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In silico high throughput screening and in vitro validation of a novel Raf/Mek dual inhibitor against colorectal carcinoma. Biologia (Bratisl) 2022. [DOI: 10.1007/s11756-022-01197-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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2
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Segota I, Edwards MM, Campello A, Rappazzo BH, Wang X, Strandburg-Peshkin A, Zhou XQ, Rachakonda A, Daie K, Lussenhop A, Lee S, Tharratt K, Deshmukh A, Sebesta EM, Zhang M, Lau S, Bennedsen S, Ginsberg J, Campbell T, Wang C, Franck C. Confirmation and variability of the Allee effect in Dictyostelium discoideum cell populations,possible role of chemical signaling within cell clusters. Phys Biol 2021; 19. [PMID: 34942613 DOI: 10.1088/1478-3975/ac4613] [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: 05/30/2021] [Accepted: 12/23/2021] [Indexed: 11/12/2022]
Abstract
In studies of the unicellular eukaryote Dictyostelium discoideum, many have anecdotally observed that cell dilution below a certain "threshold density" causes cells to undergo a period of slow growth (lag). However, little is documented about the slow growth phase and the reason for different growth dynamics below and above this threshold density. In this paper, we extend and correct our earlier work to report an extensive set of experiments, including the use of new cell counting technology, that set this slow-to-fast growth transition on a much firmer biological basis. We show that dilution below a certain density (around 10E4 cells/ml) causes cells to grow slower on average and exhibit a large degree of variability: sometimes a sample does not lag at all, while sometimes it takes many moderate density cell cycle times to recover back to fast growth. We perform conditioned media experiments to demonstrate that a chemical signal mediates this endogenous phenomenon. Finally, we argue that while simple models involving fluid transport of signal molecules or cluster-based signaling explain typical behavior, they do not capture the high degree of variability between samples but nevertheless favor an intra-cluster mechanism.
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Affiliation(s)
- Igor Segota
- Cornell University, Physics Dept., Ithaca, New York, 14853-0001, UNITED STATES
| | - Matthew M Edwards
- Cornell University, Physics Dept., Ithaca, New York, 14853-0001, UNITED STATES
| | - Arthur Campello
- Cornell University, Physics Dept., Ithaca, New York, 14853-0001, UNITED STATES
| | - Brendan H Rappazzo
- Cornell University, Physics Dept., Ithaca, New York, 14853-0001, UNITED STATES
| | - Xiaoning Wang
- Cornell University, Physics Dept., Ithaca, New York, 14853-0001, UNITED STATES
| | | | - Xiao-Qiao Zhou
- Cornell University, Physics Dept., Ithaca, New York, 14853-0001, UNITED STATES
| | - Archana Rachakonda
- Cornell University, Physics Dept., Ithaca, New York, 14853-0001, UNITED STATES
| | - Kayvon Daie
- Cornell University, Physics Dept., Ithaca, New York, 14853-0001, UNITED STATES
| | - Alexander Lussenhop
- Cornell University, Physics Dept., Ithaca, New York, 14853-0001, UNITED STATES
| | - Sungsu Lee
- Cornell University, Physics Dept., Ithaca, New York, 14853-0001, UNITED STATES
| | - Kevin Tharratt
- Cornell University, Physics Dept., Ithaca, New York, 14853-0001, UNITED STATES
| | - Amrish Deshmukh
- Cornell University, Physics Dept., Ithaca, New York, 14853-0001, UNITED STATES
| | - Elisabeth M Sebesta
- Cornell University, Physics Dept., Ithaca, New York, 14853-0001, UNITED STATES
| | - Myron Zhang
- Cornell University, Physics Dept., Ithaca, New York, 14853-0001, UNITED STATES
| | - Sharon Lau
- Cornell University, Physics Dept., Ithaca, New York, 14853-0001, UNITED STATES
| | - Sarah Bennedsen
- Cornell University, Physics Dept., Ithaca, New York, 14853-0001, UNITED STATES
| | - Jared Ginsberg
- Cornell University, Physics Dept., Ithaca, New York, 14853-0001, UNITED STATES
| | - Timothy Campbell
- Cornell University, Physics Dept., Ithaca, New York, 14853-0001, UNITED STATES
| | - Chenzheng Wang
- Cornell University, Physics Dept., Ithaca, New York, 14853-0001, UNITED STATES
| | - Carl Franck
- Physics, Cornell University, Clark Hall, Ithaca, New York, 14853-0001, UNITED STATES
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Consalvo KM, Rijal R, Tang Y, Kirolos SA, Smith MR, Gomer RH. Extracellular signaling in Dictyostelium. THE INTERNATIONAL JOURNAL OF DEVELOPMENTAL BIOLOGY 2020; 63:395-405. [PMID: 31840778 DOI: 10.1387/ijdb.190259rg] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
In the last few decades, we have learned a considerable amount about how eukaryotic cells communicate with each other, and what it is the cells are telling each other. The simplicity of Dictyostelium discoideum, and the wide variety of available tools to study this organism, makes it the equivalent of a hydrogen atom for cell and developmental biology. Studies using Dictyostelium have pioneered a good deal of our understanding of eukaryotic cell communication. In this review, we will present a brief overview of how Dictyostelium cells use extracellular signals to attract each other, repel each other, sense their local cell density, sense whether the nearby cells are starving or stressed, count themselves to organize the formation of structures containing a regulated number of cells, sense the volume they are in, and organize their multicellular development. Although we are probably just beginning to learn what the cells are telling each other, the elucidation of Dictyostelium extracellular signals has already led to the development of possible therapeutics for human diseases.
