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Huber RJ, Kim WD. Trafficking of adhesion and aggregation-modulating proteins during the early stages of Dictyostelium development. Cell Signal 2024; 121:111292. [PMID: 38986731 DOI: 10.1016/j.cellsig.2024.111292] [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: 07/03/2024] [Accepted: 07/06/2024] [Indexed: 07/12/2024]
Abstract
The social amoeba Dictyostelium discoideum has been studied for close to a century to better understand conserved cellular and developmental processes. The life cycle of this model eukaryote is composed of a unicellular growth phase and a multicellular developmental phase that is induced by starvation. When starved, individual cells undergo chemotactic aggregation to form multicellular mounds that develop into slugs. Terminal differentiation of cells within slugs forms fruiting bodies, each composed of a stalk that supports a mass of viable spores that germinate and restart the life cycle when nutrients become available. Calcium-dependent cell adhesion protein A (CadA) and countin (CtnA) are two proteins that regulate adhesion and aggregation, respectively, during the early stages of D. discoideum development. While the functions of these proteins have been well-studied, the mechanisms regulating their trafficking are not fully understood. In this study, we reveal pathways and cellular components that regulate the intracellular and extracellular amounts of CadA and CtnA during aggregation. During growth and starvation, CtnA localizes to cytoplasmic vesicles and punctae. We show that CtnA is glycosylated and this post-translational modification is required for its secretion. Upon autophagy induction, a signal peptide for secretion facilitates the release of CtnA from cells via a pathway involving the μ subunit of the AP3 complex (Apm3) and the WASP and SCAR homolog, WshA. Additionally, CtnA secretion is negatively regulated by the D. discoideum orthologs of the human non-selective cation channel mucolipin-1 (Mcln) and sorting receptor sortilin (Sort1). As for CadA, it localizes to the cell periphery in growth-phase and starved cells. The intracellular and extracellular amounts of CadA are modulated by autophagy genes (atg1, atg9), Apm3, WshA, and Mcln. We integrate these data with previously published findings to generate a comprehensive model summarizing the trafficking of CadA and CtnA in D. discoideum. Overall, this study enhances our understanding of protein trafficking during D. discoideum aggregation, and more broadly, provides insight into the multiple pathways that regulate protein trafficking and secretion in all eukaryotes.
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Affiliation(s)
- Robert J Huber
- Department of Biology, Trent University, Peterborough, Ontario, Canada.
| | - William D Kim
- Environmental and Life Sciences Graduate Program, Trent University, Peterborough, Ontario, Canada
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Abstract
The neuronal ceroid lipofuscinoses (NCLs), collectively known as Batten disease, are a group of neurological diseases that affect all ages and ethnicities worldwide. There are 13 different subtypes of NCL, each caused by a mutation in a distinct gene. The NCLs are characterized by the accumulation of undigestible lipids and proteins in various cell types. This leads to progressive neurodegeneration and clinical symptoms including vision loss, progressive motor and cognitive decline, seizures, and premature death. These diseases have commonly been characterized by lysosomal defects leading to the accumulation of undigestible material but further research on the NCLs suggests that altered protein secretion may also play an important role. This has been strengthened by recent work in biomedical model organisms, including Dictyostelium discoideum, mice, and sheep. Research in D. discoideum has reported the extracellular localization of some NCL-related proteins and the effects of NCL-related gene loss on protein secretion during unicellular growth and multicellular development. Aberrant protein secretion has also been observed in mammalian models of NCL, which has allowed examination of patient-derived cerebrospinal fluid and urine for potential diagnostic and prognostic biomarkers. Accumulated evidence links seven of the 13 known NCL-related genes to protein secretion, suggesting that altered secretion is a common hallmark of multiple NCL subtypes. This Review highlights the impact of altered protein secretion in the NCLs, identifies potential biomarkers of interest and suggests that future work in this area can provide new therapeutic insight. Summary: This Review discusses work in different model systems and humans, examining the impact of altered protein secretion in the neuronal ceroid lipofuscinoses group of diseases to provide novel therapeutic insights.
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Affiliation(s)
- Robert J Huber
- Department of Biology, Trent University, Life & Health Sciences Building, 1600 West Bank Drive, Peterborough, Ontario K9L 0G2, Canada
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Abundant Perithecial Protein (APP) from Neurospora is a primitive functional analog of ocular crystallins. Biochem Biophys Res Commun 2019; 516:796-800. [PMID: 31255285 DOI: 10.1016/j.bbrc.2019.06.102] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2019] [Accepted: 06/18/2019] [Indexed: 11/21/2022]
Abstract
The eye arose during the Cambrian explosion from pre-existing proteins that would have been recruited for the formation of the specialized components of this organ, such as the transparent lens. Proteins suitable for the role of lens crystallins would need to possess unusual physical properties and the study of such earliest analogs of ocular crystallins would add to our understanding of the nature of recruitment of proteins as lens/corneal crystallins. We show that the Abundant Perithecial Protein (APP) of the fungi Neurospora and Sordaria fulfils the criteria for an early crystallin analog. The perithecia in these fungal species are phototropic, and APP accumulates at a high concentration in the neck of the pitcher-shaped perithecium. Spores are formed at the base of the perithecium, and light contributes to their maturation. The hydrodynamic properties of APP appear to exclude dimer formation or aggregation at high protein concentrations. APP is also deficient in Ca2+ binding, a property seen in its close homolog, the calcium-binding cell adhesion molecule (DdCAD-1) from Dictyostelium discoidum. Comparable to crystallins, APP occurs in high concentrations and seems to have dispensed with Ca2+ binding in exchange for greater stability. These crystallin-like attributes of APP lead us to demonstrate that it is a primitive form of ocular crystallins.
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Batsios P, Ishikawa-Ankerhold HC, Roth H, Schleicher M, Wong CCL, Müller-Taubenberger A. Ate1-mediated posttranslational arginylation affects substrate adhesion and cell migration in Dictyostelium discoideum. Mol Biol Cell 2018; 30:453-466. [PMID: 30586322 PMCID: PMC6594445 DOI: 10.1091/mbc.e18-02-0132] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
The highly conserved enzyme arginyl-tRNA-protein transferase (Ate1) mediates arginylation, a posttranslational modification that is only incompletely understood at its molecular level. To investigate whether arginylation affects actin-dependent processes in a simple model organism, Dictyostelium discoideum, we knocked out the gene encoding Ate1 and characterized the phenotype of ate1-null cells. Visualization of actin cytoskeleton dynamics by live-cell microscopy indicated significant changes in comparison to wild-type cells. Ate1-null cells were almost completely lacking focal actin adhesion sites at the substrate-attached surface and were only weakly adhesive. In two-dimensional chemotaxis assays toward folate or cAMP, the motility of ate1-null cells was increased. However, in three-dimensional chemotaxis involving more confined conditions, the motility of ate1-null cells was significantly reduced. Live-cell imaging showed that GFP-tagged Ate1 rapidly relocates to sites of newly formed actin-rich protrusions. By mass spectrometric analysis, we identified four arginylation sites in the most abundant actin isoform of Dictyostelium, in addition to arginylation sites in other actin isoforms and several actin-binding proteins. In vitro polymerization assays with actin purified from ate1-null cells revealed a diminished polymerization capacity in comparison to wild-type actin. Our data indicate that arginylation plays a crucial role in the regulation of cytoskeletal activities.
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Affiliation(s)
- Petros Batsios
- Department of Cell Biology (Anatomy III), Ludwig Maximilian University of Munich, 82152 Planegg-Martinsried, Germany
| | - Hellen C Ishikawa-Ankerhold
- Department of Cell Biology (Anatomy III), Ludwig Maximilian University of Munich, 82152 Planegg-Martinsried, Germany
| | - Heike Roth
- Department of Cell Biology (Anatomy III), Ludwig Maximilian University of Munich, 82152 Planegg-Martinsried, Germany
| | - Michael Schleicher
- Department of Cell Biology (Anatomy III), Ludwig Maximilian University of Munich, 82152 Planegg-Martinsried, Germany
| | - Catherine C L Wong
- National Center for Protein Science Shanghai, Institute of Biochemistry and Cell Biology, Shanghai Institutes of Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Annette Müller-Taubenberger
- Department of Cell Biology (Anatomy III), Ludwig Maximilian University of Munich, 82152 Planegg-Martinsried, Germany
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Swaroop Srivastava S, Raman R, Kiran U, Garg R, Chadalawada S, Pawar AD, Sankaranarayanan R, Sharma Y. Interface interactions between βγ-crystallin domain and Ig-like domain render Ca 2+ -binding site inoperative in abundant perithecial protein of Neurospora crassa. Mol Microbiol 2018; 110:955-972. [PMID: 30216631 DOI: 10.1111/mmi.14130] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/10/2018] [Indexed: 11/30/2022]
Abstract
We describe a set of proteins in which a βγ-crystallin domain pairs with an Ig-like domain, and which are confined to microbes, like bacteria, slime molds and fungi. DdCAD-1 (Ca2+ -dependent cell adhesion molecule-1) and abundant perithecial protein (APP) represent this class of molecules. Using the crystal structure of APP-NTD (N-terminal domain of APP), we describe its mode of Ca2+ binding and provide a generalized theme for correct identification of the Ca2+ -binding site within this class of molecules. As a common feature, one of the two Ca2+ -binding sites is non-functional in the βγ-crystallin domains of these proteins. While APP-NTD binds Ca2+ with a micromolar affinity which is comparable to DdCAD-1, APP surprisingly does not bind Ca2+ . Crystal structures of APP and Ca2+ -bound APP-NTD reveal that the interface interactions in APP render its Ca2+ -binding site inoperative. Thus, heterodomain association provides a novel mode of Ca2+ -binding regulation in APP. Breaking the interface interactions (mutating Asp30Ala, Leu132Ala and Ile135Ala) or separation from the Ig-like domain removes the constraints upon the required conformational transition and enables the βγ-crystallin domain to bind Ca2+ . In mechanistic detail, our work demonstrates an interdomain interface adapted to distinct functional niches in APP and its homolog DdCAD-1.
