151
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Kovacs EM, Verma S, Thomas SG, Yap AS. Tuba and N-WASP function cooperatively to position the central lumen during epithelial cyst morphogenesis. Cell Adh Migr 2011; 5:344-50. [PMID: 21677511 DOI: 10.4161/cam.5.4.16717] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
The process of epithelial lumenogenesis requires coordination of a network of signaling machinery communicated to each cell through subsequent cell divisions. Formation of a single hollow lumen has previously been shown to require Tuba, a Cdc42 GEF, for Cdc42 activation and correct spindle orientation. Using a Caco-2 model of lumenogenesis, we show that knockdown (KD) of the actin regulator N-WASP, causes a multilumen phenotype similar to Tuba KD. Defects in lumenogenesis in Tuba KD and N-WASP KD cells are observed at the two cell stage with inappropriate marking of the pre-apical patch (PAP) - the precursor to lumen formation. Strikingly, both Tuba and N-WASP depend on each other for localization to the PAP. We conclude that N-WASP functions cooperatively with Tuba to facilitate lumenogenesis and this requires the polyproline region of N-WASP.
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Affiliation(s)
- Eva M Kovacs
- Division of Molecular Cell Biology, Institute for Molecular Bioscience, The University of Queensland-St. Lucia, QLD, Australia
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152
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Engel J, Eran Y. Subversion of mucosal barrier polarity by pseudomonas aeruginosa. Front Microbiol 2011; 2:114. [PMID: 21747810 PMCID: PMC3129012 DOI: 10.3389/fmicb.2011.00114] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2011] [Accepted: 05/09/2011] [Indexed: 02/05/2023] Open
Abstract
The lumenal surfaces of human body are lined by a monolayer of epithelia that together with mucus secreting cells and specialized immune cells form the mucosal barrier. This barrier is one of the most fundamental components of the innate immune system, protecting organisms from the vast environmental microbiota. The mucosal epithelium is comprised of polarized epithelial cells with distinct apical and basolateral surfaces that are defined by unique set of protein and lipid composition and are separated by tight junctions. The apical surface serves as a barrier to the outside world and is specialized for the exchange of materials with the lumen. The basolateral surface is adapted for interaction with other cells and for exchange with the bloodstream. A wide network of proteins and lipids regulates the formation and maintenance of the epithelium polarity. Many human pathogens have evolved virulence mechanisms that target this network and interfere with epithelial polarity to enhance binding to the apical surface, enter into cells, and/or cross the mucosal barrier. This review highlights recent advances in our understanding of how Pseudomonas aeruginosa, an important opportunistic human pathogen that preferentially infects damaged epithelial tissues, exploits the epithelial cell polarization machinery to enhance infection.
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Affiliation(s)
- Joanne Engel
- Department of Medicine, University of California at San Francisco San Francisco, CA, USA
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153
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Myllymäki SM, Teräväinen TP, Manninen A. Two distinct integrin-mediated mechanisms contribute to apical lumen formation in epithelial cells. PLoS One 2011; 6:e19453. [PMID: 21573123 PMCID: PMC3089628 DOI: 10.1371/journal.pone.0019453] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2011] [Accepted: 03/29/2011] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Formation of apical compartments underlies the morphogenesis of most epithelial organs during development. The extracellular matrix (ECM), particularly the basement membrane (BM), plays an important role in orienting the apico-basal polarity and thereby the positioning of apical lumens. Integrins have been recognized as essential mediators of matrix-derived polarity signals. The importance of β1-integrins in epithelial polarization is well established but the significance of the accompanying α-subunits have not been analyzed in detail. PRINCIPAL FINDINGS Here we demonstrate that two distinct integrin-dependent pathways regulate formation of apical lumens to ensure robust apical membrane biogenesis under different microenvironmental conditions; 1) α2β1- and α6β4-integrins were required to establish a basal cue that depends on Rac1-activity and guides apico-basal cell polarization. 2) α3β1-integrins were implicated in positioning of mitotic spindles in cysts, a process that is essential for Cdc42-driven epithelial hollowing. SIGNIFICANCE Identification of the separate processes driven by particular integrin receptors clarifies the functional hierarchies between the different integrins co-expressed in epithelial cells and provides valuable insight into the complexity of cell-ECM interactions thereby guiding future studies addressing the molecular basis of epithelial morphogenesis during development and disease.
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Affiliation(s)
- Satu Marja Myllymäki
- Biocenter Oulu, Oulu Center for Cell-Matrix Research, Department of Medical Biochemistry and Molecular Biology, University of Oulu, Oulu, Finland
| | - Terhi Piritta Teräväinen
- Biocenter Oulu, Oulu Center for Cell-Matrix Research, Department of Medical Biochemistry and Molecular Biology, University of Oulu, Oulu, Finland
| | - Aki Manninen
- Biocenter Oulu, Oulu Center for Cell-Matrix Research, Department of Medical Biochemistry and Molecular Biology, University of Oulu, Oulu, Finland
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154
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Kang RS, Fölsch H. ARH cooperates with AP-1B in the exocytosis of LDLR in polarized epithelial cells. J Cell Biol 2011; 193:51-60. [PMID: 21444685 PMCID: PMC3082197 DOI: 10.1083/jcb.201012121] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2010] [Accepted: 03/07/2011] [Indexed: 02/07/2023] Open
Abstract
The autosomal recessive hypercholesterolemia protein (ARH) is well known for its role in clathrin-mediated endocytosis of low-density lipoprotein receptors (LDLRs). During uptake, ARH directly binds to the FxNPxY signal in the cytoplasmic tail of LDLR. Interestingly, the same FxNPxY motif is used in basolateral exocytosis of LDLR from recycling endosomes (REs), which is facilitated by the epithelial-specific clathrin adaptor AP-1B. However, AP-1B directly interacts with neither the FxNPxY motif nor the second more distally located YxxØ sorting motif of LDLR. Here, we show that ARH colocalizes and cooperates with AP-1B in REs. Knockdown of ARH in polarized epithelial cells leads to specific apical missorting of truncated LDLR, which encodes only the FxNPxY motif (LDLR-CT27). Moreover, a mutation in ARH designed to disrupt the interaction of ARH with AP-1B specifically abrogates exocytosis of LDLR-CT27. We conclude that in addition to its role in endocytosis, ARH cooperates with AP-1B in basolateral exocytosis of LDLR from REs.
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Affiliation(s)
- Richard S Kang
- Department of Cell and Molecular Biology, Northwestern University, Chicago, IL 60611, USA
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155
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Abstract
Epithelial tissues are a key metazoan cell type, providing a basic structural unit for the construction of diverse animal body plans. Historically, an epithelial grade of organization was considered to be restricted to the Eumetazoa, with the majority of cell layers described for Porifera lacking any of the conserved ultrastructural characteristics of epithelia. Now with the use of genomic information from the demosponge, Amphimedon queenslandica, we identify orthologs of bilaterian genes that determine epithelial cell polarity or encode components of specialized epithelial junctions and extracellular matrix structures. Amphimedon possesses orthologs of most bilaterian epithelial polarity and adherens junction genes but few or no tight junction, septate junction, or basal lamina genes. To place this information in an evolutionary context, we extended these analyses to the completed genomes of various fungi, the choanoflagellate, Monosiga brevicollis, the placozoan, Trichoplax adhaerens, and the cnidarian, Nematostella vectensis. The results indicate that the majority of "epithelial" genes originated in metazoan or eumetazoan lineages, with only two genes, Par-1 and Discs large, antedating the choanoflagellate-metazoan split. We further explored the mechanism of evolution for each of these genes by tracking the origin of constituent domains and domain combinations. In general, domain configurations found in contemporary bilaterians are inferred to have evolved early in metazoan evolution and are identical or similar to those present in representatives of modern cnidarians, placozoans, and demosponges.