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Affiliation(s)
- Kristen M Consalvo
- Department of Biology, Texas A∧M University, College Station, Texas, USA
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Segota I, Boulet L, Franck D, Franck C. Spontaneous emergence of large-scale cell cycle synchronization in amoeba colonies. Phys Biol 2014; 11:036001. [PMID: 24732749 DOI: 10.1088/1478-3975/11/3/036001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Unicellular eukaryotic amoebae Dictyostelium discoideum are generally believed to grow in their vegetative state as single cells until starvation, when their collective aspect emerges and they differentiate to form a multicellular slime mold. While major efforts continue to be aimed at their starvation-induced social aspect, our understanding of population dynamics and cell cycle in the vegetative growth phase has remained incomplete. Here we show that cell populations grown on a substrate spontaneously synchronize their cell cycles within several hours. These collective population-wide cell cycle oscillations span millimeter length scales and can be completely suppressed by washing away putative cell-secreted signals, implying signaling by means of a diffusible growth factor or mitogen. These observations give strong evidence for collective proliferation behavior in the vegetative state.
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Affiliation(s)
- Igor Segota
- Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, NY 14853, USA
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5
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Abstract
The social amoeba Dictyostelium discoideum is one of the leading model systems used to study how cells count themselves to determine the number and/or density of cells. In this review, we describe work on three different cell-density sensing systems used by Dictyostelium. The first involves a negative feedback loop in which two secreted signals inhibit cell proliferation during the growth phase. As the cell density increases, the concentrations of the secreted factors concomitantly increase, allowing the cells to sense their density. The two signals act as message authenticators for each other, and the existence of two different signals that require each other for activity may explain why previous efforts to identify autocrine proliferation-inhibiting signals in higher eukaryotes have generally failed. The second system involves a signal made by growing cells that is secreted only when they starve. This then allows cells to sense the density of just the starving cells, and is an example of a mechanism that allows cells in a tissue to sense the density of one specific cell type. The third cell density counting system involves cells in aggregation streams secreting a signal that limits the size of fruiting bodies. Computer simulations predicted, and experiments then showed, that the factor increases random cell motility and decreases cell-cell adhesion to cause streams to break up if there are too many cells in the stream. Together, studies on Dictyostelium cell density counting systems will help elucidate how higher eukaryotes regulate the size and composition of tissues.
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Affiliation(s)
- Richard H Gomer
- Department of Biology, ILSB MS 3474, Texas A&M University, College Station, Texas 77843-3474, USA.
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Choe JM, Bakthavatsalam D, Phillips JE, Gomer RH. Dictyostelium cells bind a secreted autocrine factor that represses cell proliferation. BMC BIOCHEMISTRY 2009; 10:4. [PMID: 19187549 PMCID: PMC2644720 DOI: 10.1186/1471-2091-10-4] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/10/2008] [Accepted: 02/02/2009] [Indexed: 11/10/2022]
Abstract
BACKGROUND Dictyostelium cells secrete the proteins AprA and CfaD. Cells lacking either AprA or CfaD proliferate faster than wild type, while AprA or CfaD overexpressor cells proliferate slowly, indicating that AprA and CfaD are autocrine factors that repress proliferation. CfaD interacts with AprA and requires the presence of AprA to slow proliferation. To determine if CfaD is necessary for the ability of AprA to slow proliferation, whether AprA binds to cells, and if so whether the binding requires the presence of CfaD, we examined the binding and effect on proliferation of recombinant AprA. RESULTS We find that the extracellular accumulation of AprA increases with cell density and reaches a concentration of 0.3 microg/ml near a stationary cell density. When added to wild-type or aprA- cells, recombinant AprA (rAprA) significantly slows proliferation at 0.1 microg/ml and higher concentrations. From 4 to 64 microg/ml, the effect of rAprA is at a plateau, slowing but not stopping proliferation. The proliferation-inhibiting activity of rAprA is roughly the same as that of native AprA in conditioned growth medium. Proliferating aprA- cells show saturable binding of rAprA to 92,000 +/- 11,000 cell-surface receptors with a KD of 0.03 +/- 0.02 microg/ml. There appears to be one class of binding site, and no apparent cooperativity. Native AprA inhibits the binding of rAprA to aprA- cells with a Ki of 0.03 mug/ml, suggesting that the binding kinetics of rAprA are similar to those of native AprA. The proliferation of cells lacking CrlA, a cAMP receptor-like protein, or cells lacking CfaD are not affected by rAprA. Surprisingly, both cell types still bind rAprA. CONCLUSION Together, the data suggest that AprA functions as an autocrine proliferation-inhibiting factor by binding to cell surface receptors. Although AprA requires CfaD for activity, it does not require CfaD to bind to cells, suggesting the possibility that cells have an AprA receptor and a CfaD receptor, and activation of both receptors is required to slow proliferation. We previously found that crlA- cells are sensitive to CfaD. Combined with the results presented here, this suggests that CrlA is not the AprA or CfaD receptor, and may be the receptor for an unknown third factor that is required for AprA and CfaD activity.