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Affiliation(s)
| | - Rajeev Raman
- CSIR - Centre for Cellular and Molecular Biology (CCMB), Hyderabad, 500 007, India
| | - Uday Kiran
- CSIR - Centre for Cellular and Molecular Biology (CCMB), Hyderabad, 500 007, India
| | - Rupsi Garg
- CSIR - Centre for Cellular and Molecular Biology (CCMB), Hyderabad, 500 007, India
| | - Swathi Chadalawada
- CSIR - Centre for Cellular and Molecular Biology (CCMB), Hyderabad, 500 007, India
| | - Asmita D Pawar
- CSIR - Centre for Cellular and Molecular Biology (CCMB), Hyderabad, 500 007, India
| | - Rajan Sankaranarayanan
- CSIR - Centre for Cellular and Molecular Biology (CCMB), Hyderabad, 500 007, India.,Academy of Scientific and Innovative Research (AcSIR), New Delhi, India
| | - Yogendra Sharma
- CSIR - Centre for Cellular and Molecular Biology (CCMB), Hyderabad, 500 007, India.,Academy of Scientific and Innovative Research (AcSIR), New Delhi, India
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Dinh C, Farinholt T, Hirose S, Zhuchenko O, Kuspa A. Lectins modulate the microbiota of social amoebae. Science 2018; 361:402-406. [DOI: 10.1126/science.aat2058] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2018] [Revised: 04/20/2018] [Accepted: 06/21/2018] [Indexed: 01/19/2023]
Abstract
The social amoebaDictyostelium discoideummaintains a microbiome during multicellular development; bacteria are carried in migrating slugs and as endosymbionts within amoebae and spores. Bacterial carriage and endosymbiosis are induced by the secreted lectin discoidin I that binds bacteria, protects them from extracellular killing, and alters their retention within amoebae. This altered handling of bacteria also occurs with bacteria coated by plant lectins and leads to DNA transfer from bacteria to amoebae. Thus, lectins alter the cellular response ofD. discoideumto bacteria to establish the amoebae’s microbiome. Mammalian cells can also maintain intracellular bacteria when presented with bacteria coated with lectins, so heterologous lectins may induce endosymbiosis in animals. Our results suggest that endogenous or environmental lectins may influence microbiome homeostasis across eukaryotic phylogeny.
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Plattner H. Evolutionary Cell Biology of Proteins from Protists to Humans and Plants. J Eukaryot Microbiol 2017; 65:255-289. [PMID: 28719054 DOI: 10.1111/jeu.12449] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Revised: 07/04/2017] [Accepted: 07/07/2017] [Indexed: 01/10/2023]
Abstract
During evolution, the cell as a fine-tuned machine had to undergo permanent adjustments to match changes in its environment, while "closed for repair work" was not possible. Evolution from protists (protozoa and unicellular algae) to multicellular organisms may have occurred in basically two lineages, Unikonta and Bikonta, culminating in mammals and angiosperms (flowering plants), respectively. Unicellular models for unikont evolution are myxamoebae (Dictyostelium) and increasingly also choanoflagellates, whereas for bikonts, ciliates are preferred models. Information accumulating from combined molecular database search and experimental verification allows new insights into evolutionary diversification and maintenance of genes/proteins from protozoa on, eventually with orthologs in bacteria. However, proteins have rarely been followed up systematically for maintenance or change of function or intracellular localization, acquirement of new domains, partial deletion (e.g. of subunits), and refunctionalization, etc. These aspects are discussed in this review, envisaging "evolutionary cell biology." Protozoan heritage is found for most important cellular structures and functions up to humans and flowering plants. Examples discussed include refunctionalization of voltage-dependent Ca2+ channels in cilia and replacement by other types during evolution. Altogether components serving Ca2+ signaling are very flexible throughout evolution, calmodulin being a most conservative example, in contrast to calcineurin whose catalytic subunit is lost in plants, whereas both subunits are maintained up to mammals for complex functions (immune defense and learning). Domain structure of R-type SNAREs differs in mono- and bikonta, as do Ca2+ -dependent protein kinases. Unprecedented selective expansion of the subunit a which connects multimeric base piece and head parts (V0, V1) of H+ -ATPase/pump may well reflect the intriguing vesicle trafficking system in ciliates, specifically in Paramecium. One of the most flexible proteins is centrin when its intracellular localization and function throughout evolution is traced. There are many more examples documenting evolutionary flexibility of translation products depending on requirements and potential for implantation within the actual cellular context at different levels of evolution. From estimates of gene and protein numbers per organism, it appears that much of the basic inventory of protozoan precursors could be transmitted to highest eukaryotic levels, with some losses and also with important additional "inventions."
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Affiliation(s)
- Helmut Plattner
- Department of Biology, University of Konstanz, P. O. Box M625, Konstanz, 78457, Germany
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8
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Huber RJ, Myre MA, Cotman SL. Aberrant adhesion impacts early development in a Dictyostelium model for juvenile neuronal ceroid lipofuscinosis. Cell Adh Migr 2016; 11:399-418. [PMID: 27669405 DOI: 10.1080/19336918.2016.1236179] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Neuronal ceroid lipofuscinosis (NCL), also known as Batten disease, refers to a group of severe neurodegenerative disorders that primarily affect children. The most common subtype of the disease is caused by loss-of-function mutations in CLN3, which is conserved across model species from yeast to human. The precise function of the CLN3 protein is not known, which has made targeted therapy development challenging. In the social amoeba Dictyostelium discoideum, loss of Cln3 causes aberrant mid-to-late stage multicellular development. In this study, we show that Cln3-deficiency causes aberrant adhesion and aggregation during the early stages of Dictyostelium development. cln3- cells form ∼30% more multicellular aggregates that are comparatively smaller than those formed by wild-type cells. Loss of Cln3 delays aggregation, but has no significant effect on cell speed or cAMP-mediated chemotaxis. The aberrant aggregation of cln3- cells cannot be corrected by manually pulsing cells with cAMP. Moreover, there are no significant differences between wild-type and cln3- cells in the expression of genes linked to cAMP chemotaxis (e.g., adenylyl cyclase, acaA; the cAMP receptor, carA; cAMP phosphodiesterase, pdsA; g-protein α 9 subunit, gpaI). However, during this time in development, cln3- cells show reduced cell-substrate and cell-cell adhesion, which correlate with changes in the levels of the cell adhesion proteins CadA and CsaA. Specifically, loss of Cln3 decreases the intracellular level of CsaA and increases the amount of soluble CadA in conditioned media. Together, these results suggest that the aberrant aggregation of cln3- cells is due to reduced adhesion during the early stages of development. Revealing the molecular basis underlying this phenotype may provide fresh new insight into CLN3 function.
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Affiliation(s)
- Robert J Huber
- a Department of Biology , Trent University , Peterborough , Ontario , Canada
| | - Michael A Myre
- b Department of Biological Sciences , University of Massachusetts Lowell , Lowell , Massachusetts , USA
| | - Susan L Cotman
- c Center for Human Genetic Research, Massachusetts General Hospital , Harvard Medical School , Boston , Massachusetts , USA
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Loomis WF. Genetic control of morphogenesis in Dictyostelium. Dev Biol 2015; 402:146-61. [PMID: 25872182 PMCID: PMC4464777 DOI: 10.1016/j.ydbio.2015.03.016] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2015] [Revised: 03/12/2015] [Accepted: 03/25/2015] [Indexed: 01/06/2023]
Abstract
Cells grow, move, expand, shrink and die in the process of generating the characteristic shapes of organisms. Although the structures generated during development of the social amoeba Dictyostelium discoideum look nothing like the structures seen in metazoan embryogenesis, some of the morphogenetic processes used in their making are surprisingly similar. Recent advances in understanding the molecular basis for directed cell migration, cell type specific sorting, differential adhesion, secretion of matrix components, pattern formation, regulation and terminal differentiation are reviewed. Genes involved in Dictyostelium aggregation, slug formation, and culmination of fruiting bodies are discussed.
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Affiliation(s)
- William F Loomis
- Cell and Developmental Biology, Division of Biological Sciences, University of California San Diego, La Jolla, CA 92093, United States.
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Li SI, Buttery NJ, Thompson CRL, Purugganan MD. Sociogenomics of self vs. non-self cooperation during development of Dictyostelium discoideum. BMC Genomics 2014; 15:616. [PMID: 25048306 PMCID: PMC4118049 DOI: 10.1186/1471-2164-15-616] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2014] [Accepted: 07/14/2014] [Indexed: 12/21/2022] Open
Abstract
Background Dictyostelium discoideum, a microbial model for social evolution, is known to distinguish self from non-self and show genotype-dependent behavior during chimeric development. Aside from a small number of cell-cell recognition genes, however, little is known about the genetic basis of self/non-self recognition in this species. Based on the key hypothesis that there should be differential expression of genes if D. discoideum cells were interacting with non-clone mates, we performed transcriptomic profiling study in this species during clonal vs. chimeric development. The transcriptomic profiles of D. discoideum cells in clones vs. different chimeras were compared at five different developmental stages using a customized microarray. Effects of chimerism on global transcriptional patterns associated with social interactions were observed. Results We find 1,759 genes significantly different between chimera and clone, 1,144 genes associated significant strain differences, and 6,586 genes developmentally regulated over time. Principal component analysis showed a small amount of the transcriptional variance to chimerism-related factors (Chimerism: 0.18%, Chimerism × Timepoint: 0.03%). There are 162 genes specifically regulated under chimeric development, with continuous small differences between chimera vs. clone over development. Almost 60% of chimera-associated differential genes were differentially expressed at the 4 h aggregate stage, which corresponds to the initial transition of D. discoideum from solitary life to a multicellular phase. Conclusions A relatively small proportion of over-all variation in gene expression is explained by differences between chimeric and clonal development. The relatively small modifications in gene expression associated with chimerism is compatible with the high level of cooperation observed among different strains of D. discoideum; cells of distinct genetic backgrounds will co-aggregate indiscriminately and co-develop into fruiting bodies. Chimeric development may involve re-programming of the transcriptome through small modifications of the developmental genetic network, which may also indicate that response to social interaction involves many genes with individually small transcriptional effect. Electronic supplementary material The online version of this article (doi:10.1186/1471-2164-15-616) contains supplementary material, which is available to authorized users.
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Affiliation(s)
| | | | | | - Michael D Purugganan
- Department of Biology, Center for Genomics and Systems Biology, New York University, New York, NY, 10003, USA.
