged CRB2 wild type and mutants. RESULTS Crb2podKO mice developed proteinuria directly after birth that preceded a prominent development of disordered and effaced foot processes, upregulation of renal injury and inflammatory markers, and glomerulosclerosis. Pull-down assays revealed an interaction of CRB2 with Nephrin, mediated by their extracellular domains. Expansion microscopy showed that in mice glomeruli, Crb2 and Nephrin are organized in adjacent clusters. SRNS-associated CRB2 protein variants and a mutant that lacks a putative conserved O-glycosylation site were not transported to the cell surface. Instead, mutants accumulated in the ER, showed altered glycosylation pattern, and triggered an ER stress response. CONCLUSIONS Crb2 is an essential component of the podocyte's slit diaphragm, interacting with Nephrin. Loss of slit diaphragm targeting and increasing ER stress are pivotal factors for onset and progression of CRB2-related SRNS.
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Affiliation(s)
- Annika Möller-Kerutt
- Internal Medicine D, Department of Molecular Nephrology, University Hospital of Muenster, Muenster, Germany
| | - Juan E. Rodriguez-Gatica
- Institute of Physical and Theoretical Chemistry, Department of Biophysical Chemistry, Rheinische Friedrich Wilhelms University Bonn, Bonn, Germany
| | - Karin Wacker
- Internal Medicine D, Department of Molecular Nephrology, University Hospital of Muenster, Muenster, Germany
| | - Rohan Bhatia
- Institute of Physical and Theoretical Chemistry, Department of Biophysical Chemistry, Rheinische Friedrich Wilhelms University Bonn, Bonn, Germany
| | - Jan-Peter Siebrasse
- Institute of Physical and Theoretical Chemistry, Department of Biophysical Chemistry, Rheinische Friedrich Wilhelms University Bonn, Bonn, Germany
| | - Nanda Boon
- Leiden University Medical Center, Department of Ophthalmology, Leiden, The Netherlands
| | - Veerle Van Marck
- Gerhard-Domagk Institute of Pathology, University Hospital of Muenster, Muenster, Germany
| | - Peter Boor
- Institute of Pathology, Department of Nephrology and Immunology, RWTH Aachen University Hospital, Aachen, Germany,The Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences, Amsterdam, The Netherlands
| | - Ulrich Kubitscheck
- Institute of Physical and Theoretical Chemistry, Department of Biophysical Chemistry, Rheinische Friedrich Wilhelms University Bonn, Bonn, Germany
| | - Jan Wijnholds
- Leiden University Medical Center, Department of Ophthalmology, Leiden, The Netherlands
| | - Hermann Pavenstädt
- Internal Medicine D, Department of Molecular Nephrology, University Hospital of Muenster, Muenster, Germany
| | - Thomas Weide
- Internal Medicine D, Department of Molecular Nephrology, University Hospital of Muenster, Muenster, Germany
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15
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Hao Q, Zheng M, Weng K, Hao Y, Zhou Y, Lin Y, Gao F, Kou Z, Kawamura S, Yao K, Xu P, Chen J, Zou J. Crumbs proteins stabilize the cone mosaics of photoreceptors and improve vision in zebrafish. J Genet Genomics 2021; 48:52-62. [PMID: 33771456 DOI: 10.1016/j.jgg.2020.12.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2020] [Revised: 12/20/2020] [Accepted: 12/24/2020] [Indexed: 11/28/2022]
Abstract
Although the unique organization of vertebrate cone mosaics was first described long ago, both their underlying molecular basis and physiological significance are largely unknown. Here, we demonstrate that Crumbs proteins, the key regulators of epithelial apical polarity, establish the planar cellular polarity of photoreceptors in zebrafish. Via heterophilic Crb2a-Crb2b interactions, the apicobasal polarity protein Crb2b restricts the asymmetric planar distribution of Crb2a in photoreceptors. The planar polarized Crumbs proteins thus balance intercellular adhesions and tension between photoreceptors, thereby stabilizing the geometric organization of cone mosaics. Notably, loss of Crb2b in zebrafish induces a nearsightedness-like phenotype in zebrafish accompanied by an elongated eye axis and impairs zebrafish visual perception for predation. These data reveal a detailed mechanism for cone mosaic homeostasis via previously undiscovered apical-planar polarity coordination and propose a pathogenic mechanism for nearsightedness.
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Affiliation(s)
- Qinlong Hao
- Eye Center of the Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310009, China; The Institute of Translational Medicine, Zhejiang University, Hangzhou 310058, China
| | - Mingjie Zheng
- Eye Center of the Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310009, China; The Institute of Translational Medicine, Zhejiang University, Hangzhou 310058, China
| | - Kechao Weng
- Eye Center of the Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310009, China; The Institute of Translational Medicine, Zhejiang University, Hangzhou 310058, China
| | - Yumei Hao
- Eye Center of the Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310009, China; The Institute of Translational Medicine, Zhejiang University, Hangzhou 310058, China
| | - Yao Zhou
- Eye Center of the Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310009, China; The Institute of Translational Medicine, Zhejiang University, Hangzhou 310058, China
| | - Yuchen Lin
- Eye Center of the Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310009, China
| | - Feng Gao
- Eye Center of the Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310009, China; Department of Cardiology, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310009, China
| | - Ziqi Kou
- Eye Center of the Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310009, China; The Institute of Translational Medicine, Zhejiang University, Hangzhou 310058, China
| | - Shoji Kawamura
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, Kashiwa, Chiba 277-8562, Japan
| | - Ke Yao
- Eye Center of the Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310009, China; Zhejiang Provincial Key Lab of Ophthalmology, Hangzhou 310058, China
| | - Pinglong Xu
- MOE Laboratory of Biosystems Homeostasis & Protection and Innovation Center for Cell Signaling Network, Life Sciences Institute, Zhejiang University, Hangzhou 310058, China
| | - Jinghai Chen
- The Institute of Translational Medicine, Zhejiang University, Hangzhou 310058, China; Department of Cardiology, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310009, China
| | - Jian Zou
- Eye Center of the Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310009, China; The Institute of Translational Medicine, Zhejiang University, Hangzhou 310058, China; Zhejiang Provincial Key Lab of Ophthalmology, Hangzhou 310058, China.
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16
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Nunley H, Nagashima M, Martin K, Lorenzo Gonzalez A, Suzuki SC, Norton DA, Wong ROL, Raymond PA, Lubensky DK. Defect patterns on the curved surface of fish retinae suggest a mechanism of cone mosaic formation. PLoS Comput Biol 2020; 16:e1008437. [PMID: 33320887 PMCID: PMC7771878 DOI: 10.1371/journal.pcbi.1008437] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Revised: 12/29/2020] [Accepted: 10/13/2020] [Indexed: 11/18/2022] Open
Abstract
The outer epithelial layer of zebrafish retinae contains a crystalline array of cone photoreceptors, called the cone mosaic. As this mosaic grows by mitotic addition of new photoreceptors at the rim of the hemispheric retina, topological defects, called "Y-Junctions", form to maintain approximately constant cell spacing. The generation of topological defects due to growth on a curved surface is a distinct feature of the cone mosaic not seen in other well-studied biological patterns like the R8 photoreceptor array in the Drosophila compound eye. Since defects can provide insight into cell-cell interactions responsible for pattern formation, here we characterize the arrangement of cones in individual Y-Junction cores as well as the spatial distribution of Y-junctions across entire retinae. We find that for individual Y-junctions, the distribution of cones near the core corresponds closely to structures observed in physical crystals. In addition, Y-Junctions are organized into lines, called grain boundaries, from the retinal center to the periphery. In physical crystals, regardless of the initial distribution of defects, defects can coalesce into grain boundaries via the mobility of individual particles. By imaging in live fish, we demonstrate that grain boundaries in the cone mosaic instead appear during initial mosaic formation, without requiring defect motion. Motivated by this observation, we show that a computational model of repulsive cell-cell interactions generates a mosaic with grain boundaries. In contrast to paradigmatic models of fate specification in mostly motionless cell packings, this finding emphasizes the role of cell motion, guided by cell-cell interactions during differentiation, in forming biological crystals. Such a route to the formation of regular patterns may be especially valuable in situations, like growth on a curved surface, where the resulting long-ranged, elastic, effective interactions between defects can help to group them into grain boundaries.
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Affiliation(s)
- Hayden Nunley
- Biophysics Program, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Mikiko Nagashima
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Kamirah Martin
- Biophysics Program, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Alcides Lorenzo Gonzalez
- Neuroscience Graduate Program, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Sachihiro C. Suzuki
- Department of Biological Structure, University of Washington, Seattle, Washington, United States of America
| | - Declan A. Norton
- Department of Physics, Trinity College Dublin, Dublin, Ireland
- Department of Physics, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Rachel O. L. Wong
- Department of Biological Structure, University of Washington, Seattle, Washington, United States of America
| | - Pamela A. Raymond
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - David K. Lubensky
- Department of Physics, University of Michigan, Ann Arbor, Michigan, United States of America
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17
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Hao Y, Zhou Y, Yu Y, Zheng M, Weng K, Kou Z, Liang J, Zhang Q, Tang X, Xu P, Link BA, Yao K, Zou J. Interplay of MPP5a with Rab11 synergistically builds epithelial apical polarity and zonula adherens. Development 2020; 147:dev184457. [PMID: 33060129 DOI: 10.1242/dev.184457] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2019] [Accepted: 10/09/2020] [Indexed: 11/20/2022]
Abstract
Adherens junction remodeling regulated by apical polarity proteins constitutes a major driving force for tissue morphogenesis, although the precise mechanism remains inconclusive. Here, we report that, in zebrafish, the Crumbs complex component MPP5a interacts with small GTPase Rab11 in Golgi to transport cadherin and Crumbs components synergistically to the apical domain, thus establishing apical epithelial polarity and adherens junctions. In contrast, Par complex recruited by MPP5a is incapable of interacting with Rab11 but might assemble cytoskeleton to facilitate cadherin exocytosis. In accordance, dysfunction of MPP5a induces an invasive migration of epithelial cells. This adherens junction remodeling pattern is frequently observed in zebrafish lens epithelial cells and neuroepithelial cells. The data identify an unrecognized MPP5a-Rab11 complex and describe its essential role in guiding apical polarization and zonula adherens formation in epithelial cells.
