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

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.

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Regulatory signals affecting a selective loss of mRNA in Dictyostelium discoideum

Journal of Cell Science ◽

10.1242/jcs.94.3.501 ◽

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.

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Dectin-1-Mediated Production of Pro-Inflammatory Cytokines Induced by Yeast β-Glucans in Bovine Monocytes

Frontiers in Immunology ◽

10.3389/fimmu.2021.689879 ◽

2021 ◽

Vol 12 ◽

Author(s):

Ana R. V. Pedro ◽

Tânia Lima ◽

Ricardo Fróis-Martins ◽

Bárbara Leal ◽

Isabel C. Ramos ◽

...

Keyword(s):

Gene Expression ◽

Cell Surface ◽

Inflammatory Cytokines ◽

Surface Expression ◽

Cell Surface Receptor ◽

Dependent Manner ◽

Feed Supplements ◽

Surface Receptor ◽

Dose Dependent ◽

Pro Inflammatory Cytokines

Yeast-derived products containing β-glucans have long been used as feed supplements in domesticated animals in an attempt to increase immunity. β-glucans are mainly recognized by the cell surface receptor CLEC7A, also designated Dectin-1. Although the immune mechanisms elicited through Dectin-1 activation have been studied in detail in mice and humans, they are poorly understood in other species. Here, we evaluated the response of bovine monocytes to soluble and particulate purified β-glucans, and also to Zymosan. Our results show that particulate, but not soluble β-glucans, can upregulate the surface expression of costimulatory molecules CD80 and CD86 on bovine monocytes. In addition, stimulated cells increased production of IL-8 and of TNF, IL1B, and IL6 mRNA expression, in a dose-dependent manner, which correlated positively with CLEC7A gene expression. Production of IL-8 and TNF expression decreased significantly after CLEC7A knockdown using two different pairs of siRNAs. Overall, we demonstrated here that bovine monocytes respond to particulate β-glucans, through Dectin-1, by increasing the expression of pro-inflammatory cytokines. Our data support further studies in cattle on the induction of trained immunity using dietary β-glucans.

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Separation of chitooligosaccharides and the potent effects on gene expression of cell surface receptor CR3

International Journal of Biological Macromolecules ◽

10.1016/j.ijbiomac.2009.07.003 ◽

2009 ◽

Vol 45 (4) ◽

pp. 432-436 ◽

Cited By ~ 23

Author(s):

Xinlin Wei ◽

Yuanfeng Wang ◽

Jianbo Xiao ◽

Wenshui Xia

Keyword(s):

Gene Expression ◽

Cell Surface ◽

Cell Surface Receptor ◽

Surface Receptor

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Cyclic AMP regulation of early gene expression in Dictyostelium discoideum: mediation via the cell surface cyclic AMP receptor

Molecular and Cellular Biology ◽

10.1128/mcb.7.1.458-469.1987 ◽

1987 ◽

Vol 7 (1) ◽

pp. 458-469

Author(s):

S K Mann ◽

R A Firtel

Keyword(s):

Cyclic Amp ◽

Cell Surface ◽

Dictyostelium Discoideum ◽

Early Gene ◽

Developmental Cycle ◽

Intracellular Camp ◽

Flanking Sequence ◽

Coding Region ◽

Camp Receptor

We examined two sets of genes expressed early in the developmental cycle of Dictyostelium discoideum that appear to be regulated by cyclic AMP (cAMP). The transcripts of both sets of genes were not detectable in vegetative cells. During normal development on filter pads, RNA complementary to these genes could be detected at about 2 h, peaked around 6 to 8 h, and decreased gradually thereafter. Expression of these genes upon starvation in shaking culture was stimulated by pulsing the cells with nanomolar levels of cAMP, a condition that mimics the in vivo pulsing during normal aggregation. Expression was inhibited by caffeine or by continuous levels of cAMP, a condition found later in development when in vivo expression of these genes decreased. The inhibition of caffeine could be overcome by pulsing cells with cAMP. These results suggest that the expression is mediated via the cell surface cAMP receptor, but does not require a rise in intracellular cAMP. mRNA from a gene of the second class was induced upon starvation, peaked by 2.5 h of development, and then declined. In contrast to the other genes, its expression was maintained by continuous levels of cAMP and repressed by cAMP pulses. These and other results on a number of classes of developmentally regulated genes indicates that changing levels of cAMP, acting via the cell surface cAMP receptor, are involved in controlling these groups of genes. We also examined the structure and partial sequence of the cAMP pulse-induced genes. The two tandemly duplicated M3 genes were almost continuously homologous over the sequenced portion of the protein-coding region except for a region near the N-terminal end. The two M3 genes had regions of homology in the 5' flanking sequence and showed slight homology to the same regions in gene D2, another cAMP pulse-induced gene. D2 showed extremely significant homology over its entire sequenced length to an acetylcholinesterase. The results presented here and by others suggest that expression of many early genes in D. discoideum is regulated via the cell surface cAMP receptor. We expect that many of these genes may play essential roles in early Dictyostelium development and could code for elements of the cAMP signal transduction pathway involved in aggregation.

