51
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Schatzle J, Bush J, Dharmawardhane S, Firtel R, Gomer R, Cardelli J. Characterization of the signal transduction pathways and cis-acting DNA sequence responsible for the transcriptional induction during growth and development of the lysosomal alpha-mannosidase gene in Dictyostelium discoideum. J Biol Chem 1993. [DOI: 10.1016/s0021-9258(19)36563-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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52
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Cell-permeable non-hydrolyzable cAMP derivatives as tools for analysis of signaling pathways controlling gene regulation in Dictyostelium. J Biol Chem 1993. [DOI: 10.1016/s0021-9258(18)53256-7] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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53
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Affiliation(s)
- W F Loomis
- Department of Biology, University of California, San Diego, La Jolla 92093
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54
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Clarke M, Dominguez N, Yuen IS, Gomer RH. Growing and starving Dictyostelium cells produce distinct density-sensing factors. Dev Biol 1992; 152:403-6. [PMID: 1644228 DOI: 10.1016/0012-1606(92)90147-9] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Prestarvation factor (PSF) and conditioned medium factor (CMF) are two autocrine factors produced by Dictyostelium cells. Although secreted at different times in the Dictyostelium life cycle (PSF by growing cells and CMF by starving cells), both factors are glycoproteins that are used by cells to measure their own density, and both are important in cell aggregation. To examine the relationship between PSF and CMF, a CMF antisense transformant was tested for the production of PSF during growth. Although this transformant produced extremely low levels of CMF, its production of PSF was essentially normal. We conclude that these two factors are not products of the same gene.
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Affiliation(s)
- M Clarke
- Program in Molecular and Cell Biology, Oklahoma Medical Research Foundation, Oklahoma City 73104
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55
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Rathi A, Clarke M. Expression of early developmental genes in Dictyostelium discoideum is initiated during exponential growth by an autocrine-dependent mechanism. Mech Dev 1992; 36:173-82. [PMID: 1315152 DOI: 10.1016/0925-4773(92)90068-u] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Throughout growth, Dictyostelium cells continuously produce an autocrine factor, PSF, that accumulates in proportion to cell density. Production of PSF declines rapidly when cells are shifted to starvation conditions, and the properties of PSF are distinct from those of regulatory factors produced by starving cells. During late exponential growth, PSF induces expression of several early developmental genes, including those for proteins important in cAMP signaling and cell aggregation. Examples are the aggregation stage cAMP receptor (cAR1), the aggregation-specific form of cyclic nucleotide phosphodiesterase, and gp24 (contact sites B). Through PSF, growing cells detect environmental conditions (cell number high, food approaching depletion) that are appropriate for production of the gene products needed to initiate aggregation and development.
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Affiliation(s)
- A Rathi
- Program in Molecular and Cell Biology, Oklahoma Medical Research Foundation, Oklahoma City 73104
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56
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Yamada Y, Okamoto K. Cell-type-specific responsiveness to cAMP in cell differentiation of Dictyostelium discoideum. Dev Biol 1992; 149:235-7. [PMID: 1309457 DOI: 10.1016/0012-1606(92)90280-t] [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: 12/26/2022]
Abstract
In Dictyostelium discoideum, both prespore and prestalk differentiation require extracellular cAMP. We investigated the difference in inducibility of the two cell types by cAMP. Previous studies indicate that cAMP added in the early stage of development inhibits prespore differentiation, and this was confirmed using three species of prespore specific mRNAs. By contrast, early treatment with cAMP did not inhibit, but induced the expression of prestalk-specific mRNA. These results indicate that differentiation pathways of the two cell types have different processes in the early stage of development.
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Affiliation(s)
- Y Yamada
- Department of Botany, Faculty of Science, Kyoto University, Japan
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57
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Developmental regulation of expression of prespore-specific genes inDictyostelium discoideum. ACTA ACUST UNITED AC 1991. [DOI: 10.1007/bf02488388] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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58
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Kimmel AR, Firtel RA. cAMP signal transduction pathways regulating development of Dictyostelium discoideum. Curr Opin Genet Dev 1991; 1:383-90. [PMID: 1668648 DOI: 10.1016/s0959-437x(05)80304-1] [Citation(s) in RCA: 54] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Dictyostelium discoideum development is regulated through receptor/G protein signal transduction using cAMP as a primary extracellular signal. Signaling pathways will be discussed as well as the regulation and function of individual cAMP receptors and G alpha subunits. Finally potential downstream targets including protein kinases and nuclear events will be explored.
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Affiliation(s)
- A R Kimmel
- Laboratory of Cellular and Developmental Biology, NIDDK/NIH, Bethesda, Maryland 20892
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59
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Mann SK, Firtel RA. A developmentally regulated, putative serine/threonine protein kinase is essential for development in Dictyostelium. Mech Dev 1991; 35:89-101. [PMID: 1836954 DOI: 10.1016/0925-4773(91)90060-j] [Citation(s) in RCA: 114] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Using PCR technology, we have cloned parts of three developmentally regulated putative serine/threonine kinases from Dictyostelium. All show significant homology to members of the cAMP-dependent protein kinase A/protein kinase C subfamilies. A genomic clone encoding one of these, DdPK3, has been isolated and sequenced. The open reading frame encodes a protein of 648 amino acids with the conserved kinase domain in the C-terminal half. The protein encoded by this gene is unusual in that it contains long homopolymer runs in the N-terminal half of the protein, including a long run of 88 amino acids in which 73 are glutamine residues. To examine the function of DdPK3, a gene disruption was created via homologous recombination. Ddpk3- cells do not aggregate by themselves but will co-aggregate with wild-type cells. However, after aggregation these cells are 'sloughed off' and do not proceed further through development, but are found as a discrete mass alongside the fruiting body formed by the wild-type cells. Analysis of signal transduction pathways indicates that cAMP pulse-induced expression of aggregation stage-specific genes is normal in Ddpk3- cells, as is induction of the prestalk gene Ddras in single cell assays. However, cAMP induction of the late promoters of cAMP receptor cAR1 and of two prespore-specific genes is absent under similar conditions. These cells show normal activation of adenylate cyclase and normal phosphorylation of the G alpha protein G alpha 2 in response to cAMP. The possible role of DdPK3 in Dictyostelium development is discussed.