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Assembly of the TgrB1-TgrC1 cell adhesion complex during Dictyostelium discoideum development. Biochem J 2014; 459:241-9. [PMID: 24490801 DOI: 10.1042/bj20131594] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
In Dictyostelium discoideum, TgrB1 and TgrC1 are partners of a heterophilic cell-adhesion system. To investigate its assembly process, the split GFP complementation assay was used to track the oligomeric status of both proteins. The ability of TgrC1 to form cis-homodimers spontaneously was demonstrated by fluorescence complementation studies and confirmed by chemical cross-linking. In contrast, TgrB1 failed to form cis-homodimers in the absence of TgrC1. Treatment of cell aggregates with antibodies against TgrB1 or TgrC1 did not affect TgrC1 dimerization, but inhibited TgrB1 dimer formation, suggesting that TgrB1 cis-homodimerization is dependent on trans-interaction with TgrC1. When TgrB1 and TgrC1 conjugated with the complementary halves of GFP were co-expressed in cells, cis-heterodimers were not detected. However, weak FRET signals were detected in cells expressing TgrB1-RFP and TgrC1-GFP, suggesting that TgrB1 dimers and TgrC1 dimers were arranged juxtapose to each other in the adhesion complex. The results of the present study suggest that the assembly process is initiated upon trans-interaction of monomeric TgrB1 with TgrC1 homodimers on adjacent cells, which triggers the formation of TgrB1 dimers. The homodimerization of TgrB1 in turn induces the clustering of TgrB1 and TgrC1, and the coalescence of TgrB1-TgrC1 clusters results in the formation of large adhesion complexes.
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Cost HN, Noratel EF, Blumberg DD. AmpA protein functions by different mechanisms to influence early cell type specification and to modulate cell adhesion and actin polymerization in Dictyostelium discoideum. Differentiation 2013; 86:1-12. [PMID: 23911723 DOI: 10.1016/j.diff.2013.06.003] [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: 02/05/2013] [Revised: 06/03/2013] [Accepted: 06/20/2013] [Indexed: 11/16/2022]
Abstract
The Dictyostelium discoideum ampA gene encodes a multifunctional regulator protein that modulates cell-cell and cell-substrate adhesions and actin polymerization during growth and is necessary for correct cell type specification and patterning during development. Insertional inactivation of the ampA gene results in defects that define two distinct roles for the ampA gene during development. AmpA is necessary in a non-cell autonomous manner to prevent premature expression of a prespore gene marker. It is also necessary in a cell autonomous manner for the anterior like cells, which express the ampA gene, to migrate to the upper cup during culmination. It is also necessary to prevent excessive cell-cell agglutination when cells are developed in a submerged suspension culture. Here, we demonstrate that a supernatant source of AmpA protein, added extracellularly, can prevent the premature mis-expression of the prespore marker. Synthetic oligopeptides are used to identify the domain of the AmpA protein that is important for preventing cells from mis-expressing the prespore gene. We further demonstrate that a factor capable of inducing additional cells to express the prespore gene marker accumulates extracellularly in the absence of AmpA protein. While the secreted AmpA acts extracellularly to suppress prespore gene expression, the effects of AmpA on cell agglutination and on actin polymerization in growing cells are not due to an extracellular role of secreted AmpA protein. Rather, these effects appear to reflect a distinct cell autonomous role of the ampA gene. Finally, we show that secretion of AmpA protein is brought about by elevating the levels of expression of ampA so that the protein accumulates to an excessive level.
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Affiliation(s)
- Hoa N Cost
- Department of Biological Sciences, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250, USA
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TgrC1 mediates cell–cell adhesion by interacting with TgrB1 via mutual IPT/TIG domains during development of Dictyostelium discoideum. Biochem J 2013; 452:259-69. [DOI: 10.1042/bj20121674] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Cell–cell adhesion plays crucial roles in cell differentiation and morphogenesis during development of Dictyostelium discoideum. The heterophilic adhesion protein TgrC1 (Tgr is transmembrane, IPT, IG, E-set, repeat protein) is expressed during cell aggregation, and disruption of the tgrC1 gene results in the arrest of development at the loose aggregate stage. We have used far-Western blotting coupled with MS to identify TgrB1 as the heterophilic binding partner of TgrC1. Co-immunoprecipitation and pull-down studies showed that TgrB1 and TgrC1 are capable of binding with each other in solution. TgrB1 and TgrC1 are encoded by a pair of adjacent genes which share a common promoter. Both TgrB1 and TgrC1 are type I transmembrane proteins, which contain three extracellular IPT/TIG (immunoglobulin, plexin, transcription factor-like/transcription factor immunoglobulin) domains. Antibodies raised against TgrB1 inhibit cell reassociation at the post-aggregation stage of development and block fruiting body formation. Ectopic expression of TgrB1 and TgrC1 driven by the actin15 promoter leads to heterotypic cell aggregation of vegetative cells. Using recombinant proteins that cover different portions of TgrB1 and TgrC1 in binding assays, we have mapped the cell-binding regions in these two proteins to Lys537–Ala783 in TgrB1 and Ile336–Val360 in TgrC1, corresponding to their respective TIG3 and TIG2 domain.
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Yang C, Hou L, Yang Q, Siu CH. ATP-Binding Cassette Transporter B4 Anchors the Cell Adhesion Molecule DdCAD-1 to Cell Membrane in Dictyostelium discoideum. Indian J Microbiol 2013; 53:460-6. [PMID: 24426151 DOI: 10.1007/s12088-013-0393-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2013] [Accepted: 03/16/2013] [Indexed: 12/13/2022] Open
Abstract
In Dictyostelium, soluble cell adhesion molecule, DdCAD-1, regulates cell-cell interaction through an unknown anchoring protein on the plasma membrane. Far western blot analysis using different probes revealed that the potential DdCAD-1 interacting protein was between 64 and 98 kDa. To isolate and identify the anchoring protein, GST-DdCAD-1 and anchoring protein were cross-linked in vivo by chemical cross-linker and stable protein complex was isolated by co-immunoprecipitation assays. The protein cross-linked to DdCAD-1 was extracted from the gel slice and trypsinized. The peptides were subjected to analysis by mass spectrometry, which showed that the putative anchoring protein belongs to ATP-binding cassette transporter family.
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Affiliation(s)
- Chunxia Yang
- School of Life Science, East China Normal University, 200062 Shanghai, China
| | - Liansheng Hou
- School of Life Science, East China Normal University, 200062 Shanghai, China
| | - Qixiu Yang
- Banting and Best Department of Medical Research and the Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8 Canada
| | - Chi-Hung Siu
- Banting and Best Department of Medical Research and the Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8 Canada
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Sultana H, Neelakanta G, Rivero F, Blau-Wasser R, Schleicher M, Noegel AA. Ectopic expression of cyclase associated protein CAP restores the streaming and aggregation defects of adenylyl cyclase a deficient Dictyostelium discoideum cells. BMC DEVELOPMENTAL BIOLOGY 2012; 12:3. [PMID: 22239817 PMCID: PMC3316131 DOI: 10.1186/1471-213x-12-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/17/2011] [Accepted: 01/12/2012] [Indexed: 12/02/2022]
Abstract
Background Cell adhesion, an integral part of D. discoideum development, is important for morphogenesis and regulated gene expression in the multicellular context and is required to trigger cell-differentiation. G-protein linked adenylyl cyclase pathways are crucially involved and a mutant lacking the aggregation specific adenylyl cyclase ACA does not undergo multicellular development. Results Here, we have investigated the role of cyclase-associated protein (CAP), an important regulator of cell polarity and F-actin/G-actin ratio in the aca- mutant. We show that ectopic expression of GFP-CAP improves cell polarization, streaming and aggregation in aca- cells, but it fails to completely restore development. Our studies indicate a requirement of CAP in the ACA dependent signal transduction for progression of the development of unicellular amoebae into multicellular structures. The reduced expression of the cell adhesion molecule DdCAD1 together with csA is responsible for the defects in aca- cells to initiate multicellular development. Early development was restored by the expression of GFP-CAP that enhanced the DdCAD1 transcript levels and to a lesser extent the csA mRNA levels. Conclusions Collectively, our data shows a novel role of CAP in regulating cell adhesion mechanisms during development that might be envisioned to unravel the functions of mammalian CAP during animal embryogenesis.
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Affiliation(s)
- Hameeda Sultana
- Center for Biochemistry, Medical Faculty, University of Cologne, 50931 Köln, Germany.
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17
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Sillo A, Matthias J, Konertz R, Bozzaro S, Eichinger L. Salmonella typhimurium is pathogenic for Dictyostelium cells and subverts the starvation response. Cell Microbiol 2011; 13:1793-811. [PMID: 21824247 DOI: 10.1111/j.1462-5822.2011.01662.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
In unicellular amoebae, such as Dictyostelium discoideum, bacterial phagocytosis is a food hunting device, while in higher organisms it is the first defence barrier against microbial infection. In both cases, pathogenic bacteria exploit phagocytosis to enter the cell and multiply intracellularly. Salmonella typhimurium, the agent of food-borne gastroenteritis, is phagocytosed by both macrophages and Dictyostelium cells. By using cell biological assays and global transcriptional analysis with DNA microarrays covering the Dictyostelium genome, we show here that S. typhimurium is pathogenic for Dictyostelium cells. Depending on the degree of virulence, which in turn depended on bacterial growth conditions, Salmonella could kill Dictyostelium cells or inhibit their growth and development. In the early phase of infection in non-nutrient buffer, the ingested bacteria escaped degradation, induced a starvation-like transcriptional response but inhibited selectively genes required for chemotaxis and aggregation. This way differentiation of the host cells into spore and stalk cells was blocked or delayed, which in turn is likely to be favourable for the establishment of a replicative niche for Salmonella. Inhibition of the aggregation competence and chemotactic streaming of aggregation-competent cells in the presence of Salmonella suggests interference with cAMP signalling.
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Affiliation(s)
- Alessio Sillo
- Department of Clinical and Biological Sciences, University of Turin, AOU S. Luigi, 10043 Orbassano (Torino), Italy
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Oda H, Takeichi M. Evolution: structural and functional diversity of cadherin at the adherens junction. ACTA ACUST UNITED AC 2011; 193:1137-46. [PMID: 21708975 PMCID: PMC3216324 DOI: 10.1083/jcb.201008173] [Citation(s) in RCA: 166] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Adhesion between cells is essential to the evolution of multicellularity. Indeed, morphogenesis in animals requires firm but flexible intercellular adhesions that are mediated by subcellular structures like the adherens junction (AJ). A key component of AJs is classical cadherins, a group of transmembrane proteins that maintain dynamic cell-cell associations in many animal species. An evolutionary reconstruction of cadherin structure and function provides a comprehensive framework with which to appreciate the diversity of morphogenetic mechanisms in animals.
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Affiliation(s)
- Hiroki Oda
- JT Biohistory Research Hall, Takatsuki, Osaka 569-1125, Japan.