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Affiliation(s)
- Yumei Hao
- Eye Center of the Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310058, China
- The Institute of Translational Medicine, Zhejiang University, Hangzhou 310058, China
| | - Yao Zhou
- Eye Center of the Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310058, China
- The Institute of Translational Medicine, Zhejiang University, Hangzhou 310058, China
| | - Yinhui Yu
- Eye Center of the Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310058, China
| | - Mingjie Zheng
- Eye Center of the Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310058, China
- The Institute of Translational Medicine, Zhejiang University, Hangzhou 310058, China
| | - Kechao Weng
- Eye Center of the Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310058, China
- The Institute of Translational Medicine, Zhejiang University, Hangzhou 310058, China
| | - Ziqi Kou
- Eye Center of the Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310058, China
- The Institute of Translational Medicine, Zhejiang University, Hangzhou 310058, China
| | - Jiancheng Liang
- Eye Center of the Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310058, China
- The Institute of Translational Medicine, Zhejiang University, Hangzhou 310058, China
| | - Qian Zhang
- Life Sciences Institute and Innovation Center for Cell Signaling Network, Zhejiang University, Hangzhou 310058, China
| | - Xiajing Tang
- Eye Center of the Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310058, China
| | - Pinglong Xu
- Life Sciences Institute and Innovation Center for Cell Signaling Network, Zhejiang University, Hangzhou 310058, China
| | - Brian A Link
- Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Ke Yao
- Eye Center of the Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310058, China
- Zhejiang Provincial Key Lab of Ophthalmology, Hangzhou 310058, China
| | - Jian Zou
- Eye Center of the Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310058, China
- The Institute of Translational Medicine, Zhejiang University, Hangzhou 310058, China
- Zhejiang Provincial Key Lab of Ophthalmology, Hangzhou 310058, China
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18
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Nadolski NJ, Balay SD, Wong CXL, Waskiewicz AJ, Hocking JC. Abnormal Cone and Rod Photoreceptor Morphogenesis in gdf6a Mutant Zebrafish. Invest Ophthalmol Vis Sci 2020; 61:9. [PMID: 32293666 PMCID: PMC7401959 DOI: 10.1167/iovs.61.4.9] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Purpose Analysis of photoreceptor morphology and gene expression in mispatterned eyes of zebrafish growth differentiation factor 6a (gdf6a) mutants. Methods Rod and cone photoreceptors were compared between gdf6a mutant and control zebrafish from larval to late adult stages using transgenic labels, immunofluorescence, and confocal microscopy, as well as by transmission electron microscopy. To compare transcriptomes between larval gdf6a mutant and control zebrafish, RNA-Seq was performed on isolated eyes. Results Although rod and cone photoreceptors differentiate in gdf6a mutant zebrafish, the cells display aberrant growth and morphology. The cone outer segments, the light-detecting sensory endings, are reduced in size in the mutant larvae and fail to recover to control size at subsequent stages. In contrast, rods form temporarily expanded outer segments. The inner segments, which generate the required energy and proteins for the outer segments, are shortened in both rods and cones at all stages. RNA-Seq analysis provides a set of misregulated genes associated with the observed abnormal photoreceptor morphogenesis. Conclusions GDF6 mutations were previously identified in patients with Leber congenital amaurosis. Here, we reveal a unique photoreceptor phenotype in the gdf6a mutant zebrafish whereby rods and cones undergo abnormal maturation distinct for each cell type. Further, subsequent development shows partial recovery of cell morphology and maintenance of the photoreceptor layer. By conducting a transcriptomic analysis of the gdf6a larval eyes, we identified a collection of genes that are candidate regulators of photoreceptor size and morphology.
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19
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Zebrafish Crb1, Localizing Uniquely to the Cell Membranes around Cone Photoreceptor Axonemes, Alleviates Light Damage to Photoreceptors and Modulates Cones' Light Responsiveness. J Neurosci 2020; 40:7065-7079. [PMID: 32817065 DOI: 10.1523/jneurosci.0497-20.2020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2020] [Revised: 06/26/2020] [Accepted: 07/22/2020] [Indexed: 11/21/2022] Open
Abstract
The crumbs (crb) apical polarity genes are essential for the development and functions of epithelia. Adult zebrafish retinal neuroepithelium expresses three crb genes (crb1, crb2a, and crb2b); however, it is unknown whether and how Crb1 differs from other Crb proteins in expression, localization, and functions. Here, we show that, unlike zebrafish Crb2a and Crb2b as well as mammalian Crb1 and Crb2, zebrafish Crb1 does not localize to the subapical regions of photoreceptors and Müller glial cells; rather, it localizes to a small region of cone outer segments: the cell membranes surrounding the axonemes. Moreover, zebrafish Crb1 is not required for retinal morphogenesis and photoreceptor patterning. Interestingly, Crb1 promotes rod survival under strong white light irradiation in a previously unreported non--cell-autonomous fashion; in addition, Crb1 delays UV and blue cones' chromatin condensation caused by UV light irradiation. Finally, Crb1 plays a role in cones' responsiveness to light through an arrestin-translocation-independent mechanism. The localization of Crb1 and its functions do not differ between male and female fish. We conclude that zebrafish Crb1 has diverged from other vertebrate Crb proteins, representing a neofunctionalization in Crb biology during evolution.SIGNIFICANCE STATEMENT Apicobasal polarity of epithelia is an important property that underlies the morphogenesis and functions of epithelial tissues. Epithelial apicobasal polarity is controlled by many polarity genes, including the crb genes. In vertebrates, multiple crb genes have been identified, but the differences in their expression patterns and functions are not fully understood. Here, we report a novel subcellular localization of zebrafish Crb1 in retinal cone photoreceptors and evidence for its new functions in photoreceptor maintenance and light responsiveness. This study expands our understanding of the biology of the crb genes in epithelia, including retinal neuroepithelium.
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20
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Deveau C, Jiao X, Suzuki SC, Krishnakumar A, Yoshimatsu T, Hejtmancik JF, Nelson RF. Thyroid hormone receptor beta mutations alter photoreceptor development and function in Danio rerio (zebrafish). PLoS Genet 2020; 16:e1008869. [PMID: 32569302 PMCID: PMC7332105 DOI: 10.1371/journal.pgen.1008869] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Revised: 07/02/2020] [Accepted: 05/18/2020] [Indexed: 01/16/2023] Open
Abstract
We investigate mutations in trβ2, a splice variant of thrb, identifying changes in function, structure, and behavior in larval and adult zebrafish retinas. Two N-terminus CRISPR mutants were identified. The first is a 6BP+1 insertion deletion frameshift resulting in a truncated protein. The second is a 3BP in frame deletion with intact binding domains. ERG recordings of isolated cone signals showed that the 6BP+1 mutants did not respond to red wavelengths of light while the 3BP mutants did respond. 6BP+1 mutants lacked optomotor and optokinetic responses to red/black and green/black contrasts. Both larval and adult 6BP+1 mutants exhibit a loss of red-cone contribution to the ERG and an increase in UV-cone contribution. Transgenic reporters show loss of cone trβ2 activation in the 6BP+1 mutant but increase in the density of cones with active blue, green, and UV opsin genes. Antibody reactivity for red-cone LWS1 and LWS2 opsin was absent in the 6BP+1 mutant, as was reactivity for arrestin3a. Our results confirm a critical role for trβ2 in long-wavelength cone development. There are four cone photoreceptors responsible for color vision in zebrafish: red, green, blue, and UV. The thyroid hormone receptor trβ2 is localized in the vertebrate retina. We know that it is necessary for the development of cones expressing long-wavelength-sensitive opsins (red cones), but here we investigate the functional alterations that accompany a loss of trβ2. Our work contributes to the ongoing investigations of retinal development and the involvement of thyroid hormone receptors. As suggested by previous morphological findings, fish became red colorblind when trβ2 was knocked out, and the contributions of the other three cone types shifted. Our work highlights the plasticity of photoreceptor patterning as we see changes in opsin peaks and cone sensitivity, increases in contributions of UV cones, and an attempt at a mosaic pattern in the adult retina, all in the absence of trβ2 and red cones. We now have an increased understanding of mechanisms underlying retinal development.