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Affiliation(s)
- S K Mann
- Department of Biology, University of California, San Diego, La Jolla 92093
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60
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Schenk PW, Van Es S, Kesbeke F, Snaar-Jagalska BE. Involvement of cyclic AMP cell surface receptors and G-proteins in signal transduction during slug migration of Dictyostelium discoideum. Dev Biol 1991; 145:110-8. [PMID: 1850366 DOI: 10.1016/0012-1606(91)90217-q] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The presence of G-proteins, interacting with cAMP surface receptors, was investigated in vegetative cells, aggregation-competent cells, and migrating slugs of Dictyostelium discoideum. Our results indicate that G-proteins are present in all stages. In vegetative cells there is a limited number of cAMP receptors but no effect of GTP tau S on cAMP binding could be detected; in addition, no effect of cAMP on GTP tau S binding or GTPase activity was observed. In both aggregation-competent cells and slugs GTP tau S inhibits cAMP binding, while cAMP stimulates GTP tau S binding and high-affinity GTPase. Since the presence of G-proteins coupled to cAMP receptors could be demonstrated in slugs, the involvement of the effector enzymes adenylate cyclase and phospholipase C was investigated. The results show that adenylate cyclase activity is stimulated by GTP tau S in both stages and that in cells from migrating slugs the Ins(1,4,5)P3 production is increased upon stimulation with cAMP. The possible involvement of G-proteins in signal transduction during the slug stage of D. discoideum is discussed.
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Affiliation(s)
- P W Schenk
- Cell Biology and Genetics Unit, Zoological Laboratory, Leiden University, The Netherlands
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61
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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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62
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Singleton CK, Delude RL, Ken R, Manning SS, McPherson CE. Structure, expression, and regulation of members of the developmentally controlled V and H gene classes from Dictyostelium. DEVELOPMENTAL GENETICS 1991; 12:88-97. [PMID: 2049884 DOI: 10.1002/dvg.1020120116] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
We have examined the expression and structure of vegetative specific genes belonging to the V and H gene classes. Both classes of genes are deactivated at the onset of development by a reduction in the rate of transcription. Thus, the genes must be reactivated when the terminally differentiated spores germinate and the resulting amebae return to the vegetative state. During germination, activation of expression of most members of the V gene class was found to parallel the emergence of amoebae from the spore coats. The activation of the V genes did not occur when protein synthesis was inhibited. The timing of activation of the H genes was more heterogeneous and did not parallel emergence. H gene activation occurred even when protein synthesis was inhibited. V4 was found to be the only vegetative specific gene that was responsive to the presence of bacteria. V4 expression was induced by 25-100 fold via transcriptional activation when bacteria were added to amebae growing axenically. Isolation and sequence analysis of the corresponding genomic clones revealed that two V genes, V18 and V1, encode ribosomal proteins. Promoter analysis has delineated the sequences necessary for expression and regulation for several of the V and H genes. In all cases, expression was determined by sequences within the first several hundred base pairs of the transcription start site. For V18 and V14, a positive constitutive element was identified in addition to the sequences involved in regulation. Finally, all of the characterizations and findings are discussed in terms of postulated models for V and H gene expression and regulation.
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MESH Headings
- Amino Acid Sequence
- Base Sequence
- Blotting, Northern
- Cloning, Molecular
- Cycloheximide/pharmacology
- DNA, Fungal
- Dictyostelium/genetics
- Dictyostelium/growth & development
- Dictyostelium/physiology
- Gene Expression Regulation, Fungal
- Genes, Fungal
- Molecular Sequence Data
- Promoter Regions, Genetic
- Regulatory Sequences, Nucleic Acid
- Ribosomal Proteins/genetics
- Sequence Homology, Nucleic Acid
- Spores, Fungal
- Transcription, Genetic
- Transcriptional Activation
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Affiliation(s)
- C K Singleton
- Department of Molecular Biology, Vanderbilt University, Nashville, TN 37235
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63
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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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64
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Whitbread JA, Sims M, Katz ER. Evidence for the presence of a growth factor in Dictyostelium discoideum. DEVELOPMENTAL GENETICS 1991; 12:78-81. [PMID: 2049882 DOI: 10.1002/dvg.1020120114] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Polypeptide hormones, recognized for their ability to regulate cell growth and differentiation, have been classified as growth factors. These growth factors have been extensively described in higher eukaryotic organisms and cell lines [Hedin and Westermark, Cell 37:9-20, 1984]. Here we report the identification and partial characterization of a putative growth factor present in vegetative amoebae of the cellular slime mold Dictyostelium discoideum. A mutant was selected and found to be temperature sensitive due to the absence of an extracellular protein suggestive of a growth factor. The putative growth factor (DGF) is a protein resistant to both heat and strong detergent treatment but sensitive to reducing agents. The physiological significance of DGF is as yet unknown. DGF is of interest both in relation to understanding the events which control cell proliferation in Dictyostelium and in its relationship to other known growth factors.
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65
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Rathi A, Kayman SC, Clarke M. Induction of gene expression in Dictyostelium by prestarvation factor, a factor secreted by growing cells. DEVELOPMENTAL GENETICS 1991; 12:82-7. [PMID: 2049883 DOI: 10.1002/dvg.1020120115] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
During growth, Dictyostelium cells continuously secrete a factor, PSF, that accumulates in proportion to cell density. At sufficient concentration, it triggers the production of discoidin I and certain lysosomal enzymes. Our earlier studies demonstrated these effects of PSF on protein and enzyme levels [Clarke et al., Differentiation 34:79-87, 1987; Clarke et al., Dev Genet 9: 315-326, 1988]. In the present study, we have examined whether PSF induces increased mRNA levels. By Northern blot analysis, we have found that discoidin I mRNA accumulates in exponentially growing NC4 cells as the cells reach high density; significant levels of mRNA are detectable in cells growing either on plates or in suspension, beginning about four generations before the end of exponential growth. High levels of discoidin I mRNA are also found in low-density cells grown in the presence of buffer conditioned by high-density cells. These results indicate that PSF induces the accumulation of discoidin I mRNA. Other "early developmental" genes, pCZ22 and the early I genes (16, 18, and 111), are also expressed in exponentially growing cells at high density or in the presence of conditioned buffer. We conclude that several genes previously found to be preferentially expressed very early in development are actually induced during late exponential growth by PSF.
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Affiliation(s)
- A Rathi
- Program in Molecular and Cell Biology, Oklahoma Medical Research Foundation, Oklahoma City 73104
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66
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Richards AJ, Corney AJ, Hames BD. Cell-type-specific genes expressed late in Dictyostelium development show markedly different responses to 3'5' cyclic AMP. Mol Microbiol 1990; 4:1279-91. [PMID: 2177818 DOI: 10.1111/j.1365-2958.1990.tb00707.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The maintenance of late gene expression by 3'5' cyclic AMP was re-examined using several newly isolated cell-type-specific genes. Expression of all the prespore-enriched genes ceased immediately upon disaggregation of developing cells and pre-existing mRNA was rapidly degraded. For most genes, cAMP had little or no effect either alone or in combination with conditioned medium factors. The expression of the non-cell-type-specific genes 7E and 2C also ceased upon cell disaggregation but cAMP triggered a full re-induction of expression although the timing of the response differed markedly between these two genes. In contrast to earlier interpretations, these data argue that for none of these late prespore genes is cAMP alone sufficient for the maintenance of expression. The responses of the two prestalk mRNAs examined were gene-specific. Prestalk 5D mRNA decayed slowly upon disaggregation and was partially stabilized by cAMP whereas prestalk 5G mRNA increased upon disaggregation and was inhibited by cAMP.