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Affiliation(s)
- Jonathan M Choe
- Department of Biochemistry and Cell Biology, MS-140, Rice University, Houston, TX 77005-1892, USA
| | | | - Jonathan E Phillips
- Department of Biochemistry and Cell Biology, MS-140, Rice University, Houston, TX 77005-1892, USA
| | - Richard H Gomer
- Department of Biochemistry and Cell Biology, MS-140, Rice University, Houston, TX 77005-1892, USA
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Kolbinger A, Gao T, Brock D, Ammann R, Kisters A, Kellermann J, Hatton D, Gomer RH, Wetterauer B. A cysteine-rich extracellular protein containing a PA14 domain mediates quorum sensing in Dictyostelium discoideum. EUKARYOTIC CELL 2005; 4:991-8. [PMID: 15947191 PMCID: PMC1151990 DOI: 10.1128/ec.4.6.991-998.2005] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Much remains to be understood about quorum-sensing factors that allow cells to sense their local density. Dictyostelium discoideum is a simple eukaryote that grows as single-celled amoebae and switches to multicellular development when food becomes limited. As the growing cells reach a high density, they begin expressing discoidin genes. The cells secrete an unknown factor, and at high cell densities the concomitant high levels of the factor induce discoidin expression. We report here the enrichment of discoidin-inducing complex (DIC), an approximately 400-kDa protein complex that induces discoidin expression during growth and development. Two proteins in the DIC preparation, DicA1 and DicB, were identified by sequencing proteolytic digests. DicA1 and DicB were expressed in Escherichia coli and tested for their ability to induce discoidin during growth and development. Recombinant DicB was unable to induce discoidin expression, while recombinant DicA1 was able to induce discoidin expression. This suggests that DicA1 is an active component of DIC and indicates that posttranslational modification is dispensable for activity. DicA1 mRNA is expressed in vegetative and developing cells. The mature secreted form of DicA1 has a molecular mass of 80 kDa and has a 24-amino-acid cysteine-rich repeat that is similar to repeats in Dictyostelium proteins, such as the extracellular matrix protein ecmB/PstA, the prespore cell-inducing factor PSI, and the cyclic AMP phosphodiesterase inhibitor PDI. Together, the data suggest that DicA1 is a component of a secreted quorum-sensing signal regulating discoidin gene expression during Dictyostelium growth and development.
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Affiliation(s)
- Alexandra Kolbinger
- Howard Hughes Medical Institute and Department of Biochemistry and Cell Biology, MS-140, Rice University, 6100 S. Main Street, Houston, TX 77005-1892, USA
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Hiscock SJ, Kües U. Cellular and molecular mechanisms of sexual incompatibility in plants and fungi. INTERNATIONAL REVIEW OF CYTOLOGY 1999; 193:165-295. [PMID: 10494623 DOI: 10.1016/s0074-7696(08)61781-7] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
Plants and fungi show an astonishing diversity of mechanisms to promote outbreeding, the most widespread of which is sexual incompatibility. Sexual incompatibility involves molecular recognition between mating partners. In fungi and algae, highly polymorphic mating-type loci mediate mating through complementary interactions between molecules encoded or regulated by different mating-type haplotypes, whereas in flowering plants polymorphic self-incompatibility loci regulate mate recognition through oppositional interactions between molecules encoded by the same self-incompatibility haplotypes. This subtle mechanistic difference is a consequence of the different life cycles of fungi, algae, and flowering plants. Recent molecular and biochemical studies have provided fascinating insights into the mechanisms of mate recognition and are beginning to shed light on evolution and population genetics of these extraordinarily polymorphic genetic systems of incompatibility.