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Affiliation(s)
- Bryony Fahey
- The University of Queensland, Brisbane, Australia
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156
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Sixt M, Lämmermann T. In vitro analysis of chemotactic leukocyte migration in 3D environments. Methods Mol Biol 2011; 769:149-65. [PMID: 21748675 DOI: 10.1007/978-1-61779-207-6_11] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Cell migration on two-dimensional (2D) substrates follows entirely different rules than cell migration in three-dimensional (3D) environments. This is especially relevant for leukocytes that are able to migrate in the absence of adhesion receptors within the confined geometry of artificial 3D extracellular matrix scaffolds and within the interstitial space in vivo. Here, we describe in detail a simple and economical protocol to visualize dendritic cell migration in 3D collagen scaffolds along chemotactic gradients. This method can be adapted to other cell types and may serve as a physiologically relevant paradigm for the directed locomotion of most amoeboid cells.
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Affiliation(s)
- Michael Sixt
- Institute of Science and Technology Austria, Am Campus 1, Klosterneuburg, Austria.
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157
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Tang M, Iijima M, Kamimura Y, Chen L, Long Y, Devreotes P. Disruption of PKB signaling restores polarity to cells lacking tumor suppressor PTEN. Mol Biol Cell 2010; 22:437-47. [PMID: 21169559 PMCID: PMC3038642 DOI: 10.1091/mbc.e10-06-0522] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
By limiting phosphotidylinositol 3,4,5-triphosphate (PIP(3)) levels, tumor suppressor PTEN not only controls cell growth but also maintains cell polarity required for cytokinesis and chemotaxis. To identify the critical targets of PIP(3) that link it to the cytoskeleton, we deleted secondary genes to reverse the deficiencies of pten- cells in Dictyostelium. The polarity defects in pten- cells correlate with elevated phosphorylations of PKB substrates. Deletion of AKT orthologue, PkbA, or a subunit of its activator TORC2, reduced the phosphorylations and suppressed the cytokinesis and chemotaxis defects in pten- cells. In these double mutants, the excessive PIP(3) levels and, presumably, activation of other PIP(3)-binding proteins had little or no effect on the cytoskeleton. In bands with increased phosphorylation in pten- cells, we found PKB substrates, PI5K, GefS, GacG, and PakA. Disruption of PakA in pten- cells restored a large fraction of the cells to normal behavior. Consistently, expression of phosphomimetic PakA in pten- cells exacerbated the defects but nonphosphorylatable PakA had no effect. Thus, among many putative PTEN- and PIP(3)-dependent events, phosphorylation of PKB substrates is the key downstream regulator of cell polarity.
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Affiliation(s)
- Ming Tang
- Department of Cell Biology, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA
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158
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Pirraglia C, Walters J, Myat MM. Pak1 control of E-cadherin endocytosis regulates salivary gland lumen size and shape. Development 2010; 137:4177-89. [PMID: 21068057 DOI: 10.1242/dev.048827] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Generating and maintaining proper lumen size and shape in tubular organs is essential for organ function. Here, we demonstrate a novel role for p21-activated kinase 1 (Pak1) in defining the size and shape of the Drosophila embryonic salivary gland lumen by regulating the size and elongation of the apical domain of individual cells. Pak1 mediates these effects by decreasing and increasing E-cadherin levels at the adherens junctions and basolateral membrane, respectively, through Rab5- and Dynamin-dependent endocytosis. We also demonstrate that Cdc42 and Merlin act together with Pak1 to control lumen size. A role for Pak1 in E-cadherin endocytosis is supported by our studies of constitutively active Pak1, which induces the formation of multiple intercellular lumens in the salivary gland in a manner dependent on Rab5, Dynamin and Merlin. These studies demonstrate a novel and crucial role for Pak1 and E-cadherin endocytosis in determining lumen size and shape, and also identify a mechanism for multiple lumen formation, a poorly understood process that occurs in normal embryonic development and pathological conditions.
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Affiliation(s)
- Carolyn Pirraglia
- BCMB Program of Weill Graduate School of Medical Sciences at Cornell University, New York, NY 10065, USA
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159
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Abstract
The fur on a cat's back, the scales on a fish, or the bristles on a fly are all beautifully organized, with a high degree of polarization in their surface organization. Great progress has been made in understanding how individual cell polarity is established, but our understanding of how cells coordinate their polarity in forming coherent tissues is still fragmentary. The organization of cells in the plane of the epithelium is known as planar cell polarity (PCP), and studies in the past decade have delineated a genetic pathway for the control of PCP. This review will first briefly review data from the Drosophila field, where PCP was first identified and genetically characterized, and then explore how vertebrate tissues become polarized during development.
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160
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McCaffrey LM, Macara IG. Widely conserved signaling pathways in the establishment of cell polarity. Cold Spring Harb Perspect Biol 2010; 1:a001370. [PMID: 20066082 DOI: 10.1101/cshperspect.a001370] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
How are the asymmetric distributions of proteins, lipids, and RNAs established and maintained in various cell types? Studies from diverse organisms show that Par proteins, GTPases, kinases, and phosphoinositides participate in conserved signaling pathways to establish and maintain cell polarity.
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Affiliation(s)
- Luke Martin McCaffrey
- Department of Microbiology, Center for Cell Signaling, University of Virginia School of Medicine, Charlottesville, Virginia 22908-5077, USA
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161
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Wang Y, Kaiser MS, Larson JD, Nasevicius A, Clark KJ, Wadman SA, Roberg-Perez SE, Ekker SC, Hackett PB, McGrail M, Essner JJ. Moesin1 and Ve-cadherin are required in endothelial cells during in vivo tubulogenesis. Development 2010; 137:3119-28. [PMID: 20736288 DOI: 10.1242/dev.048785] [Citation(s) in RCA: 141] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Endothelial tubulogenesis is a crucial step in the formation of functional blood vessels during angiogenesis and vasculogenesis. Here, we use in vivo imaging of living zebrafish embryos expressing fluorescent fusion proteins of beta-Actin, alpha-Catenin, and the ERM family member Moesin1 (Moesin a), to define a novel cord hollowing process that occurs during the initial stages of tubulogenesis in intersegmental vessels (ISVs) in the embryo. We show that the primary lumen elongates along cell junctions between at least two endothelial cells during embryonic angiogenesis. Moesin1-EGFP is enriched around structures that resemble intracellular vacuoles, which fuse with the luminal membrane during expansion of the primary lumen. Analysis of silent heart mutant embryos shows that initial lumen formation in the ISVs is not dependent on blood flow; however, stabilization of a newly formed lumen is dependent upon blood flow. Zebrafish moesin1 knockdown and cell transplantation experiments demonstrate that Moesin1 is required in the endothelial cells of the ISVs for in vivo lumen formation. Our analyses suggest that Moesin1 contributes to the maintenance of apical/basal cell polarity of the ISVs as defined by adherens junctions. Knockdown of the adherens junction protein Ve-cadherin disrupts formation of the apical membrane and lumen in a cell-autonomous manner. We suggest that Ve-cadherin and Moesin1 function to establish and maintain apical/basal polarity during multicellular lumen formation in the ISVs.
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Affiliation(s)
- Ying Wang
- Department of Genetics, Development and Cell Biology, Iowa State University, Ames, IA 50011, USA
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162
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Lampugnani MG, Orsenigo F, Rudini N, Maddaluno L, Boulday G, Chapon F, Dejana E. CCM1 regulates vascular-lumen organization by inducing endothelial polarity. J Cell Sci 2010; 123:1073-80. [PMID: 20332120 DOI: 10.1242/jcs.059329] [Citation(s) in RCA: 140] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Little is known about the molecular mechanisms that regulate the organization of vascular lumen. In this paper we show that lumen formation correlates with endothelial polarization. Adherens junctions (AJs) and VE-cadherin (VEC, encoded by CDH5) are required for endothelial apicobasal polarity in vitro and during embryonic development. Silencing of CDH5 gene expression leads to abrogation of endothelial polarity accompanied by strong alterations in lumenal structure. VEC co-distributes with members of the Par polarity complex (Par3 and PKCzeta) and is needed for activation of PKCzeta. CCM1 is encoded by the CCM1 gene, which is mutated in 60% of patients affected by cerebral cavernous malformation (CCM). The protein interacts with VEC and directs AJ organization and AJ association with the polarity complex, both in cell-culture models and in human CCM1 lesions. Both VEC and CCM1 control Rap1 concentration at cell-cell junctions. We propose that VEC, CCM1 and Rap1 form a signaling complex. In the absence of any of these proteins, AJs are dismantled, cell polarity is lost and vascular lumenal structure is severely altered.