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Affiliation(s)
- A J Richards
- Department of Biochemistry, University of Leeds, UK
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67
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Takemoto K, Takeuchi I, Tasaka M. cAMP regulation of the expression of prespore-specific genes, SP96 and Dp87, in disaggregated slug cells of Dictyostelium discoideum. CELL DIFFERENTIATION AND DEVELOPMENT : THE OFFICIAL JOURNAL OF THE INTERNATIONAL SOCIETY OF DEVELOPMENTAL BIOLOGISTS 1990; 31:89-96. [PMID: 2171724 DOI: 10.1016/0922-3371(90)90012-l] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
By Northern transfer and in vitro transcription assays, we examined how cAMP controlled the expression of prespore genes, Dp87 and SP96, in disaggregated slug cells of Dictyostelium discoideum. The transcription of these genes was halted soon after disaggregation and the remaining mRNAs were completely lost within 2 h. Addition of cAMP to cells which had lost the mRNAs induced the transcription of these genes, and the mRNAs were re-accumulated after a lag period of 30 min. The cAMP signal was transduced through the cell surface receptor. Protein synthesis was not needed for the induction of the transcription but was required for the accumulation of the mRNAs. We conclude that prespore gene expression is controlled by cAMP in two different ways: direct induction of transcription of the genes, and stabilization of the transcribed mRNAs by a protein(s) synthesized after addition of cAMP.
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Affiliation(s)
- K Takemoto
- Department of Botany, Faculty of Science, Kyoto University, Japan
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68
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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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69
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Kwong L, Weeks G. The effects of presumptive morphogens on prestalk and prespore gene expression in monolayers of Dictyostelium discoideum. Differentiation 1990. [DOI: 10.1111/j.1432-0436.1990.tb00541.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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70
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Abstract
The DIFs are unusual, chlorinated molecules which induce stalk cell differentiation during the later, multicellular phase of Dictyostelium development. Here we provide evidence that one or more DIFs have a role during early development, when small amounts are known to be made. Initial indications came from an optical technique which detects changes in shape or cohesion of cells in suspension (Gerisch and Hess, PNAS 71, 2118, 1974). After a period of optical inactivity at the start of development, cell suspensions normally produce spontaneous spike-shaped light-scattering oscillations synchronised by oscillations in extracellular cAMP levels, followed by sinusoidal oscillations where the synchroniser is not known. DIFs 1 and 2 produce optical responses from cells at all these early stages of development. The phase of both spiked and sinusoidal oscillations can be shifted, indicating an effect on the oscillator in each case. We find further: (1) cAMP oscillations and cAMP relay during spiked oscillations are transiently inhibited by DIF-1. (2) DIF-1 causes a transient decrease in cellular cGMP levels in cells taken before oscillations commence and likewise inhibits the cGMP response to a cAMP stimulus in cells taken later in development. Cytoskeletal organization and hence cell shape might be affected by DIF-1 by this indirect route. (3) The effects of DIF-1 are transient, even though it is essentially stable in the cell suspension. Cells somehow adapt to DIF-1. (4) The effects are chemically specific: DIF-1 and DIF-2 are active at 10(-7) to 10(-8) M, with DIF-2 being the more active, whereas related compounds have little or no activity at 10(-6) M. These results indicate that cells are responsive to DIFs 1 and 2 from the start of development and suggest a wider role for the DIFs. This role might involve effects on cAMP signalling and on intracellular second messengers.
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Affiliation(s)
- B Wurster
- Fakultät für Biologie, Universität Konstanz, Federal Republic of Germany
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71
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Corney AJ, Richards AJ, Phillpots T, Hames BD. Developmental regulation of cell-type-enriched mRNAs in Dictyostelium discoideum. Mol Microbiol 1990; 4:613-23. [PMID: 2161991 DOI: 10.1111/j.1365-2958.1990.tb00630.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
We describe sixteen new families of cDNA clones representing mRNAs that are expressed preferentially in either prespore or prestalk cells during development of Dictyostelium discoideum and two new mRNAs that are expressed in a non-cell-type-specific manner. None of the prespore-enriched mRNAs are detectable in Dictyostelium cells until 13-15 h of development but then they increase dramatically and peak at 18-22 h. Upon dissociation of developing aggregates, all these mRNAs rapidly decay to low levels. In marked contrast to data presented for prespore genes by other workers, cyclic AMP either has no effect on the mRNA levels in dissociated cells or is only weakly effective in restoring normal expression. A prestalk-enriched mRNA examined, 5G mRNA, is similarly expressed late in development but is also expressed in vegetative cells. The level of 5G mRNA is only moderately affected by cell disaggregation.
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Affiliation(s)
- A J Corney
- Department of Biochemistry, University of Leeds, UK
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72
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Vocke CD, Cox EC. Analysis of developmentally expressed antigens in Polysphondylium pallidum. DEVELOPMENTAL GENETICS 1990; 11:427-38. [PMID: 2096018 DOI: 10.1002/dvg.1020110517] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
A series of monoclonal antibodies were previously raised against developing Polysphondylium pallidum cells. In this work, six of these antibodies have been used as probes to identify and characterize antigens regulated during development. Soluble and membrane fractions of P. pallidum cells at six stages of development or three stages of cyclic adenosine monophosphate (cAMP)-induced development were run in sodium dodecyl sulfate (SDS)-polyacrylamide gels and subjected to Western blot analysis. Three of the monoclonals, anti-Tp200, anti-Tp423, and anti-Pg101, stain sorogen tips. Tp423 and Tp200 are membrane-associated antigens; both are stable to urea extraction, and Tp200 remains in the membrane after NaOH extraction. Tp423 is present in starved cells but is more prominent in sorogens and particularly in cAMP-developed cells. In contrast, Tp200 is first detected in early to mid-aggregation and is more abundant late in development. Pg101, which is expressed as a gradient with its highest concentration in tips, first appears in tight aggregates but is much more abundant in sorogens; unlike the Tp antigens, Pg101 is not greatly induced in cAMP-developed cells. All three of these antigens undergo changes in apparent molecular weight at the tight aggregate or sorogen stage: The gel mobilities of Tp200 and Pg101 increase, whereas that of Tp423 decreases. In addition to the tip-specific monoclonals, two monoclonals that stain all but the tips of sorogens have been used for analysis. One of these, anti-3D10Pnk stains most cells within secondary tips, whereas anti-3D10Dif does not. 3D10Dif is membrane associated; it is present very early in development, increasing two- to threefold through the sorogen stage and diminishing in late cAMP-developed cells. 3D10Pnk is a mostly soluble species first detected in late streaming. Anti-1c3, a sixth monoclonal, which stains nuclei uniformly throughout sorogens, is also developmentally expressed. 1c3 is mainly membrane associated and is expressed from late streaming through the sorogen stage.