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Siu CH, Sriskanthadevan S, Wang J, Hou L, Chen G, Xu X, Thomson A, Yang C. Regulation of spatiotemporal expression of cell-cell adhesion molecules during development of Dictyostelium discoideum. Dev Growth Differ 2011; 53:518-27. [DOI: 10.1111/j.1440-169x.2011.01267.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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Sriskanthadevan S, Zhu Y, Manoharan K, Yang C, Siu CH. The cell adhesion molecule DdCAD-1 regulates morphogenesis through differential spatiotemporal expression in Dictyostelium discoideum. Development 2011; 138:2487-97. [PMID: 21561987 DOI: 10.1242/dev.060129] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
During development of Dictyostelium, multiple cell types are formed and undergo a coordinated series of morphogenetic movements guided by their adhesive properties and other cellular factors. DdCAD-1 is a unique homophilic cell adhesion molecule encoded by the cadA gene. It is synthesized in the cytoplasm and transported to the plasma membrane by contractile vacuoles. In chimeras developed on soil plates, DdCAD-1-expressing cells showed greater propensity to develop into spores than did cadA-null cells. When development was performed on non-nutrient agar, wild-type cells sorted from the cadA-null cells and moved to the anterior zone. They differentiated mostly into stalk cells and eventually died, whereas the cadA-null cells survived as spores. To assess the role of DdCAD-1 in this novel behavior of wild-type and mutant cells, cadA-null cells were rescued by the ectopic expression of DdCAD-1-GFP. Morphological studies have revealed major spatiotemporal changes in the subcellular distribution of DdCAD-1 during development. Whereas DdCAD-1 became internalized in most cells in the post-aggregation stages, it was prominent in the contact regions of anterior cells. Cell sorting was also restored in cadA(-) slugs by exogenous recombinant DdCAD-1. Remarkably, DdCAD-1 remained on the surface of anterior cells, whereas it was internalized in the posterior cells. Additionally, DdCAD-1-expressing cells migrated slower than cadA(-) cells and sorted to the anterior region of chimeric slugs. These results show that DdCAD-1 influences the sorting behavior of cells in slugs by its differential distribution on the prestalk and prespore cells.
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Affiliation(s)
- Shrivani Sriskanthadevan
- The Banting and Best Department of Medical Research, University of Toronto, Toronto, ON M5S 1A8, Canada
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Kim JS, Seo JH, Yim HS, Kang SO. Homeoprotein Hbx4 represses the expression of the adhesion molecule DdCAD-1 governing cytokinesis and development. FEBS Lett 2011; 585:1864-72. [DOI: 10.1016/j.febslet.2011.04.052] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2011] [Accepted: 04/11/2011] [Indexed: 10/18/2022]
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Shina MC, Müller R, Blau-Wasser R, Glöckner G, Schleicher M, Eichinger L, Noegel AA, Kolanus W. A cytohesin homolog in Dictyostelium amoebae. PLoS One 2010; 5:e9378. [PMID: 20186335 PMCID: PMC2826412 DOI: 10.1371/journal.pone.0009378] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2009] [Accepted: 02/02/2010] [Indexed: 01/28/2023] Open
Abstract
BACKGROUND Dictyostelium, an amoeboid motile cell, harbors several paralogous Sec7 genes that encode members of three distinct subfamilies of the Sec7 superfamily of Guanine nucleotide exchange factors. Among them are proteins of the GBF/BIG family present in all eukaryotes. The third subfamily represented with three members in D. discoideum is the cytohesin family that has been thought to be metazoan specific. Cytohesins are characterized by a Sec7 PH tandem domain and have roles in cell adhesion and migration. PRINCIPAL FINDINGS Dictyostelium SecG exhibits highest homologies to the cytohesins. It harbors at its amino terminus several ankyrin repeats that are followed by the Sec7 PH tandem domain. Mutants lacking SecG show reduced cell-substratum adhesion whereas cell-cell adhesion that is important for development is not affected. Accordingly, multicellular development proceeds normally in the mutant. During chemotaxis secG(-) cells elongate and migrate in a directed fashion towards cAMP, however speed is moderately reduced. SIGNIFICANCE The data indicate that SecG is a relevant factor for cell-substrate adhesion and reveal the basic function of a cytohesin in a lower eukaryote.
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Affiliation(s)
- Maria Christina Shina
- Center for Biochemistry, Medical Faculty, Center for Molecular Medicine Cologne (CMMC) and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Köln, Germany
| | - Rolf Müller
- Center for Biochemistry, Medical Faculty, Center for Molecular Medicine Cologne (CMMC) and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Köln, Germany
| | - Rosemarie Blau-Wasser
- Center for Biochemistry, Medical Faculty, Center for Molecular Medicine Cologne (CMMC) and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Köln, Germany
| | - Gernot Glöckner
- Center for Biochemistry, Medical Faculty, Center for Molecular Medicine Cologne (CMMC) and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Köln, Germany
- Leibniz Institute for Age Research - Fritz-Lipmann-Institute e.V., Jena, Germany
| | - Michael Schleicher
- Institute of Anatomy and Cell Biology and Center for Integrated Protein Science (CIPSM), Ludwig-Maximilians-University, Muenchen, Germany
| | - Ludwig Eichinger
- Center for Biochemistry, Medical Faculty, Center for Molecular Medicine Cologne (CMMC) and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Köln, Germany
| | - Angelika A. Noegel
- Center for Biochemistry, Medical Faculty, Center for Molecular Medicine Cologne (CMMC) and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Köln, Germany
- * E-mail: (AAN); (WK)
| | - Waldemar Kolanus
- Laboratory of Molecular Immunology, LIMES Institute of the University of Bonn, Bonn, Germany
- * E-mail: (AAN); (WK)
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Sriskanthadevan S, Lee T, Lin Z, Yang D, Siu CH. Cell adhesion molecule DdCAD-1 is imported into contractile vacuoles by membrane invagination in a Ca2+- and conformation-dependent manner. J Biol Chem 2009; 284:36377-36386. [PMID: 19875452 DOI: 10.1074/jbc.m109.057257] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The cadA gene in Dictyostelium encodes a Ca(2+)-dependent cell adhesion molecule DdCAD-1 that contains two beta-sandwich domains. DdCAD-1 is synthesized in the cytoplasm as a soluble protein and then transported by contractile vacuoles to the plasma membrane for surface presentation or secretion. DdCAD-1-green fluorescent protein (GFP) fusion protein was expressed in cadA-null cells for further investigation of this unconventional protein transport pathway. Both morphological and biochemical characterizations showed that DdCAD-1-GFP was imported into contractile vacuoles. Time-lapse microscopy of transfectants revealed the transient appearance of DdCAD-1-GFP-filled vesicular structures in the lumen of contractile vacuoles, suggesting that DdCAD-1 could be imported by invagination of contractile vacuole membrane. To assess the structural requirements in this transport process, the N-terminal and C-terminal domains of DdCAD-1 were expressed separately in cells as GFP fusion proteins. Both fusion proteins failed to enter the contractile vacuole, suggesting that the integrity of DdCAD-1 is required for import. Such a requirement was also observed in in vitro reconstitution assays using His(6)-tagged fusion proteins and purified contractile vacuoles. Import of DdCAD-1 was compromised when two of its three Ca(2+)-binding sites were mutated, indicating a role for Ca(2+) in the import process. Spectral analysis showed that mutations in the Ca(2+)-binding sites resulted in subtle conformational changes. Indeed, proteins with altered conformation failed to enter the contractile vacuole, suggesting that the import signal is somehow integrated in the three-dimensional structure of DdCAD-1.
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Affiliation(s)
- Shrivani Sriskanthadevan
- Banting and Best Department of Medical Research and Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Teresa Lee
- Banting and Best Department of Medical Research and Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Zhi Lin
- Department of Biological Sciences, National University of Singapore, Singapore 117543
| | - Daiwen Yang
- Department of Biological Sciences, National University of Singapore, Singapore 117543
| | - Chi-Hung Siu
- Banting and Best Department of Medical Research and Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada.
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Jeon TJ, Lee S, Weeks G, Firtel RA. Regulation of Dictyostelium morphogenesis by RapGAP3. Dev Biol 2009; 328:210-20. [PMID: 19284976 DOI: 10.1016/j.ydbio.2009.01.016] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2008] [Revised: 12/16/2008] [Accepted: 01/08/2009] [Indexed: 12/01/2022]
Abstract
Rap1 is a key regulator of cell adhesion and cell motility in Dictyostelium. Here, we identify a Rap1-specific GAP protein (RapGAP3) and provide evidence that Rap1 signaling regulates cell-cell adhesion and cell migration within the multicellular organism. RapGAP3 mediates the deactivation of Rap1 at the late mound stage of development and plays an important role in regulating cell sorting during apical tip formation, when the anterior-posterior axis of the organism is formed, by controlling cell-cell adhesion and cell migration. The loss of RapGAP3 results in a severely altered morphogenesis of the multicellular organism at the late mound stage. Direct measurement of cell motility within the mound shows that rapGAP3(-) cells have a reduced speed of movement and, compared to wild-type cells, have a reduced motility towards the apex. rapGAP3(-) cells exhibit some increased EDTA/EGTA sensitive cell-cell adhesion at the late mound stage. RapGAP3 transiently and rapidly translocates to the cell cortex in response to chemoattractant stimulation, which is dependent on F-actin polymerization. We suggest that the altered morphogenesis and the cell-sorting defect of rapGAP3(-) cells may result in reduced directional movement of the mutant cells to the apex of the mound.