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163
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Onodera T, Sakai T, Hsu JCF, Matsumoto K, Chiorini JA, Yamada KM. Btbd7 regulates epithelial cell dynamics and branching morphogenesis. Science 2010; 329:562-5. [PMID: 20671187 PMCID: PMC3412157 DOI: 10.1126/science.1191880] [Citation(s) in RCA: 119] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
During embryonic development, many organs form by extensive branching of epithelia through the formation of clefts and buds. In cleft formation, buds are delineated by the conversion of epithelial cell-cell adhesions to cell-matrix adhesions, but the mechanisms of cleft formation are not clear. We have identified Btbd7 as a dynamic regulator of branching morphogenesis. Btbd7 provides a mechanistic link between the extracellular matrix and cleft propagation through its highly focal expression leading to local regulation of Snail2 (Slug), E-cadherin, and epithelial cell motility. Inhibition experiments show that Btbd7 is required for branching of embryonic mammalian salivary glands and lungs. Hence, Btbd7 is a regulatory gene that promotes epithelial tissue remodeling and formation of branched organs.
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Affiliation(s)
- Tomohiro Onodera
- Laboratory of Cell and Developmental Biology, National Institutes of Health, Bethesda, Maryland 20892-4370, USA
| | - Takayoshi Sakai
- Laboratory of Cell and Developmental Biology, National Institutes of Health, Bethesda, Maryland 20892-4370, USA
- Department of Oral-Facial Disorders, Osaka University Graduate School of Dentistry, Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Jeff Chi-feng Hsu
- Laboratory of Cell and Developmental Biology, National Institutes of Health, Bethesda, Maryland 20892-4370, USA
| | - Kazue Matsumoto
- Laboratory of Cell and Developmental Biology, National Institutes of Health, Bethesda, Maryland 20892-4370, USA
| | - John A. Chiorini
- Molecular Physiology and Therapeutics Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, Maryland 20892-4370, USA
| | - Kenneth M. Yamada
- Laboratory of Cell and Developmental Biology, National Institutes of Health, Bethesda, Maryland 20892-4370, USA
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164
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165
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Alarcon VB. Cell polarity regulator PARD6B is essential for trophectoderm formation in the preimplantation mouse embryo. Biol Reprod 2010; 83:347-58. [PMID: 20505164 DOI: 10.1095/biolreprod.110.084400] [Citation(s) in RCA: 107] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
In preimplantation mouse development, the first cell lineages to be established are the trophectoderm (TE) and inner cell mass. TE possesses epithelial features, including apical-basal cell polarity and intercellular junctions, which are crucial to generate a fluid-filled cavity in the blastocyst. Homologs of the partitioning defective (par) genes in Caenorhabditis elegans are critical regulators of cell polarity. However, their roles in regulating TE differentiation and blastocyst formation remain unclear. Here, the role of mouse Pard6b, a homolog of par-6 gene and a component of the PAR-atypical protein kinase C (aPKC) complex, was investigated. Pard6b expression was knocked down by microinjecting RNA interference construct into zygotes. Pard6b-knockdown embryos cleaved and compacted normally but failed to form the blastocyst cavity. The cavitation failure is likely the result of defective intercellular junctions, because Pard6b knockdown caused abnormal distribution of actin filaments and TJP1 (ZO-1) tight junction (TJ) protein and interfered with cavitation in chimeras containing cells from normal embryos. Defective TJ formation may be caused by abnormal cell polarization, because the apical localization of PRKCZ (aPKCzeta) was absent in Pard6b-knockdown embryos. Pard6b knockdown also diminished the expression of CDX2, a TE-lineage transcription factor, in the outer cells. TEAD4, a transcriptional activator that is required for Cdx2 expression and cavity formation, was not essential for the transcription of Pard6b. Taken together, Pard6b is necessary for blastocyst morphogenesis, particularly the development of TE-specific features-namely, the apical-basal cell polarity, formation of TJ, paracellular permeability sealing, and up-regulated expression of Cdx2.
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Affiliation(s)
- Vernadeth B Alarcon
- Institute for Biogenesis Research, Department of Anatomy, Biochemistry, and Physiology, John A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii 96813, USA.
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166
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Eritja N, Llobet D, Domingo M, Santacana M, Yeramian A, Matias-Guiu X, Dolcet X. A novel three-dimensional culture system of polarized epithelial cells to study endometrial carcinogenesis. THE AMERICAN JOURNAL OF PATHOLOGY 2010; 176:2722-31. [PMID: 20395448 DOI: 10.2353/ajpath.2010.090974] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Development of three-dimensional (3D) cultures that mimic in vivo tissue organization has a pivotal role in the investigation of the involvement of cell adhesion and polarity genes in the pathogenesis of epithelial cancers. Here we describe a novel 3D culture model with primary mouse endometrial epithelial cells. In this model, isolated endometrial epithelial cells develop single-lumened, polarized glandular structures resembling those observed in endometrial tissue. Our in vitro 3D culture model of endometrial glands requires the use of serum-free defined medium with only epidermal growth factor and insulin as growth supplements and 3% Matrigel as reconstituted extracellular matrix. Under these culture conditions, glands of epithelial cells displaying typical apicobasal polarity and proper positioning of tight and adherent junctions are formed by hollowing as early as 7 to 8 days in culture. Addition of the phosphatidylinositol 3-kinase inhibitor LY294002 completely inhibits bromodeoxyuridine incorporation and cyclinD1 expression, confirming that in vitro growth of endometrial glands depends on phosphatidylinositol 3-kinase/Akt signaling. To prove that our culture method is a good model to study endometrial carcinogenesis, we knocked down E-cadherin or phosphatase and tensin homolog expression by lentivirus-delivered short hairpin RNAs. Down-regulation of E-cadherin resulted in complete loss of epithelial cell polarity and glandular formation, whereas phosphatase and tensin homolog down-regulation resulted in increased proliferation of glandular epithelial cells. These properties indicate that our 3D culture model is suitable to study the effect of growth factors, drugs, and gene alterations in endometrial carcinogenesis and to study normal endometrial biology/physiology.
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Affiliation(s)
- Núria Eritja
- Oncologic Pathology Group, Hospital Universitari Arnau de Vilanova, Institut de Recerca Biomèdica de Lleida, IRBLleida, University of Lleida, Lleida, Spain
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167
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McCarter SD, Johnson DL, Kitt KN, Donohue C, Adams A, Wilson JM. Regulation of tight junction assembly and epithelial polarity by a resident protein of apical endosomes. Traffic 2010; 11:856-66. [PMID: 20214753 DOI: 10.1111/j.1600-0854.2010.01052.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The establishment of tight junctions and cell polarity is an essential process in all epithelia. Endotubin is an integral membrane protein found in apical endosomes of developing epithelia when tight junctions and epithelial polarity first arise. We found that the disruption of endotubin function in cells in culture by siRNA or overexpression of the C-terminal cytoplasmic domain of endotubin causes defects in organization and function of tight junctions. We observe defects in localization of tight junction proteins, reduced transepithelial resistance, increased lanthanum penetration between cells and reduced ability of cells to form cysts in three-dimensional culture. In addition, in cells overexpressing the C-terminal domain of endotubin, we observe a delay in re-establishing the normal distribution of endosomes after calcium switch. These results suggest that endotubin regulates trafficking of polarity proteins and tight junction components out of the endosomal compartment, thereby providing a critical link between a resident protein of apical endosomes and tight junctions.