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Affiliation(s)
- C D Vocke
- Department of Molecular Biology, Princeton University, NJ 18544
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73
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Loomis WF. Essential Genes for Development ofDictyostelium. PROGRESS IN MOLECULAR AND SUBCELLULAR BIOLOGY 1990. [DOI: 10.1007/978-3-642-75178-3_7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
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74
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Ramji DP, Richards AJ, Jagger P, Bleasby A, Hames BD. Two cyclic AMP-regulated genes from Dictyostelium discoideum encode homologous proteins. Mol Microbiol 1990; 4:129-35. [PMID: 2157129 DOI: 10.1111/j.1365-2958.1990.tb02022.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Expression of the 7E and 2C genes late in Dictyostelium development ceases upon cell disaggregation but, in contrast to many other genes we have studied, expression is fully restored by exogenous cAMP (A. J. Richards et al., submitted). The 7E and 2C genes encode polypeptides of similar size (9220 and 10573 Daltons, respectively), each of which contains an unusually high proportion of serine plus glycine residues (41% and 59%, respectively). Each protein possesses a relatively serine-rich N-terminus and glycine-rich C-terminus and contains the conserved sequence S(X)SSS(X2)SS(X)SS(X2)SFGS. These data suggest that genes 7E and 2C may have arisen by duplication of a common ancestor. Computer analysis indicates that both gene products are probably intracellular structural proteins that form extended coil structures.
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Affiliation(s)
- D P Ramji
- Department of Biochemistry, University of Leeds, UK
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75
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Fontana DR, Price PL. Cell-cell contact elicits cAMP secretion and alters cAMP signaling in Dictyostelium discoideum. Differentiation 1989. [DOI: 10.1111/j.1432-0436.1989.tb00746.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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76
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Firtel RA, van Haastert PJ, Kimmel AR, Devreotes PN. G protein linked signal transduction pathways in development: dictyostelium as an experimental system. Cell 1989; 58:235-9. [PMID: 2546676 DOI: 10.1016/0092-8674(89)90837-4] [Citation(s) in RCA: 121] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- R A Firtel
- Department of Biology, University of California, San Diego, La Jolla 92093
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77
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Blumberg DD, Comer JF, Walton EM. Ca++ antagonists distinguish different requirements for cAMP-mediated gene expression in the cellular slime mold, Dictyostelium discoideum. Differentiation 1989; 41:14-21. [PMID: 2553517 DOI: 10.1111/j.1432-0436.1989.tb00727.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Cyclic AMP is essential for the accumulation of many prespore mRNAs and can advance the time of appearance of mRNAs specifically enriched in prestalk cells. Additionally, when late-developing cells are washed free of cAMP, a number of growth phase mRNAs reaccumulate. This reaccumulation can be suppressed by cAMP. These effects of cAMP are all mediated through the cell surface cAMP receptor and can occur under conditions where the receptor-associated adenylate cyclase is inactive, indicating that the initial intracellular transduction event necessary for expression of these mRNAs does not depend upon cAMP synthesis. The dihydropyridine derivatives, nifedipine and nitrendipine, are highly specific Ca++ channel blockers. They are shown here to prevent the influx of Ca++ from the external medium that occurs in response to cAMP binding to the cell surface receptor during development. These two compounds as well as another Ca++ antagonist, 8-N,N-diethylamino)octyl-3,4,5-trimethoxy-benzoate (TMB-8) and a calmodulin inhibitor, N-(6-amino-hexyl)-5-chloro-1-naphthalene sulfonamide (W7), all specifically decrease cAMP-mediated prespore mRNA accumulation in a dose-dependent manner. They also prevent cAMP from suppressing the expression of the growth phase genes. The growth phase mRNAs reaccumulate in cAMP-treated cells in the presence of increasing concentrations of these drugs. By contrast, cAMP induction of the pre-stalk-enriched mRNA is not as significantly affected by these agents. These results raise the possibility that the cell surface cAMP receptor can couple to different signal transduction systems and thereby induce or suppress the expression of different sets of cAMP-regulated genes during development.
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Affiliation(s)
- D D Blumberg
- Department of Biological Sciences, University of Maryland Baltimore County, Catonsville 21228
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78
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Rubino S, Mann SK, Hori RT, Pinko C, Firtel RA. Molecular analysis of a developmentally regulated gene required for Dictyostelium aggregation. Dev Biol 1989; 131:27-36. [PMID: 2909407 DOI: 10.1016/s0012-1606(89)80035-1] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
We have previously shown that the developmentally regulated gene D2 is induced during aggregation by pulses of cAMP, which act via the cell surface receptor and consequent signal transduction pathways (W. Rowekamp and R.A. Firtel, 1980, Dev. Biol. 79, 409-418; S.K.O. Mann and R.A. Firtel, 1987, Mol. Cell. Biol. 7, 458-469; S.K.O. Mann, C. Pinko, and R.A. Firtel, 1988, Dev. Biol., in press). In this manuscript, we compare the complete derived amino acid sequence for D2 to two cloned and sequenced eukaryotic esterases and examine the requirement of the D2 gene product for development. Amino acid sequence data comparisons suggest that D2 encodes a serine esterase with strong sequence identity to Torpedo acetylcholine esterase and a Drosophila esterase. The protein has a putative leader sequence, suggesting that it is shunted into vesicles. Using an antisense gene construct driven by a Discoidin I promoter, whose transcriptional activity depends on the growth conditions of the cells, we show that inhibition of D2 mRNA accumulation results in an abnormal developmental program that includes the absence of normal streaming and incomplete aggregate formation and subsequent development. We suggest that D2 encodes an esterase function required for proper aggregation and subsequent development.
