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Negrete J, Pumir A, Hsu HF, Westendorf C, Tarantola M, Beta C, Bodenschatz E. Noisy Oscillations in the Actin Cytoskeleton of Chemotactic Amoeba. PHYSICAL REVIEW LETTERS 2016; 117:148102. [PMID: 27740793 DOI: 10.1103/physrevlett.117.148102] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Indexed: 06/06/2023]
Abstract
Biological systems with their complex biochemical networks are known to be intrinsically noisy. Here we investigate the dynamics of actin polymerization of amoeboid cells, which are close to the onset of oscillations. We show that the large phenotypic variability in the polymerization dynamics can be accurately captured by a generic nonlinear oscillator model in the presence of noise. We determine the relative role of the noise with a single dimensionless, experimentally accessible parameter, thus providing a quantitative description of the variability in a population of cells. Our approach, which rests on a generic description of a system close to a Hopf bifurcation and includes the effect of noise, can characterize the dynamics of a large class of noisy systems close to an oscillatory instability.
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Affiliation(s)
- Jose Negrete
- Max Planck Institute for Dynamics and Self-Organization (MPIDS), D-37077 Göttingen, Germany
| | - Alain Pumir
- Max Planck Institute for Dynamics and Self-Organization (MPIDS), D-37077 Göttingen, Germany
- Laboratoire de Physique, Ecole Normale Supérieure de Lyon, Université de Lyon 1 and Centre National de la Recherche Scientifique, F-69007 Lyon, France
| | - Hsin-Fang Hsu
- Max Planck Institute for Dynamics and Self-Organization (MPIDS), D-37077 Göttingen, Germany
| | - Christian Westendorf
- Max Planck Institute for Dynamics and Self-Organization (MPIDS), D-37077 Göttingen, Germany
| | - Marco Tarantola
- Max Planck Institute for Dynamics and Self-Organization (MPIDS), D-37077 Göttingen, Germany
| | - Carsten Beta
- Max Planck Institute for Dynamics and Self-Organization (MPIDS), D-37077 Göttingen, Germany
- Institute of Physics and Astronomy, University of Potsdam, D-14476 Potsdam, Germany
| | - Eberhard Bodenschatz
- Max Planck Institute for Dynamics and Self-Organization (MPIDS), D-37077 Göttingen, Germany
- Institute for Nonlinear Dynamics, University of Göttingen, D-37073 Göttingen, Germany
- Laboratory of Atomic and Solid-State Physics and Sibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, New York 14853, USA
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Mir H, Alex T, Rajawat J, Kadam A, Begum R. Response of Dictyostelium discoideum to UV-C and involvement of poly (ADP-ribose) polymerase. Cell Prolif 2015; 48:363-74. [PMID: 25858552 DOI: 10.1111/cpr.12182] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Accepted: 12/05/2014] [Indexed: 11/29/2022] Open
Abstract
OBJECTIVES Radiation and chemical mutagens are direct DNA-damaging agents and ultraviolet (UV) radiation is frequently used in biological studies. Consequent to ozone depletion, UV-C could become a great challenge to living organisms on earth, in the near future. The present study has focused on the role of poly (ADP-ribose) polymerase (PARP) during UV-C-induced growth and developmental changes in Dictyostelium discoideum, a phylogenetically important unicellular eukaryote. MATERIALS AND METHODS Dictyostelium discoideum cells were exposed to different doses of UV-C and PARP activity, and effects of its inhibition were studied. Expression of developmentally regulated genes yakA, car1, aca, csA, regA, ctnA, ctnB, gp24, hspD and dsn were analysed using semiquantitative RT-PCR. RESULTS We report that the D. discoideum cells displayed PARP activation within 2 min of UV-C irradiation and there was increase in NO levels in a dose-dependent manner. UV-C-irradiated cells had impaired growth, delayed or blocked development and delayed germination compared to control cells. In our previous studies we have shown that inhibition of PARP recovered oxidative stress-induced changes in D. discoideum; however, intriguingly PARP inhibition did not correct all defects as effectively in UV-C-irradiated cells. This possibly was due to interplay with increased NO signalling. CONCLUSIONS Our results signify that UV-C and oxidative stress affected growth and development in D. discoideum by different mechanisms; these studies could provide major clues to complex mechanisms of growth and development in higher organisms.