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Affiliation(s)
- Ciana Deveau
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Rockville, Maryland, United States of America
- * E-mail:
| | - Xiaodong Jiao
- National Eye Institute, National Institutes of Health, Rockville, Maryland, United States of America
| | - Sachihiro C. Suzuki
- Okinawa Institute of Science and Technology Graduate University, Okinawa, Japan
| | - Asha Krishnakumar
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Rockville, Maryland, United States of America
| | | | - J Fielding Hejtmancik
- National Eye Institute, National Institutes of Health, Rockville, Maryland, United States of America
| | - Ralph F. Nelson
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Rockville, Maryland, United States of America
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21
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Tait CM, Chinnaiya K, Manning E, Murtaza M, Ashton JP, Furley N, Hill CJ, Alves CH, Wijnholds J, Erdmann KS, Furley A, Rashbass P, Das RM, Storey KG, Placzek M. Crumbs2 mediates ventricular layer remodelling to form the spinal cord central canal. PLoS Biol 2020; 18:e3000470. [PMID: 32150534 PMCID: PMC7108746 DOI: 10.1371/journal.pbio.3000470] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Revised: 03/31/2020] [Accepted: 02/18/2020] [Indexed: 11/27/2022] Open
Abstract
In the spinal cord, the central canal forms through a poorly understood process termed dorsal collapse that involves attrition and remodelling of pseudostratified ventricular layer (VL) cells. Here, we use mouse and chick models to show that dorsal ventricular layer (dVL) cells adjacent to dorsal midline Nestin(+) radial glia (dmNes+RG) down-regulate apical polarity proteins, including Crumbs2 (CRB2) and delaminate in a stepwise manner; live imaging shows that as one cell delaminates, the next cell ratchets up, the dmNes+RG endfoot ratchets down, and the process repeats. We show that dmNes+RG secrete a factor that promotes loss of cell polarity and delamination. This activity is mimicked by a secreted variant of Crumbs2 (CRB2S) which is specifically expressed by dmNes+RG. In cultured MDCK cells, CRB2S associates with apical membranes and decreases cell cohesion. Analysis of Crb2F/F/Nestin-Cre+/- mice, and targeted reduction of Crb2/CRB2S in slice cultures reveal essential roles for transmembrane CRB2 (CRB2TM) and CRB2S on VL cells and dmNes+RG, respectively. We propose a model in which a CRB2S-CRB2TM interaction promotes the progressive attrition of the dVL without loss of overall VL integrity. This novel mechanism may operate more widely to promote orderly progenitor delamination.
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Affiliation(s)
- Christine M Tait
- Department of Biomedical Science and Bateson Centre, University of Sheffield, Sheffield, United Kingdom
| | - Kavitha Chinnaiya
- Department of Biomedical Science and Bateson Centre, University of Sheffield, Sheffield, United Kingdom
| | - Elizabeth Manning
- Department of Biomedical Science and Bateson Centre, University of Sheffield, Sheffield, United Kingdom
| | - Mariyam Murtaza
- Department of Biomedical Science and Bateson Centre, University of Sheffield, Sheffield, United Kingdom
| | - John-Paul Ashton
- Department of Biomedical Science and Bateson Centre, University of Sheffield, Sheffield, United Kingdom
| | - Nicholas Furley
- Department of Biomedical Science and Bateson Centre, University of Sheffield, Sheffield, United Kingdom
| | - Chris J Hill
- Department of Biomedical Science and Bateson Centre, University of Sheffield, Sheffield, United Kingdom
| | - C Henrique Alves
- Department of Ophthalmology, Leiden University Medical Centre, Leiden, the Netherlands
| | - Jan Wijnholds
- Department of Ophthalmology, Leiden University Medical Centre, Leiden, the Netherlands
| | - Kai S Erdmann
- Department of Biomedical Science and Bateson Centre, University of Sheffield, Sheffield, United Kingdom
| | - Andrew Furley
- Department of Biomedical Science and Bateson Centre, University of Sheffield, Sheffield, United Kingdom
| | - Penny Rashbass
- Department of Biomedical Science and Bateson Centre, University of Sheffield, Sheffield, United Kingdom
| | - Raman M Das
- Division of Cell and Developmental Biology, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Kate G Storey
- Division of Cell and Developmental Biology, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Marysia Placzek
- Department of Biomedical Science and Bateson Centre, University of Sheffield, Sheffield, United Kingdom
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The extracellular and intracellular regions of Crb2a play distinct roles in guiding the formation of the apical zonula adherens. Biomed Pharmacother 2020; 125:109942. [PMID: 32044715 DOI: 10.1016/j.biopha.2020.109942] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Revised: 01/18/2020] [Accepted: 01/23/2020] [Indexed: 11/22/2022] Open
Abstract
The transmembrane protein Crumbs (Crb), a key regulator of apical polarity, has a known involvement in establishment of the apical zonula adherens in epithelia, although the precise mechanism remains elusive. The zonula adherens are required to maintain the integrity and orderly arrangement of epithelia. Loss of the zonula adherens leads to morphogenetic defects in the tissues derived from epithelium. In this study, we revealed that the intracellular tail of Crb2a promoted the apical distribution of adherens junctions (AJs) in zebrafish retinal and lens epithelia, but caused assembly into unstable punctum adherens-like adhesion plaques. The extracellular region of Crb2a guided the transformation of AJs from the punctum adherens into stable zonula adherens. Accordingly, a truncated form of Crb2a lacking the extracellular region (Crb2aΔEX) could only partially rescue the retinal patterning defects in crb2a null mutant zebrafish (crb2am289). By contrast, constitutive over-expression of Crb2aΔEX disrupted the integrity of the outer limiting membrane in photoreceptors, which is derived from the zonula adherens of the retinal neuroepithelium. This study demonstrated that both the extracellular region and the intracellular tail of Crb2a are required to guide the formation of the apical zonula adherens.
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Kujawski S, Crespo C, Luz M, Yuan M, Winkler S, Knust E. Loss of Crb2b-lf leads to anterior segment defects in old zebrafish. Biol Open 2020; 9:bio047555. [PMID: 31988089 PMCID: PMC7044448 DOI: 10.1242/bio.047555] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Accepted: 01/09/2020] [Indexed: 12/02/2022] Open
Abstract
Defects in the retina or the anterior segment of the eye lead to compromised vision and affect millions of people. Understanding how these ocular structures develop and are maintained is therefore of paramount importance. The maintenance of proper vision depends, among other factors, on the function of genes controlling apico-basal polarity. In fact, mutations in polarity genes are linked to retinal degeneration in several species, including human. Here we describe a novel zebrafish crb2b allele (crb2be40 ), which specifically affects the crb2b long isoform. crb2be40 mutants are viable and display normal ocular development. However, old crb2be40 mutant fish develop multiple defects in structures of the anterior segment, which includes the cornea, the iris and the lens. Phenotypes are characterised by smaller pupils due to expansion of the iris and tissues of the iridocorneal angle, an increased number of corneal stromal keratocytes, an abnormal corneal endothelium and an expanded lens capsule. These findings illustrate a novel role for crb2b in the maintenance of the anterior segment and hence add an important function to this polarity regulator, which may be conserved in other vertebrates including humans.
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Affiliation(s)
- Satu Kujawski
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany
| | - Cátia Crespo
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany
| | - Marta Luz
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany
| | - Michaela Yuan
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany
| | - Sylke Winkler
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany
| | - Elisabeth Knust
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany
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24
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Sidor C, Stevens TJ, Jin L, Boulanger J, Röper K. Rho-Kinase Planar Polarization at Tissue Boundaries Depends on Phospho-regulation of Membrane Residence Time. Dev Cell 2020; 52:364-378.e7. [PMID: 31902655 PMCID: PMC7008249 DOI: 10.1016/j.devcel.2019.12.003] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2019] [Revised: 10/24/2019] [Accepted: 12/09/2019] [Indexed: 12/24/2022]
Abstract
The myosin II activator Rho-kinase (Rok) is planar polarized at the tissue boundary of the Drosophila embryonic salivary gland placode through a negative regulation by the apical polarity protein Crumbs that is anisotropically localized at the boundary. However, in inner cells of the placode, both Crumbs and Rok are isotropically enriched at junctions. We propose that modulation of Rok membrane residence time by Crumbs’ downstream effectors can reconcile both behaviors. Using FRAP combined with in silico simulations, we find that the lower membrane dissociation rate (koff) of Rok at the tissue boundary with low Crumbs explains this boundary-specific effect. The S/T kinase Pak1, recruited by Crumbs and Cdc42, negatively affects Rok membrane association in vivo and in vitro can phosphorylate Rok near the pleckstrin homology (PH) domain that mediates membrane association. These data reveal an important mechanism of the modulation of Rok membrane residence time via affecting the koff that may be widely employed during tissue morphogenesis. Rho-kinase is planar polarized at tissue boundaries, complementary to Crumbs Crumbs and downstream Pak1 modulate Rok residence time by affecting koff Pak1 can phosphorylate Rok near the PH and Rho-binding domains Rok phosphorylation affects residence time and allows polarization at boundaries
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Affiliation(s)
- Clara Sidor
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge, UK.
| | - Tim J Stevens
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge, UK
| | - Li Jin
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge, UK
| | - Jérôme Boulanger
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge, UK
| | - Katja Röper
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge, UK.
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25
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Identification and Characterization of Cis-Regulatory Elements for Photoreceptor-Type-Specific Transcription in ZebraFish. Methods Mol Biol 2020; 2092:123-145. [PMID: 31786786 DOI: 10.1007/978-1-0716-0175-4_10] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/06/2022]
Abstract
Tissue-specific or cell-type-specific transcription of protein-coding genes is controlled by both trans-regulatory elements (TREs) and cis-regulatory elements (CREs). However, it is challenging to identify TREs and CREs, which are unknown for most genes. Here, we describe a protocol for identifying two types of transcription-activating CREs-core promoters and enhancers-of zebrafish photoreceptor type-specific genes. This protocol is composed of three phases: bioinformatic prediction, experimental validation, and characterization of the CREs. To better illustrate the principles and logic of this protocol, we exemplify it with the discovery of the core promoter and enhancer of the mpp5b apical polarity gene (also known as ponli), whose red, green, and blue (RGB) cone-specific transcription requires its enhancer, a member of the rainbow enhancer family. While exemplified with an RGB-cone-specific gene, this protocol is general and can be used to identify the core promoters and enhancers of other protein-coding genes.
