1
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Hashimura H, Morimoto YV, Hirayama Y, Ueda M. Calcium responses to external mechanical stimuli in the multicellular stage of Dictyostelium discoideum. Sci Rep 2022; 12:12428. [PMID: 35859163 PMCID: PMC9300675 DOI: 10.1038/s41598-022-16774-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2022] [Accepted: 07/15/2022] [Indexed: 11/09/2022] Open
Abstract
Calcium acts as a second messenger to regulate many cellular functions, including cell motility. In Dictyostelium discoideum, the cytosolic calcium level oscillates synchronously, and calcium waves propagate through the cell population during the early stages of development, including aggregation. In the unicellular phase, the calcium response through Piezo channels also functions in mechanosensing. However, calcium dynamics during multicellular morphogenesis are still unclear. Here, live imaging of cytosolic calcium revealed that calcium wave propagation, depending on cAMP relay, disappeared at the onset of multicellular body (slug) formation. Later, other forms of occasional calcium bursts and their propagation were observed in both anterior and posterior regions of migrating slugs. This calcium signaling also occurred in response to mechanical stimuli. Two pathways—calcium release from the endoplasmic reticulum via IP3 receptor and calcium influx from outside the cell—were involved in calcium signals induced by mechanical stimuli. These data suggest that calcium signaling is involved in mechanosensing in both the unicellular and multicellular phases of Dictyostelium development using different molecular mechanisms.
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Affiliation(s)
- Hidenori Hashimura
- Department of Biological Sciences, Graduate School of Science, Osaka University, 1-3 Yamadaoka, Suita, Osaka, 565-0871, Japan.,RIKEN Center for Biosystems Dynamics Research (BDR), 6-2-3 Furuedai, Suita, Osaka, 565-0874, Japan.,Graduate School of Arts and Sciences, University of Tokyo, 3-8-1 Komaba, Meguro, Tokyo, 153-8902, Japan
| | - Yusuke V Morimoto
- RIKEN Center for Biosystems Dynamics Research (BDR), 6-2-3 Furuedai, Suita, Osaka, 565-0874, Japan. .,Faculty of Computer Science and Systems Engineering, Kyushu Institute of Technology, 680-4 Kawazu, Iizuka, Fukuoka, 820-8502, Japan. .,Japan Science and Technology Agency, PRESTO, 4-1-8 Honcho, Kawaguchi, Saitama, 332-0012, Japan.
| | - Yusei Hirayama
- Faculty of Computer Science and Systems Engineering, Kyushu Institute of Technology, 680-4 Kawazu, Iizuka, Fukuoka, 820-8502, Japan
| | - Masahiro Ueda
- Department of Biological Sciences, Graduate School of Science, Osaka University, 1-3 Yamadaoka, Suita, Osaka, 565-0871, Japan.,RIKEN Center for Biosystems Dynamics Research (BDR), 6-2-3 Furuedai, Suita, Osaka, 565-0874, Japan.,Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka, 565-0871, Japan
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2
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Nelson SA, Li Z, Newton IP, Fraser D, Milne RE, Martin DMA, Schiffmann D, Yang X, Dormann D, Weijer CJ, Appleton PL, Näthke IS. Tumorigenic fragments of APC cause dominant defects in directional cell migration in multiple model systems. Dis Model Mech 2012; 5:940-7. [PMID: 22563063 PMCID: PMC3484875 DOI: 10.1242/dmm.008607] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Nonsense mutations that result in the expression of truncated, N-terminal, fragments of the adenomatous polyposis coli (APC) tumour suppressor protein are found in most sporadic and some hereditary colorectal cancers. These mutations can cause tumorigenesis by eliminating β-catenin-binding sites from APC, which leads to upregulation of β-catenin and thereby results in the induction of oncogenes such as MYC. Here we show that, in three distinct experimental model systems, expression of an N-terminal fragment of APC (N-APC) results in loss of directionality, but not speed, of cell motility independently of changes in β-catenin regulation. We developed a system to culture and fluorescently label live pieces of gut tissue to record high-resolution three-dimensional time-lapse movies of cells in situ. This revealed an unexpected complexity of normal gut cell migration, a key process in gut epithelial maintenance, with cells moving with spatial and temporal discontinuity. Quantitative comparison of gut tissue from wild-type mice and APC heterozygotes (APCMin/+; multiple intestinal neoplasia model) demonstrated that cells in precancerous epithelia lack directional preference when moving along the crypt-villus axis. This effect was reproduced in diverse experimental systems: in developing chicken embryos, mesoderm cells expressing N-APC failed to migrate normally; in amoeboid Dictyostelium, which lack endogenous APC, expressing an N-APC fragment maintained cell motility, but the cells failed to perform directional chemotaxis; and multicellular Dictyostelium slug aggregates similarly failed to perform phototaxis. We propose that N-terminal fragments of APC represent a gain-of-function mutation that causes cells within tissue to fail to migrate directionally in response to relevant guidance cues. Consistent with this idea, crypts in histologically normal tissues of APCMin/+ intestines are overpopulated with cells, suggesting that a lack of migration might cause cell accumulation in a precancerous state.