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Affiliation(s)
- H Mir
- Department of Biochemistry, Faculty of Science, The Maharaja Sayajirao University of Baroda, Vadodara, Gujarat, 390002, India
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Priebe M, Bernhardt M, Blum C, Tarantola M, Bodenschatz E, Salditt T. Scanning x-ray nanodiffraction on Dictyostelium discoideum. Biophys J 2014; 107:2662-73. [PMID: 25468345 PMCID: PMC4255453 DOI: 10.1016/j.bpj.2014.10.027] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2014] [Revised: 09/30/2014] [Accepted: 10/14/2014] [Indexed: 12/22/2022] Open
Abstract
We have performed scanning x-ray nanobeam diffraction experiments on single cells of the amoeba Dictyostelium discoideum. Cells have been investigated in 1), freeze-dried, 2), frozen-hydrated (vitrified), and 3), initially alive states. The spatially resolved small-angle x-ray scattering signal shows characteristic streaklike patterns in reciprocal space, which we attribute to fiber bundles of the actomyosin network. From the intensity distributions, an anisotropy parameter can be derived that indicates pronounced local variations within the cell. In addition to nanobeam small-angle x-ray scattering, we have evaluated the x-ray differential phase contrast in view of the projected electron density. Different experimental aspects of the x-ray experiment, sample preparation, and data analysis are discussed. Finally, the x-ray results are correlated with optical microscopy (differential phase contrast and confocal microscopy of mutant strains with fluorescently labeled actin and myosin II), which have been carried out in live and fixed states, including optical microscopy under cryogenic conditions.
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Affiliation(s)
- Marius Priebe
- Institut für Röntgenphysik, Georg-August-Universität Göttingen, Göttingen, Germany
| | - Marten Bernhardt
- Institut für Röntgenphysik, Georg-August-Universität Göttingen, Göttingen, Germany
| | - Christoph Blum
- Max Planck Institute for Dynamics and Self-Organization, Göttingen, Germany
| | - Marco Tarantola
- Max Planck Institute for Dynamics and Self-Organization, Göttingen, Germany
| | | | - Tim Salditt
- Institut für Röntgenphysik, Georg-August-Universität Göttingen, Göttingen, Germany.
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Actin cytoskeleton of chemotactic amoebae operates close to the onset of oscillations. Proc Natl Acad Sci U S A 2013; 110:3853-8. [PMID: 23431176 DOI: 10.1073/pnas.1216629110] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The rapid reorganization of the actin cytoskeleton in response to external stimuli is an essential property of many motile eukaryotic cells. Here, we report evidence that the actin machinery of chemotactic Dictyostelium cells operates close to an oscillatory instability. When averaging the actin response of many cells to a short pulse of the chemoattractant cAMP, we observed a transient accumulation of cortical actin reminiscent of a damped oscillation. At the single-cell level, however, the response dynamics ranged from short, strongly damped responses to slowly decaying, weakly damped oscillations. Furthermore, in a small subpopulation, we observed self-sustained oscillations in the cortical F-actin concentration. To substantiate that an oscillatory mechanism governs the actin dynamics in these cells, we systematically exposed a large number of cells to periodic pulse trains of different frequencies. Our results indicate a resonance peak at a stimulation period of around 20 s. We propose a delayed feedback model that explains our experimental findings based on a time-delay in the regulatory network of the actin system. To test the model, we performed stimulation experiments with cells that express GFP-tagged fusion proteins of Coronin and actin-interacting protein 1, as well as knockout mutants that lack Coronin and actin-interacting protein 1. These actin-binding proteins enhance the disassembly of actin filaments and thus allow us to estimate the delay time in the regulatory feedback loop. Based on this independent estimate, our model predicts an intrinsic period of 20 s, which agrees with the resonance observed in our periodic stimulation experiments.
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Westendorf C, Bae AJ, Erlenkamper C, Galland E, Franck C, Bodenschatz E, Beta C. Live cell flattening - traditional and novel approaches. PMC BIOPHYSICS 2010; 3:9. [PMID: 20403171 PMCID: PMC2873278 DOI: 10.1186/1757-5036-3-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/11/2009] [Accepted: 04/19/2010] [Indexed: 11/10/2022]
Abstract
Eukaryotic cell flattening is valuable for improving microscopic observations, ranging from bright field (BF) to total internal reflection fluorescence (TIRF) microscopy. Fundamental processes, such as mitosis and in vivo actin polymerization, have been investigated using these techniques. Here, we review the well known agar overlayer protocol and the oil overlay method. In addition, we present more elaborate microfluidics-based techniques that provide us with a greater level of control. We demonstrate these techniques on the social amoebae Dictyostelium discoideum, comparing the advantages and disadvantages of each method.PACS Codes: 87.64.-t, 47.61.-k, 87.80.Ek.