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Affiliation(s)
- Sarah D McCarter
- Department of Cell Biology & Anatomy, University of Arizona, 1501 N. Campbell Avenue, Tucson, AZ 85724, USA
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168
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A developmental framework for endodermal differentiation and polarity. Proc Natl Acad Sci U S A 2010; 107:5214-9. [PMID: 20142472 DOI: 10.1073/pnas.0910772107] [Citation(s) in RCA: 150] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
The endodermis is a root cell layer common to higher plants and of fundamental importance for root function and nutrient uptake. The endodermis separates outer (peripheral) from inner (central) cell layers by virtue of its Casparian strips, precisely aligned bands of specialized wall material. Here we reveal that the membrane at the Casparian strip is a diffusional barrier between the central and peripheral regions of the plasma membrane and that it mediates attachment to the extracellular matrix. This membrane region thus functions like a tight junction in animal epithelia, although plants lack the molecular modules that establish tight junction in animals. We have also identified a pair of influx and efflux transporters that mark both central and peripheral domains of the plasma membrane. These transporters show opposite polar distributions already in meristems, but their localization becomes refined and restricted upon differentiation. This "central-peripheral" polarity coexists with the apical-basal polarity defined by PIN proteins within the same cells, but utilizes different polarity determinants. Central-peripheral polarity can be already observed in early embryogenesis, where it reveals a cellular polarity within the quiescent center precursor cell. A strict diffusion block between polar domains is common in animals, but had never been described in plants. Yet, its relevance to endodermal function is evident, as central and peripheral membranes of the endodermis face fundamentally different root compartments. Further analysis of endodermal transporter polarity and manipulation of its barrier function will greatly promote our understanding of plant nutrition and stress tolerance in roots.
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169
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The polarity protein Pard3 is required for centrosome positioning during neurulation. Dev Biol 2010; 341:335-45. [PMID: 20138861 DOI: 10.1016/j.ydbio.2010.01.034] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2009] [Revised: 01/22/2010] [Accepted: 01/27/2010] [Indexed: 12/12/2022]
Abstract
Microtubules are essential regulators of cell polarity, architecture and motility. The organization of the microtubule network is context-specific. In non-polarized cells, microtubules are anchored to the centrosome and form radial arrays. In most epithelial cells, microtubules are noncentrosomal, align along the apico-basal axis and the centrosome templates a cilium. It follows that cells undergoing mesenchyme-to-epithelium transitions must reorganize their microtubule network extensively, yet little is understood about how this process is orchestrated. In particular, the pathways regulating the apical positioning of the centrosome are unknown, a central question given the role of cilia in fluid propulsion, sensation and signaling. In zebrafish, neural progenitors undergo progressive epithelialization during neurulation, and thus provide a convenient in vivo cellular context in which to address this question. We demonstrate here that the microtubule cytoskeleton gradually transitions from a radial to linear organization during neurulation and that microtubules function in conjunction with the polarity protein Pard3 to mediate centrosome positioning. Pard3 depletion results in hydrocephalus, a defect often associated with abnormal cerebrospinal fluid flow that has been linked to cilia defects. These findings thus bring to focus cellular events occurring during neurulation and reveal novel molecular mechanisms implicated in centrosome positioning.
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170
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Polarity protein alterations in carcinoma: a focus on emerging roles for polarity regulators. Curr Opin Genet Dev 2010; 20:41-50. [PMID: 20093003 DOI: 10.1016/j.gde.2009.12.001] [Citation(s) in RCA: 104] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2009] [Revised: 12/12/2009] [Accepted: 12/16/2009] [Indexed: 12/24/2022]
Abstract
In this review we discuss both gene expression and protein localization changes of polarity proteins in carcinoma. We highlight the importance of protein mislocalization and its possible role in cancer. We also discuss the emerging role of polarity proteins as regulators of proliferation, apoptosis, tissue polarity, epithelial-mesenchymal transition, in addition to their known role in cell junction biogenesis.
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171
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Ivanov AI, Young C, Den Beste K, Capaldo CT, Humbert PO, Brennwald P, Parkos CA, Nusrat A. Tumor suppressor scribble regulates assembly of tight junctions in the intestinal epithelium. THE AMERICAN JOURNAL OF PATHOLOGY 2009; 176:134-45. [PMID: 19959811 DOI: 10.2353/ajpath.2010.090220] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Formation of the epithelial barrier and apico-basal cell polarity represent two characteristics and mutually dependent features of differentiated epithelial monolayers. They are controlled by special adhesive structures, tight junctions (TJs), and polarity protein complexes that define the apical and the basolateral plasma membrane. The functional interplay between TJs and polarity complexes remains poorly understood. We investigated the role of Scribble, a basolateral polarity protein and known tumor suppressor, in regulating TJs in human intestinal epithelium. Scribble was enriched at TJs in T84 and SK-CO15 intestinal epithelial cell monolayers and sections of normal human colonic mucosa. siRNA-mediated knockdown of Scribble in SK-CO15 cells attenuated development of epithelial barrier and inhibited TJ reassembly independently of other basolateral polarity proteins Lgl-1 and Dlg-1. Scribble selectively co-imunoprecipitated with TJ protein ZO-1, and ZO-1 was important for Scribble recruitment to intercellular junctions and TJ reassembly. Lastly, Scribble was mislocalized from TJs and its expression down-regulated in interferon-gamma-treated T84 cell monolayers and inflamed human intestinal mucosa in vivo. We conclude that Scribble is an important regulator of TJ functions and plasticity in the intestinal epithelium. Down-regulation of Scribble may mediate mucosal barrier breakdown during intestinal inflammation.
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Affiliation(s)
- Andrei I Ivanov
- Gastroenterology and Hepatology Division, Department of Medicine, University of Rochester, 601 Elmwood Avenue, Box 646, Rochester, NY 14642, USA.
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172
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Peeling as a novel, simple, and effective method for isolation of apical membrane from intact polarized epithelial cells. Anal Biochem 2009; 395:25-32. [DOI: 10.1016/j.ab.2009.08.007] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2009] [Revised: 08/04/2009] [Accepted: 08/06/2009] [Indexed: 11/23/2022]
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173
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Meerschaert K, Tun MP, Remue E, De Ganck A, Boucherie C, Vanloo B, Degeest G, Vandekerckhove J, Zimmermann P, Bhardwaj N, Lu H, Cho W, Gettemans J. The PDZ2 domain of zonula occludens-1 and -2 is a phosphoinositide binding domain. Cell Mol Life Sci 2009; 66:3951-66. [PMID: 19784548 PMCID: PMC3724457 DOI: 10.1007/s00018-009-0156-6] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2009] [Revised: 09/02/2009] [Accepted: 09/04/2009] [Indexed: 02/02/2023]
Abstract
Zonula occludens proteins (ZO) are postsynaptic density protein-95 discs large-zonula occludens (PDZ) domain-containing proteins that play a fundamental role in the assembly of tight junctions and establishment of cell polarity. Here, we show that the second PDZ domain of ZO-1 and ZO-2 binds phosphoinositides (PtdInsP) and we identified critical residues involved in the interaction. Furthermore, peptide and PtdInsP binding of ZO PDZ2 domains are mutually exclusive. Although lipid binding does not seem to be required for plasma membrane localisation of ZO-1, phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P (2)) binding to the PDZ2 domain of ZO-2 regulates ZO-2 recruitment to nuclear speckles. Knockdown of ZO-2 expression disrupts speckle morphology, indicating that ZO-2 might play an active role in formation and stabilisation of these subnuclear structures. This study shows for the first time that ZO isoforms bind PtdInsPs and offers an alternative regulatory mechanism for the formation and stabilisation of protein complexes in the nucleus.