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Affiliation(s)
- Taeck J Jeon
- Section of Cell and Developmental Biology, Division of Biological Sciences, Center for Molecular Genetics, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0380, USA
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25
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Hulpiau P, van Roy F. Molecular evolution of the cadherin superfamily. Int J Biochem Cell Biol 2008; 41:349-69. [PMID: 18848899 DOI: 10.1016/j.biocel.2008.09.027] [Citation(s) in RCA: 305] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2008] [Revised: 09/19/2008] [Accepted: 09/24/2008] [Indexed: 02/02/2023]
Abstract
This review deals with the large and pleiotropic superfamily of cadherins and its molecular evolution. We compiled literature data and an in-depth phylogenetic analysis of more than 350 members of this superfamily from about 30 species, covering several but not all representative branches within metazoan evolution. We analyzed the sequence homology between either ectodomains or cytoplasmic domains, and we reviewed protein structural data and genomic architecture. Cadherins and cadherin-related molecules are defined by having an ectodomain in which at least two consecutive calcium-binding cadherin repeats are present. There are usually 5 or 6 domains, but in some cases as many as 34. Additional protein modules in the ectodomains point at adaptive evolution. Despite the occurrence of several conserved motifs in subsets of cytoplasmic domains, these domains are even more diverse than ectodomains and most likely have evolved separately from the ectodomains. By fine tuning molecular classifications, we reduced the number of solitary superfamily members. We propose a cadherin major branch, subdivided in two families and 8 subfamilies, and a cadherin-related major branch, subdivided in four families and 11 subfamilies. Accordingly, we propose a more appropriate nomenclature. Although still fragmentary, our insight into the molecular evolution of these remarkable proteins is steadily growing. Consequently, we can start to propose testable hypotheses for structure-function relationships with impact on our models of molecular evolution. An emerging concept is that the ever evolving diversity of cadherin structures is serving dual and important functions: specific cell adhesion and intricate cell signaling.
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Affiliation(s)
- Paco Hulpiau
- Department for Molecular Biomedical Research, VIB, Ghent, Belgium
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26
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Vicente JJ, Galardi-Castilla M, Escalante R, Sastre L. Structural and functional studies of a family of Dictyostelium discoideum developmentally regulated, prestalk genes coding for small proteins. BMC Microbiol 2008; 8:1. [PMID: 18173832 PMCID: PMC2257962 DOI: 10.1186/1471-2180-8-1] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2007] [Accepted: 01/03/2008] [Indexed: 11/21/2022] Open
Abstract
BACKGROUND The social amoeba Dictyostelium discoideum executes a multicellular development program upon starvation. This morphogenetic process requires the differential regulation of a large number of genes and is coordinated by extracellular signals. The MADS-box transcription factor SrfA is required for several stages of development, including slug migration and spore terminal differentiation. RESULTS Subtractive hybridization allowed the isolation of a gene, sigN (SrfA-induced gene N), that was dependent on the transcription factor SrfA for expression at the slug stage of development. Homology searches detected the existence of a large family of sigN-related genes in the Dictyostelium discoideum genome. The 13 most similar genes are grouped in two regions of chromosome 2 and have been named Group1 and Group2 sigN genes. The putative encoded proteins are 87-89 amino acids long. All these genes have a similar structure, composed of a first exon containing a 13 nucleotides long open reading frame and a second exon comprising the remaining of the putative coding region. The expression of these genes is induced at10 hours of development. Analyses of their promoter regions indicate that these genes are expressed in the prestalk region of developing structures. The addition of antibodies raised against SigN Group 2 proteins induced disintegration of multi-cellular structures at the mound stage of development. CONCLUSION A large family of genes coding for small proteins has been identified in D. discoideum. Two groups of very similar genes from this family have been shown to be specifically expressed in prestalk cells during development. Functional studies using antibodies raised against Group 2 SigN proteins indicate that these genes could play a role during multicellular development.
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Affiliation(s)
- Juan J Vicente
- Instituto de Investigaciones Biomédicas, CSIC/UAM, C/Arturo Duperier, 4. 28029, Madrid. Spain
| | - María Galardi-Castilla
- Instituto de Investigaciones Biomédicas, CSIC/UAM, C/Arturo Duperier, 4. 28029, Madrid. Spain
| | - Ricardo Escalante
- Instituto de Investigaciones Biomédicas, CSIC/UAM, C/Arturo Duperier, 4. 28029, Madrid. Spain
| | - Leandro Sastre
- Instituto de Investigaciones Biomédicas, CSIC/UAM, C/Arturo Duperier, 4. 28029, Madrid. Spain
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GrlJ, a Dictyostelium GABAB-like receptor with roles in post-aggregation development. BMC DEVELOPMENTAL BIOLOGY 2007; 7:44. [PMID: 17501984 PMCID: PMC1885808 DOI: 10.1186/1471-213x-7-44] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/19/2006] [Accepted: 05/14/2007] [Indexed: 11/10/2022]
Abstract
BACKGROUND The G-protein-coupled receptor (GPCR) family represents the largest and most important group of targets for chemotherapeutics. They are extremely versatile receptors that transduce signals as diverse as biogenic amines, purins, odorants, ions and pheromones from the extracellular compartment to the interior via biochemical processes involving GTP-binding proteins. Until recently, the cyclic AMP receptors (cARs) were the only known G protein coupled receptors in Dictyostelium discoideum. The completed genome sequence revealed the presence of several families of GPCRs in Dictyostelium, among them members of the family 3 of GPCRs, the GABAB/glutamate like receptor family, which in higher eukaryotes is involved in neuronal signaling. RESULTS D. discoideum has seventeen Family 3 members of GPCRs, denoted GrlA through GrlR. Their transcripts are detected throughout development with increased levels during early and late development. We have examined here GrlJ. GFP-tagged GrlJ localises to the plasma-membrane and to internal membranes. Inactivation of the grlJ gene leads to precocious development, and the mutant completes development ~6 hours earlier. Alterations were also noted at the slug stage and in spore formation. grlJ- slugs were longer and broke apart several times on their way to culmination forming smaller but proportionate fruiting bodies. Spores from grlJ- fruiting bodies were malformed and less viable, although the spore differentiation factors were synthesized and sensed normally. Expression of a GFP-tagged full length GrlJ rescued the phenotype. CONCLUSION Our data suggest that GrlJ acts at several stages of Dictyostelium development and that it is a negative regulator in Dictyostelium development.
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Guo R, Sakamoto H, Sugiura S, Ogawa M. Endothelial cell motility is compatible with junctional integrity. J Cell Physiol 2007; 211:327-35. [PMID: 17167782 DOI: 10.1002/jcp.20937] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Confluent endothelial cells in culture are generally regarded as a model of resting endothelium in blood vessels (i.e., forming junctions at points of cell-cell contact, losing ability to proliferate in response to growth factors, and remaining stationary). However, incompatibility between junctional integrity and endothelial cell motility remains uncertain. The aim of this study was to determine whether endothelial cells (in colonies generated from differentiating embryonic stem cells in contact with OP9 stromal cell layer) have a resting endothelial phenotype (i.e., lack motility). Time-lapse analyses showed that though endothelial cells were connected to each other through adherens junctions and tight junctions, they were moving continuously within the colonies. Endothelial cell movement was accompanied by formation of lamellipodia, which transiently accumulated green fluorescent protein-tagged beta-actin and p41-Arc (a subunit of the actin-related protein 2/3 complex) at their anterior tips, suggesting that the movement is an active behavior of endothelial cells. Endothelial cell-specific expression of yellow fluorescent protein-tagged vascular endothelial-cadherin and claudin-5 revealed that adherens junctions and tight junctions persisted during endothelial cell migration. Furthermore, intercellular junctions underwent dynamic remodeling at the leading edge of moving endothelial cells. These results suggest that endothelial cells can remain highly motile without losing intercellular junctions.
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Affiliation(s)
- Renyong Guo
- Department of Cell Differentiation, Institute of Molecular Embryology and Genetics, Kumamoto University, Kumamoto, Japan
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29
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Lin Z, Sriskanthadevan S, Huang H, Siu CH, Yang D. Solution structures of the adhesion molecule DdCAD-1 reveal new insights into Ca2+-dependent cell-cell adhesion. Nat Struct Mol Biol 2006; 13:1016-22. [PMID: 17057715 DOI: 10.1038/nsmb1162] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2006] [Accepted: 10/03/2006] [Indexed: 02/06/2023]
Abstract
DdCAD-1 is a novel Ca(2+)-dependent cell adhesion molecule that lacks a hydrophobic signal peptide and a transmembrane domain. DdCAD-1 is expressed by the social amoeba Dictyostelium discoideum at the onset of development. It is synthesized as a soluble protein and then transported to the plasma membrane by contractile vacuoles. Here we describe the novel features of the solution structures of Ca(2+)-free and Ca(2+)-bound monomeric DdCAD-1. DdCAD-1 contains two beta-sandwich domains, belonging to the betagamma-crystallin and immunoglobulin fold classes, respectively. Whereas the N-terminal domain has a major role in homophilic binding, the C-terminal domain tethers the protein to the cell membrane. From structural and mutational analyses, we propose a model for the Ca(2+)-bound DdCAD-1 dimer as a basis for understanding DdCAD-1-mediated cell-cell adhesion at the molecular level. Our results provide new insights into Ca(2+)-dependent mechanisms for cell-cell adhesion.
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Affiliation(s)
- Zhi Lin
- Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543
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Ohashi H, Umeda N, Hirazawa N, Ozaki Y, Miura C, Miura T. Antiparasitic effect of calcium and magnesium ion-free buffer treatments against a common monogenean Neobenedenia girellae. Parasitology 2006; 134:229-36. [PMID: 17032471 DOI: 10.1017/s0031182006001430] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2006] [Revised: 05/30/2006] [Accepted: 07/20/2006] [Indexed: 11/07/2022]
Abstract
This study investigated a new effective method for controlling the capsalid monogenean Neobenedenia girellae. We examined in vitro and in vivo the effect on the percentage survival of N. girellae in buffers containing different metallic ions. Decreased survival was observed in buffer solutions lacking two ions. In particular, the percentage survival of N. girellae was significantly decreased after 10 min exposure to buffer containing neither Ca(2+) nor Mg(2+). Transmission electron microscopic observations showed that treatment with this buffer disrupted intercellular junctions. This significant effect on percentage survival of N. girellae using Ca(2+)/Mg(2+)-free buffer was confirmed in an in vivo assay. Ca(2+)/Mg(2+)-free buffer had no effect on the condition of the host, spotted halibut Verasper variegates (Pleuronectidae). These results suggest that treatment with Ca(2+)/Mg(2+)-free buffer is a new effective control method, which could replace existing control methods.