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Affiliation(s)
- Christian Westendorf
- Max-Planck-Institut für Dynamik und Selbstorganisation, 37077 Göttingen, Germany
| | - Albert J Bae
- Max-Planck-Institut für Dynamik und Selbstorganisation, 37077 Göttingen, Germany
- Laboratory of Atomic and Solid-State Physics, Cornell University, Ithaca, NY 14853, USA
| | | | | | - Carl Franck
- Laboratory of Atomic and Solid-State Physics, Cornell University, Ithaca, NY 14853, USA
| | - Eberhard Bodenschatz
- Max-Planck-Institut für Dynamik und Selbstorganisation, 37077 Göttingen, Germany
- Laboratory of Atomic and Solid-State Physics, Cornell University, Ithaca, NY 14853, USA
- Institut für Nichtlineare Dynamik, Georg-August-Universität Göttingen, 37073 Göttingen, Germany
| | - Carsten Beta
- Max-Planck-Institut für Dynamik und Selbstorganisation, 37077 Göttingen, Germany
- Institut für Physik und Astronomie, Universität Potsdam, 14476 Potsdam, Germany
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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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Dharmawardhane S, Cubitt AB, Clark AM, Firtel RA. Regulatory role of the G alpha 1 subunit in controlling cellular morphogenesis in Dictyostelium. Development 1994; 120:3549-61. [PMID: 7821221 DOI: 10.1242/dev.120.12.3549] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
To determine the function of the Dictyostelium G alpha 1 subunit during aggregation and multicellular development, we analyzed the phenotypes of g alpha 1 null cells and strains overexpressing either wild-type G alpha 1 or two putative constitutively active mutations of G alpha 1. Strains overexpressing the wild-type or mutant G alpha 1 proteins showed very abnormal culmination with an aberrant stalk differentiation. The similarity of the phenotypes between G alpha 1 overexpression and expression of a putative constitutively active G alpha 1 subunit suggests that these phenotypes are due to increased G alpha 1 activity rather than resulting from a non-specific interference of other pathways. In contrast, g alpha 1 null strains showed normal morphogenesis except that the stalks were thinner and longer than those of wild-type culminants. Analysis of cell-type-specific gene expression using lacZ reporter constructs indicated that strains overexpressing G alpha 1 show a loss of ecmB expression in the central core of anterior prestalk AB cells. However, expression of ecmB in anterior-like cells and the expression of prestalk A-specific gene ecmA and the prespore-specific gene SP60/cotC appeared normal. Using a G alpha 1/lacZ reporter construct, we show that G alpha 1 expression is cell-type-specific during the multicellular stages, with a pattern of expression similar to ecmB, being preferentially expressed in the anterior prestalk AB cells and anterior-like cells. The developmental and molecular phenotypes of G alpha 1 overexpression and the cell-type-specific expression of G alpha 1 suggest that G alpha 1-mediated signaling pathways play an essential role in regulating multicellular development by controlling prestalk morphogenesis, possibly by acting as a negative regulator of prestalk AB cell differentiation. During the aggregation phase of development, g alpha 1 null cells display a delayed peak in cAMP-stimulated accumulation of cGMP compared to wild-type cells, while G alpha 1 overexpressors and dominant activating mutants show parallel kinetics of activation but decreased levels of cGMP accumulation compared to that seen in wild-type cells. These data suggest that G alpha 1 plays a role in the regulation of the activation and/or adaptation of the guanylyl cyclase pathway. In contrast, the activation of adenylyl cyclase, another pathway activated by cAMP stimulation, was unaffected in g alpha 1 null cells and cell lines overexpressing wild-type G alpha 1 or the G alpha 1 (Q206L) putative dominant activating mutation.(ABSTRACT TRUNCATED AT 400 WORDS)
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Affiliation(s)
- S Dharmawardhane
- Department of Biology, University of California, San Diego, La Jolla 92093-0634
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Yoshida H, Yamada Y, Okamoto K. DC6, a novel type of Dictyostelium discoideum gene regulated by secreted factors but not by cAMP. Differentiation 1991; 46:161-6. [PMID: 1717330 DOI: 10.1111/j.1432-0436.1991.tb00877.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
We have isolated a gene, DC6, which is induced in the early aggregative stages of development in Dictyostelium discoideum. The increase in DC6 expression is dependent on high cell density, indicating that cellular interactions are required for DC6 induction. In low-cell-density cultures, the induction of DC6 occurs if supplied with conditioned medium of developing cells, suggesting that secreted factors are involved in DC6 induction. The expression of DC6 is not affected (1) in the presence of caffeine or adenosine, which block the production or the action of cAMP pulses, (2) in the presence of high concentrations of cAMP, or (3) in mutant strains (Synag7 and FrigidA), which are defective in transduction pathways of cAMP pulse signals. These results indicate that the induction of DC6 does not require extracellular cAMP pulse signals, which are known to regulate the expression of many genes in the early development. Independence of cAMP signals and dependence on other unknown cellular interactions are prominent characteristics of DC6.