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Affiliation(s)
- S Rubino
- Department of Biology, University of California, San Diego, La Jolla 92093
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79
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Abstract
Extracellular cAMP induces the intracellular synthesis and subsequent secretion of cAMP in Dictyostelium discoideum (relay). cAMP relay was strongly diminished in mutant HB3 which shows abnormal development by making very small fruiting bodies. Extracellular cAMP binds to receptors on the surface of mutant cells and induces the rapid activation of adenylate cyclase. Intracellular cAMP rises to a concentration as high as that in wild-type cells but only a very small amount of cAMP is secreted. cAMP secretion in wild-type cells starts immediately after cAMP production, and is proportional to the intracellular cAMP concentration. In the mutant cells cAMP secretion starts a few minutes after cAMP production; by that time most of the intracellular cAMP is already degraded by phosphodiesterase and little cAMP is available for secretion. We conclude that mutant HB3 has a defect in the mechanism by which Dictyostelium cells secrete cAMP.
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Affiliation(s)
- F Kesbeke
- Zoological Laboratory, University of Leiden, The Netherlands
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80
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Mann SK, Pinko C, Firtel RA. cAMP regulation of early gene expression in signal transduction mutants of Dictyostelium. Dev Biol 1988; 130:294-303. [PMID: 2846388 DOI: 10.1016/0012-1606(88)90435-6] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
We have examined the regulation of three early developmentally regulated genes in Dictyostelium. Two of these genes (D2 and M3) are induced by pulses of cAMP and the other (K5) is repressed. Expression of these genes has been examined in a number of developmental mutants that are specifically blocked in various aspects of the signal transduction/cAMP relay system involved in aggregation and control of early development. The mutant strains include Synag mutants, which are blocked in receptor-mediated activation of adenylate cyclase and do not relay cAMP pulses; FrigidA mutants, which are blocked in receptor-mediated activation of both adenylate cyclase and the putative phosphoinositol bisphosphate (PIP2) turnover pathway and appear to be mutations in the gene encoding one of the G alpha protein subunits; and a StreamerF allele, which lacks cGMP-specific cGMP phosphodiesterase. From the analysis of the developmental expression of these genes under a variety of conditions in these mutant strains, we have drawn a number of conclusions concerning the modes of regulation of these genes. Full induction of D2 and M3 genes requires cAMP interaction with the cell surface receptor and an "oscillation" of the receptor between active and adapted forms. Induction of these genes does not require activation of the signal transduction pathway that leads to adenylate cyclase activation and cAMP relay, but does require activation of other receptor-mediated intracellular signal transduction pathways, possibly that involving PIP2 turnover. Likewise, repression of the K5 gene requires pulses of cAMP. Expression of this gene is insensitive to cAMP pulses in FrigidA mutants, suggesting that a signal transduction pathway is necessary for its repression. Results using the StreamerF mutant suggest that the rise in cGMP in response to cAMP/receptor interactions may not be directly related to control of the pulse-induced genes. In addition, we have examined the effect of caffeine, which M. Brenner and S.D. Thomas (1984, Dev. Biol., 101, 136-146) showed preferentially blocks the cAMP relay system by blocking receptor-mediated activation of adenylate cyclase. We show that in many of the mutants and in an axenic wild-type strain, caffeine causes the induction of pulse-induced gene expression to almost wild-type levels or in some cases to higher than wild-type levels. Our data suggest that caffeine works by activating some step in the signal transduction pathway that must lie downstream from both the receptor and at least one of the G proteins and thus has effects other than simply blocking the receptor-mediated cAMP relay system.
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Affiliation(s)
- S K Mann
- Department of Biology, University of California, San Diego, La Jolla 92093
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81
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Knecht DA, Loomis WF. Developmental consequences of the lack of myosin heavy chain in Dictyostelium discoideum. Dev Biol 1988; 128:178-84. [PMID: 3384173 DOI: 10.1016/0012-1606(88)90280-1] [Citation(s) in RCA: 58] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Two different Dictyostelium discoideum cell lines that lack myosin heavy chain protein (MHC A) have been previously described. One cell line (mhcA) was created by antisense RNA inactivation of the endogenous mRNA and the other (HMM) by insertional mutagenesis of the endogenous myosin gene. The two cell lines show similar developmental defects; they are delayed in aggregation and become arrested at the mound stage. However, when cells that lack myosin heavy chain are mixed with wild-type cells, some of the mutant cells are capable of completing development to form mature spores. The pattern of expression of a number of developmentally regulated genes has been examined in both mutant cell lines. Although morphogenesis becomes aberrant before aggregation is completed, all of the markers that we have examined are expressed normally. These include genes expressed prior to aggregation as well as prespore genes expressed later in development. It appears that the signals necessary for cell-type differentiation are generated in the aborted structures formed by cells lacking MHC A. The mhcA cells have negligible amounts of MHC A protein while the HMM cells express normal amounts of a fragment of the myosin heavy chain protein similar to heavy meromyosin (HMM). The expression of myosin light chain was examined in these two cell lines. HMM cells accumulate normal amounts of the 18,000-D light chain, while the amount of light chain in mhcA cells is dramatically reduced. It is likely that the light chains assemble normally with the HMM fragment in HMM cells, while in cells lacking myosin heavy chain (mhcA) the light chains are unstable.
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Affiliation(s)
- D A Knecht
- Center for Molecular Genetics, University of California San Diego, La Jolla 92093
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82
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West CM, Erdos GW. The expression of glycoproteins in the extracellular matrix of the cellular slime mold Dictyostelium discoideum. CELL DIFFERENTIATION 1988; 23:1-16. [PMID: 3370674 DOI: 10.1016/0045-6039(88)90032-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
In this report we examine the accumulation of glycoconjugates in the extracellular medium and insoluble matrices surrounding developing cells of the cellular slime mold Dictyostelium discoideum. Conditions were employed which permitted advanced development (slug stage and beyond) in suspension culture. Under these conditions, up to one-third of the total culture protein appeared as non-sedimentable, extracellular material over the course of 48 h of incubation. Most of the secreted molecules expressed carbohydrate antigens (glycoantigens) as detected by Western blotting, using a panel of six monoclonal antibodies. Since the glycoantigens are secreted, immunoelectron microscopy was used to localize the glycoantigens in the extracellular matrices surrounding normally developing cells, including the slime sheath, stalk tube, inner spore coat, outer spore coat, and intercellular fluid between spores. Each glycoantigen had a characteristic distribution, and each extracellular matrix space contained a unique combination of glycoantigens. Thus, although each of these matrices (except inter-spore fluid) contains cellulose as a primary component, they could be distinguished on the basis of their glycoantigen and, by inference, glycoprotein compositions. Furthermore, there were differences between anterior and posterior regions of both slime sheaths and stalk tubes. These observations show that secretion as detected in suspension culture occurs under normal conditions as a part of the process of depositing extracellular matrices around the cells. The distributions show that the cell aggregate positionally regulates the expression and deposition of secretory glycoproteins; the resultant patterns of expression of unique protein-linked carbohydrate structures imply a functional role in matrix organization and possibly cell activity which can now be explored.