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Affiliation(s)
- H Ohashi
- Laboratory of Fish Reproductive Physiology, Faculty of Agriculture, Ehime University, Matsuyama, Ehime 790-8566, Japan
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Secko DM, Siu CH, Spiegelman GB, Weeks G. An activated Ras protein alters cell adhesion by dephosphorylating Dictyostelium DdCAD-1. MICROBIOLOGY-SGM 2006; 152:1497-1505. [PMID: 16622066 DOI: 10.1099/mic.0.28709-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
RasG-regulated signal transduction has been linked to a variety of growth-specific processes and appears to also play a role in the early development of Dictyostelium discoideum. In an attempt to uncover some of the molecular components involved in Ras-mediated signalling, several proteins have been described previously, including the cell adhesion molecule DdCAD-1, whose phosphorylation state was affected by the expression of the constitutively activated RasG, RasG(G12T). Here it has been shown that a cadA null strain lacks the phosphoproteins that were tentatively identified as DdCAD-1, confirming its previous designation. Further investigation revealed that cells expressing RasG(G12T) exhibited increased cell-cell cohesion, concomitant with reduced levels of DdCAD-1 phosphorylation. This increased cohesion was DdCAD-1-dependent and was correlated with increased localization of DdCAD-1 at the cell surface. DdCAD-1 phosphorylation was also found to decrease during Dictyostelium aggregation. These results revealed a possible role for protein phosphorylation in regulating DdCAD-1-mediated cell adhesion during early development. In addition, the levels of DdCAD-1 protein were substantially reduced in a rasG null cell line. These results indicate that RasG affects both the expression and dephosphorylation of DdCAD-1 during early development.
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Affiliation(s)
- David M Secko
- Department of Microbiology and Immunology, University of British Columbia, Life Sciences Centre, 2350 Health Sciences Mall, Vancouver, British Columbia V6T 1Z4, Canada
| | - Chi-Hung Siu
- Banting and Best Department of Medical Research, and Department of Biochemistry, University of Toronto, Toronto, Ontario M5G 1L6, Canada
| | - George B Spiegelman
- Department of Microbiology and Immunology, University of British Columbia, Life Sciences Centre, 2350 Health Sciences Mall, Vancouver, British Columbia V6T 1Z4, Canada
| | - Gerald Weeks
- Department of Microbiology and Immunology, University of British Columbia, Life Sciences Centre, 2350 Health Sciences Mall, Vancouver, British Columbia V6T 1Z4, Canada
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Sugimoto H, Endoh H. Analysis of fruiting body development in the aggregative ciliate Sorogena stoianovitchae (Ciliophora, Colpodea). J Eukaryot Microbiol 2006; 53:96-102. [PMID: 16579811 DOI: 10.1111/j.1550-7408.2005.00077.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The fruiting body-forming ciliate Sorogena stoianovitchae is a protist that is multicellular in one stage of its life cycle. When nutrient levels are depleted, a number of Sorogena cells aggregate beneath the water surface to form an aerial fruiting body. Based on morphologies and the inhibition of protein synthesis, fruiting body development is divided into five distinct stages: (1) aggregation before sunrise, (2) compact aggregation after sunrise, (3) secretion of mucous matrix, (4) stalk-elongation, and (5) completion of the fruiting-body. In the aggregation stage, the cells were trapped in a matrix material that stained orange with 4',6-diamino-2-phenylindole (DAPI), but differed from the mucous matrix in the later stage. A short interruption of the dark period, at 6-8 h after the onset of dark, inhibited fruiting body development. Irrespective of the length of the dark period (10-16 h), the cells remained in the aggregation stage until the beginning of the light period. Therefore, an uninterrupted dark period of more than 8 h is critical for the initial aggregation of cells, but subsequent development is triggered by light.
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Affiliation(s)
- Hiroki Sugimoto
- Division of Life Science, Graduate School of Natural Science and Technology, Kanazawa University, Kanazawa 920-1192, Japan.
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Muramoto T, Urushihara H. Small GTPase RacF2 affects sexual cell fusion and asexual development in Dictyostelium discoideum through the regulation of cell adhesion. Dev Growth Differ 2006; 48:199-208. [PMID: 16573737 DOI: 10.1111/j.1440-169x.2006.00857.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Cells of Dictyostelium discoideum become sexually mature when submerged and in darkness, and fuse with opposite mating-type cells as gametes. The gene for a Rho GTPase, RacF2, is one of the extremely gamete-enriched genes (>100-fold) identified by us previously. Here, we isolated knockout, overexpression, constitutively active and dominant negative mutants of RacF2, and analyzed their phenotypes. These mutants showed anomalies in the extent of sexual cell fusion and asexual development as well as in EDTA-sensitive cell-cell adhesion. It is suggested that RacF2 controls the process of sexual and asexual development through the regulation of cellular adhesiveness. An analysis of the expression of all 18 rac family genes by real-time polymerase chain reaction revealed that four additional genes, rac1b, rac1c, racF1 and racG, were induced during maturation, suggesting their possible involvement in sexual cell interactions.
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Affiliation(s)
- Tetsuya Muramoto
- Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba 305-8572, Japan.
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Liu CI, Cheng TL, Chen SZ, Huang YC, Chang WT. LrrA, a novel leucine-rich repeat protein involved in cytoskeleton remodeling, is required for multicellular morphogenesis in Dictyostelium discoideum. Dev Biol 2005; 285:238-51. [PMID: 16051212 DOI: 10.1016/j.ydbio.2005.05.045] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2004] [Revised: 05/07/2005] [Accepted: 05/25/2005] [Indexed: 12/17/2022]
Abstract
Cell sorting by differential cell adhesion and movement is a fundamental process in multicellular morphogenesis. We have identified a Dictyostelium discoideum gene encoding a novel protein, LrrA, which composes almost entirely leucine-rich repeats (LRRs) including a putative leucine zipper motif. Transcription of lrrA appeared to be developmentally regulated with robust expression during vegetative growth and early development. lrrA null cells generated by homologous recombination aggregated to form loose mounds, but subsequent morphogenesis was blocked without formation of the apical tip. The cells adhered poorly to a substratum and did not form tight cell-cell agglomerates in suspension; in addition, they were unable to polarize and exhibit chemotactic movement in the submerged aggregation and Dunn chamber chemotaxis assays. Fluorescence-conjugated phalloidin staining revealed that both vegetative and aggregation competent lrrA(-) cells contained numerous F-actin-enriched microspikes around the periphery of cells. Quantitative analysis of the fluorescence-stained F-actin showed that lrrA(-) cells exhibited a dramatically increase in F-actin as compared to the wild-type cells. When developed together with wild-type cells, lrrA(-) cells were unable to move to the apical tip and sorted preferentially to the rear and lower cup regions. These results indicate that LrrA involves in cytoskeleton remodeling, which is needed for normal chemotactic aggregation and efficient cell sorting during multicellular morphogenesis, particularly in the formation of apical tip.
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Affiliation(s)
- Chia-I Liu
- Department of Biochemistry, National Cheng Kung University Medical College, Tainan 701, Taiwan, ROC
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35
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Fache S, Dalous J, Engelund M, Hansen C, Chamaraux F, Fourcade B, Satre M, Devreotes P, Bruckert F. Calcium mobilization stimulatesDictyostelium discoideumshear-flow-induced cell motility. J Cell Sci 2005; 118:3445-57. [PMID: 16079287 DOI: 10.1242/jcs.02461] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Application of hydrodynamic mild shear stress to adherent Dictyostelium discoideum vegetative cells triggers active actin cytoskeleton remodeling resulting in net cell movement along the flow. The average cell speed is strongly stimulated by external calcium (Ca2+, K50%=22 μM), but the directionality of the movement is almost unaffected. This calcium concentration is ten times higher than the one promoting cell adhesion to glass surfaces (K50%=2 μM). Addition of the calcium chelator EGTA or the Ca2+-channel blocker gadolinium (Gd3+) transiently stops cell movement. Monitoring the evolution of cell-surface contact area with time reveals that calcium stimulates cell speed by increasing the amplitude of both protrusion and retraction events at the cell edge, but not the frequency. As a consequence, with saturating external calcium concentrations, cells are sensitive to very low shear forces (20 pN; σ=0.1 Pa). Moreover, a null-mutant lacking the unique Gβ subunit does not respond to external Ca2+ changes (K50%>1000 μM), although the directionality of the movement is comparable with that of wild-type cells. Furthermore, cells lacking the inositol 1,4,5-trisphosphate receptor (IP3-receptor) exhibit a markedly reduced Ca2+ sensitivity. Thus, calcium release from internal stores and calcium entry through the plasma membrane modulate cell speed in response to shear stress.
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Affiliation(s)
- Sébastien Fache
- Structures et Propriétés des Architectures Moléculaires (UMR 5919 CNRS), Département de Recherche Fondamentale sur la Matière Condensée, CEA-Grenoble, DRFMC/SI3M, 17 rue des Martyrs, 38054 Grenoble Cedex 09, France
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36
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Lin Z, Huang H, Siu CH, Yang D. (1)H, (13)C and (15)N resonance assignments of Ca(2+)-free DdCAD-1: a Ca(2+)-dependent cell-cell adhesion molecule. JOURNAL OF BIOMOLECULAR NMR 2004; 30:375-376. [PMID: 15756470 DOI: 10.1007/s10858-005-2336-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2004] [Accepted: 07/23/2004] [Indexed: 05/24/2023]
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37
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Bowers-Morrow VM, Ali SO, Williams KL. Comparison of molecular mechanisms mediating cell contact phenomena in model developmental systems: an exploration of universality. Biol Rev Camb Philos Soc 2004; 79:611-42. [PMID: 15366765 DOI: 10.1017/s1464793103006389] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Are there universal molecular mechanisms associated with cell contact phenomena during metazoan ontogenesis? Comparison of adhesion systems in disparate model systems indicates the existence of unifying principles. Requirements for multicellularity are (a) the construction of three-dimensional structures involving a crucial balance between adhesiveness and motility; and (b) the establishment of integration at molecular, cellular, tissue, and organismal levels of organization. Mechanisms for (i) cell-cell and cell-substrate adhesion, (ii) cell movement, (iii) cell-cell communication, (iv) cellular responses, (v) regulation of these processes, and (vi) their integration with patterning, growth, and other developmental processes are all crucial to metazoan development, and must have been present for the emergence and radiation of Metazoa. The principal unifying themes of this review are the dynamics and regulation of cell contact phenomena. Our knowledge of the dynamic molecular mechanisms underlying cell contact phenomena remains fragmentary. Here we examine the molecular bases of cell contact phenomena using extant model developmental systems (representing a wide range of phyla) including the simplest i.e. sponges, and the eukaryotic protist Dictyostelium discoideum, the more complex Drosophila melanogaster, and vertebrate systems. We discuss cell contact phenomena in a broad developmental context. The molecular language of cell contact phenomena is complex; it involves a plethora of structurally and functionally diverse molecules, and diverse modes of intermolecular interactions mediated by protein and/or carbohydrate moieties. Reasons for this are presumably the necessity for a high degree of specificity of intermolecular interactions, the requirement for a multitude of different signals, and the apparent requirement for an increasingly large repertoire of cell contact molecules in more complex developmental systems, such as the developing vertebrate nervous system. However, comparison of molecular models for dynamic adhesion in sponges and in vertebrates indicates that, in spite of significant differences in the details of the way specific cell-cell adhesion is mediated, similar principles are involved in the mechanisms employed by members of disparate phyla. Universal requirements are likely to include (a) rapidly reversible intermolecular interactions; (b) low-affinity intermolecular interactions with fast on-off rates; (c) the compounding of multiple intermolecular interactions; (d) associated regulatory signalling systems. The apparent widespread employment of molecular mechanisms involving cadherin-like cell adhesion molecules suggests the fundamental importance of cadherin function during development, particularly in epithelial morphogenesis, cell sorting, and segregation of cells.