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26
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Physiological roles of avian eyes in light perception and their responses to photoperiodicity. WORLD POULTRY SCI J 2019. [DOI: 10.1017/s0043933916000416] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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27
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Kujawski S, Sonawane M, Knust E. penner/lgl2 is required for the integrity of the photoreceptor layer in the zebrafish retina. Biol Open 2019; 8:8/4/bio041830. [PMID: 31015218 PMCID: PMC6503998 DOI: 10.1242/bio.041830] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The vertebrate retina is a complex tissue built from multiple neuronal cell types, which develop from a pseudostratified neuroepithelium. These cells are arranged into a highly organized and stereotypic pattern formed by nuclear and plexiform layers. The process of lamination as well as the maturation and differentiation of photoreceptor cells rely on the establishment and maintenance of apico-basal cell polarity and formation of adhesive junctions. Defects in any of these processes can result in impaired vision and are causally related to a variety of human diseases leading to blindness. While the importance of apical polarity regulators in retinal stratification and disease is well established, little is known about the function of basal regulators in retinal development. Here, we analyzed the role of Lgl2, a basolateral polarity factor, in the zebrafish retina. Lgl2 is upregulated in photoreceptor cells and in the retinal pigment epithelium by 72 h post fertilization. In both cell types, Lgl2 is localized basolaterally. Loss of zygotic Lgl2 does not interfere with retinal lamination or photoreceptor cell polarity or maturation. However, knockdown of both maternal and zygotic Lgl2 leads to impaired cell adhesion. As a consequence, severe layering defects occur in the distal retina, manifested by a breakdown of the outer plexiform layer and the outer limiting membrane. These results define zebrafish Lgl2 as an important regulator of retinal lamination, which, given the high degree of evolutionary conservation, may be preserved in other vertebrates, including human. Summary: Knockdown of penner/lgl2 leads to a breakdown of the outer plexiform layer and the outer limiting membrane in the zebrafish retina due to impaired cell adhesion.
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Affiliation(s)
- Satu Kujawski
- Max-Planck-Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108 01307 Dresden, Germany
| | - Mahendra Sonawane
- Tata Institute of Fundamental Research, Department of Biological Sciences, Homi Bhabha Road, Navy Nagar, Colaba, Mumbai 400005, India
| | - Elisabeth Knust
- Max-Planck-Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108 01307 Dresden, Germany
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28
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Regulation of the apical extension morphogenesis tunes the mechanosensory response of microvilliated neurons. PLoS Biol 2019; 17:e3000235. [PMID: 31002663 PMCID: PMC6493769 DOI: 10.1371/journal.pbio.3000235] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Revised: 05/01/2019] [Accepted: 04/03/2019] [Indexed: 12/25/2022] Open
Abstract
Multiple types of microvilliated sensory cells exhibit an apical extension thought to be instrumental in the detection of sensory cues. The investigation of the mechanisms underlying morphogenesis of sensory apparatus is critical to understand the biology of sensation. Most of what we currently know comes from the study of the hair bundle of the inner ear sensory cells, but morphogenesis and function of other sensory microvilliated apical extensions remain poorly understood. We focused on spinal sensory neurons that contact the cerebrospinal fluid (CSF) through the projection of a microvilliated apical process in the central canal, referred to as cerebrospinal fluid-contacting neurons (CSF-cNs). CSF-cNs respond to pH and osmolarity changes as well as mechanical stimuli associated with changes of flow and tail bending. In vivo time-lapse imaging in zebrafish embryos revealed that CSF-cNs are atypical neurons that do not lose their apical attachment and form a ring of actin at the apical junctional complexes (AJCs) that they retain during differentiation. We show that the actin-based protrusions constituting the microvilliated apical extension arise and elongate from this ring of actin, and we identify candidate molecular factors underlying every step of CSF-cN morphogenesis. We demonstrate that Crumbs 1 (Crb1), Myosin 3b (Myo3b), and Espin orchestrate the morphogenesis of CSF-cN apical extension. Using calcium imaging in crb1 and espin mutants, we further show that the size of the apical extension modulates the amplitude of CSF-cN sensory response to bending of the spinal cord. Based on our results, we propose that the apical actin ring could be a common site of initiation of actin-based protrusions in microvilliated sensory cells. Furthermore, our work provides a set of actors underlying actin-based protrusion elongation shared by different sensory cell types and highlights the critical role of the apical extension shape in sensory detection. A study of differentiating spinal sensory neurons in vivo uncovers critical factors required for the morphogenesis of sensory microvilli and reveals fine modulation of mechanosensory responses by microvillus length.
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29
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Quinn PM, Alves CH, Klooster J, Wijnholds J. CRB2 in immature photoreceptors determines the superior-inferior symmetry of the developing retina to maintain retinal structure and function. Hum Mol Genet 2019; 27:3137-3153. [PMID: 29893966 DOI: 10.1093/hmg/ddy194] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Accepted: 05/11/2018] [Indexed: 11/13/2022] Open
Abstract
The mammalian apical-basal determinant Crumbs homolog-1 (CRB1) plays a crucial role in retinal structure and function by the maintenance of adherens junctions between photoreceptors and Müller glial cells. Patients with mutations in the CRB1 gene develop retinal dystrophies, including early-onset retinitis pigmentosa and Leber congenital amaurosis. Previously, we showed that Crb1 knockout mice developed a slow-progressing retinal phenotype at foci in the inferior retina, although specific ablation of Crb2 in immature photoreceptors leads to an early-onset phenotype throughout the retina. Here, we conditionally disrupted one or both alleles of Crb2 in immature photoreceptors, on a genetic background lacking Crb1, and studied the retinal dystrophies thereof. Our data showed that disruption of one allele of Crb2 in immature photoreceptors caused a substantial aggravation of the Crb1 phenotype in the entire inferior retina. The photoreceptor layer showed early-onset progressive thinning limited to the inferior retina, although the superior retina maintained intact. Surprisingly, disruption of both alleles of Crb2 in immature photoreceptors further aggravated the phenotype. Throughout the retina, photoreceptor synapses were disrupted and photoreceptor nuclei intermingled with nuclei of the inner nuclear layer. In the superior retina, the ganglion cell layer appeared thicker because of ectopic nuclei of photoreceptors. In conclusion, the data suggest that CRB2 is required to maintain retinal progenitor and photoreceptor cell adhesion and prevent photoreceptor ingression into the immature inner retina. We hypothesize, from these animal models, that decreased levels of CRB2 in immature photoreceptors adjust retinitis pigmentosa because of the loss of CRB1 into Leber congenital amaurosis phenotype.
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Affiliation(s)
- Peter M Quinn
- Department of Ophthalmology, Leiden University Medical Center, Leiden, The Netherlands
| | - C Henrique Alves
- Department of Ophthalmology, Leiden University Medical Center, Leiden, The Netherlands
| | - Jan Klooster
- Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences, Amsterdam, The Netherlands
| | - Jan Wijnholds
- Department of Ophthalmology, Leiden University Medical Center, Leiden, The Netherlands.,Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences, Amsterdam, The Netherlands
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30
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Skouloudaki K, Papadopoulos DK, Tomancak P, Knust E. The apical protein Apnoia interacts with Crumbs to regulate tracheal growth and inflation. PLoS Genet 2019; 15:e1007852. [PMID: 30645584 PMCID: PMC6333334 DOI: 10.1371/journal.pgen.1007852] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Accepted: 11/25/2018] [Indexed: 12/21/2022] Open
Abstract
Most organs of multicellular organisms are built from epithelial tubes. To exert their functions, tubes rely on apico-basal polarity, on junctions, which form a barrier to separate the inside from the outside, and on a proper lumen, required for gas or liquid transport. Here we identify apnoia (apn), a novel Drosophila gene required for tracheal tube elongation and lumen stability at larval stages. Larvae lacking Apn show abnormal tracheal inflation and twisted airway tubes, but no obvious defects in early steps of tracheal maturation. apn encodes a transmembrane protein, primarily expressed in the tracheae, which exerts its function by controlling the localization of Crumbs (Crb), an evolutionarily conserved apical determinant. Apn physically interacts with Crb to control its localization and maintenance at the apical membrane of developing airways. In apn mutant tracheal cells, Crb fails to localize apically and is trapped in retromer-positive vesicles. Consistent with the role of Crb in apical membrane growth, RNAi-mediated knockdown of Crb results in decreased apical surface growth of tracheal cells and impaired axial elongation of the dorsal trunk. We conclude that Apn is a novel regulator of tracheal tube expansion in larval tracheae, the function of which is mediated by Crb.
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Affiliation(s)
- Kassiani Skouloudaki
- Max-Planck Institute for Molecular Cell Biology and Genetics, Dresden, Germany
- * E-mail: (EK); (KS)
| | | | - Pavel Tomancak
- Max-Planck Institute for Molecular Cell Biology and Genetics, Dresden, Germany
| | - Elisabeth Knust
- Max-Planck Institute for Molecular Cell Biology and Genetics, Dresden, Germany
- * E-mail: (EK); (KS)
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31
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Jiménez-Amilburu V, Stainier DYR. The transmembrane protein Crb2a regulates cardiomyocyte apicobasal polarity and adhesion in zebrafish. Development 2019; 146:dev.171207. [DOI: 10.1242/dev.171207] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2018] [Accepted: 04/08/2019] [Indexed: 12/21/2022]
Abstract
Tissue morphogenesis requires changes in cell-cell adhesion as well as in cell shape and polarity. Cardiac trabeculation is a morphogenetic process essential to form a functional ventricular wall. Here we show that zebrafish hearts lacking Crb2a, a component of the Crumbs polarity complex, display compact wall integrity defects and fail to form trabeculae. Crb2a localization is very dynamic at a time when other cardiomyocyte junctional proteins also relocalize. Before the initiation of cardiomyocyte delamination to form the trabecular layer, Crb2a is expressed in all ventricular cardiomyocytes and colocalizes with the junctional protein ZO-1. Subsequently, Crb2a becomes localized all along the apical membrane of compact layer cardiomyocytes and is downregulated in the delaminating cardiomyocytes. We show that blood flow and Nrg/ErbB2 signaling regulate Crb2a localization dynamics. crb2a−/− display a multilayered wall with polarized cardiomyocytes, a unique phenotype. Our data further indicate that Crb2a regulates cardiac trabeculation by controlling the localization of tight and adherens junction proteins in cardiomyocytes. Importantly, transplantation data show that Crb2a controls CM behavior in a cell-autonomous manner in the sense that crb2a−/− cardiomyocytes transplanted into wild-type animals were always found in the trabecular layer. Altogether, our study reveals a critical role for Crb2a during cardiac development.