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Affiliation(s)
- C M West
- Department of Anatomy and Cell Biology, College of Medicine, University of Florida, Gainesville 32610
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83
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Abstract
Cyclic AMP and DIF-1 (1-(3,5-dichloro-2,6-dihydroxy-4-methoxyphenyl)-1-hexanone) together induce stalk cell differentiation in vitro in Dictyostelium discoideum strain V12M2. The induction can proceed in two stages: in the first, cyclic AMP brings cells to a DIF-responsive state; in the second, DIF-1 alone can induce stalk cell formation. We report here that during the DIF-1-dependent stage, cyclic AMP is a potent inhibitor of stalk cell differentiation. Addition of cyclic AMP at this stage to V12M2 cells appreciably delays, but does not prevent, stalk cell formation. In contrast, stalk cell differentiation in the more common strain NC4 is completely suppressed by the continued presence of cyclic AMP. This fact explains earlier failures to induce stalk cells in vitro in NC4. We now consistently obtain efficient stalk cell induction in NC4 by removing cyclic AMP in the DIF-1-dependent stage. Cyclic AMP also inhibits the production of a stalk-specific protein (ST310) in both NC4 and a V12M2 derivative. Adenosine, a known antagonist of cyclic AMP action, does not relieve this inhibition by cyclic AMP and does not itself promote stalk cell formation. Finally, stalk cell differentiation of NC4 cells at low density appears to require factors in addition to cyclic AMP and DIF-1, but their nature is not yet known. The inhibition of stalk cell differentiation by cyclic AMP may be important in establishing the prestalk/prespore pattern during normal development, and in preventing the maturation of prestalk into stalk cells until culmination.
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Affiliation(s)
- M Berks
- MRC Laboratory of Molecular Biology, Cambridge, England
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84
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West CM, Brownstein SA. EDTA treatment alters protein glycosylation in the cellular slime mold Dictyostelium discoideum. Exp Cell Res 1988; 175:26-36. [PMID: 3126078 DOI: 10.1016/0014-4827(88)90252-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
We have found that treatment of cells with EDTA resulted in the accumulation of lower molecular weight forms of two cell-type-specific glycoproteins. These new glycoproteins lacked a developmentally regulated glycoantigen defined by monoclonal antibody 54.2. Since EDTA dissociated the cells, the possible involvement of cell separation was tested by immobilizing cells in soft agarose. Glycoantigen expression on these proteins was found to be dependent on cAMP and high oxygen tension but not on cell contact, and was reversibly sensitive to EDTA regardless of the state of cell association. The EDTA effect was mimicked by other soluble, but not particulate, membrane impermeable chelators, could be competed by Zn2+ better than Mg2+, and appeared to involve an intracellular mechanism. Studies with [14C]EDTA showed that EDTA equilibrated with a cellular compartment in a temperature-dependent, Zn2+-insensitive fashion with half-time kinetics of loading and unloading of 30-40 min. If the compartment was assumed to be labeled with the same concentration of EDTA as was present extracellularly, calculations showed that its volume was circa 2% of the total cell volume. This compartment probably consists of intracellular vesicles based on the similar labeling of this compartment with a bulk fluid phase marker, inulin. The data suggest that this step in glycosylation, which was found to be delayed 1 or more hours subsequent to protein synthesis, involves an intracellular, transition metal ion-dependent process which can be modulated by chelators entering the cell through the endocytic pathway.
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Affiliation(s)
- C M West
- Department of Anatomy and Cell Biology, University of Florida College of Medicine, Gainesville 32610-0235
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85
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Spek W, van Drunen K, van Eijk R, Schaap P. Opposite effects of adenosine on two types of cAMP-induced gene expression in Dictyostelium indicate the involvement of at least two different intracellular pathways for the transduction of cAMP signals. FEBS Lett 1988; 228:231-4. [PMID: 2830141 DOI: 10.1016/0014-5793(88)80005-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Adenosine promotes the cAMP-induced increase of mRNAs, probed with the cDNAs D11 and D14, which are preferentially expressed in prestalk cells, while it inhibits cAMP-induced prespore gene expression. Half-maximal inhibition of prespore gene expression occurs at about 300 muM, while prestalk stimulation by adenosine occurs at about 100-fold lower concentrations and requires the presence of cAMP. These results indicate that adenosine interferes with the transduction to cAMP to gene expression and suggest the involvement of two different adenosine target sites. Our data furthermore indicate that the transduction of extracellular cAMP to prespore gene or prestalk gene expression occurs via divergent pathways.
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Affiliation(s)
- W Spek
- Cell Biology and Genetics Unit, Zoological Laboratory, University of Leiden, The Netherlands
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86
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Tsang A, Grant C, Kay C, Bain G, Greenwood M, Noce T, Tasaka M. Characterization of an unusual cAMP receptor and its related polypeptides in Dictyostelium discoideum. DEVELOPMENTAL GENETICS 1988; 9:237-45. [PMID: 3243023 DOI: 10.1002/dvg.1020090406] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Several lines of evidence indicate that cAMP modulates developmental gene activity via cell-surface receptors. We describe here a novel cAMP receptor, CABP1, whose properties are consistent with the idea that this protein is involved in gene regulation. Firstly, immunological techniques using anti-CABP1 antibodies as probes showed that this cAMP receptor can be detected on the surface of developing cells. Secondly, there is a steady migration of CABP1 to the nucleus during development. Thirdly, some genetic variants exhibiting an altered pattern of development are found to possess modified CABP1. We also showed that CABP1 co-purifies with at least seven other polypeptides which share common epitopes with CABP1. Interestingly, four of the CABP1-related polypeptides can be detected on the cell surface as well as in the nucleus.