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Affiliation(s)
- Scott A Nelson
- Division of Cell and Developmental Biology, College of Life Science, University of Dundee, Dundee, DD1 5EH, Scotland, UK
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3
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Abstract
Signal transducers and activators of transcription (STAT) proteins are one of the important mediators of phosphotyrosine-regulated signaling in metazoan cells. These proteins are components of JAK/STAT signal transduction pathways, which regulate immune responses, cell fate, proliferation, cell migration, and programmed cell death in multicellular organisms. The cellular slime mould, Dictyostelium discoideum, is the simplest multicellular organism using molecules homologous to STATs, Dd-STATa-d. The Dd-STATa null mutant displays delayed aggregation, no phototaxis and fails culmination. Here, the functions of Dictyostelium STATs during development and their associated signaling molecules are discussed.
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Affiliation(s)
- Takefumi Kawata
- Department of Biology, Faculty of Science, Toho University, Funabashi 274-8510, Japan.
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4
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Chuai M, Dormann D, Weijer CJ. Imaging cell signalling and movement in development. Semin Cell Dev Biol 2009; 20:947-55. [DOI: 10.1016/j.semcdb.2009.09.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2009] [Revised: 09/01/2009] [Accepted: 09/03/2009] [Indexed: 10/20/2022]
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5
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Kawabe Y, Morio T, James JL, Prescott AR, Tanaka Y, Schaap P. Activated cAMP receptors switch encystation into sporulation. Proc Natl Acad Sci U S A 2009; 106:7089-94. [PMID: 19369200 PMCID: PMC2678454 DOI: 10.1073/pnas.0901617106] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2009] [Indexed: 11/18/2022] Open
Abstract
Metazoan embryogenesis is controlled by a limited number of signaling modules that are used repetitively at successive developmental stages. The development of social amoebas shows similar reiterated use of cAMP-mediated signaling. In the model Dictyostelium discoideum, secreted cAMP acting on 4 cAMP receptors (cARs1-4) coordinates cell movement during aggregation and fruiting body formation, and induces the expression of aggregation and sporulation genes at consecutive developmental stages. To identify hierarchy in the multiple roles of cAMP, we investigated cAR heterogeneity and function across the social amoeba phylogeny. The gene duplications that yielded cARs 2-4 occurred late in evolution. Many species have only a cAR1 ortholog that duplicated independently in the Polysphondylids and Acytostelids. Disruption of both cAR genes of Polysphondylium pallidum (Ppal) did not affect aggregation, but caused complete collapse of fruiting body morphogenesis. The stunted structures contained disorganized stalk cells, which supported a mass of cysts instead of spores; cAMP triggered spore gene expression in Ppal, but not in the cAR null mutant, explaining its sporulation defect. Encystation is the survival strategy of solitary amoebas, and lower taxa, like Ppal, can still encyst as single cells. Recent findings showed that intracellular cAMP accumulation suffices to trigger encystation, whereas it is a complementary requirement for sporulation. Combined, the data suggest that cAMP signaling in social amoebas evolved from cAMP-mediated encystation in solitary amoebas; cAMP secretion in aggregates prompted the starving cells to form spores and not cysts, and additionally organized fruiting body morphogenesis. cAMP-mediated aggregation was the most recent innovation.