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Affiliation(s)
- Vanesa Jiménez-Amilburu
- Department of Developmental Genetics, Max Planck Institute for Heart and Lung Research, 61231 Bad Nauheim, Germany
| | - Didier Y. R. Stainier
- Department of Developmental Genetics, Max Planck Institute for Heart and Lung Research, 61231 Bad Nauheim, Germany
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32
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Liao ML, Peng WH, Kan D, Chien CL. Distribution patterns of the zebrafish neuronal intermediate filaments inaa and inab. J Neurosci Res 2018; 97:202-214. [PMID: 30387501 DOI: 10.1002/jnr.24347] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Revised: 09/27/2018] [Accepted: 10/03/2018] [Indexed: 01/27/2023]
Abstract
It has been reported that the neuronal intermediate filament (IF) α-internexin may plays a role in the formation of the neuronal cytoskeleton during mammalian development. From a phylogenetic viewpoint, zebrafish express inaa and inab as homologs of mammalian α-internexin. However, the distribution patterns of the inaa and inab proteins throughout zebrafish development have not been well-characterized. We generated antibodies specific for zebrafish inaa and inab and analyzed the distribution of these two proteins in developing zebrafish. Inaa was identified in the major subdivisions of embryonic and larval brains as early as 1 day postfertilization (dpf), including the telencephalon, optic tectum, and cerebellum, and inab was also detected in the same regions from 3 dpf to the adult stage. Moreover, we demonstrated for the first time that inaa was distinctively expressed in the photoreceptor-like cells of the pineal gland, where inab was sparsely detected. Besides, the expression of inaa in male adult fish was found to be stable under different photoperiod conditions. Thus, we suggest that inaa is one of useful markers for studies of zebrafish cone photoreceptors not only in the retina but also in the pineal gland. In conclusion, we report that the distribution patterns of inaa and inab are phylogenetically conserved in the telencephalon, optic tectum, and cerebellum. Moreover, inaa and inab had different expression patterns in the pineal gland and retina during zebrafish development. Both inaa and inab are neuronal IFs and their functional roles may be different in various aspects of zebrafish neuronal development.
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Affiliation(s)
- Meng-Lin Liao
- Department of Anatomy and Cell Biology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Wei-Hau Peng
- Department of Anatomy and Cell Biology, College of Medicine, National Taiwan University, Taipei, Taiwan.,School of Medicine for International Student, College of Medicine, I-Shou University (Yanchao Campus), Kaohsiung, Taiwan
| | - Daphne Kan
- Center of Genomic Medicine, National Taiwan University, Taipei, Taiwan
| | - Chung-Liang Chien
- Department of Anatomy and Cell Biology, College of Medicine, National Taiwan University, Taipei, Taiwan.,Center of Genomic Medicine, National Taiwan University, Taipei, Taiwan
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33
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Crespo C, Knust E. Characterisation of maturation of photoreceptor cell subtypes during zebrafish retinal development. Biol Open 2018; 7:bio.036632. [PMID: 30237290 PMCID: PMC6262866 DOI: 10.1242/bio.036632] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Photoreceptor cells (PRCs) mature from simple epithelial cells, a process characterised by growth and compartmentalisation of the apical membrane into an inner and an outer segment. So far, a PRC subtype-specific description of morphological and cellular changes in the developing zebrafish retina is missing. Here, we performed an in-depth characterisation of four of the five PRC subtypes of the zebrafish retina between 51 and 120 h post fertilisation, including quantification of the size of different compartments, localisation of polarity proteins and positioning of organelles. One of the major findings was the anisotropic and subtype-specific growth of the different PRC compartments. In addition, a transient accumulation of endoplasmic reticulum in rod PRCs, changes in chromatin organisation in UV sensitive cones and differential expression of polarity proteins during the initial stages of PRC maturation were observed. The results obtained provide a developmental timeline that can be used as a platform for future studies on PRC maturation and function. This platform was applied to document that increased exposure to light leads to smaller apical domains of PRCs. Summary: We characterised subtype-specific growth of the different photoreceptor compartments, organelle distribution and the influence of light on the growth of the apical membrane.
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Affiliation(s)
- Cátia Crespo
- Max-Planck-Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307, Dresden, Germany
| | - Elisabeth Knust
- Max-Planck-Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307, Dresden, Germany
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34
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Tenenbaum CM, Misra M, Alizzi RA, Gavis ER. Enclosure of Dendrites by Epidermal Cells Restricts Branching and Permits Coordinated Development of Spatially Overlapping Sensory Neurons. Cell Rep 2018; 20:3043-3056. [PMID: 28954223 DOI: 10.1016/j.celrep.2017.09.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2016] [Revised: 08/24/2017] [Accepted: 08/31/2017] [Indexed: 12/25/2022] Open
Abstract
Spatial arrangement of different neuron types within a territory is essential to neuronal development and function. How development of different neuron types is coordinated for spatial coexistence is poorly understood. In Drosophila, dendrites of four classes of dendritic arborization (C1-C4da) neurons innervate overlapping receptive fields within the larval epidermis. These dendrites are intermittently enclosed by epidermal cells, with different classes exhibiting varying degrees of enclosure. The role of enclosure in neuronal development and its underlying mechanism remain unknown. We show that the membrane-associated protein Coracle acts in C4da neurons and epidermal cells to locally restrict dendrite branching and outgrowth by promoting enclosure. Loss of C4da neuron enclosure results in excessive branching and growth of C4da neuron dendrites and retraction of C1da neuron dendrites due to local inhibitory interactions between neurons. We propose that enclosure of dendrites by epidermal cells is a developmental mechanism for coordinated innervation of shared receptive fields.
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Affiliation(s)
- Conrad M Tenenbaum
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA
| | - Mala Misra
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA
| | - Rebecca A Alizzi
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA
| | - Elizabeth R Gavis
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA.
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35
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Abstract
The symmetric tissue and body plans of animals are paradoxically constructed with asymmetric cells. To understand how the yin-yang duality of symmetry and asymmetry are reconciled, we asked whether apical polarity proteins orchestrate the development of the mirror-symmetric zebrafish neural tube by hierarchically modulating apical cell-cell adhesions. We found that apical polarity proteins localize by a pioneer-intermediate-terminal order. Pioneer proteins establish the mirror symmetry of the neural rod by initiating two distinct types of apical adhesions: the parallel apical adhesions (PAAs) cohere cells of parallel orientation and the novel opposing apical adhesions (OAAs) cohere cells of opposing orientation. Subsequently, the intermediate proteins selectively augment the PAAs when the OAAs dissolve by endocytosis. Finally, terminal proteins are required to inflate the neural tube by generating osmotic pressure. Our findings suggest a general mechanism to construct mirror-symmetric tissues: tissue symmetry can be established by organizing asymmetric cells opposingly via adhesions. Apical polarity proteins localize in a pioneer-intermediate-terminal order The orderly localized proteins orchestrate apical adhesion dynamics step by step Apical adhesions assemble asymmetric cells opposingly into a symmetric tissue
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36
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Pichaud F. PAR-Complex and Crumbs Function During Photoreceptor Morphogenesis and Retinal Degeneration. Front Cell Neurosci 2018; 12:90. [PMID: 29651238 PMCID: PMC5884931 DOI: 10.3389/fncel.2018.00090] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2017] [Accepted: 03/15/2018] [Indexed: 12/30/2022] Open
Abstract
The fly photoreceptor has long been used as a model to study sensory neuron morphogenesis and retinal degeneration. In particular, elucidating how these cells are built continues to help further our understanding of the mechanisms of polarized cell morphogenesis, intracellular trafficking and the causes of human retinal pathologies. The conserved PAR complex, which in flies consists of Cdc42-PAR6-aPKC-Bazooka, and the transmembrane protein Crumbs (Crb) are key players during photoreceptor morphogenesis. While the PAR complex regulates polarity in many cell types, Crb function in polarity is relatively specific to epithelial cells. Together Cdc42-PAR6-aPKC-Bazooka and Crb orchestrate the differentiation of the photoreceptor apical membrane (AM) and zonula adherens (ZA), thus allowing these cells to assemble into a neuro-epithelial lattice. In addition to its function in epithelial polarity, Crb has also been shown to protect fly photoreceptors from light-induced degeneration, a process linked to Rhodopsin expression and trafficking. Remarkably, mutations in the human Crumbs1 (CRB1) gene lead to retinal degeneration, making the fly photoreceptor a powerful disease model system.