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Affiliation(s)
- Kris Meerschaert
- Department of Medical Protein Research, VIB, 9000 Ghent, Belgium
- Department of Biochemistry, Faculty of Medicine and Health Sciences, Ghent University, Albert Baertsoenkaai 3, 9000 Ghent, Belgium
- Present Address: Ablynx nv, Technologiepark, 9052 Ghent/Zwijnaarde, Belgium
| | - Moe Phyu Tun
- Departments of Chemistry, University of Illinois, Chicago, IL 60607-7061 USA
| | - Eline Remue
- Department of Medical Protein Research, VIB, 9000 Ghent, Belgium
- Department of Biochemistry, Faculty of Medicine and Health Sciences, Ghent University, Albert Baertsoenkaai 3, 9000 Ghent, Belgium
| | - Ariane De Ganck
- Department of Medical Protein Research, VIB, 9000 Ghent, Belgium
- Department of Biochemistry, Faculty of Medicine and Health Sciences, Ghent University, Albert Baertsoenkaai 3, 9000 Ghent, Belgium
| | - Ciska Boucherie
- Department of Medical Protein Research, VIB, 9000 Ghent, Belgium
- Department of Biochemistry, Faculty of Medicine and Health Sciences, Ghent University, Albert Baertsoenkaai 3, 9000 Ghent, Belgium
| | - Berlinda Vanloo
- Department of Medical Protein Research, VIB, 9000 Ghent, Belgium
- Department of Biochemistry, Faculty of Medicine and Health Sciences, Ghent University, Albert Baertsoenkaai 3, 9000 Ghent, Belgium
| | | | - Joël Vandekerckhove
- Department of Medical Protein Research, VIB, 9000 Ghent, Belgium
- Department of Biochemistry, Faculty of Medicine and Health Sciences, Ghent University, Albert Baertsoenkaai 3, 9000 Ghent, Belgium
| | | | - Nitin Bhardwaj
- Departments of Bioengineering, University of Illinois, Chicago, IL 60607-7061 USA
| | - Hui Lu
- Departments of Bioengineering, University of Illinois, Chicago, IL 60607-7061 USA
| | - Wonhwa Cho
- Departments of Chemistry, University of Illinois, Chicago, IL 60607-7061 USA
- Department of Chemistry (M/C 111), University of Illinois at Chicago, 845 West Taylor Street, Chicago, IL 60607-7061 USA
| | - Jan Gettemans
- Department of Medical Protein Research, VIB, 9000 Ghent, Belgium
- Department of Biochemistry, Faculty of Medicine and Health Sciences, Ghent University, Albert Baertsoenkaai 3, 9000 Ghent, Belgium
- Department of Medical Protein Research, Faculty of Medicine and Health Sciences, Flanders Interuniversity Institute for Biotechnology, Ghent University, Albert Baertsoenkaai 3, 9000 Ghent, Belgium
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174
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Koch A, Poirier F, Jacob R, Delacour D. Galectin-3, a novel centrosome-associated protein, required for epithelial morphogenesis. Mol Biol Cell 2009; 21:219-31. [PMID: 19923323 PMCID: PMC2808235 DOI: 10.1091/mbc.e09-03-0193] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
We investigated the role of galectin-3 on polarization of epithelial renal cells, using three-dimensional cultures of MDCK cells and also galectin-3 null mutant mouse kidneys. Collectively, data show that the absence of galectin-3 influences the stabilization of centrosomes and primary cilia, with effects on epithelial cell organization. Galectin-3 is a β-galactoside–binding protein widely expressed in all epithelia where it is involved in tissue homeostasis and cancer progression. We recently reported unique abnormalities in the identity of membrane domains in galectin-3 null mutant mice, suggesting that galectin-3 may participate in epithelial polarity program. We investigated the potential role of galectin-3 on early events in polarization of epithelial renal cells, using three-dimensional cultures of MDCK cells and also galectin-3 null mutant mouse kidneys. We show that depletion in galectin-3 systematically leads to severe perturbations of microtubular network associated with defects in membrane compartimentation, both in vitro and in vivo. Moreover, the absence of galectin-3 impinges on the morphology of the primary cilium, which is three times longer and unusually shaped. By immunological and biochemical approaches, we could demonstrate that endogenous galectin-3 is normally associated with basal bodies and centrosomes, where it closely interacts with core proteins, such as centrin-2. However, this association transiently occurs during the process of epithelial polarization. Interestingly, galectin-3–depleted cells contain numerous centrosome-like structures, demonstrating an unexpected function of this protein in the formation and/or stability of the centrosomes. Collectively, these data establish galectin-3 as a key determinant in epithelial morphogenesis via its effect on centrosome biology.
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Affiliation(s)
- Annett Koch
- Department of Cell Biology and Cell Pathology, Philipps University, D-35033 Marburg, Germany
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175
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Schlüter MA, Pfarr CS, Pieczynski J, Whiteman EL, Hurd TW, Fan S, Liu CJ, Margolis B. Trafficking of Crumbs3 during cytokinesis is crucial for lumen formation. Mol Biol Cell 2009; 20:4652-63. [PMID: 19776356 DOI: 10.1091/mbc.e09-02-0137] [Citation(s) in RCA: 114] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Although lumen generation has been extensively studied through so-called cyst-formation assays in Madin-Darby canine kidney (MDCK) cells, an underlying mechanism that leads to the initial appearance of a solitary lumen remains elusive. Lumen formation is thought to take place at early stages in aggregates containing only a few cells. Evolutionarily conserved polarity protein complexes, namely the Crumbs, Par, and Scribble complexes, establish apicobasal polarity in epithelial cells, and interference with their function impairs the regulated formation of solitary epithelial lumina. Here, we demonstrate that MDCK cells form solitary lumina during their first cell division. Before mitosis, Crumbs3a becomes internalized and concentrated in Rab11-positive recycling endosomes. These compartments become partitioned in both daughter cells and are delivered to the site of cytokinesis, thus forming the first apical membrane, which will eventually form a lumen. Endosome trafficking in this context appears to depend on the mitotic spindle apparatus and midzone microtubules. Furthermore, we show that this early lumen formation is regulated by the apical polarity complexes because Crumbs3 assists in the recruitment of aPKC to the forming apical membrane and interference with their function can lead to the formation of a no-lumen or multiple-lumen phenotype at the two-cell stage.
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Affiliation(s)
- Marc A Schlüter
- Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI 48109, USA
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176
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Newly formed E-cadherin contacts do not activate Cdc42 or induce filopodia protrusion in human keratinocytes. Biol Cell 2009; 102:13-24. [PMID: 19583567 DOI: 10.1042/bc20090048] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
BACKGROUND INFORMATION The appropriate regulation of cell-cell adhesion is an important event in the homoeostasis of different cell types. In epithelial cells, tight adhesion mediated by E-cadherin receptors is essential for the differentiation and functionality of epithelial sheets. Upon assembly of cadherin-mediated cell-cell contacts, it is well established that the small GTPases Rho and Rac are activated and are necessary for junction stability. However, the role of the small GTPase Cdc42 in cadherin adhesion is less clear. Cdc42 can be activated by E-cadherin in a breast tumour cell line, but the requirement for Cdc42 function for new junction assembly or maintenance has been contradictory. Cdc42 participation in cell-cell contacts has been inferred from the presence of filopodia, the typical F-actin structure induced by Cdc42 activation, as cells approach each other to establish cell-cell contacts. Yet, under these conditions, the contribution of migration to filopodia protrusion cannot be excluded and the results are difficult to interpret. RESULTS In the present study, we set out to address (a) whether Cdc42 is activated by new E-cadherin cell-cell contacts when junction assembly occurs without prior migration and (b) whether Cdc42 function is necessary for cadherin stability. We found that junction formation in confluent keratinocytes or upon E-cadherin clustering decreased Cdc42-GTP levels. In the absence of serum- and migration-induced Cdc42 activation, we demonstrated that cell-cell contacts do not induce filopodia or require Cdc42 function to assemble. CONCLUSION We conclude that Cdc42 does not participate in the early events that initiate stable cadherin adhesion in keratinocytes. Yet, it is feasible that Cdc42 may be activated at later time points or by other receptors. Cdc42 can then participate in additional functions during polarization, such as Golgi re-positioning or basolateral trafficking.
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177
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Kondylis V, Pizette S, Rabouille C. The early secretory pathway in development: A tale of proteins and mRNAs. Semin Cell Dev Biol 2009; 20:817-27. [DOI: 10.1016/j.semcdb.2009.03.012] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2008] [Revised: 03/16/2009] [Accepted: 03/17/2009] [Indexed: 12/24/2022]
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178
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Stenzel N, Fetzer CP, Heumann R, Erdmann KS. PDZ-domain-directed basolateral targeting of the peripheral membrane protein FRMPD2 in epithelial cells. J Cell Sci 2009; 122:3374-84. [PMID: 19706687 DOI: 10.1242/jcs.046854] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Multi-PDZ (PSD-95/Discs large/Zonula-occludens-1) domain proteins play a crucial role in the establishment and maintenance of cell polarization. The novel multi-PDZ domain protein FRMPD2 is a potential scaffolding protein consisting of an N-terminal KIND domain, a FERM domain and three PDZ domains. Here we show that FRMPD2 is localized in a polarized fashion in epithelial cells at the basolateral membrane and partially colocalizes with the tight-junction marker protein Zonula-occludens-1. Downregulation of FRMPD2 protein in Caco-2 cells is associated with an impairment of tight junction formation. We find that the FERM domain of FRMPD2 binds phosphatidylinositols and is sufficient for membrane localization. Moreover, we demonstrate that recruitment of FRMPD2 to cell-cell junctions is strictly E-cadherin-dependent, which is in line with our identification of catenin family proteins as binding partners for FRMPD2. We demonstrate that the FERM domain and binding of the PDZ2 domain to the armadillo protein p0071 are required for basolateral restriction of FRMPD2. Moreover, the PDZ2 domain of FRMPD2 is sufficient to partially redirect an apically localized protein to the basolateral membrane. Our results provide novel insights into the molecular function of FRMPD2 and into the targeting mechanism of peripheral membrane proteins in polarized epithelial cells.