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Affiliation(s)
- H Yoshida
- Department of Botany, Faculty of Science, Kyoto University, Japan
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Fosnaugh KL, Loomis WF. Coordinate regulation of the spore coat genes in Dictyostelium discoideum. DEVELOPMENTAL GENETICS 1991; 12:123-32. [PMID: 1646690 DOI: 10.1002/dvg.1020120120] [Citation(s) in RCA: 57] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Genomic clones of the genes coding for the three major spore coat proteins, SP60, SP70, and SP96, were used to measure the accumulation of their respective mRNAs in mutant and wild-type cells allowed to develop under a variety of conditions. These prespore-specific mRNAs were found to be both temporally and quantitatively coordinate under all conditions indicating that they may be subject to identical regulatory processes. Accumulation of the spore coat mRNAs is dependent upon the function of both cAMP receptors and G alpha 2 proteins during the aggregation stage as well as upon concomitant protein synthesis. When cells are dissociated from aggregates at 10 hr of development and rapidly shaken in 0.1 mM EDTA they form clumps but do not accumulate any of the prespore-specific RNAs assayed. However, if either 0.1 mM Ca++ or 20 microM cAMP is added to these cells, the spore coat mRNAs accumulate. Lower concentrations of either Ca++ or cAMP had no effect. These results suggest that expression of the spore coat genes normally involves a Ca+(+)-dependent process, but the Ca++ requirement can be overcome by adding high concentrations of exogenous cAMP. Addition of 50 nM DIF to dissociated cell blocks the accumulation of the spore coat mRNAs even when cAMP or Ca++ is present. The upstream regions of the spore coat genes were compared to those of another gene, D19, that codes for the prespore-specific protein SP29. Short sequences related to CACCCAC were found at about the same position relative to the transcriptional start sites of these coordinately regulated genes.
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Yamada Y, Okamoto K. Three steps in prespore differentiationin Dictyostelium discoideum with different requirements of cellular interaction. Differentiation 1990. [DOI: 10.1111/j.1432-0436.1990.tb00540.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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A pharmacologically distinct cyclic AMP receptor is responsible for the regulation of gp80 expression in Dictyostelium discoideum. Mol Cell Biol 1990. [PMID: 2162472 DOI: 10.1128/mcb.10.7.3297] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The EDTA-resistant cell-cell adhesion expressed at the aggregation stage of Dictyostelium discoideum is mediated by a cell surface glycoprotein of Mr 80,000 (gp80). The expression of gp80 is developmentally regulated by cyclic AMP (cAMP). In vitro nuclear run-on experiments show that transcription of the gp80 gene is initiated soon after the onset of development. The basal level of gp80 transcription is significantly augmented by exogenous cAMP pulses. Interestingly, in analog studies, 2'-deoxy-cAMP, 8-bromo-cAMP, and N6-monobutyryl-cAMP are all capable of inducing a rapid accumulation of gp80 mRNA, suggesting the presence of a unique cAMP receptor that responds equally well to these analogs. To determine whether intracellular cAMP plays a role in the regulation of gp80 expression, caffeine was used to block cAMP-induced receptor-mediated adenylate cyclase activation. Expression of gp80 mRNA was blocked in caffeine-treated cells but could be substantially restored by treatment with exogenous cAMP pulses, suggesting that adenylate cyclase activation is not required. gp80 expression was also examined in the signal transduction mutants synag 7 and frigid A. In both mutants, gp80 was expressed at the basal level. Pulses of cAMP as well as 2'-deoxy-cAMP and N6-monobutyryl-cAMP were capable of restoring the normal level of gp80 expression in synag 7 cells. These results, taken together, indicate bimodal regulation of gp80 expression during development and the involvement of a novel cAMP receptor in the transmembrane signalling pathway that regulates gp80 gene expression.