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Affiliation(s)
- Franck Pichaud
- Medical Research Council, Laboratory for Molecular Cell Biology, University College London, London, United Kingdom
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37
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Das S, Knust E. A dual role of the extracellular domain of Drosophila Crumbs for morphogenesis of the embryonic neuroectoderm. Biol Open 2018; 7:7/1/bio031435. [PMID: 29374056 PMCID: PMC5829512 DOI: 10.1242/bio.031435] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Epithelia are highly polarised tissues and several highly conserved polarity protein complexes serve to establish and maintain polarity. The transmembrane protein Crumbs (Crb), the central component of the Crb protein complex, is required, among others, for the maintenance of polarity in most epithelia in the Drosophila embryo. However, different epithelia exhibit different phenotypic severity upon loss of crb. Using a transgenomic approach allowed us to more accurately define the role of crb in different epithelia. In particular, we provide evidence that the loss of epithelial tissue integrity in the ventral epidermis of crb mutant embryos is due to impaired actomyosin activity and an excess number of neuroblasts. We demonstrate that the intracellular domain of Crb could only partially rescue this phenotype, while it is able to completely restore tissue integrity in other epithelia. Based on these results we suggest a dual role of the extracellular domain of Crb in the ventral neuroectoderm. First, it is required for apical enrichment of the Crb protein, which in turn regulates actomyosin activity and thereby ensures tissue integrity; and second, the extracellular domain of Crb stabilises the Notch receptor and thereby ensures proper Notch signalling and specification of the correct number of neuroblasts. Summary: Using a transgenomic approach we determine specific roles of the intra- and extracellular domain of the Crumbs protein for the maintenance of apico-basal epithelial polarity and epithelial morphogenesis in Drosophila embryos.
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Affiliation(s)
- Shradha Das
- Max-Planck-Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany
| | - Elisabeth Knust
- Max-Planck-Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany
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Fu J, Nagashima M, Guo C, Raymond PA, Wei X. Novel Animal Model of Crumbs-Dependent Progressive Retinal Degeneration That Targets Specific Cone Subtypes. Invest Ophthalmol Vis Sci 2018; 59:505-518. [PMID: 29368007 PMCID: PMC5786287 DOI: 10.1167/iovs.17-22572] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Accepted: 12/10/2017] [Indexed: 01/01/2023] Open
Abstract
Purpose Human Crb1 is implicated in some forms of retinal degeneration, suggesting a role in photoreceptor maintenance. Multiple Crumbs (Crb) polarity genes are expressed in vertebrate retina, although their functional roles are not well understood. To gain further insight into Crb and photoreceptor maintenance, we compared retinal cell densities between wild-type and Tg(RH2-2:Crb2b-sfEX/RH2-2:GFP)pt108b transgenic zebrafish, in which the extracellular domain of Crb2b-short form (Crb2b-sfEX) is expressed in the retina as a secreted protein, which disrupts the planar organization of RGB cones (red, green, and blue) by interfering with Crb2a/2b-based cone-cone adhesion. Methods We used standard morphometric techniques to assess age-related changes in retinal cell densities in adult zebrafish (3 to 27 months old), and to assess effects of the Crb2b-sfEX transgene on retinal structure and photoreceptor densities. Linear cell densities were measured in all retinal layers in radial sections with JB4-Feulgen histology. Planar (surface) densities of cones were determined in retinal flat-mounts. Cell counts from wild-type and pt108b transgenic fish were compared with both a "photoreceptor maintenance index" and statistical analysis of cell counts. Results Age-related changes in retinal cell linear densities and cone photoreceptor planar densities in wild-type adult zebrafish provided a baseline for analysis. Expression of Crb2b-sfEX caused progressive and selective degeneration of RGB cones, but had no effect on ultraviolet-sensitive (UV) cones, and increased numbers of rod photoreceptors. Conclusions These differential responses of RGB cones, UV cones, and rods to sustained exposure to Crb2b-sfEX suggest that Crb-based photoreceptor maintenance mechanisms are highly selective.
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Affiliation(s)
- Jinling Fu
- Department of Ophthalmology, the Second Hospital of Jilin University, Changchun, Jilin, China
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States
| | - Mikiko Nagashima
- Department of Molecular, Cellular, and Developmental Biology, College of Literature, Science, and the Arts, University of Michigan, Ann Arbor, Michigan, United States
| | - Chuanyu Guo
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States
| | - Pamela A. Raymond
- Department of Molecular, Cellular, and Developmental Biology, College of Literature, Science, and the Arts, University of Michigan, Ann Arbor, Michigan, United States
| | - Xiangyun Wei
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States
- Department of Developmental Biology, University of Pittsburgh, School of Medicine, Pittsburgh, Pennsylvania, United States
- Department of Microbiology and Molecular Genetics, University of Pittsburgh, School of Medicine, Pittsburgh, Pennsylvania, United States
- Louis J. Fox Center for Vision Restoration, University of Pittsburgh, School of Medicine, Pittsburgh, Pennsylvania, United States
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Hochapfel F, Denk L, Mendl G, Schulze U, Maaßen C, Zaytseva Y, Pavenstädt H, Weide T, Rachel R, Witzgall R, Krahn MP. Distinct functions of Crumbs regulating slit diaphragms and endocytosis in Drosophila nephrocytes. Cell Mol Life Sci 2017; 74:4573-4586. [PMID: 28717874 PMCID: PMC11107785 DOI: 10.1007/s00018-017-2593-y] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Revised: 06/26/2017] [Accepted: 07/13/2017] [Indexed: 10/19/2022]
Abstract
Mammalian podocytes, the key determinants of the kidney's filtration barrier, differentiate from columnar epithelial cells and several key determinants of apical-basal polarity in the conventional epithelia have been shown to regulate podocyte morphogenesis and function. However, little is known about the role of Crumbs, a conserved polarity regulator in many epithelia, for slit-diaphragm formation and podocyte function. In this study, we used Drosophila nephrocytes as model system for mammalian podocytes and identified a conserved function of Crumbs proteins for cellular morphogenesis, nephrocyte diaphragm assembly/maintenance, and endocytosis. Nephrocyte-specific knock-down of Crumbs results in disturbed nephrocyte diaphragm assembly/maintenance and decreased endocytosis, which can be rescued by Drosophila Crumbs as well as human Crumbs2 and Crumbs3, which were both expressed in human podocytes. In contrast to the extracellular domain, which facilitates nephrocyte diaphragm assembly/maintenance, the intracellular FERM-interaction motif of Crumbs is essential for regulating endocytosis. Moreover, Moesin, which binds to the FERM-binding domain of Crumbs, is essential for efficient endocytosis. Thus, we describe here a new mechanism of nephrocyte development and function, which is likely to be conserved in mammalian podocytes.
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Affiliation(s)
- Florian Hochapfel
- Molecular and Cellular Anatomy, University of Regensburg, Universitätsstr. 31, 93053, Regensburg, Germany
- Medizinische Klinik und Poliklinik D, Universitätsklinikum Münster, Domagkstr. 3a, 48149, Münster, Germany
| | - Lucia Denk
- Molecular and Cellular Anatomy, University of Regensburg, Universitätsstr. 31, 93053, Regensburg, Germany
| | - Gudrun Mendl
- Molecular and Cellular Anatomy, University of Regensburg, Universitätsstr. 31, 93053, Regensburg, Germany
| | - Ulf Schulze
- Medizinische Klinik und Poliklinik D, Universitätsklinikum Münster, Domagkstr. 3a, 48149, Münster, Germany
| | - Christine Maaßen
- Molecular and Cellular Anatomy, University of Regensburg, Universitätsstr. 31, 93053, Regensburg, Germany
| | - Yulia Zaytseva
- Molecular and Cellular Anatomy, University of Regensburg, Universitätsstr. 31, 93053, Regensburg, Germany
| | - Hermann Pavenstädt
- Medizinische Klinik und Poliklinik D, Universitätsklinikum Münster, Domagkstr. 3a, 48149, Münster, Germany
| | - Thomas Weide
- Medizinische Klinik und Poliklinik D, Universitätsklinikum Münster, Domagkstr. 3a, 48149, Münster, Germany
| | - Reinhard Rachel
- Molecular and Cellular Anatomy, University of Regensburg, Universitätsstr. 31, 93053, Regensburg, Germany
| | - Ralph Witzgall
- Molecular and Cellular Anatomy, University of Regensburg, Universitätsstr. 31, 93053, Regensburg, Germany
| | - Michael P Krahn
- Molecular and Cellular Anatomy, University of Regensburg, Universitätsstr. 31, 93053, Regensburg, Germany.
- Medizinische Klinik und Poliklinik D, Universitätsklinikum Münster, Domagkstr. 3a, 48149, Münster, Germany.