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Affiliation(s)
- Nina Stenzel
- Department of Biochemistry II, Ruhr-University Bochum, 44780 Bochum, Germany
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179
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Elia N, Lippincott-Schwartz J. Culturing MDCK cells in three dimensions for analyzing intracellular dynamics. CURRENT PROTOCOLS IN CELL BIOLOGY 2009; Chapter 4:4.22.1-4.22.18. [PMID: 19499508 DOI: 10.1002/0471143030.cb0422s43] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Epithelial cells grown in three-dimensional (3-D) cultures of extracellular matrix differentiate into a multicellular structure of polarized cells. This process shares many characteristics with the physiological development of an epithelial tissue and the formation of polarity in epithelial cells. Imaging 3-D cultures of polarized epithelial cells is therefore a powerful tool to study epithelial architecture and morphogenesis under close-to-physiological conditions. The new generation of confocal microscopes allows live-cell imaging of fluorescently tagged molecules in these cultures. This opens up new opportunities for studying how molecules behave and are distinguished asymmetrically within a 3-D setting. This unit discusses technical aspects for culturing and imaging MDCK 3-D culture for both fixed 3-D cultures and live-cell imaging.
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Affiliation(s)
- Natalie Elia
- Cell Biology and Metabolism Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, USA
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180
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Revenu C, Gilmour D. EMT 2.0: shaping epithelia through collective migration. Curr Opin Genet Dev 2009; 19:338-42. [DOI: 10.1016/j.gde.2009.04.007] [Citation(s) in RCA: 119] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2009] [Accepted: 04/09/2009] [Indexed: 12/14/2022]
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181
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Abstract
A diverse group of developmental biologists who study cell polarity gathered in late March 2009 at the RIKEN Center for Developmental Biology in Kobe, Japan, for a symposium entitled ;Shape and Polarity'. The organizers, Masatoshi Takeichi, Fumio Matsuzaki, Hitoshi Sawa [RIKEN Center for Developmental Biology (CDB), Kobe, Japan] and Carl-Philipp Heisenberg (Max Planck Institute, Dresden, Germany), put together an engaging program that highlighted recent progress towards understanding the mechanisms of cell polarization during development, and the functions of cell polarity in shaping development.
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Affiliation(s)
- Bob Goldstein
- Department of Biology, University of North Carolina, Chapel Hill, Chapel Hill, NC 27599, USA.
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182
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Xiong Y, Antalffy G, Enyedi Á, Strehler EE. Apical localization of PMCA2w/b is lipid raft-dependent. Biochem Biophys Res Commun 2009; 384:32-6. [PMID: 19379709 PMCID: PMC2731683 DOI: 10.1016/j.bbrc.2009.04.044] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2009] [Accepted: 04/11/2009] [Indexed: 01/20/2023]
Abstract
Alternative splicing of the first intracellular loop differentially targets plasma membrane calcium ATPase (PMCA) isoform 2 to the apical or basolateral membrane in MDCK cells. To determine if the targeting is affected by lipid interactions, we stably expressed PMCA2w/b and PMCA2z/b in MDCK cells, and analyzed the PMCA distribution by confocal fluorescence microscopy and membrane fractionation. PMCA2w/b showed clear apical and lateral distribution, whereas PMCA2z/b was mainly localized to the basolateral membrane. A significant fraction of PMCA2w/b partitioned into low-density membranes associated with lipid rafts. Depletion of membrane cholesterol by methyl-beta-cyclodextrin resulted in reduced lipid raft association and a striking loss of PMCA2w/b from the apical membrane, whereas the lateral localization of PMCA2z/b remained unchanged. Our data indicate that alternative splicing differentially affects the lipid interactions of PMCA2w/b and PMCA2z/b and that the apical localization of PMCA2w/b is lipid raft-dependent and sensitive to cholesterol depletion.
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Affiliation(s)
- Yuning Xiong
- Department of Biochemistry and Molecular Biology, College of Medicine, Mayo Clinic, Rochester, MN, USA
| | - Géza Antalffy
- National Blood Center, Department of Molecular Cell Biology, H-1113 Budapest, Hungary
| | - Ágnes Enyedi
- National Blood Center, Department of Molecular Cell Biology, H-1113 Budapest, Hungary
| | - Emanuel E. Strehler
- Department of Biochemistry and Molecular Biology, College of Medicine, Mayo Clinic, Rochester, MN, USA
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183
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Wang JK, Lee MS, Tseng IC, Chou FP, Chen YW, Fulton A, Lee HS, Chen CJ, Johnson MD, Lin CY. Polarized epithelial cells secrete matriptase as a consequence of zymogen activation and HAI-1-mediated inhibition. Am J Physiol Cell Physiol 2009; 297:C459-70. [PMID: 19535514 DOI: 10.1152/ajpcell.00201.2009] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Matriptase, a transmembrane serine protease, is broadly expressed by, and crucial for the integrity of, the epithelium. Matriptase is synthesized as a zymogen and undergoes autoactivation to become an active protease that is immediately inhibited by, and forms complexes with, hepatocyte growth factor activator inhibitor (HAI-1). To investigate where matriptase is activated and how it is secreted in vivo, we determined the expression and activation status of matriptase in seminal fluid and urine and the distribution and subcellular localization of the protease in the prostate and kidney. The in vivo studies revealed that while the latent matriptase is localized at the basolateral surface of the ductal epithelial cells of both organs, only matriptase-HAI-1 complexes and not latent matriptase are detected in the body fluids, suggesting that activation, inhibition, and transcytosis of matriptase would have to occur for the secretion of matriptase. These complicated processes involved in the in vivo secretion were also observed in polarized Caco-2 intestinal epithelial cells. The cells target latent matriptase to the basolateral plasma membrane where activation, inhibition, and secretion of matriptase appear to take place. However, a proportion of matriptase-HAI-1 complexes, but not the latent matriptase, appears to undergo transcytosis to the apical plasma membrane for secretion. When epithelial cells lose their polarity, they secrete both latent and activated matriptase. Although most epithelial cells retain very low levels of matriptase-HAI-1 complex by rapidly secreting the complex, gastric chief cells may activate matriptase and store matriptase-HAI-1 complexes in the pepsinogen-secretory granules, suggesting an intracellular activation and regulated secretion in these cells. Taken together, while zymogen activation and closely coupled HAI-1-mediated inhibition are common features for matriptase regulation, the cellular location of matriptase activation and inhibition, and the secretory route for matriptase-HAI-1 complex may vary along with the functional divergence of different epithelial cells.
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Affiliation(s)
- Jehng-Kang Wang
- Department of Biochemistry, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan
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184
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Abstract
The ability to form epithelial lumina is a central architectural characteristic of virtually all organs and indispensable for their function. Ontogenetically, the kidney is one of the best-characterized organs, but concepts of the regulated formation of its hollow epithelial structures are still emerging. Epithelial cell lines provide the opportunity to study molecular mechanisms in simplified assays modeling cyst and tube formation. In these systems, several groups have identified molecules implicated in lumen formation, and their downregulation results in either multiple-lumen or no-lumen phenotypes. On the basis of these phenotypes, we propose a working model, assigning proteins to groups with similar functions. Defects within these specific protein groups lead to distinct epithelial phenotypes. Studies of mesenchymal-to-epithelial transition underline the importance of these protein groups, but converting these basic models of lumen formation to an understanding of the mesenchymal to tubule formation during kidney development is still challenging.
