Inositol 1,4,5-trisphosphate and calcium stimulate actin polymerization in Dictyostelium discoideum

1986 ◽  
Vol 82 (1) ◽  
pp. 41-51
Author(s):  
G.N. Europe-Finner ◽  
P.C. Newell
Keyword(s):  
Cyclic Amp ◽  
Dictyostelium Discoideum ◽  
Actin Polymerization ◽  
Cell Surface Receptor ◽  
Receptor Stimulation ◽  
Normal Cells ◽  
Cellular Slime Mould ◽  
Inositol 1,4,5 Trisphosphate ◽  
Surface Receptor ◽  
Cellular Slime

The effect of chemoattractants such as cyclic AMP and folate on amoebae of the cellular slime mould Dictyostelium discoideum is to cause a series of rapid intracellular responses. One of the most rapid of these responses is the polymerization of actin associated with the cytoskeleton, an event correlated with pseudopodium formation, which occurs within 3–5 s of chemotactic receptor stimulation. We report that this response can be mimicked by addition of 5 microM-inositol 1,4,5-triphosphate (IP3) or by addition of 100 microM-Ca2+ to saponin-permeabilized amoebae. The data suggest that cytoskeletal actin polymerization occurs in normal cells as a result of IP3 formation in response to cell surface receptor stimulation and the consequent release of Ca2+ from internal stores.

Pharmacological characterization of cyclic AMP receptors mediating gene regulation in Dictyostelium discoideum

1986 ◽  
Vol 6 (7) ◽  
pp. 2402-2408
Author(s):  
B Haribabu ◽  
R P Dottin
Keyword(s):  
Gene Expression ◽  
Cyclic Amp ◽  
Cell Surface ◽  
Dictyostelium Discoideum ◽  
Cell Surface Receptor ◽  
Intracellular Camp ◽  
Response Curves ◽  
Pharmacological Characterization ◽  
Surface Receptor ◽  
Extracellular Molecules

Extracellular molecules regulate gene expression in eucaryotes. Exogenous cyclic AMP (cAMP) affects the expression of a large number of developmentally regulated genes in Dictyostelium discoideum. Here, we determine the specificity of the receptor(s) which mediates gene expression by using analogs of cAMP. The order of potency with which these analogs affect the expression of specific genes is consistent with the specificity of their binding to a cell surface receptor and is distinct from their affinity for intracellular cAMP-dependent protein kinase. Dose-response curves with cAMP and adenosine 3',5'-monophosphorothioate, a nonhydrolyzable analog, revealed that the requirement for high concentrations of exogenous cAMP for regulating gene expression is due to the rapid degradation of cAMP by phosphodiesterase. The addition of low concentrations of cAMP (100 nM) or analogs in pulses also regulates gene expression. Both the genes that are positively regulated by exogenous cAMP and the discoidin gene, which is negatively regulated, respond to cAMP analogs to the same degree. Genes expressed in prespore or prestalk cells are also similarly regulated. These data suggest that the effects are mediated through the same receptor. The specificity of this receptor is indistinguishable from that of the well-characterized cell surface cAMP receptor.

scholarly journals Pharmacological characterization of cyclic AMP receptors mediating gene regulation in Dictyostelium discoideum.

1986 ◽  
Vol 6 (7) ◽  
pp. 2402-2408 ◽  
Author(s):  
B Haribabu ◽  
R P Dottin
Keyword(s):  
Gene Expression ◽  
Cyclic Amp ◽  
Cell Surface ◽  
Dictyostelium Discoideum ◽  
Cell Surface Receptor ◽  
Intracellular Camp ◽  
Response Curves ◽  
Pharmacological Characterization ◽  
Surface Receptor ◽  
Extracellular Molecules

Extracellular molecules regulate gene expression in eucaryotes. Exogenous cyclic AMP (cAMP) affects the expression of a large number of developmentally regulated genes in Dictyostelium discoideum. Here, we determine the specificity of the receptor(s) which mediates gene expression by using analogs of cAMP. The order of potency with which these analogs affect the expression of specific genes is consistent with the specificity of their binding to a cell surface receptor and is distinct from their affinity for intracellular cAMP-dependent protein kinase. Dose-response curves with cAMP and adenosine 3',5'-monophosphorothioate, a nonhydrolyzable analog, revealed that the requirement for high concentrations of exogenous cAMP for regulating gene expression is due to the rapid degradation of cAMP by phosphodiesterase. The addition of low concentrations of cAMP (100 nM) or analogs in pulses also regulates gene expression. Both the genes that are positively regulated by exogenous cAMP and the discoidin gene, which is negatively regulated, respond to cAMP analogs to the same degree. Genes expressed in prespore or prestalk cells are also similarly regulated. These data suggest that the effects are mediated through the same receptor. The specificity of this receptor is indistinguishable from that of the well-characterized cell surface cAMP receptor.