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Affiliation(s)
- S J Hiscock
- Department of Plant Sciences, University of Oxford, United Kingdom
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Christensen ST, Leick V, Rasmussen L, Wheatley DN. Signaling in unicellular eukaryotes. INTERNATIONAL REVIEW OF CYTOLOGY 1997; 177:181-253. [PMID: 9378617 DOI: 10.1016/s0074-7696(08)62233-0] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Aspects of intercellular and intracellular signaling systems in cell survival, proliferation, differentiation, chemosensory behavior, and programmed cell death in free-living unicellular eukaryotes have been reviewed. Comparisons have been made with both bacteria and metazoa. The central organisms were flagellates (Trypanosoma, Leishmania, and Crithidia), slime molds (Dictyostelium), yeast cells (Saccharomyces cerevisiae), and ciliates (Paramecium, Euplotes, and Tetrahymena). There are two novel aspects in this review. First, cellular responses are viewed in an evolutionary perspective, rather than from the more prevailing one, in which the unicellular eukaryotes are seen by the mammalian organisms. Second, results obtained with cell cultures in minimal, chemically defined nutrient media at low cell densities where intercellular signaling is strongly reduced are discussed. These results shed light on control mechanisms and their cooperation inside the living cell. Intracellular systems have many common features in unicellular and multicellular organisms.
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Affiliation(s)
- S T Christensen
- Department of Medical Biochemistry and Genetics, Panum Institute, University of Copenhagen, Denmark
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Clarke M, Gomer RH. PSF and CMF, autocrine factors that regulate gene expression during growth and early development of Dictyostelium. EXPERIENTIA 1995; 51:1124-34. [PMID: 8536800 DOI: 10.1007/bf01944730] [Citation(s) in RCA: 80] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Throughout growth and development, Dictyostelium cells secrete autocrine factors that accumulate in proportion to cell density. At sufficient concentration, these factors cause changes in gene expression. Vegetative Dictyostelium cells continuously secrete prestarvation factor (PSF). The bacteria upon which the cells feed inhibit their response to PSF, allowing the cells to monitor their own density in relation to that of their food supply. At high PSF/bacteria ratios, which occur during late exponential growth, PSF induces the expression of several genes whose products are needed for cell aggregation. When the food supply has been depleted, PSF production declines, and a second density-sensing pathway is activated. Starving cells secrete conditioned medium factor (CMF), a glycoprotein of Mr 80 kDa that is essential for the development of differentiated cell types. Antisense mutagenesis has shown that cells lacking CMF cannot aggregate, and preliminary data suggest that CMF regulates cAMP signal transduction. Calculations indicate that a mechanism of simultaneously secreting and recognizing a signal molecule, as used by Dictyostelium to monitor cell density, could also be used to determine the total number of cells in a tissue.
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Affiliation(s)
- M Clarke
- Oklahoma Medical Research Foundation, Program in Molecular and Cell Biology, Oklahoma City 73104, USA
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Vallesi A, Giuli G, Bradshaw RA, Luporini P. Autocrine mitogenic activity of pheromones produced by the protozoan ciliate Euplotes raikovi. Nature 1995; 376:522-4. [PMID: 7637785 DOI: 10.1038/376522a0] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Diffusible polypeptide pheromones (formerly referred to as mating-type factors, sex factors or gamones), which distinguish otherwise morphologically identical vegetative cell (mating) types from one another, are produced by some species of ciliates. Their most striking effect can be observed by exposing cells of one type to a pheromone secreted by another co-specific cell type. In the presence of this 'non-self' signal, these cells interrupt their vegetative life to unite temporarily in mating pairs. Thus ciliate pheromones have traditionally been associated only with mating induction. However, the identification of autocrine pheromone receptors suggests a broader role, which is supported by the hypothesis that ciliates evolved their mating-type mechanism for pursuing self-recognition. We now report studies, in the cosmopolitan marine sand-dwelling protozoan ciliate Euplotes raikovi, demonstrating that these molecules promote the vegetative reproduction (mitogenic proliferation or growth) of the same cells from which they originate. As, understandably, such autocrine pheromone activity is primary to that of targeting and inducing a foreign cell to mate (paracrine functions), this finding provides an example of how the original function of a molecule can be obscured during evolution by the acquisition of a new one.
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Affiliation(s)
- A Vallesi
- Dipartimento di Biologia Molecolare, Cellulare e Animale, University of Camerino, Italy
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Döring V, Schleicher M, Noegel A. Dictyostelium annexin VII (synexin). cDNA sequence and isolation of a gene disruption mutant. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(19)47401-2] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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