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Affiliation(s)
- Yoshinori Kawabe
- College of Life Sciences, University of Dundee, Dundee, Angus, DD15EH, United Kingdom; and
| | - Takahiro Morio
- Graduate School of Life and Environmental Sciences, University of Tsukuba, Ibaraki, 305-8572, Japan
| | - John L. James
- College of Life Sciences, University of Dundee, Dundee, Angus, DD15EH, United Kingdom; and
| | - Alan R. Prescott
- Graduate School of Life and Environmental Sciences, University of Tsukuba, Ibaraki, 305-8572, Japan
| | - Yoshimasa Tanaka
- Graduate School of Life and Environmental Sciences, University of Tsukuba, Ibaraki, 305-8572, Japan
| | - Pauline Schaap
- College of Life Sciences, University of Dundee, Dundee, Angus, DD15EH, United Kingdom; and
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6
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Alvarez-Curto E, Weening K, Schaap P. Pharmacological profiling of the Dictyostelium adenylate cyclases ACA, ACB and ACG. Biochem J 2007; 401:309-16. [PMID: 16952277 PMCID: PMC1698679 DOI: 10.1042/bj20060880] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Intracellular and secreted cAMPs play crucial roles in controlling cell movement and gene regulation throughout development of the social amoeba Dictyostelium discoideum. cAMP is produced by three structurally distinct ACs (adenylate cyclases), ACA, ACG and ACB, which have distinctive but overlapping patterns of expression and, as concluded from gene disruption studies, seemingly overlapping functions. In addition to gene disruption, acute pharmacological abrogation of protein activity can be a powerful tool to identify the protein's role in the biology of the organism. We analysed the effects of a range of compounds on the activity of ACA, ACB and ACG to identify enzyme-specific modulators. Caffeine, which was previously used to specifically block ACA function, also inhibited cAMP accumulation by ACB and ACG. IPA (2',3'-O-isopropylidene adenosine) specifically inhibits ACA when measured in intact cells, without affecting ACB or ACG. All three enzymes are inhibited by the P-site inhibitor DDA (2',5'-dideoxyadenosine) when assayed in cell lysates, but not in intact cells. Tyrphostin A25 [alpha-cyano-(3,4,5-trihydroxy)cinnamonitrile] and SQ22536 [9-(tetrahydro-2'-furyl)adenine] proved to be effective and specific inhibitors for ACG and ACA respectively. Both compounds acted directly on enzyme activity assayed in cell lysates, but only SQ22536 was also a specific inhibitor when added to intact cells.
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Affiliation(s)
| | - Karin E. Weening
- School of Life Sciences, University of Dundee, Dundee, Scotland, U.K
| | - Pauline Schaap
- School of Life Sciences, University of Dundee, Dundee, Scotland, U.K
- To whom correspondence should be addressed, at MSI/WTB/JBC Complex, Dow Street, Dundee DD1 5EH, Scotland, U.K. (email )
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7
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Singleton CK, Kirsten JH, Dinsmore CJ. Function of ammonium transporter A in the initiation of culmination of development in Dictyostelium discoideum. EUKARYOTIC CELL 2006; 5:991-6. [PMID: 16835443 PMCID: PMC1489295 DOI: 10.1128/ec.00058-06] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The histidine kinase DhkC controls a phosphorelay involved in regulating the slug versus culmination choice during the multicellular developmental program of Dictyostelium discoideum. When the relay is active, slug migration is favored due to the activation of a cyclic AMP (cAMP) phosphodiesterase and the resultant lowering of the intracellular and extracellular levels of cAMP. Ammonia signaling represents one input into the DhkC phosphorelay, and previous studies indicated that the ammonium transporter C inhibits the relay in response to low ammonia levels. Evidence is presented that another member of the family of ammonium transporters, AmtA, also regulates the slug/culmination choice. Under standard conditions of development, the wild-type strain requires a transitional period of 2 to 3 h to go from fingers to culminants, with some slugs forming and migrating briefly prior to culmination. In contrast, amtA null cells, like cells that lack DhkC, possessed a transitional period of only 1 to 2 h and rarely formed slugs. Disruption of amtA in an amtC null strain overcame the slugger phenotype of that strain and restored its ability to culminate. Strains lacking AmtA were insensitive to the ability of ammonia to promote and prolong slug migration. These findings lead to the proposal that AmtA functions in ammonia sensing as an activator of the DhkC phosphorelay in response to perceived high ammonia levels.