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Affiliation(s)
- A Tsang
- Department of Biology, McGill University, Montreal, Quebec, Canada
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87
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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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88
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Hjorth A, Datta S, Khanna NC, Firtel RA. Analysis of cis and trans elements involved in cAMP-inducible gene expression in Dictyostelium discoideum. DEVELOPMENTAL GENETICS 1988; 9:435-54. [PMID: 2907423 DOI: 10.1002/dvg.1020090422] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Expression of the Dictyostelium discoideum pst-cath (CP2) gene is transcriptionally regulated during multicellular development, and the gene is inducible in competent single cells following administration of exogenous cAMP. The 5' flanking region of pst-cath (CP2) that extends from -313 to the Cap site (+1) has previously been shown to contain sufficient cis-acting regulatory elements for proper developmental and cAMP-inducible expression of a foreign gene [Datta and Firtel, 1987, Mol Cell Biol 7:149-159]. The -283 to -201 region includes two exceptional "G-boxes" centered at -233 and -217 respectively, and this approximately 80 bp region is essential for basal as well as regulated expression of the pst-cath (CP2) gene. Here we summarize results obtained from a detailed analysis of a series of linker-scanner mutants and mutants that carry small internal deletions within the essential 80-bp region. Insertion of a synthetic oligonucleotide that includes the downstream G-box is demonstrated to rescue a low level of cAMP-inducible expression following insertion into cassette mutants. The effect of introducing a change in the relative spacing between regulatory elements has also been investigated. We have analyzed nuclear extracts for the presence of DNA-binding proteins that interact specifically with the pst-cath (CP2) regulatory region and identified two such putative trans-acting factors: 1) the AT-factor that is observed within a few hours following the onset of starvation and that binds tightly to stretches of alternating adenine-thymine residues (poly(dA-dT]; and 2) the AG-factor that is present in nuclear extracts of aggregated cells. Competition studies have demonstrated significant differences in the affinity that characterizes the binding of the two factors to G-box-containing sequences. The binding specificities of these DNA-binding proteins have been analyzed using gel mobility-shift and DNaseI footprinting assays.
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Affiliation(s)
- A Hjorth
- Department of Biology, University of California San Diego, La Jolla 92093
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89
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Van Lookeren Campagne MM, Wang M, Spek W, Peters D, Schaap P. Lithium respecifies cyclic AMP-induced cell-type specific gene expression in Dictyostelium. DEVELOPMENTAL GENETICS 1988; 9:589-96. [PMID: 2854027 DOI: 10.1002/dvg.1020090435] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
We investigated the effect of LiCl on pattern formation and cAMP-regulated gene expression in Dictyostelium discoideum. In intact slugs, 5 mM LiCl induces an almost complete redifferentiation of prespore into prestalk cells. We found that LiCl acts by interfering with the transduction of extracellular cAMP to cell-type-specific gene expression; LiCl inhibits the induction of prespore-specific gene expression by cAMP, while it promotes the induction of prestalk-associated gene expression by cAMP. Our results indicate that two divergent pathways transduce the extracellular cAMP signal to, respectively, prestalk and prespore gene expression.
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90
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Manrow RE, Shapiro RA, Herrick D, Steel LF, Blinder D, Jacobson A. Regulation of mRNA stability and the poly(A) problem in Dictyostelium discoideum. DEVELOPMENTAL GENETICS 1988; 9:403-19. [PMID: 2468435 DOI: 10.1002/dvg.1020090420] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
This paper reviews our studies of three aspects of post-transcriptional regulation in Dictyostelium discoideum: 1) the determinants of mRNA stability in vegetative amoebae; 2) the effects of disaggregation and cyclic AMP on the decay rates of cell-type-specific mRNAs in late developing cells; and 3) the cytoplasmic function of the 3' poly(A) tracts present on most mRNAs. We find that: 1) mRNA stability in vegetative amoebae is not dependent on mRNA size, ribosome loading, or poly(A) tract length, but may be determined by specific 3'-untranslated sequences within a given mRNA; 2) mRNA decay rates in late developing cells are heterogeneous, and cyclic AMP does not act directly to stabilize cell-type-specific mRNAs; and 3) poly(A) is most likely involved in the initiation of protein synthesis via an interaction with cytoplasmic poly(A)-binding proteins.
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Affiliation(s)
- R E Manrow
- Dept. of Molecular Genetics and Microbiology, University of Massachusetts Medical Center, Worcester 01655
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91
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Fontana DR, Price PL. Contact alters cAMP metabolism in aggregation-competent Dictyostelium amoebae. DEVELOPMENTAL GENETICS 1988; 9:279-92. [PMID: 2854020 DOI: 10.1002/dvg.1020090410] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
cAMP and cell-cell contact are involved in the coordination of differentiation and morphogenesis in Dictyostelium discoideum. The experiments described in this paper establish a relationship between cAMP and cell-cell contact. Contact between Enterobacter aerogenes and aggregation-competent Dictyostelium amoebae and contact between Dictyostelium amoebae themselves results in the transient secretion of cAMP and an alteration in the amount of cAMP secreted in response to subsequent stimulation by cAMP, i.e., an alteration in magnitude of a cAMP relay response. The subsequent cAMP relay response can be enhanced or diminished depending upon the number of contacts formed and the concentration of cAMP present at the time of contact. Latex beads are capable of evoking cAMP secretion. However, the bead/amoebal contact is unable to alter the magnitude of a subsequent response to cAMP. This suggests that a nonspecific interaction via cell-cell contact elicits transient cAMP secretion in aggregation-competent Dictyostelium amoebae. The two responses to cell-cell contact are distinct from each other and distinct from the cAMP relay response. 1) The dose-response curves for the responses to Enterobacter contact are clearly different. 2) Contact with latex beads can elicit cAMP secretion but not alter the magnitude of a subsequent cAMP relay response. 3) The temperature dependences of the contact-induced responses and the cAMP relay response show that only the contact-induced cAMP secretion is inhibited at 12 and 15 degrees C, while only the cAMP relay response is inhibited at 28 degrees C. A 4-second application of cAMP at the time that contact is initiated enhances both contact-induced responses. Whether the relationship between these two developmental regulators is important for the regulation of Dictyostelium development has yet to be established.
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Affiliation(s)
- D R Fontana
- Dept. of Microbiology, University of Minnesota Medical School, Minneapolis 55455
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92
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Bozzone DM, Kohnken RE, Berger EA. Relationships between cell-cell interactions, cAMP, and gene expression in a developmental mutant of Dictyostelium discoideum. Neurochem Res 1987; 12:1005-12. [PMID: 2825056 DOI: 10.1007/bf00970929] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Previous work has led us to propose that close cell-cell associations during D. discoideum development serve as a signal to deactivate expression of discoidin I mRNA, and that intracellular cAMP serves as a mediator of this regulatory pathway. This model is based in part on the failure of a morphogenetic mutant, EB-21, to deactivate discoidin I expression under conditions where these cells fail to acquire cell-cell cohesiveness and hence remain as single cells, unlike the wild type strain which forms multicellular aggregates. Here we show that the failure of EB-21 to express specific cohesiveness depends on developmental conditions, and that under conditions where close cell-cell associations are allowed to form, discoidin I mRNA expression is deactivated normally. Furthermore, in both wild type and EB-21 there is a close correlation between formation close cell-cell associations and elevation of intracellular cAMP under different developmental conditions. Additional analyses of the biological behavior of EB-21 indicate that it acquires a normal cAMP chemotactic signal-response system, and that the morphogenetic defect cannot be corrected by co-development with wild type cells. The results are discussed in terms of possible relationships between cell-cell interactions, cAMP metabolism, and developmental gene expression in this organism.