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Ma PC, Siu CH. A pharmacologically distinct cyclic AMP receptor is responsible for the regulation of gp80 expression in Dictyostelium discoideum. Mol Cell Biol 1990; 10:3297-306. [PMID: 2162472 PMCID: PMC360746 DOI: 10.1128/mcb.10.7.3297-3306.1990] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The EDTA-resistant cell-cell adhesion expressed at the aggregation stage of Dictyostelium discoideum is mediated by a cell surface glycoprotein of Mr 80,000 (gp80). The expression of gp80 is developmentally regulated by cyclic AMP (cAMP). In vitro nuclear run-on experiments show that transcription of the gp80 gene is initiated soon after the onset of development. The basal level of gp80 transcription is significantly augmented by exogenous cAMP pulses. Interestingly, in analog studies, 2'-deoxy-cAMP, 8-bromo-cAMP, and N6-monobutyryl-cAMP are all capable of inducing a rapid accumulation of gp80 mRNA, suggesting the presence of a unique cAMP receptor that responds equally well to these analogs. To determine whether intracellular cAMP plays a role in the regulation of gp80 expression, caffeine was used to block cAMP-induced receptor-mediated adenylate cyclase activation. Expression of gp80 mRNA was blocked in caffeine-treated cells but could be substantially restored by treatment with exogenous cAMP pulses, suggesting that adenylate cyclase activation is not required. gp80 expression was also examined in the signal transduction mutants synag 7 and frigid A. In both mutants, gp80 was expressed at the basal level. Pulses of cAMP as well as 2'-deoxy-cAMP and N6-monobutyryl-cAMP were capable of restoring the normal level of gp80 expression in synag 7 cells. These results, taken together, indicate bimodal regulation of gp80 expression during development and the involvement of a novel cAMP receptor in the transmembrane signalling pathway that regulates gp80 gene expression.
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Affiliation(s)
- P C Ma
- Banting and Best Department of Medical Research, University of Toronto, Ontario, Canada
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Bomblies L, Biegelmann E, Döring V, Gerisch G, Krafft-Czepa H, Noegel AA, Schleicher M, Humbel BM. Membrane-enclosed crystals in Dictyostelium discoideum cells, consisting of developmentally regulated proteins with sequence similarities to known esterases. J Cell Biol 1990; 110:669-79. [PMID: 2307702 PMCID: PMC2116030 DOI: 10.1083/jcb.110.3.669] [Citation(s) in RCA: 32] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Developing cells of Dictyostelium discoideum contain crystalline inclusion bodies. The interlattice spaces of the crystals are approximately 11 nm, and their edge dimensions vary in aggregating cells from 0.1 to 0.5 micron. The crystals are enclosed by a membrane with the characteristics of RER. To unravel the nature of the crystals we isolated them under electron microscopical control and purified the two major proteins that cofractionate with the crystals, one of an apparent molecular mass of 69 kD, the other of 56 kD. This latter protein proved to be identical with the protein encoded by the developmentally regulated D2 gene of D. discoideum, as shown by its reactivity with antibodies raised against the bacterially expressed product of a D2 fusion gene. The D2 gene is known to be strictly regulated at the transcript level and to be controlled by cAMP signals. Accordingly, very little of the 56-kD protein was detected in growth phase cells, maximal expression was observed at the aggregation stage, and the expression was stimulated by cAMP pulses. The 69-kD protein is the major constituent of the crystals and is therefore called "crystal protein." This protein is developmentally regulated and accumulates in aggregating cells similar to the D2 protein, but is not, or is only slightly regulated by cAMP pulses. mAbs specific for either the crystal protein or the D2 protein, labeled the intracellular crystals as demonstrated by the use of immunoelectron microscopy. The complete cDNA-derived amino acid sequence of the crystal protein indicates a hydrophobic leader and shows a high degree of sequence similarity with Torpedo acetylcholinesterase and rat lysophospholipase. Because the D2 protein also shows sequence similarities with various esterases, the vesicles filled with crystals of these proteins are named esterosomes.