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Affiliation(s)
- Charles K Singleton
- Department of Biological Sciences, Vanderbilt University, VU Station B 351634, Nashville, Tennessee 37235-1634, USA.
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8
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Williams JG. Transcriptional regulation of Dictyostelium pattern formation. EMBO Rep 2006; 7:694-8. [PMID: 16819464 PMCID: PMC1500839 DOI: 10.1038/sj.embor.7400714] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2006] [Accepted: 04/13/2006] [Indexed: 11/10/2022] Open
Abstract
On starvation, Dictyostelium cells form a terminally differentiated structure, known as the fruiting body, which comprises stalk and spore cells. Their precursors--prestalk and prespore cells--are spatially separated and accessible in a migratory structure known as the slug. This simplicity and manipulability has made Dictyostelium attractive to both experimental and theoretical developmental biologists. However, this outward simplicity conceals a surprising degree of developmental sophistication. Multiple prestalk subtypes are formed and undertake a co-ordinated series of morphogenetic cell movements to generate the fruiting body. This review describes recent advances in understanding the signalling pathways that generate prestalk-cell heterogeneity, focusing on the roles of the prestalk-cell inducer differentiation-inducing factor-1 (DIF-1), the tip inducer cAMP and the transcription factors that mediate their actions; these include signal transducer and activator of transcription (STAT) proteins, basic leucine zipper (bZIP) proteins and a Myb protein of a class previously described only in plants.
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Affiliation(s)
- Jeffrey G Williams
- School of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, UK.
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9
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Abstract
Accurate cellular localization is crucial for the effective function of most signalling molecules and nuclear translocation is central to the function of transcription factors. The passage of large molecules between the cytoplasm and nucleus is restricted, and this restriction affords a mechanism to regulate transcription by controlling the access of transcription factors to the nucleus. In this Review, we focus on the signal transducer and activator of transcription (STAT) family of transcription factors. The regulation of the nuclear trafficking of STAT-family members is diverse. Some STAT proteins constitutively shuttle between the nucleus and cytoplasm, whereas others require tyrosine phosphorylation for nuclear localization. In either case, the regulation of nuclear trafficking can provide a target for therapeutic intervention.
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Affiliation(s)
- Nancy C Reich
- Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, New York 11777, USA.
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10
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Kirsten JH, Xiong Y, Dunbar AJ, Rai M, Singleton CK. Ammonium transporter C of Dictyostelium discoideum is required for correct prestalk gene expression and for regulating the choice between slug migration and culmination. Dev Biol 2005; 287:146-56. [PMID: 16188250 DOI: 10.1016/j.ydbio.2005.08.043] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2005] [Revised: 08/04/2005] [Accepted: 08/29/2005] [Indexed: 10/25/2022]
Abstract
Ammonium transporter C (AmtC) is one of three transporters in Dictyostelium that have been proposed to regulate entry and exit of ammonia in a cell type dependent manner and to mediate ammonia signaling. Previous work demonstrated that disruption of the amtC gene results in a slugger phenotype in which the cells remain as migrating slugs when they should form fruiting bodies. More detailed studies on the null strain revealed that differentiation of prestalk cell types was delayed and maintenance of prestalk cell gene expression was defective. There was little or no expression of ecmB, a marker for the initiation of culmination. Normal expression of CudA, a nuclear protein required for culmination, was absent in the anterior prestalk zone. The absence of CudA within the tip region was attributable to the lack of nuclear localization of the transcription factor STATa, despite expression of adenylyl cyclase A mRNA in the slug tips. Disruption of the histidine kinase gene dhkC in the amtC null strain restored STATa and CudA expression and the ability to culminate. The results suggest that the lack of nuclear translocation of STATa results from low cAMP due to a misregulated and overactive DhkC phosphorelay in the amtC null strain.
