Chemotactic and osmotic signals share a cGMP transduction pathway in <i>Dictyostelium discoideum</i>

Kuwayama, Hidekazu; Haastert, Peter J.M. van

doi:10.1016/s0014-5793(98)00183-5

Cited by 21 publications

(19 citation statements)

References 26 publications

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“…Together, these findings show that the B-domain cAMP probe specifically and robustly detects cAMP derived from ACA in chemotaxis-competent cells. Moreover, the results with aca -cells clearly show that the FRET response is not affected by the exogenous cAMP stimulus nor does it respond to changes in intracellular cGMP levels, which occur normally in aca -cells (Kuwayama and Van Haastert, 1998).…”

Section: The Monomeric Camp Fret Sensor Does Not Alter the Developmenmentioning

confidence: 84%

Real-time measurements of cAMP production in liveDictyosteliumcells

Bagorda

Das

Rericha

et al. 2009

Journal of Cell Science

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following chemoattractant addition. Furthermore, cells lacking ACB, the other adenylyl cyclase expressed in chemotaxing cells, behave similarly to wild-type cells. We also establish that the RegA is the major phosphodiesterase that degrades intracellular cAMP in chemotaxis-competent cells. Interestingly, we failed to measure intracellular cAMP compartmentalization in actively chemotaxing cells. We conclude that cytosolic cAMP, which is destined to activate PKA, is regulated by ACA and RegA and does not compartmentalize during chemotaxis. Supplementary material available online at

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Section: The Monomeric Camp Fret Sensor Does Not Alter the Developmenmentioning

confidence: 84%

Real-time measurements of cAMP production in liveDictyosteliumcells

Bagorda

Das

Rericha

et al. 2009

Journal of Cell Science

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“…Consistent with this interpretation, EDTA treatment, which stimulates cGMP production in response to osmotic stress (Oyama, 1996), also stimulated the activation of Rap1. The activation of guanylyl cyclase in response to osmotic shock does not appear to involve the heterotrimeric G protein complex, as gβ-null cells have no deficiency in cGMP accumulation (Kuwayama and van Haastert, 1998). However, GTPγS stimulates guanylyl cyclase in vitro (Janssens et al, 1988;Janssens et al, 1989) and in electro-permeabilized cells (Schoen et al, 1996), suggesting an interaction between guanylyl cyclase and a GTP-binding protein.…”

Section: Discussionmentioning

confidence: 99%

Evidence for a role for the Dictyostelium Rap1 in cell viability and the response to osmotic stress

Kang

Kae

et al. 2002

Journal of Cell Science

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The Dictyostelium genome contains a single rapA gene,which encodes a Rap1 monomeric G protein. As attempts at generating rapA-null Dictyostelium cells had been unsuccessful,expression of antisense RNA from the rapA gene under control of the folate repressible discoidin promoter was used to reduce cellular levels of the Rap1 protein. As Rap1 levels gradually decreased following antisense rapA RNA induction, growth rate and cell viability also decreased, a result consistent with the idea that rapA is an essential gene. The Rap1-depleted cells exhibited reduced viability in response to osmotic shock. The accumulation of cGMP in response to 0.4 M sorbitol was reduced after rapA antisense RNA induction and was enhanced in cells expressing the constitutively activated Rap1(G12V) protein, suggesting a role for Rap1 in the generation of cGMP. Dictyostelium Rap1 formed a complex with the Ras-binding domain of RalGDS only when it was in a GTP-bound state. This assay was used to demonstrate that activation of Rap1 in response to 0.4 M sorbitol occurred with initial kinetics similar to those observed for the accumulation of cGMP. Furthermore, the addition of 2 mM EDTA to osmotically shocked cells, a treatment that enhances cGMP accumulation, also enhanced Rap1 activation. These results suggest a direct role for Rap1 in the activation of guanylyl cyclase during the response to hyperosmotic conditions. Rap1 was also activated in response to low temperature but not in response to low osmolarity or high temperature.

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“…Besides chemoattractants, guanylate cyclase is also activated by osmotic shock in i o (e.g. 0.3 M glucose), a pathway that does not require the presence of Gβ [11][12][13]. This activation is relatively slow, resulting in maximal cGMP levels at about 15 min after stimulation, compared with 10 s after stimulation with cAMP or folic acid.…”

Section: Introductionmentioning

confidence: 99%

Guanylate cyclase in Dictyostelium discoideum with the topology of mammalian adenylate cyclase

Roelofs

Snippe

Kleineidam

et al. 2001

Biochemical Journal

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The core of adenylate and guanylate cyclases is formed by an intramolecular or intermolecular dimer of two cyclase domains arranged in an antiparallel fashion. Metazoan membrane-bound adenylate cyclases are composed of 12 transmembrane spanning regions, and two cyclase domains which function as a heterodimer and are activated by G-proteins. In contrast, membrane-bound guanylate cyclases have only one transmembrane spanning region and one cyclase domain, and are activated by extracellular ligands to form a homodimer. In the cellular slime mould, Dictyosteliumdiscoideum, membrane-bound guanylate cyclase activity is induced after cAMP stimulation; a G-protein-coupled cAMP receptor and G-proteins are essential for this activation. We have cloned a Dictyostelium gene, DdGCA, encoding a protein with 12 transmembrane spanning regions and two cyclase domains. Sequence alignment demonstrates that the two cyclase domains are transposed, relative to these domains in adenylate cyclases. DdGCA expressed in Dictyostelium exhibits high guanylate cyclase activity and no detectable adenylate cyclase activity. Deletion of the gene indicates that DdGCA is not essential for chemotaxis or osmo-regulation. The knock-out strain still exhibits substantial guanylate cyclase activity, demonstrating that Dictyostelium contains at least one other guanylate cyclase.

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Chemotactic and osmotic signals share a cGMP transduction pathway in Dictyostelium discoideum

Cited by 21 publications

References 26 publications

Real-time measurements of cAMP production in liveDictyosteliumcells

Real-time measurements of cAMP production in liveDictyosteliumcells

Evidence for a role for the Dictyostelium Rap1 in cell viability and the response to osmotic stress

Guanylate cyclase in Dictyostelium discoideum with the topology of mammalian adenylate cyclase

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