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Nagashima M, Hadidjojo J, Barthel LK, Lubensky DK, Raymond PA. Anisotropic Müller glial scaffolding supports a multiplex lattice mosaic of photoreceptors in zebrafish retina. Neural Dev 2017; 12:20. [PMID: 29141686 PMCID: PMC5688757 DOI: 10.1186/s13064-017-0096-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Accepted: 10/19/2017] [Indexed: 11/21/2022] Open
Abstract
Background The multiplex, lattice mosaic of cone photoreceptors in the adult fish retina is a compelling example of a highly ordered epithelial cell pattern, with single cell width rows and columns of cones and precisely defined neighbor relationships among different cone types. Cellular mechanisms patterning this multiplex mosaic are not understood. Physical models can provide new insights into fundamental mechanisms of biological patterning. In earlier work, we developed a mathematical model of photoreceptor cell packing in the zebrafish retina, which predicted that anisotropic mechanical tension in the retinal epithelium orients planar polarized adhesive interfaces to align the columns as cone photoreceptors are generated at the retinal margin during post-embryonic growth. Methods With cell-specific fluorescent reporters and in vivo imaging of the growing retinal margin in transparent juvenile zebrafish we provide the first view of how cell packing, spatial arrangement, and cell identity are coordinated to build the lattice mosaic. With targeted laser ablation we probed the tissue mechanics of the retinal epithelium. Results Within the lattice mosaic, planar polarized Crumbs adhesion proteins pack cones into a single cell width column; between columns, N-cadherin-mediated adherens junctions stabilize Müller glial apical processes. The concentration of activated pMyosin II at these punctate adherens junctions suggests that these glial bands are under tension, forming a physical barrier between cone columns and contributing to mechanical stress anisotropies in the epithelial sheet. Unexpectedly, we discovered that the appearance of such parallel bands of Müller glial apical processes precedes the packing of cones into single cell width columns, hinting at a possible role for glia in the initial organization of the lattice mosaic. Targeted laser ablation of Müller glia directly demonstrates that these glial processes support anisotropic mechanical tension in the planar dimension of the retinal epithelium. Conclusions These findings uncovered a novel structural feature of Müller glia associated with alignment of photoreceptors into a lattice mosaic in the zebrafish retina. This is the first demonstration, to our knowledge, of planar, anisotropic mechanical forces mediated by glial cells. Electronic supplementary material The online version of this article (10.1186/s13064-017-0096-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Mikiko Nagashima
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, 830 North University Avenue, Ann Arbor, MI, 48109-1048, USA
| | - Jeremy Hadidjojo
- Department of Physics, University of Michigan, 450 Church Street, Ann Arbor, MI, 48109-1040, USA
| | - Linda K Barthel
- Microscopy and Image Analysis Laboratory, University of Michigan, Ann Arbor, MI, USA
| | - David K Lubensky
- Department of Physics, University of Michigan, 450 Church Street, Ann Arbor, MI, 48109-1040, USA.
| | - Pamela A Raymond
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, 830 North University Avenue, Ann Arbor, MI, 48109-1048, USA.
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Hazime K, Malicki JJ. Apico-basal Polarity Determinants Encoded by crumbs Genes Affect Ciliary Shaft Protein Composition, IFT Movement Dynamics, and Cilia Length. Genetics 2017; 207:1041-1051. [PMID: 28882989 PMCID: PMC5676222 DOI: 10.1534/genetics.117.300260] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Accepted: 08/23/2017] [Indexed: 02/04/2023] Open
Abstract
One of the most obvious manifestations of polarity in epithelia is the subdivision of the cell surface by cell junctions into apical and basolateral domains. crumbs genes are among key regulators of this form of polarity. Loss of crumbs function disrupts the apical cell junction belt and crumbs overexpression expands the apical membrane size. Crumbs proteins contain a single transmembrane domain and localize to cell junction area at the apical surface of epithelia. In some tissues, they are also found in cilia. To test their role in ciliogenesis, we investigated mutant phenotypes of zebrafish crumbs genes. In zebrafish, mutations of three crumbs genes, oko meduzy/crb2a, crb3a, and crb2b, affect cilia length in a subset of tissues. In oko meduzy (ome), this is accompanied by accumulation of other Crumbs proteins in the ciliary compartment. Moreover, intraflagellar transport (IFT) particle components accumulate in the ciliary shaft of ome;crb3a double mutants. Consistent with the above, Crb3 knockdown in mammalian cells affects the dynamics of IFT particle movement. These findings reveal crumbs-dependent mechanisms that regulate the localization of ciliary proteins, including Crumbs proteins themselves, and show that crumbs genes modulate intraflagellar transport and cilia elongation.
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Affiliation(s)
- Khodor Hazime
- Bateson Centre, Department of Biomedical Science, University of Sheffield, S10 2TN, United Kingdom
| | - Jarema J Malicki
- Bateson Centre, Department of Biomedical Science, University of Sheffield, S10 2TN, United Kingdom
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Bazellières E, Aksenova V, Barthélémy-Requin M, Massey-Harroche D, Le Bivic A. Role of the Crumbs proteins in ciliogenesis, cell migration and actin organization. Semin Cell Dev Biol 2017; 81:13-20. [PMID: 29056580 DOI: 10.1016/j.semcdb.2017.10.018] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2017] [Revised: 10/09/2017] [Accepted: 10/18/2017] [Indexed: 02/07/2023]
Abstract
Epithelial cell organization relies on a set of proteins that interact in an intricate way and which are called polarity complexes. These complexes are involved in the determination of the apico-basal axis and in the positioning and stability of the cell-cell junctions called adherens junctions at the apico-lateral border in invertebrates. Among the polarity complexes, two are present at the apical side of epithelial cells. These are the Par complex including aPKC, PAR3 and PAR6 and the Crumbs complex including, CRUMBS, PALS1 and PATJ/MUPP1. These two complexes interact directly and in addition to their already well described functions, they play a role in other cellular processes such as ciliogenesis and polarized cell migration. In this review, we will focus on these aspects that involve the apical Crumbs polarity complex and its relation with the cortical actin cytoskeleton which might provide a more comprehensive hypothesis to explain the many facets of Crumbs cell and tissue properties.
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Affiliation(s)
- Elsa Bazellières
- Aix-Marseille University, CNRS, IBDM, Case 907, 13288 Marseille, Cedex 09, France
| | - Veronika Aksenova
- Aix-Marseille University, CNRS, IBDM, Case 907, 13288 Marseille, Cedex 09, France
| | | | | | - André Le Bivic
- Aix-Marseille University, CNRS, IBDM, Case 907, 13288 Marseille, Cedex 09, France.
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43
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Quinn PM, Pellissier LP, Wijnholds J. The CRB1 Complex: Following the Trail of Crumbs to a Feasible Gene Therapy Strategy. Front Neurosci 2017; 11:175. [PMID: 28424578 PMCID: PMC5380682 DOI: 10.3389/fnins.2017.00175] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Accepted: 03/16/2017] [Indexed: 12/24/2022] Open
Abstract
Once considered science fiction, gene therapy is rapidly becoming scientific reality, targeting a growing number of the approximately 250 genes linked to hereditary retinal disorders such as retinitis pigmentosa and Leber's congenital amaurosis. Powerful new technologies have emerged, leading to the development of humanized models for testing and screening these therapies, bringing us closer to the goal of personalized medicine. These tools include the ability to differentiate human induced pluripotent stem cells (iPSCs) to create a “retina-in-a-dish” model and the self-formed ectodermal autonomous multi-zone, which can mimic whole eye development. In addition, highly specific gene-editing tools are now available, including the CRISPR/Cas9 system and the recently developed homology-independent targeted integration approach, which allows gene editing in non-dividing cells. Variants in the CRB1 gene have long been associated with retinopathies, and more recently the CRB2 gene has also been shown to have possible clinical relevance with respect to retinopathies. In this review, we discuss the role of the CRB protein complex in patients with retinopathy. In addition, we discuss new opportunities provided by stem cells and gene-editing tools, and we provide insight into how the retinal therapeutic pipeline can be improved. Finally, we discuss the current state of adeno-associated virus-mediated gene therapy and how it can be applied to treat retinopathies associated with mutations in CRB1.
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Affiliation(s)
- Peter M Quinn
- Department of Ophthalmology, Leiden University Medical CenterLeiden, Netherlands
| | - Lucie P Pellissier
- Unité Physiologie de la Reproduction et des Comportements, INRA UMR85, Centre National de la Recherche Scientifique UMR-7247, Institut Français du Cheval et de l'Équitation, Université François RabelaisNouzilly, France
| | - Jan Wijnholds
- Department of Ophthalmology, Leiden University Medical CenterLeiden, Netherlands.,Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and SciencesAmsterdam, Netherlands
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Rainbow Enhancers Regulate Restrictive Transcription in Teleost Green, Red, and Blue Cones. J Neurosci 2017; 37:2834-2848. [PMID: 28193687 DOI: 10.1523/jneurosci.3421-16.2017] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2016] [Revised: 12/31/2016] [Accepted: 01/27/2017] [Indexed: 01/24/2023] Open
Abstract
Photoreceptor-specific transcription of individual genes collectively constitutes the transcriptional profile that orchestrates the structural and functional characteristics of each photoreceptor type. It is challenging, however, to study the transcriptional specificity of individual photoreceptor genes because each gene's distinct spatiotemporal transcription patterns are determined by the unique interactions between a specific set of transcription factors and the gene's own cis-regulatory elements (CREs), which remain unknown for most of the genes. For example, it is unknown what CREs underlie the zebrafish mpp5bponli (ponli) and crumbs2b (crb2b) apical polarity genes' restrictive transcription in the red, green, and blue (RGB) cones in the retina, but not in other retinal cell types. Here we show that the intronic enhancers of both the ponli and crb2b genes are conserved among teleost species and that they share sequence motifs that are critical for RGB cone-specific transcription. Given their similarities in sequences and functions, we name the ponli and crb2b enhancers collectively rainbow enhancers. Rainbow enhancers may represent a cis-regulatory mechanism to turn on a group of genes that are commonly and restrictively expressed in RGB cones, which largely define the beginning of the color vision pathway.SIGNIFICANCE STATEMENT Dim-light achromatic vision and bright-light color vision are initiated in rod and several types of cone photoreceptors, respectively; these photoreceptors are structurally distinct from each other. In zebrafish, although quite different from rods and UV cones, RGB cones (red, green, and blue cones) are structurally similar and unite into mirror-symmetric pentamers (G-R-B-R-G) by adhesion. This structural commonality and unity suggest that a set of genes is commonly expressed only in RGB cones but not in other cells. Here, we report that the rainbow enhancers activate RGB cone-specific transcription of the ponli and crb2b genes. This study provides a starting point to study how RGB cone-specific transcription defines RGB cones' distinct functions for color vision.