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Affiliation(s)
- Janet H Kirsten
- Department of Biological Sciences, Vanderbilt University, VU Station B 351634, Nashville, TN 37235-1634, USA
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11
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Abstract
During starvation-induced Dictyostelium development, up to several hundred thousand amoeboid cells aggregate, differentiate and form a fruiting body. The chemotactic movement of the cells is guided by the rising phase of the outward propagating cAMP waves and results in directed periodic movement towards the aggregation centre. In the mound and slug stages of development, cAMP waves continue to play a major role in the coordination of cell movement, cell-type-specific gene expression and morphogenesis; however, in these stages where cells are tightly packed, cell-cell adhesion/contact-dependent signalling mechanisms also play important roles in these processes.
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Affiliation(s)
- Cornelis J Weijer
- Division of Cell and Developmental Biology, School of Life Sciences, University of Dundee, Wellcome Trust Biocentre, Dundee DD1 5EH, UK.
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12
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Shimada N, Nishio K, Maeda M, Urushihara H, Kawata T. Extracellular matrix family proteins that are potential targets of Dd-STATa in Dictyostelium discoideum. JOURNAL OF PLANT RESEARCH 2004; 117:345-353. [PMID: 15309638 DOI: 10.1007/s10265-004-0165-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2004] [Accepted: 06/18/2004] [Indexed: 05/24/2023]
Abstract
Dd-STATa is a functional Dictyostelium homologue of metazoan STAT (signal transducers and activators of transcription) proteins, which is activated by cAMP and is thereby translocated into the nuclei of anterior tip cells of the prestalk region of the slug. By using in situ hybridization analyses, we found that the SLF308 cDNA clone, which contains the ecmF gene that encodes a putative extracellular matrix protein and is expressed in the anterior tip cells, was greatly down-regulated in the Dd-STATa-null mutant. Disruption of the ecmF gene, however, resulted in almost no phenotypic change. The absence of any obvious mutant phenotype in the ecmF-null mutant could be due to a redundancy of similar genes. In fact, a search of the Dictyostelium whole genome database demonstrates the existence of an additional 16 homologues, all of which contain a cellulose-binding module. Among these homologues, four genes show Dd-STATa-dependent expression, while the others are Dd-STATa-independent. We discuss the potential role of Dd-STATa in morphogenesis via its effect on the interaction between cellulose and these extracellular matrix family proteins.
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Affiliation(s)
- Nao Shimada
- Department of Biology, Faculty of Science, Toho University, 2-2-1 Miyama, Funabashi, Chiba 274-8510, Japan
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13
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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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14
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McBride KM, Reich NC. The ins and outs of STAT1 nuclear transport. SCIENCE'S STKE : SIGNAL TRANSDUCTION KNOWLEDGE ENVIRONMENT 2003; 2003:RE13. [PMID: 12915721 DOI: 10.1126/stke.2003.195.re13] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
There is an inherent elegance in being in the right place at the right time. The STAT1 transcription factor possesses regulatory signals that ensure its distribution to the right cellular location at the right time. Latent STAT1 resides primarily in the cytoplasm, and there it responds to hormone signaling through tyrosine phosphorylation by Janus kinases or growth factor receptors. After phosphorylation, STAT1 dimerizes, and this conformational change reveals a nuclear import signal that is recognized by a specific nuclear import carrier. In the nucleus, the STAT1 dimer dissociates from the import carrier and binds to specific DNA target sites in the promoters of regulated genes. STAT1 is subsequently dephosphorylated in the nucleus by a constitutively active tyrosine phosphatase, leading to its dissociation from DNA. A nuclear export signal of STAT1 appears to be masked when dimers are bound to DNA, but it becomes accessible to the CRM1 export carrier after dissociation from DNA. CRM1 binds STAT1 and transports the transcription factor back to the cytoplasm. Studies show that the regulatory trafficking signals that guide the nuclear import and export of STAT1 reside within its DNA binding domain. The location of these signals indicates that their function has coevolved with the ability of STAT1 to bind DNA and regulate gene expression. The nuclear import and subsequent recycling of STAT1 to the cytoplasm are integral to its function as a signal transducer and activator of transcription.