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

Journal of Cell Science ◽

10.1242/jcs.82.1.41 ◽

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.

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Cyclic AMP regulation of early gene expression in Dictyostelium discoideum: mediation via the cell surface cyclic AMP receptor.

Molecular and Cellular Biology ◽

10.1128/mcb.7.1.458 ◽

1987 ◽

Vol 7 (1) ◽

pp. 458-469 ◽

Cited By ~ 57

Author(s):

S K Mann ◽

R A Firtel

Keyword(s):

Cyclic Amp ◽

Cell Surface ◽

Dictyostelium Discoideum ◽

Early Gene ◽

Developmental Cycle ◽

Intracellular Camp ◽

Flanking Sequence ◽

Coding Region ◽

Camp Receptor

We examined two sets of genes expressed early in the developmental cycle of Dictyostelium discoideum that appear to be regulated by cyclic AMP (cAMP). The transcripts of both sets of genes were not detectable in vegetative cells. During normal development on filter pads, RNA complementary to these genes could be detected at about 2 h, peaked around 6 to 8 h, and decreased gradually thereafter. Expression of these genes upon starvation in shaking culture was stimulated by pulsing the cells with nanomolar levels of cAMP, a condition that mimics the in vivo pulsing during normal aggregation. Expression was inhibited by caffeine or by continuous levels of cAMP, a condition found later in development when in vivo expression of these genes decreased. The inhibition of caffeine could be overcome by pulsing cells with cAMP. These results suggest that the expression is mediated via the cell surface cAMP receptor, but does not require a rise in intracellular cAMP. mRNA from a gene of the second class was induced upon starvation, peaked by 2.5 h of development, and then declined. In contrast to the other genes, its expression was maintained by continuous levels of cAMP and repressed by cAMP pulses. These and other results on a number of classes of developmentally regulated genes indicates that changing levels of cAMP, acting via the cell surface cAMP receptor, are involved in controlling these groups of genes. We also examined the structure and partial sequence of the cAMP pulse-induced genes. The two tandemly duplicated M3 genes were almost continuously homologous over the sequenced portion of the protein-coding region except for a region near the N-terminal end. The two M3 genes had regions of homology in the 5' flanking sequence and showed slight homology to the same regions in gene D2, another cAMP pulse-induced gene. D2 showed extremely significant homology over its entire sequenced length to an acetylcholinesterase. The results presented here and by others suggest that expression of many early genes in D. discoideum is regulated via the cell surface cAMP receptor. We expect that many of these genes may play essential roles in early Dictyostelium development and could code for elements of the cAMP signal transduction pathway involved in aggregation.

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Exogenous Cyclic AMP, Cholera Toxin, and Endotoxin Induce Expression of the Lipopolysaccharide Receptor CD14 in Murine Bone Marrow Cells: Role of Purinoreceptors

Clinical and Diagnostic Laboratory Immunology ◽

10.1128/cdli.6.6.885-890.1999 ◽

1999 ◽

Vol 6 (6) ◽

pp. 885-890 ◽

Cited By ~ 6

Author(s):

Thierry Pedron ◽

Robert Girard ◽

Richard Chaby

Keyword(s):

Bone Marrow ◽

Cyclic Amp ◽

Cholera Toxin ◽

Bone Marrow Cells ◽

Specific Binding ◽

Cell Surface Receptor ◽

Intracellular Camp ◽

Purine Derivatives ◽

Murine Bone Marrow ◽

Surface Receptor

ABSTRACT Little is known about the mechanisms of lipopolysaccharide (LPS) signaling in immature cells that do not express the LPS receptor CD14 yet. Bone marrow granulocytes do not constitutively express CD14 but can be stimulated by low doses of LPS in the absence of serum and then express an inducible form of LPS receptor (iLpsR). We show that in addition to LPS, cholera toxin (CT) and various cyclic AMP (cAMP) analogs can also induce the expression of iLpsR, which was identified as CD14. Induction was independent of intracellular cAMP. The hypothesis that cAMP analogs act via a cell surface receptor was suggested by the unresponsiveness of trypsin-treated cells to these inducers and by the specific binding of [3H]cAMP to the cells. This binding was not inhibited by LPS or CT but was inhibited by various purine derivatives. However, the receptor involved is not a conventional purinoreceptor since both an agonist and an antagonist of such receptors were able to induce iLpsR expression. The results suggest that cAMP analogs and other purine derivatives induce iLpsR after interaction with an unconventional, trypsin-sensitive, purinoreceptor distinct from LPS and CT receptors.

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