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38
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Powell RR, Temesvari LA. Involvement of a Rab8-like protein of Dictyostelium discoideum, Sas1, in the formation of membrane extensions, secretion and adhesion during development. MICROBIOLOGY-SGM 2004; 150:2513-2525. [PMID: 15289548 DOI: 10.1099/mic.0.27073-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Establishment of cell-cell adhesions, regulation of actin, and secretion are critical during development. Rab8-like GTPases have been shown to modulate these cellular events, suggesting an involvement in developmental processes. To further elucidate the function of Rab8-like GTPases in a developmental context, a Rab8-related protein (Sas1) of Dictyostelium discoideum was examined, the expression of which increases at the onset of development. Dictyostelium cell lines expressing inactive (N128I mutant) and constitutively active (Q74L mutant) Sas1 as green fluorescent protein (GFP)-Sas1 chimeras were generated. Cells expressing Sas1Q74L displayed numerous actin-rich membrane protrusions, increased secretion, and were unable to complete development. In particular, these cells demonstrated a reduction in adhesion as well as in the levels of a cell adhesion molecule, gp24 (DdCAD-1). In contrast, cells expressing Sas1N128I exhibited increased cell-cell adhesion and increased levels of gp24. Counting factor is a multisubunit signalling complex that is secreted in early development and controls aggregate size by negatively regulating the levels of cell adhesion molecules, including gp24. Interestingly, the Sas1Q74L mutant demonstrated increased levels of extracellular countin, a subunit of counting factor, suggesting that Sas1 may regulate trafficking of counting factor components. Together, the data suggest that Sas1 may be a key regulator of actin, adhesion and secretion during development.
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Affiliation(s)
- Rhonda R Powell
- Department of Biological Sciences, 132 Long Hall, Clemson University, Clemson, SC 29634, USA
| | - Lesly A Temesvari
- Department of Biological Sciences, 132 Long Hall, Clemson University, Clemson, SC 29634, USA
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39
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Chisholm RL, Firtel RA. Insights into morphogenesis from a simple developmental system. Nat Rev Mol Cell Biol 2004; 5:531-41. [PMID: 15232571 DOI: 10.1038/nrm1427] [Citation(s) in RCA: 140] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Rex L Chisholm
- Cell and Molecular Biology, Center for Genetic Medicine, Feinberg School of Medicine, Northwestern University, 303 East Chicago Avenue, Chicago, Illinois 60611, USA.
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40
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Zhukovskaya NV, Fukuzawa M, Tsujioka M, Jermyn KA, Kawata T, Abe T, Zvelebil M, Williams JG. Dd-STATb, a Dictyostelium STAT protein with a highly aberrant SH2 domain, functions as a regulator of gene expression during growth and early development. Development 2004; 131:447-58. [PMID: 14701681 DOI: 10.1242/dev.00927] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Dictyostelium, the only known non-metazoan organism to employ SH2 domain:phosphotyrosine signaling, possesses STATs (signal transducers and activators of transcription) and protein kinases with orthodox SH2 domains. Here, however, we describe a novel Dictyostelium STAT containing a remarkably divergent SH2 domain. Dd-STATb displays a 15 amino acid insertion in its SH2 domain and the conserved and essential arginine residue, which interacts with phosphotyrosine in all other known SH2 domains, is substituted by leucine. Despite these abnormalities, Dd-STATb is biologically functional. It has a subtle role in growth, so that Dd-STATb-null cells are gradually lost from the population when they are co-cultured with parental cells, and microarray analysis identified several genes that are either underexpressed or overexpressed in the Dd-STATb null strain. The best characterised of these,discoidin 1, is a marker of the growth-development transition and it is overexpressed during growth and early development of Dd-STATb null cells. Dimerisation of STAT proteins occurs by mutual SH2 domain:phosphotyrosine interactions and dimerisation triggers STAT nuclear accumulation. Despite its aberrant SH2 domain, the Dd-STATb protein sediments at the size expected for a homodimer and it is constitutively enriched in the nucleus. Moreover, these properties are retained when the predicted site of tyrosine phosphorylation is substituted by phenylalanine. These observations suggest a non-canonical mode of activation of Dd-STATb that does not rely on orthodox SH2 domain:phosphotyrosine interactions.
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Affiliation(s)
- Natasha V Zhukovskaya
- School of Life Sciences, University of Dundee, MSI/WTB Complex, Dow Street, Dundee DD1 5EH, UK
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41
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Bruckert F, Décavé E, Garrivier D, Cosson P, Bréchet Y, Fourcade B, Satre M. Dictyostelium discoideum adhesion and motility under shear flow: experimental and theoretical approaches. J Muscle Res Cell Motil 2003; 23:651-8. [PMID: 12952064 DOI: 10.1023/a:1024407107588] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Among the different assays to measure cell adhesion, shear-flow detachment chambers offer the advantage to study both passive and active aspects of the phenomena on large cell numbers. Mathematical modeling allows full exploitation of the data by relating molecular parameters to cell mechanics. Using D. discoideum as a model system, we explain how cell detachment kinetics gives access to the rate constants describing the passive association or dissociation of the cell membrane to a given substrate.
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Affiliation(s)
- Franz Bruckert
- Laboratoire de Biochimie et Biophysique des Systèmes Intégrés (UMR 5092), Département Réponse et Dynamique Cellulaires, CEA-Grenoble, 17 rue des Martyrs, 38054 Grenoble Cedex 09, France.
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42
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Noegel AA, Blau-Wasser R, Sultana H, Müller R, Israel L, Schleicher M, Patel H, Weijer CJ. The cyclase-associated protein CAP as regulator of cell polarity and cAMP signaling in Dictyostelium. Mol Biol Cell 2003; 15:934-45. [PMID: 14595119 PMCID: PMC329405 DOI: 10.1091/mbc.e03-05-0269] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Cyclase-associated protein (CAP) is an evolutionarily conserved regulator of the G-actin/F-actin ratio and, in yeast, is involved in regulating the adenylyl cyclase activity. We show that cell polarization, F-actin organization, and phototaxis are altered in a Dictyostelium CAP knockout mutant. Furthermore, in complementation assays we determined the roles of the individual domains in signaling and regulation of the actin cytoskeleton. We studied in detail the adenylyl cyclase activity and found that the mutant cells have normal levels of the aggregation phase-specific adenylyl cyclase and that receptor-mediated activation is intact. However, cAMP relay that is responsible for the generation of propagating cAMP waves that control the chemotactic aggregation of starving Dictyostelium cells was altered, and the cAMP-induced cGMP production was significantly reduced. The data suggest an interaction of CAP with adenylyl cyclase in Dictyostelium and an influence on signaling pathways directly as well as through its function as a regulatory component of the cytoskeleton.
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Affiliation(s)
- Angelika A Noegel
- Center for Biochemistry, Medical Faculty, University of Cologne, 50931 Cologne, Germany
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43
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Duchaud E, Rusniok C, Frangeul L, Buchrieser C, Givaudan A, Taourit S, Bocs S, Boursaux-Eude C, Chandler M, Charles JF, Dassa E, Derose R, Derzelle S, Freyssinet G, Gaudriault S, Médigue C, Lanois A, Powell K, Siguier P, Vincent R, Wingate V, Zouine M, Glaser P, Boemare N, Danchin A, Kunst F. The genome sequence of the entomopathogenic bacterium Photorhabdus luminescens. Nat Biotechnol 2003; 21:1307-13. [PMID: 14528314 DOI: 10.1038/nbt886] [Citation(s) in RCA: 410] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2003] [Accepted: 08/18/2003] [Indexed: 11/09/2022]
Abstract
Photorhabdus luminescens is a symbiont of nematodes and a broad-spectrum insect pathogen. The complete genome sequence of strain TT01 is 5,688,987 base pairs (bp) long and contains 4,839 predicted protein-coding genes. Strikingly, it encodes a large number of adhesins, toxins, hemolysins, proteases and lipases, and contains a wide array of antibiotic synthesizing genes. These proteins are likely to play a role in the elimination of competitors, host colonization, invasion and bioconversion of the insect cadaver, making P. luminescens a promising model for the study of symbiosis and host-pathogen interactions. Comparison with the genomes of related bacteria reveals the acquisition of virulence factors by extensive horizontal transfer and provides clues about the evolution of an insect pathogen. Moreover, newly identified insecticidal proteins may be effective alternatives for the control of insect pests.
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Affiliation(s)
- Eric Duchaud
- Laboratoire de Génomique des Microorganismes Pathogènes, Institut Pasteur, 28 rue du Dr. Roux, 75724 Paris Cedex 15, France
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44
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Muramoto T, Suzuki K, Shimizu H, Kohara Y, Kohriki E, Obara S, Tanaka Y, Urushihara H. Construction of a gamete-enriched gene pool and RNAi-mediated functional analysis in Dictyostelium discoideum. Mech Dev 2003; 120:965-75. [PMID: 12963116 DOI: 10.1016/s0925-4773(03)00136-9] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Macrocysts in Dictyostelium discoideum possess prototypic features of sexual reproduction and are useful for understanding the basic mechanisms of the reproductive process. Here, we randomly analyzed 1,071 gamete cDNAs, and then constructed a gamete-specific subtraction library, FC-IC. Nucleotide sequences of all 903 FC-IC clones were determined and clustered into 272 independent genes. Expression analysis based on real-time RT-PCR revealed 67 gamete-enriched genes, among which those involved in 'signal transduction' and 'multicellular organization' are prevalent. One of them, FC-IC0003, appeared also to be mating-type specific, and was named gmsA. RNAi-mediated silencing as well as disruption of gmsA reduced the cellular competency for sexual cell fusion, indicating the involvement of this gene in the sexual development of D. discoideum.