scholarly journals Adenosine 3′:5′-cyclic monophosphate-binding protein from the cellular slime mould Dictyostelium discoideum (Short Communication)

1973 ◽  
Vol 133 (3) ◽  
pp. 601-603 ◽  
Author(s):  
Al M. Malkinson ◽  
Janet Kwasniak ◽  
John M. Ashworth
Keyword(s):  
Cyclic Amp ◽  
Dictyostelium Discoideum ◽  
Short Communication ◽  
Specific Activity ◽  
Binding Protein ◽  
Protein S ◽  
Fold Increase ◽  
Axenic Medium ◽  
Cellular Slime Mould ◽  
Cellular Slime

During the differentiation of myxamoebae of Dictyostelium discoideum strain Ax-2 grown in axenic medium there is a seven- to ten-fold increase in the specific activity of cyclic AMP-binding protein(s). Evidence is presented for the belief that cyclic AMP phosphodiesterase and cyclic AMP-binding protein are distinct molecular species.

Regulatory signals affecting a selective loss of mRNA in Dictyostelium discoideum

1989 ◽  
Vol 94 (3) ◽  
pp. 501-509
Author(s):  
H.H. Hassanain ◽  
W. Kopachik
Keyword(s):  
Cyclic Amp ◽  
Cell Surface ◽  
Dictyostelium Discoideum ◽  
Transcript Level ◽  
Cell Surface Receptor ◽  
Cell Contact ◽  
Specific Cell ◽  
Mrna Levels ◽  
Stage Of Development ◽  
Surface Receptor

We identified signals that affect mRNA levels complementary to a gene that is highly expressed in vegetative Dictyostelium discoideum cells. This gene has been cloned as cDNA in the plasmid pcD-D2. The level of transcripts homologous to pcD-D2 fell dramatically in strain XP55 during the aggregation stage of development when cells differentiate on agar. The level, however, did not fall simply as a result of starvation or aggregation-specific cell contact. Rather, before the level is reduced cells must be deprived of amino acids and cyclic AMP administered in amounts and at intervals in pulses to mimic cyclic AMP signal-relay in aggregation. This effect can be blocked either with cyclic AMP-S (a non-hydrolysable cyclic AMP analogue) or adenosine, both of which prevent cyclic AMP binding to the cyclic AMP cell surface receptor. It is also blocked in ‘frigid’ aggregation-deficient mutants HC85 and HC112 known to be defective in a G alpha protein. We conclude that the transcript level is balanced by positive nutritional signals acting against negative signals transduced in part through a cell surface cyclic AMP receptor.

scholarly journals Growth of myxamoebae of the cellular slime mould Dictyostelium discoideum in axenic culture

1970 ◽  
Vol 119 (2) ◽  
pp. 171-174 ◽  
Author(s):  
D. J. Watts ◽  
J. M. Ashworth
Keyword(s):  
Cell Differentiation ◽  
Dictyostelium Discoideum ◽  
Axenic Culture ◽  
Axenic Medium ◽  
Cellular Slime Mould ◽  
Slime Mould ◽  
Solid Media ◽  
Cellular Slime

1. A simple axenic medium suitable for the growth of the myxamoebae of a strain of the cellular slime mould Dictyostelium discoideum is described. 2. Procedures suitable for the growth of this strain in liquid and on solid media are described. 3. Conditions suitable for initiating the cell differentiation of myxamoebae grown axenically are described.

scholarly journals Glycoproteins that exhibit extensive size polymorphisms in Dictyostelium discoideum.

Genetics ◽  
1989 ◽  
Vol 122 (1) ◽  
pp. 59-64 ◽  
Author(s):  
E Smith ◽  
A A Gooley ◽  
G C Hudson ◽  
K L Williams
Keyword(s):  
Linkage Group ◽  
Dictyostelium Discoideum ◽  
Allelic Variation ◽  
Surface Glycoprotein ◽  
Developmentally Regulated ◽  
Electrophoretic Variants ◽  
Cellular Slime Mould ◽  
Repeat Units ◽  
Group I ◽  
Cellular Slime

Abstract Electrophoretic variants which arise from amino acid substitutions, leading to charge differences between proteins are ubiquitous and have been used extensively for genetic analysis. Less well documented are polymorphisms in the size of proteins. Here we report that a group of glycoproteins, which share a common carbohydrate epitope, vary in size in different isolates of the cellular slime mould, Dictyostelium discoideum. One of these proteins, PsA, a developmentally regulated prespore-specific surface glycoprotein, has previously been shown to exist in three size forms due to allelic variation at the pspA locus on linkage group I. In this report, a second glycoprotein, PsB, which is also prespore specific but found inside prespore cells, is studied. PsB maps to linkage group II and exhibits at least four different sizes in the isolates examined. We propose that the size polymorphisms are the product of allelic variation at the pspB locus, due to differences in the number of repeat units.

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