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Affiliation(s)
- Marc A Schlüter
- Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI 48109-2200, USA
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185
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Antoniou A, Raynaud P, Cordi S, Zong Y, Tronche F, Stanger B, Jacquemin P, Pierreux CE, Clotman F, Lemaigre FP. Intrahepatic bile ducts develop according to a new mode of tubulogenesis regulated by the transcription factor SOX9. Gastroenterology 2009; 136:2325-33. [PMID: 19403103 PMCID: PMC2743481 DOI: 10.1053/j.gastro.2009.02.051] [Citation(s) in RCA: 265] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/28/2008] [Revised: 01/13/2009] [Accepted: 02/06/2009] [Indexed: 02/07/2023]
Abstract
BACKGROUND & AIMS A number of diseases are characterized by defective formation of the intrahepatic bile ducts. In the embryo, hepatoblasts differentiate to cholangiocytes, which give rise to the bile ducts. Here, we investigated duct development in mouse liver and characterized the role of the SRY-related HMG box transcription factor 9 (SOX9). METHODS We identified SOX9 as a new biliary marker and used it in immunostaining experiments to characterize bile duct morphogenesis. The expression of growth factors was determined by in situ hybridization and immunostaining, and their role was studied on cultured hepatoblasts. SOX9 function was investigated by phenotyping mice with a liver-specific inactivation of Sox9. RESULTS Biliary tubulogenesis started with formation of asymmetrical ductal structures, lined on the portal side by cholangiocytes and on the parenchymal side by hepatoblasts. When the ducts grew from the hilum to the periphery, the hepatoblasts lining the asymmetrical structures differentiated to cholangiocytes, thereby allowing formation of symmetrical ducts lined only by cholangiocytes. We also provide evidence that transforming growth factor-beta promotes differentiation of the hepatoblasts lining the asymmetrical structures. In the absence of SOX9, the maturation of asymmetrical structures into symmetrical ducts was delayed. This was associated with abnormal expression of CCAAT/Enhancer Binding Protein alpha and Homolog of Hairy/Enhancer of Split-1, as well as of the transforming growth factor-beta receptor type II, which are regulators of biliary development. CONCLUSIONS Our results suggest that biliary development proceeds according to a new mode of tubulogenesis characterized by transient asymmetry and whose timing is controlled by SOX9.
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Affiliation(s)
- Aline Antoniou
- Université catholique de Louvain, de Duve Institute, Avenue Hippocrate 75/7529, 1200 Brussels, Belgium
| | - Peggy Raynaud
- Université catholique de Louvain, de Duve Institute, Avenue Hippocrate 75/7529, 1200 Brussels, Belgium
| | - Sabine Cordi
- Université catholique de Louvain, de Duve Institute, Avenue Hippocrate 75/7529, 1200 Brussels, Belgium
| | - Yiwei Zong
- Division of Gastroenterology, Abramson Family Cancer Research Institute, University of Pennsylvania School of Medicine, 512 BRB II/III, 421 Curie Boulevard, Philadelphia, PA 19104-6160, USA
| | - François Tronche
- CNRS UMR 7148, Institut de Biologie, Collège de France, Place Marcelin Berthelot 11, 75231 Paris, France
| | - Ben Stanger
- Division of Gastroenterology, Abramson Family Cancer Research Institute, University of Pennsylvania School of Medicine, 512 BRB II/III, 421 Curie Boulevard, Philadelphia, PA 19104-6160, USA
| | - Patrick Jacquemin
- Université catholique de Louvain, de Duve Institute, Avenue Hippocrate 75/7529, 1200 Brussels, Belgium
| | - Christophe E. Pierreux
- Université catholique de Louvain, de Duve Institute, Avenue Hippocrate 75/7529, 1200 Brussels, Belgium
| | - Frederic Clotman
- Université catholique de Louvain, de Duve Institute, Avenue Hippocrate 75/7529, 1200 Brussels, Belgium
| | - Frederic P. Lemaigre
- Université catholique de Louvain, de Duve Institute, Avenue Hippocrate 75/7529, 1200 Brussels, Belgium
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186
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Xu J, Lamouille S, Derynck R. TGF-beta-induced epithelial to mesenchymal transition. Cell Res 2009; 19:156-72. [PMID: 19153598 DOI: 10.1038/cr.2009.5] [Citation(s) in RCA: 2039] [Impact Index Per Article: 135.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
During development and in the context of different morphogenetic events, epithelial cells undergo a process called epithelial to mesenchymal transition or transdifferentiation (EMT). In this process, the cells lose their epithelial characteristics, including their polarity and specialized cell-cell contacts, and acquire a migratory behavior, allowing them to move away from their epithelial cell community and to integrate into surrounding tissue, even at remote locations. EMT illustrates the differentiation plasticity during development and is complemented by another process, called mesenchymal to epithelial transition (MET). While being an integral process during development, EMT is also recapitulated under pathological conditions, prominently in fibrosis and in invasion and metastasis of carcinomas. Accordingly, EMT is considered as an important step in tumor progression. TGF-beta signaling has been shown to play an important role in EMT. In fact, adding TGF-beta to epithelial cells in culture is a convenient way to induce EMT in various epithelial cells. Although much less characterized, epithelial plasticity can also be regulated by TGF-beta-related bone morphogenetic proteins (BMPs), and BMPs have been shown to induce EMT or MET depending on the developmental context. In this review, we will discuss the induction of EMT in response to TGF-beta, and focus on the underlying signaling and transcription mechanisms.
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Affiliation(s)
- Jian Xu
- Department of Cell and Tissue Biology, Programs in Cell Biology and Developmental Biology, University of California-San Francisco, San Francisco, CA, USA
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188
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Alford LM, Ng MM, Burgess DR. Cell polarity emerges at first cleavage in sea urchin embryos. Dev Biol 2009; 330:12-20. [PMID: 19298809 DOI: 10.1016/j.ydbio.2009.02.039] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2008] [Revised: 02/24/2009] [Accepted: 02/25/2009] [Indexed: 12/26/2022]
Abstract
In protostomes, cell polarity is present after fertilization whereas most deuterostome embryos show minimal polarity during the early cleavages. We now show establishment of cell polarity as early as the first cleavage division in sea urchin embryos. We find, using the apical markers G(M1), integrins, and the aPKC-PAR6 complex, that cells are polarized upon insertion of distinct basolateral membrane at the first division. This early apical-basolateral polarity, similar to that found in much larger cleaving amphibian zygotes, reflects precocious functional epithelial cell polarity. Isolated cleavage blastomeres exhibit polarized actin-dependent fluid phase endocytosis only on the G(M1), integrin, microvillus-containing apical surface. A role for a functional PAR complex in cleavage plane determination was shown with experiments interfering with aPKC activity, which results in several spindle defects and compromised blastula development. These studies suggest that cell and embryonic polarity is established at the first cleavage, mediated in part by the Par complex of proteins, and is achieved by directed insertion of basolateral membrane in the cleavage furrow.
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Affiliation(s)
- Lea M Alford
- Biology Department, Boston College, 140 Commonwealth Ave., Chestnut Hill, MA 02467, USA
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189
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Ferrari A, Veligodskiy A, Berge U, Lucas MS, Kroschewski R. ROCK-mediated contractility, tight junctions and channels contribute to the conversion of a preapical patch into apical surface during isochoric lumen initiation. J Cell Sci 2009; 121:3649-63. [PMID: 18946028 DOI: 10.1242/jcs.018648] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Epithelial cells assemble into three-dimensional aggregates to generate lumen-containing organ substructures. Cells therein contact the extracellular matrix with their basal surface, neighbouring cells with their contact surface and the lumen with their apical surface. We investigated the development of single MDCK cells into aggregates with lumen using quantitative live-cell imaging to identify morphogenetic rules for lumen formation. In two-cell aggregates, membrane insertion into the contact surface established a preapical patch (PAP) characterized by the presence of the apical marker gp135, microvilli and the absence of E-cadherin. This PAP originated from a compartment that had hallmarks of an apical recycling endosome, and matured through Brefeldin-A-sensitive membrane trafficking and the establishment of tight junctions around itself. As a result of the activity of water and ion channels, an optically resolvable lumen formed. Initially, this lumen enlarged without changes in aggregate volume or cell number but with decreasing cell volumes. Additionally, the ROCK1/2-myosin-II pathway counteracted PAP and lumen formation. Thus, lumen formation results from PAP establishment, PAP maturation, lumen initiation and lumen enlargement. These phases correlate with distinct cell surface and volume patterns, which suggests that such morphometric parameters are regulated by trafficking, ROCK-mediated contractility and hydrostatic pressure or vice versa.