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Affiliation(s)
- Tetsuya Muramoto
- Institute of Biological Sciences, University of Tsukuba, Tsukuba-shi 305-8572, Japan
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45
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Harris TJC, Ravandi A, Awrey DE, Siu CH. Cytoskeleton interactions involved in the assembly and function of glycoprotein-80 adhesion complexes in dictyostelium. J Biol Chem 2003; 278:2614-23. [PMID: 12421828 DOI: 10.1074/jbc.m206241200] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Adhesion complexes typically assemble from clustered receptors that link to the cytoskeleton via cytoplasmic adapter proteins. However, it is unclear how phospholipid-anchored adhesion molecules, such as the Dictyostelium receptor gp80, interact with the cytoskeleton. gp80 has been found to form adhesion complexes from raftlike membrane domains, which can be isolated as a Triton X-100-insoluble floating fraction (TIFF). We report here that the actin-binding protein ponticulin mediates TIFF-cytoskeleton interactions. Analysis of gp80-null cells revealed that these interactions were minimal in the absence of gp80. During development, gp80 was required to enhance these interactions as its adhesion complexes assembled. Whereas ponticulin and gp80 could partition independently into TIFF, gp80 was shown to recruit ponticulin to cell-cell contacts and to increase its partitioning into TIFF. However, these proteins did not co-immunoprecipitate. Furthermore, sterol sequestration abrogated the association of ponticulin with TIFF without affecting gp80, suggesting that sterols may mediate the interactions between ponticulin and gp80. In ponticulin-null cells, large gp80 adhesion complexes assembled in the absence of ponticulin despite the lack of cytoskeleton association. We propose that such nascent gp80 adhesion complexes produce expanded raftlike domains that recruit ponticulin and thereby establish stable cytoskeleton interactions to complete the assembly process.
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Affiliation(s)
- Tony J C Harris
- Banting and Best Department of Medical Research, University of Toronto, Ontario M5G 1L6, Canada
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46
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Abstract
Little is known about cell-substrate adhesion and how motile and adhesive forces work together in moving cells. The ability to rapidly screen a large number of insertional mutants prompted us to perform a genetic screen in Dictyostelium to isolate adhesion-deficient mutants. The resulting substrate adhesion-deficient (sad) mutants grew in plastic dishes without attaching to the substrate. The cells were often larger than their wild-type parents and displayed a rough surface with many apparent blebs. One of these mutants, sadA-, completely lacked substrate adhesion in growth medium. The sadA- mutant also showed slightly impaired cytokinesis, an aberrant F-actin organization, and a phagocytosis defect. Deletion of the sadA gene by homologous recombination recreated the original mutant phenotype. Expression of sadA-GFP in sadA-null cells restored the wild-type phenotype. In sadA-GFP-rescued mutant cells, sadA-GFP localized to the cell surface, appropriate for an adhesion molecule. SadA contains nine putative transmembrane domains and three conserved EGF-like repeats in a predicted extracellular domain. The EGF repeats are similar to corresponding regions in proteins known to be involved in adhesion, such as tenascins and integrins. Our data combined suggest that sadA is the first substrate adhesion receptor to be identified in Dictyostelium.
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Affiliation(s)
- Petra Fey
- Department of Cell and Molecular Biology, Northwestern University Medical School, Chicago, IL 60611, USA
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47
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Wong E, Yang C, Wang J, Fuller D, Loomis WF, Siu CH. Disruption of the gene encoding the cell adhesion molecule DdCAD-1 leads to aberrant cell sorting and cell-type proportioning during Dictyostelium development. Development 2002; 129:3839-50. [PMID: 12135922 DOI: 10.1242/dev.129.16.3839] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The cadA gene in Dictyostelium encodes the Ca2+-dependent cell adhesion molecule DdCAD-1, which is expressed soon after the initiation of development. To investigate the biological role of DdCAD-1, the cadA gene was disrupted by homologous recombination. The cadA-null cells showed a 50% reduction in EDTA-sensitive cell adhesion. The remaining EDTA-sensitive adhesion sites were resistant to dissociation by anti-DdCAD-1 antibody, suggesting that they were distinct adhesion sites. Cells that lacked DdCAD-1 were able to complete development and form fruiting bodies. However, they displayed abnormal slug morphology and culmination was delayed by ∼6 hours. The yield of spores was reduced by ∼50%. The proportion of prestalk cells in cadA– slugs showed a 2.5-fold increase over the parental strain. When cadA– cells were transfected with pcotB::GFP to label prespore cells, aberrant cell-sorting patterns in slugs became apparent. When mutant prestalk cells were mixed with wild-type prespore cells, mutant prestalk cells were unable to return to the anterior position of chimeric slugs, suggesting defects in the sorting mechanism. The wild-type phenotype was restored when cadA– cells were transfected with a cadA-expression vector. These results indicate that, in addition to cell-cell adhesion, DdCAD-1 plays a role in cell type proportioning and pattern formation.
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Affiliation(s)
- Estella Wong
- Banting and Best Department of Medical Research and Department of Biochemistry, University of Toronto, Toronto, Ontario M5G 1L6, Canada
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Lilien J, Balsamo J, Arregui C, Xu G. Turn-off, drop-out: functional state switching of cadherins. Dev Dyn 2002; 224:18-29. [PMID: 11984870 DOI: 10.1002/dvdy.10087] [Citation(s) in RCA: 118] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
The classic cadherins are a group of calcium dependent, homophilic cell-cell adhesion molecules that drive morphogenetic rearrangements and maintain the integrity of cell groups through the formation of adherens junctions. The formation and maintenance of cadherin-mediated adhesions is a multistep process and mechanisms have evolved to regulate each step. This suggests that functional state switching plays an important role in development. Among the many challenges ahead is to determine the developmental role that functional state switching plays in tissue morphogenesis and to define the roles of each of the several regulatory interactions that participate in switching. One correlate of the loss of cadherin-mediated adhesion, the "turn-off" of cadherin function, is the exit, or "drop-out" of cells from neural and epithelial layers and their conversion to a motile phenotype. We suggest that epithelial mesenchymal conversions may be initiated by signaling pathways that result in the loss of cadherin function. Tyrosine phosphorylation of beta-catenin is one such mechanism. Enhanced phosphorylation of tyrosine residues on beta-catenin is almost invariably associated with loss of the cadherin-actin connection concomitant with loss of adhesive function. There are several tyrosine kinases and phosphatases that have been shown to have the potential to alter the phosphorylation state of beta-catenin and thus the function of cadherins. Our laboratory has focused on the role of the nonreceptor tyrosine phosphatase PTP1B in regulating the phosphorylation of beta-catenin on tyrosine residues. Our data suggest that PTP1B is crucial for maintenance of N-cadherin-mediated adhesions in embryonic neural retina cells. By using an L-cell model system constitutively expressing N-cadherin, we have worked out many of the molecular interactions essential for this regulatory interaction. Extracellular cues that bias this critical regulatory interaction toward increased phosphorylation of beta-catenin may be a critical component of many developmental events.
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Affiliation(s)
- Jack Lilien
- Department of Biological Sciences, The University of Iowa, Iowa City, IA 52242, USA.
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Harris TJ, Ravandi A, Siu CH. Assembly of glycoprotein-80 adhesion complexes in Dictyostelium. Receptor compartmentalization and oligomerization in membrane rafts. J Biol Chem 2001; 276:48764-74. [PMID: 11604403 DOI: 10.1074/jbc.m108030200] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The phospholipid-anchored membrane glycoprotein (gp)-80 mediates cell-cell adhesion through a homophilic trans-interaction mechanism during Dictyostelium development and is enriched in a Triton X-100-insoluble floating fraction. To elucidate how gp80 adhesion complexes assemble in the plasma membrane, gp80-gp80 and gp80-raft interactions were investigated. A low density raft-like membrane fraction was isolated using a detergent-free method. It was enriched in sterols, the phospholipid-anchored proteins gp80, gp138, and ponticulin, as well as DdCD36 and actin, corresponding to components found in the Triton X-100-insoluble floating fraction. Chemical cross-linking revealed that gp80 oligomers were enriched in the raft-like membrane fraction, implicating stable oligomer-raft interactions. However, gp80 oligomers resisted sterol sequestration and were partially dissociated with Triton X-100, suggesting that compartmentalization in rafts was not solely responsible for their formation. The trans-dimer known to mediate adhesion was identified, but cis-oligomerization predominated and displayed greater accumulation during development. In fact, oligomerization was dependent on the level of gp80 expression and occurred among isolated gp80 extracellular domains, indicating that it was mediated by direct gp80-gp80 interactions. Rafts existed in gp80-null cells and such pre-existent membrane domains may provide optimal microenvironments for gp80 cis-oligomerization and the assembly of adhesion complexes.
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Affiliation(s)
- T J Harris
- Banting and Best Department of Medical Research, University of Toronto, Toronto, Ontario M5G 1L6, Canada
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Coates JC, Harwood AJ. Cell-cell adhesion and signal transduction duringDictyosteliumdevelopment. J Cell Sci 2001; 114:4349-58. [PMID: 11792801 DOI: 10.1242/jcs.114.24.4349] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The development of the non-metazoan eukaryote Dictyostelium discoideum displays many of the features of animal embryogenesis, including regulated cell-cell adhesion. During early development, two proteins, DdCAD-1 and csA, mediate cell-cell adhesion between amoebae as they form a loosely packed multicellular mass. The mechanism governing this process is similar to epithelial sheet sealing in animals. Although cell differentiation can occur in the absence of cell contact, regulated cell-cell adhesion is an important component of Dictyostelium morphogenesis, and a third adhesion molecule, gp150, is required for multicellular development past the aggregation stage.Cell-cell junctions that appear to be adherens junctions form during the late stages of Dictyostelium development. Although they are not essential to establish the basic multicellular body plan, these junctions are required to maintain the structural integrity of the fruiting body. The Dictyostelium β-catenin homologue Aardvark (Aar) is present in adherens junctions, which are lost in its absence. As in the case of its metazoan counterparts, Aar also has a function in cell signalling and regulates expression of the pre-spore gene psA.It is becoming clear that cell-cell adhesion is an integral part of Dictyostelium development. As in animals, cell adhesion molecules have a mechanical function and may also interact with the signal-transduction processes governing morphogenesis.
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Affiliation(s)
- J C Coates
- MRC Laboratory for Molecular Cell Biology and Department of Biology, University College London, Gower Street, London, WC1E 6BT, UK
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