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Affiliation(s)
- L Bomblies
- Max-Planck-Institut für Biochemie, Martinsried, Federal Republic of Germany
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Müller-Taubenberger A, Westphal M, Noegel A, Gerisch G. A developmentally regulated gene product from Dictyostelium discoideum shows high homology to human alpha-L-fucosidase. FEBS Lett 1989; 246:185-92. [PMID: 2540036 DOI: 10.1016/0014-5793(89)80280-7] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
A cDNA library of poly(A+)-RNA has been prepared from membrane-bound polysomes of Dictyostelium discoideum and screened for clones hybridizing to mRNA species that encode developmentally regulated proteins. The clone investigated in this paper recognizes a 1.8 kb transcript that accumulates strongly between the growth phase and aggregation stage. Stimulation of cells with pulses of cAMP enhances the accumulation. The amino acid sequence derived from a complete cDNA and from a genomic clone displays extensive sequence identity to human liver alpha-L-fucosidase. The D. discoideum DNA sequence encodes a 50.5 kDa polypeptide with a hydrophobic signal peptide at the N-terminus. Antibodies against a synthetic peptide corresponding to amino acids 262-275 of the deduced protein sequence recognize a developmentally regulated 50 kDa protein in D. discoideum that is recovered in the particulate fraction.
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Ludérus ME, van Driel R. Interaction between the chemotactic cAMP receptor and a detergent-insoluble membrane residue of Dictyostelium discoideum. Modulation by guanine nucleotides. J Biol Chem 1988. [DOI: 10.1016/s0021-9258(18)68480-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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Mann SK, Pinko C, Firtel RA. Control of early gene expression in Dictyostelium. DEVELOPMENTAL GENETICS 1988; 9:337-50. [PMID: 2854022 DOI: 10.1002/dvg.1020090415] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
We have examined the expression of a cAMP pulse-repressed and two cAMP pulse-induced genes in response to cAMP and caffeine under a number of different physiological conditions, and in several classes of development mutants altered in cAMP-mediated signal transduction pathways. The data presented help characterize the mutants with regard to early gene expression. Analysis of the data indicates that full induction of the pulse-induced or repression of the pulse-repressed genes requires cycles of activation and adaptation of the cAMP receptor but does not require a rise in intracellular cAMP. Comparison of the results obtained between different mutant classes suggests that repression and activation of the two classes of genes can be uncoupled, implying that different intracellular mechanisms control these processes. In addition, we examined the effects of caffeine and show that it can induce pulse-induced mRNA accumulation in the absence of cAMP.
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Affiliation(s)
- S K Mann
- Department of Biology, University of California, San Diego, La Jolla 92093
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Drummond IA, Chisholm RL. The effect of caffeine, adenosine, and buffer ionic composition on the induction of cell-surface cAMP binding during starvation of Dictyostelium discoideum. DEVELOPMENTAL GENETICS 1988; 9:293-301. [PMID: 2854021 DOI: 10.1002/dvg.1020090411] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
We have analyzed the effects of the cAMP relay inhibitor, caffeine, and the receptor antagonist, adenosine, on the regulation of the cell-surface cAMP receptor in suspension-starved Dictyostelium discoideum cells by measuring ammonium sulfate-stabilized binding of [3-H]cAMP to intact cells. When cells were starved in fast (230 r.p.m.) shaken suspension in 10 mM Na+/5 mM K+ phosphate buffer, pH 6.5, plus 1 mM CaCl2 and 2.5 mM MgCl2, and assayed for specific cAMP binding, receptor accumulation peaked at approximately 6 hours, reaching a maximum of 1.5 pmol cAMP bound/10(7) cells (saturation binding). Neither caffeine nor adenosine inhibited the accumulation of cAMP receptors. Similar results were obtained in caffeine-treated, slow shaken (90 r.p.m.) suspension cultures. These results suggest that starvation alone is sufficient stimulus to induce the cAMP receptor. We have also tested the effects of different buffer ionic compositions on the accumulation of cAMP receptors. Elevation of the monovalent ion concentration to 30-40 mM was found to significantly inhibit the induction of cAMP receptors.
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Affiliation(s)
- I A Drummond
- Department of Cell Biology and Anatomy, Northwestern University Medical School, Chicago, IL 60611
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