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Affiliation(s)
- D M Bozzone
- Cell Biology Group, Worcester Foundation for Experimental Biology, Shrewsbury, Massachusetts 91545
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93
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Kimmel AR. Different molecular mechanisms for cAMP regulation of gene expression during Dictyostelium development. Dev Biol 1987; 122:163-71. [PMID: 3036630 DOI: 10.1016/0012-1606(87)90342-3] [Citation(s) in RCA: 85] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Alterations in cAMP concentrations have been implicated in developmentally regulated gene expression in Dictyostelium. Using a variety of culture conditions to control the metabolism of cAMP during cytodifferentiation, I have examined the role of the cyclic nucleotide in development. Conditions which allow intracellular synthesis of cAMP promote the normal developmental repression of gene M4-1 by a mechanism which is completely independent of the formation of multicellular aggregates. If, however, cells are inhibited in their ability to activate adenylate cyclase and, thus, intracellular cAMP signaling, they prove unable to repress M4-1, even in the presence of exogenous cAMP. In contrast, expression of genes which exhibit maximal activity after aggregate formation depends upon accumulation of extracellular cAMP. Inhibition of intracellular cAMP signaling does not prevent the expression of these genes if cultures are simultaneously exposed to high levels of exogenously added extracellular cAMP. These results indicate that there are at least two independent mechanisms involved in the developmental regulation of gene expression by cAMP in Dictyostelium. I discuss plausible molecular mechanisms through which cAMP might alter gene expression.
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94
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Clarke M, Kayman SC, Riley K. Density-dependent induction of discoidin-I synthesis in exponentially growing cells of Dictyostelium discoideum. Differentiation 1987; 34:79-87. [PMID: 3622952 DOI: 10.1111/j.1432-0436.1987.tb00053.x] [Citation(s) in RCA: 97] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The synthesis of the lectin, discoidin I, by vegetative cells of Dictyostelium discoideum (strain NC4) was monitored using immunoblot analysis and indirect immunofluorescence. Suspension cultures were used, so that the D. discoideum cell density and the concentration of bacteria could be controlled. Discoidin-I production was found to be a function of the relative densities of D. discoideum cells and food bacteria. Synthesis was initiated in exponentially growing D. discoideum cells approximately three generations before depletion of the food supply. In the growth medium of cells producing discoidin I, a soluble activity was detected that caused low-density cells to begin discoidin-I synthesis. This activity was not dialyzable and was destroyed by heat. A similar activity was produced by AX3 cells during axenic growth. Density-dependent induction of other 'early developmental' proteins was also detected in wild-type cells. These findings suggest that the expression of several 'early developmental' genes is regulated by a mechanism that measures cell density relative to food supply, not by starvation per se.
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95
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Wang M, Van Haastert PJ, Scbaap P. Multiple effects of differentiation-inducing factor on prespore differentiation and cyclic-AMP signal transduction in Dictyostelium. Differentiation 1987. [DOI: 10.1111/j.1432-0436.1987.tb01537.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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96
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Singleton CK, Delude RL, McPherson CE. Characterization of genes which are deactivated upon the onset of development in Dictyostelium discoideum. Dev Biol 1987; 119:433-41. [PMID: 3803712 DOI: 10.1016/0012-1606(87)90047-9] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
We have identified and begun characterizations of the differential expression of 15 genes whose corresponding mRNA levels decrease during the preaggregative period of the developmental program of Dictyostelium discoideum. Upon the onset of development, the mRNAs decrease from 5- to 1000-fold over the first 8 hr. The rates of loss of each mRNA were similar to one another but distinct, and the decreases were dependent on progress through the developmental program. One exception to this dependency was observed, and the decrease in this mRNA was dependent on the absolute time after initiation of development instead of progress through development. With two exceptions, the decreases in mRNA levels were dependent on developmental conditions and were not seen when cells were shaken in starvation buffer. When the polysomal distributions of each species were examined, three classes were found: most showed no significant shifts off of polysomes upon initiation of development, two were characterized by a 20% shift to nonpolysomal RNA fractions upon development, and two gave a 40-50% shift. Collectively, these characterizations reveal differences in behavior which suggest that deactivation of genes upon initiation of development in Dictyostelium involves more than one regulatory pathway.
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97
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98
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Bozzone DM, Berger EA. Distinct developmental regulation and properties of the responsiveness of different genes to cyclic AMP in Dictyostelium discoideum. Differentiation 1987; 33:197-206. [PMID: 3036635 DOI: 10.1111/j.1432-0436.1987.tb01558.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Cyclic AMP (cAMP) is known to be an important mediator of gene expression in eukaryotic cells. At present, little is known about the developmental events which render specific genes responsive to cAMP in distinct cell types, or about the biochemical mechanisms by which cAMP exerts these regulatory effects. By examining the effects of cAMP treatment on specific mRNA levels in Dictyostelium discoideum cells with different 'developmental histories', we defined the developmental states in which specific genes display responsiveness to cAMP. We focused on two specific rapid responses: the ability of cAMP to inhibit the expression of an 'early' developmentally regulated mRNA (discoidin-I) and to stimulate the expression of a 'late', prespore-specific mRNA (PL3). Using this approach, we showed that, for both mRNAs, the ability to respond rapidly to cAMP is absent from vegetative cells grown on bacteria, and is acquired during development on filters. Furthermore, we identified several developmental states in which the discoidin-I response to cAMP is present, but in which the PL3 response is not. In experiments designed to examine the effects of cAMP analogues on the levels of these two mRNAs, we demonstrated that the analogue specificities of the discoidin-I and PL3 responses are different, and that the specificity for the PL3 response depends on the developmental state. The developmental kinetics and analogue specificity of the PL3 response suggest a two-step mode of action of cAMP in activating the expression of this gene. We discuss possible implications of these findings for the mechanisms of action of exogenous cAMP as well as for the role of cAMP in controlling the changes in gene expression that accompany normal development.
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99
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Barclay SL, Smith AM. Identification and analysis of the regulation of a prestalk cell-surface antigen of Dictyostelium discoideum. Differentiation 1987. [DOI: 10.1111/j.1432-0436.1987.tb01546.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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100
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Nellen W, Datta S, Reymond C, Sivertsen A, Mann S, Crowley T, Firtel RA. Molecular biology in Dictyostelium: tools and applications. Methods Cell Biol 1987; 28:67-100. [PMID: 3600419 DOI: 10.1016/s0091-679x(08)61637-4] [Citation(s) in RCA: 195] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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