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Affiliation(s)
- Kevin M McBride
- Department of Pathology, State University of New York at Stony Brook, Stony Brook, NY 11794, USA
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16
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Abstract
Cells display a highly complex spatiotemporal organization, required to exert a wide variety of different functions, for example, detection, processing, and propagation of nerve impulses by neurons; contraction and relaxation by muscle cells; movement by leukocytes; and adsorption and secretion of nutrients and metabolites by epithelial cells lining the gut. Successful execution of these complex processes requires highly dynamic information transfer between different regions and compartments within cells. Through the development of fluorescent sensors for intracellular signaling molecules coupled with improved microscopic imaging techniques, it has now become possible to investigate signal propagation in cells with high spatial and temporal resolution.
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Affiliation(s)
- Cornelis J Weijer
- School of Life Sciences, University of Dundee, Wellcome Trust Biocentre, Dundee DD1 5EH, UK.
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17
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Dormann D, Libotte T, Weijer CJ, Bretschneider T. Simultaneous quantification of cell motility and protein-membrane-association using active contours. CELL MOTILITY AND THE CYTOSKELETON 2002; 52:221-30. [PMID: 12112136 DOI: 10.1002/cm.10048] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
We present a new method for the quantification of dynamic changes in fluorescence intensities at the cell membrane of moving cells. It is based on an active contour method for cell-edge detection, which allows tracking of changes in cell shape and position. Fluorescence intensities at specific cortical subregions can be followed in space and time and correlated with cell motility. The translocation of two GFP tagged proteins (CRAC and GRP1) from the cytosol to the membrane in response to stimulation with the chemoattractant cAMP during chemotaxis of Dictyostelium cells and studies of the spatio-temporal dynamics of this process exemplify the method: We show that the translocation can be correlated with motility parameters and that quantitative differences in the rate of association and dissociation from the membrane can be observed for the two PH domain containing proteins. The analysis of periodic CRAC translocation to the leading edge of a cell responding to natural cAMP waves in a mound demonstrates the power of this approach. It is not only capable of tracking the outline of cells within aggregates in front of a noisy background, but furthermore allows the construction of spatio-temporal polar plots, capturing the dynamics of the protein distribution at the cell membrane within the cells' moving co-ordinate system. Compilation of data by means of normalised polar plots is suggested as a future tool, which promises the so-far impossible practicability of extensive statistical studies and automated comparison of complex spatio-temporal protein distribution patterns.
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Affiliation(s)
- Dirk Dormann
- School of Life Sciences, The Wellcome Trust Biocentre, University of Dundee, Dundee, Scotland
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18
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Dormann D, Weijer G, Parent CA, Devreotes PN, Weijer CJ. Visualizing PI3 kinase-mediated cell-cell signaling during Dictyostelium development. Curr Biol 2002; 12:1178-88. [PMID: 12176327 DOI: 10.1016/s0960-9822(02)00950-8] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Starving amoebae of Dictyostelium discoideum communicate by relaying extracellular cAMP signals, which direct chemotactic movement, resulting in the aggregation of thousands of cells into multicellular aggregates. Both cAMP relay and chemotaxis require the activation of PI3 kinase signaling. The spatiotemporal dynamics of PI3 kinase signaling can be followed in individual cells via the cAMP-induced membrane recruitment of a GFP-tagged PH domain-containing protein, CRAC, which is required for the activation of adenylylcyclase. RESULTS We show that polarized periodic CRAC-GFP translocation occurs during the aggregation and mound stages of development in response to periodic cAMP signals. The duration of CRAC translocation to the membrane is determined by the duration of the rising phase of the cAMP signal. The system shows rapid adaptation and responds to the rate of change of the extracellular cAMP concentration. When the cells are in close contact, it takes 10 s for the signal to propagate from one cell to the next. In slugs, all cells show a permanent polarized PI3 kinase signaling in their leading edge, which is dependent on cell-cell contact. CONCLUSIONS Measuring the redistribution of GFP-tagged CRAC has enabled us to study the dynamics of PI3 kinase-mediated cell-cell communication at the individual cell level in the multicellular stages of Dictyostelium development. This approach should also be useful to study the interactions between cell-cell signaling, cell polarization, and movement in the development of other organisms.