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Liao ML, Peng WH, Kan D, Chien CL. Developmental pattern of the neuronal intermediate filament inaa in the zebrafish retina. J Comp Neurol 2016; 524:3810-3826. [PMID: 27159642 DOI: 10.1002/cne.24033] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2016] [Revised: 04/28/2015] [Accepted: 04/29/2016] [Indexed: 12/17/2022]
Abstract
α-Internexin is a member of the neuronal intermediate filament (nIF) protein family, which also includes peripherin and neurofilament (NF) triplet proteins. Previous studies found that expression of α-internexin precedes that of the NF triplet proteins in mammals and suggested that α-internexin plays a key role in the neuronal cytoskeleton network during development. In this study, we aimed to analyze the expression patterns and function of internexin neuronal intermediate filament protein-alpha a (inaa), the encoding gene of which is a homolog of the mammalian α-internexin, during retinal development in zebrafish. Via in vitro and in vivo studies, we demonstrated that zebrafish inaa is an α-internexin homolog that shares characteristics with nIFs. An immunohistochemical analysis of zebrafish revealed that inaa was distributed dynamically in the developing retina. It was widely localized in retinal neuroepithelial cells at 1 day postfertilization (dpf), and was mainly found in the ganglion cell layer (GCL) and inner part of the inner nuclear layer (INL) from 3-9 dpf; after 14 dpf, it was restricted to the outer nuclear layer (ONL). Moreover, we demonstrated for the first time that inaa acted distinctively from the cytoskeletal scaffold of zebrafish cone photoreceptors during development. In conclusion, we demonstrated the morphological features of a novel nIF, inaa, and illustrated its developmental expression pattern in the zebrafish retina. J. Comp. Neurol. 524:3810-3826, 2016. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Meng-Lin Liao
- Department of Anatomy and Cell Biology, College of Medicine; National Taiwan University; Taipei Taiwan
| | - Wei-Hau Peng
- Department of Anatomy and Cell Biology, College of Medicine; National Taiwan University; Taipei Taiwan
| | - Daphne Kan
- Center of Genomic Medicine; National Taiwan University; Taipei Taiwan
| | - Chung-Liang Chien
- Department of Anatomy and Cell Biology, College of Medicine; National Taiwan University; Taipei Taiwan
- Center of Genomic Medicine; National Taiwan University; Taipei Taiwan
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Nemetschke L, Knust E. Drosophila Crumbs prevents ectopic Notch activation in developing wings by inhibiting ligand-independent endocytosis. Development 2016; 143:4543-4553. [DOI: 10.1242/dev.141762] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2016] [Accepted: 10/21/2016] [Indexed: 12/13/2022]
Abstract
Many signalling components are apically restricted in epithelial cells, and receptor localisation and abundance is key for morphogenesis and tissue homeostasis. Hence, controlling apicobasal epithelial polarity is crucial for proper signalling. Notch is a ubiquitously expressed, apically localised receptor, which performs a plethora of functions; therefore, its activity has to be tightly regulated. Here, we show that Drosophila Crumbs, an evolutionarily conserved polarity determinant, prevents Notch endocytosis in developing wings through direct interaction between the two proteins. Notch endocytosis in the absence of Crumbs results in the activation of the ligand-independent, Deltex-dependent Notch signalling pathway, and does not require the ligands Delta and Serrate or γ-secretase activity. This function of Crumbs is not due to general defects in apicobasal polarity, as localisation of other apical proteins is unaffected. Our data reveal a mechanism to explain how Crumbs directly controls localisation and trafficking of the potent Notch receptor, and adds yet another aspect of Crumbs regulation in Notch pathway activity. Furthermore, our data highlight a close link between the apical determinant Crumbs, receptor trafficking and tissue homeostasis.
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Affiliation(s)
- Linda Nemetschke
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, Dresden 01307, Germany
| | - Elisabeth Knust
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, Dresden 01307, Germany
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47
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Crumbs2 promotes cell ingression during the epithelial-to-mesenchymal transition at gastrulation. Nat Cell Biol 2016; 18:1281-1291. [PMID: 27870829 DOI: 10.1038/ncb3442] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Accepted: 10/20/2016] [Indexed: 12/18/2022]
Abstract
During gastrulation of the mouse embryo, individual cells ingress in an apparently stochastic pattern during the epithelial-to-mesenchymal transition (EMT). Here we define a critical role of the apical protein Crumbs2 (CRB2) in the gastrulation EMT. Static and live imaging show that ingressing cells in Crumbs2 mutant embryos become trapped at the primitive streak, where they continue to express the epiblast transcription factor SOX2 and retain thin E-cadherin-containing connections to the epiblast surface that trap them at the streak. CRB2 is distributed in a complex anisotropic pattern on apical cell edges, and the level of CRB2 on a cell edge is inversely correlated with the level of myosin IIB. The data suggest that the distributions of CRB2 and myosin IIB define which cells will ingress, and we propose that cells with high apical CRB2 are basally extruded from the epiblast by neighbouring cells with high levels of apical myosin.
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48
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Nguyen MB, Vuong LT, Choi KW. Ebi modulates wing growth by ubiquitin-dependent downregulation of Crumbs in Drosophila. Development 2016; 143:3506-3513. [PMID: 27702784 DOI: 10.1242/dev.142059] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2016] [Accepted: 08/12/2016] [Indexed: 12/11/2022]
Abstract
Notch signaling at the dorsoventral (DV) boundary is essential for patterning and growth of wings in Drosophila The WD40 domain protein Ebi has been implicated in the regulation of Notch signaling at the DV boundary. Here we show that Ebi regulates wing growth by antagonizing the function of the transmembrane protein Crumbs (Crb). Ebi physically binds to the extracellular domain of Crb (Crbext), and this interaction is specifically mediated by WD40 repeats 7-8 of Ebi and a laminin G domain of Crbext Wing notching resulting from reduced levels of Ebi is suppressed by decreasing the Crb function. Consistent with this antagonistic genetic relationship, Ebi knockdown in the DV boundary elevates the Crb protein level. Furthermore, we show that Ebi is required for downregulation of Crb by ubiquitylation. Taken together, we propose that the interplay of Crb expression in the DV boundary and ubiquitin-dependent Crb downregulation by Ebi provides a mechanism for the maintenance of Notch signaling during wing development.
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Affiliation(s)
- Minh Binh Nguyen
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Korea
| | - Linh Thuong Vuong
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Korea
| | - Kwang-Wook Choi
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Korea
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49
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Román-Fernández A, Bryant DM. Complex Polarity: Building Multicellular Tissues Through Apical Membrane Traffic. Traffic 2016; 17:1244-1261. [PMID: 27281121 DOI: 10.1111/tra.12417] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2016] [Revised: 06/06/2016] [Accepted: 06/06/2016] [Indexed: 12/20/2022]
Abstract
The formation of distinct subdomains of the cell surface is crucial for multicellular organism development. The most striking example of this is apical-basal polarization. What is much less appreciated is that underpinning an asymmetric cell surface is an equally dramatic intracellular endosome rearrangement. Here, we review the interplay between classical cell polarity proteins and membrane trafficking pathways, and discuss how this marriage gives rise to cell polarization. We focus on those mechanisms that regulate apical polarization, as this is providing a number of insights into how membrane traffic and polarity are regulated at the tissue level.
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Affiliation(s)
- Alvaro Román-Fernández
- Cancer Research UK Beatson Institute, Switchback Road, Glasgow, G61 1BD, UK.,Institute of Cancer Sciences, University of Glasgow, Garscube Estate, Switchback Road, Glasgow, G61 1BD, UK
| | - David M Bryant
- Cancer Research UK Beatson Institute, Switchback Road, Glasgow, G61 1BD, UK.,Institute of Cancer Sciences, University of Glasgow, Garscube Estate, Switchback Road, Glasgow, G61 1BD, UK
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Vichas A, Laurie MT, Zallen JA. The Ski2-family helicase Obelus regulates Crumbs alternative splicing and cell polarity. J Cell Biol 2016; 211:1011-24. [PMID: 26644515 PMCID: PMC4674277 DOI: 10.1083/jcb.201504083] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The conserved Ski2-family helicase Obelus regulates alternative splicing of the Crumbs polarity protein to control epithelial polarity and junctional organization in Drosophila. Alternative splicing can have profound consequences for protein activity, but the functions of most alternative splicing regulators are not known. We show that Obelus, a conserved Ski2-family helicase, is required for cell polarity and adherens junction organization in the Drosophila melanogaster embryo. In obelus mutants, epithelial cells display an expanded apical domain, aggregation of adherens junctions at the cell membrane, and microtubule-dependent defects in centrosome positioning. Through whole-genome transcriptome analysis, we found that Obelus is required for the alternative splicing of a small number of transcripts in the early embryo, including the pre-mRNA that encodes the apical polarity protein Crumbs. In obelus mutants, inclusion of an alternative exon results in increased expression of a Crumbs isoform that contains an additional epidermal growth factor–like repeat in the extracellular domain. Overexpression of this alternative Crumbs isoform recapitulates the junctional aggregation and centrosome positioning defects of obelus mutants. These results indicate that regulation of Crumbs alternative splicing by the Obelus helicase modulates epithelial polarity during development.
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Affiliation(s)
- Athea Vichas
- Developmental Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065 Howard Hughes Medical Institute, Memorial Sloan Kettering Cancer Center, New York, NY 10065
| | - Matthew T Laurie
- Developmental Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065 Howard Hughes Medical Institute, Memorial Sloan Kettering Cancer Center, New York, NY 10065
| | - Jennifer A Zallen
- Developmental Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065 Howard Hughes Medical Institute, Memorial Sloan Kettering Cancer Center, New York, NY 10065
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