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Affiliation(s)
- Aldo Ferrari
- Institute of Biochemistry, ETH Zurich, Schafmattstrasse 18, 8093 Zurich, Switzerland
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190
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Affiliation(s)
- Seyeon Chung
- Department of Cell Biology, The Johns Hopkins University School of Medicine, 725 N. Wolfe Street, Baltimore, MD 21296, USA
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191
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Geldner N. Cell polarity in plants: a PARspective on PINs. CURRENT OPINION IN PLANT BIOLOGY 2009; 12:42-8. [PMID: 18993110 DOI: 10.1016/j.pbi.2008.09.009] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2008] [Revised: 09/16/2008] [Accepted: 09/23/2008] [Indexed: 05/21/2023]
Abstract
Plants have acquired the ability for organized multicellular development independent from animals. Because of this, they represent an independent example in nature for the development of coordinated, complex cell polarity from the simple polarity found in unicellular eukaryotes. Plants display a striking array of polarized cell types, with different axes of polarity being defined in one cell. The most investigated and best understood aspect of plant polarity is the apical-basal polarity of the PIN family of auxin efflux facilitators, which are of crucial importance for the organization of the entire plant body. Striking differences exist between the PAR-polarity modules known in animals and the ways PINs polarize plant cells. Nonetheless, a common regulatory logic probably applies to all polarizing eukaryotic cells, which includes self-reinforcing, positive feedback loops, intricate interactions between membrane-attached proteins, lipid signatures, and the targeting of transmembrane proteins to the correct domains of the plasma membrane.
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Affiliation(s)
- Niko Geldner
- Department of Plant Molecular Biology (DBMV), University of Lausanne, UNIL-Sorge, Biophore Building, Lausanne, Switzerland.
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192
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Abstract
In the past 20 years, the discovery and characterization of the molecular machinery that controls cellular polarization have enabled us to achieve a better understanding of many biological processes. Spatial asymmetry or establishment of cell polarity during embryogenesis, epithelial morphogenesis, neuronal differentiation, and migration of fibroblasts and T cells are thought to rely on a small number of evolutionarily conserved proteins and pathways. Correct polarization is crucial for normal cell physiology and tissue homeostasis, and is lost in cancer. Thus, cell polarity signaling is likely to have an important function in tumor progression. Recent findings have identified a regulator of cell polarity, the Par complex, as an important signaling node in tumorigenesis. In normal cell types, the Par complex is part of the molecular machinery that regulates cell polarity and maintains normal cell homeostasis. As such, the polarity regulators are proposed to have a tumor suppressor function, consistent with the loss of polarity genes associated with hyperproliferation in Drosophila melanogaster. However, recent studies showing that some members of this complex also display pro-oncogenic activities suggest a more complex regulation of the polarity machinery during cellular transformation. Here, we examine the existing data about the different functions of the Par complex. We discuss how spatial restriction, binding partners and substrate specificity determine the signaling properties of Par complex proteins. A better understanding of these processes will very likely shed some light on how the Par complex can switch from a normal polarity regulation function to promotion of transformation downstream of oncogenes.
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193
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Martín‐Belmonte F, Rodríguez‐Fraticelli AE. Chapter 3 Acquisition of Membrane Polarity in Epithelial Tube Formation. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2009; 274:129-82. [DOI: 10.1016/s1937-6448(08)02003-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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194
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Gordon SR. Cell Migration along the Basement Membrane during Wound Repair. The Corneal Endothelium as a Model System. BIOENGINEERING RESEARCH OF CHRONIC WOUNDS 2009. [DOI: 10.1007/978-3-642-00534-3_3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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195
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The epithelial polarity program: machineries involved and their hijacking by cancer. Oncogene 2008; 27:6939-57. [DOI: 10.1038/onc.2008.345] [Citation(s) in RCA: 135] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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196
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Li R, Gundersen GG. Beyond polymer polarity: how the cytoskeleton builds a polarized cell. Nat Rev Mol Cell Biol 2008; 9:860-73. [PMID: 18946475 DOI: 10.1038/nrm2522] [Citation(s) in RCA: 294] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Cell polarity relies on the asymmetric organization of cellular components and structures. Actin and microtubules are well suited to provide the structural basis for cell polarization because of their inherent structural polarity along the polymer lattices and intrinsic dynamics that allow them to respond rapidly to polarity cues. In general, the actin cytoskeleton drives the symmetry-breaking process that enables the establishment of a polarized distribution of regulatory molecules, whereas microtubules build on this asymmetry and maintain the stability of the polarized organization. Crosstalk coordinates the functions of the two cytoskeletal systems.
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Affiliation(s)
- Rong Li
- The Stowers Institute for Medical Research, 1000 East 50th Street, Kansas City, Missouri 64110, USA.
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197
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Etienne-Manneville S. Polarity proteins in glial cell functions. Curr Opin Neurobiol 2008; 18:488-94. [PMID: 18840525 DOI: 10.1016/j.conb.2008.09.014] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2008] [Revised: 09/18/2008] [Accepted: 09/24/2008] [Indexed: 12/31/2022]
Abstract
Glial cells, which include myelinating oligodendrocytes, Schwann cells and astrocytes, fulfil a large variety of functions that are critical for the development, functioning and regeneration of neurons. Some of these glial functions have been shown to require polarization of the intracellular machinery. Although the initial signals leading to glial cell polarization during development and in the adult are not completely elucidated, crucial molecules such as proteins of the extracellular matrix and their membrane receptors have been identified. A general picture of the intracellular signalling pathways controlling polarity in glial cells is also emerging and shows that highly conserved and ubiquitously expressed polarity proteins are involved.
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198
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Abstract
The high frequency of phosphoinositide 3-kinase (PI3K) pathway alterations in cancer has led to a surge in the development of PI3K inhibitors. Many of these targeted therapies are currently in clinical trials and show great promise for the treatment of PI3K-addicted tumors. These recent developments call for a re-evaluation of the oncogenic mechanisms behind PI3K pathway alterations. This pathway is unique in that every major node is frequently mutated or amplified in a wide variety of solid tumors. Receptor tyrosine kinases upstream of PI3K, the p110 alpha catalytic subunit of PI3K, the downstream kinase, AKT, and the negative regulator, PTEN, are all frequently altered in cancer. In this review, we will examine the oncogenic properties of these genetic alterations to understand whether they are redundant or distinct and propose treatment strategies tailored for these genetic lesions.
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199
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Class 1A PI3K regulates vessel integrity during development and tumorigenesis. Proc Natl Acad Sci U S A 2008; 105:9739-44. [PMID: 18621722 DOI: 10.1073/pnas.0804123105] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
PI3K is important in the regulation of growth, proliferation, and survival of tumor cells. We show that class 1A PI3K is also critical in the tumor microenvironment by regulating the integrity of the tumor vasculature. Using Tie2Cre-mediated deletion of the PI3K regulatory subunits (p85alpha, p55alpha, p50alpha, and p85beta), we generated mice with endothelial cell-specific loss of class 1A PI3K. Complete loss of all subunits caused acute embryonic lethality at E11.5 due to hemorrhaging, whereas retention of a single p85alpha allele yielded viable mice that survived to adulthood. These heterozygous mice exhibited no vascular defects until challenged with a pathological insult, such as tumor cells or high levels of VEGF. Under these pathological conditions, heterozygous mice exhibited localized vascular abnormalities, including vessel leakage and the inability to maintain large vessels, which caused a deceleration of tumorigenesis. Furthermore, we show that a PI3K inhibitor can mimic the effects of class 1A PI3K loss, which suggests that targeting class 1A PI3K may be a promising therapy for blocking tumor angiogenesis.
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