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Affiliation(s)
- Dirk Dormann
- School of Life Science, University of Dundee, Wellcome Trust Biocentre, Dundee, United Kingdom
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19
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Dormann D, Weijer CJ. Propagating chemoattractant waves coordinate periodic cell movement inDictyosteliumslugs. Development 2001; 128:4535-43. [PMID: 11714678 DOI: 10.1242/dev.128.22.4535] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Migration and behaviour of Dictyostelium slugs results from coordinated movement of its constituent cells. It has been proposed that cell movement is controlled by propagating waves of cAMP as during aggregation and in the mound. We report the existence of optical density waves in slugs; they are initiated in the tip and propagate backwards. The waves reflect periodic cell movement and are mediated by cAMP, as injection of cAMP or cAMP phosphodiesterase disrupts wave propagation and results in effects on cell movement and, therefore, slug migration. Inhibiting the function of the cAMP receptor cAR1 blocks wave propagation, showing that the signal is mediated by cAR1. Wave initiation is strictly dependent on the tip; in decapitated slugs no new waves are initiated and slug movement stops until a new tip regenerates. Isolated tips continue to migrate while producing waves. We conclude from these observations that the tip acts as a pacemaker for cAMP waves that coordinate cell movement in slugs.Movies available on-line
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Affiliation(s)
- D Dormann
- School of Life Sciences, Division of Cell and Developmental Biology, Wellcome Trust Biocentre, University of Dundee, Dundee DD1 5EH, UK
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20
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Verkerke-van Wijk I, Fukuzawa M, Devreotes PN, Schaap P. Adenylyl cyclase A expression is tip-specific in Dictyostelium slugs and directs StatA nuclear translocation and CudA gene expression. Dev Biol 2001; 234:151-60. [PMID: 11356026 DOI: 10.1006/dbio.2001.0232] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
cAMP oscillations, generated by adenylyl cyclase A (ACA), coordinate cell aggregation in Dictyostelium and have also been implicated in organizer function during multicellular development. We used a gene fusion of the ACA promoter with a labile lacZ derivative to study the expression pattern of ACA. During aggregation, most cells expressed ACA, but thereafter expression was lost in all cells except those of the anterior tip. Before aggregation, ACA transcription was strongly upregulated by nanomolar cAMP pulses. Postaggregative transcription was sustained by nanomolar cAMP pulses, but downregulated by a continuous micromolar cAMP stimulus and by the stalk-cell-inducing factor DIF. Earlier work showed that the transcription factor StatA displays tip-specific nuclear translocation and directs tip-specific expression of the nuclear protein CudA, which is essential for culmination. Both StatA and CudA were present in nuclei throughout the entire slug in an aca null mutant that expresses ACA from the constitutive actin15 promoter. This suggests that the tip-specific expression of ACA directs tip-specific nuclear translocation of StatA and tip-specific expression of CudA.
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Fukuzawa M, Araki T, Adrian I, Williams JG. Tyrosine phosphorylation-independent nuclear translocation of a dictyostelium STAT in response to DIF signaling. Mol Cell 2001; 7:779-88. [PMID: 11336701 DOI: 10.1016/s1097-2765(01)00222-2] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
We describe a Dictyostelium STAT, Dd-STATc, which regulates the speed of early development and the timing of terminal differentiation. Dd-STATc also functions as a repressor, which directs graded expression of the ecmA gene in different prestalk cell populations. Developing Dictyostelium cells produce a chlorinated hexaphenone, DIF, which directs prestalk cell differentiation. Dd-STATc is tyrosine phosphorylated, dimerizes, and translocates to the nucleus when cells are exposed to DIF. Surprisingly, however, SH2 domain-phosphotyrosine interaction is not necessary for the DIF-induced nuclear translocation of Dd-STATc. In this respect, Dd-STATc activation resembles several recently described, noncanonical mammalian STAT signaling processes. We show instead that DIF mediates nuclear translocation via sequences located in the divergent, N-terminal half of the Dd-STATc molecule.
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Affiliation(s)
- M Fukuzawa
- School of Life Sciences, University of Dundee, Dundee DD1 5EH, United Kingdom
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