Developmental control of cAMP-induced Ca2+-influx by cGMP: influx is delayed and reduced in a cGMP-phosphodiesterase D deficient mutant of Dictyostelium discoideum

• Published in: Cell calcium (Edinburgh) Vol. 37; no. 1; pp. 57 - 67
• Main Authors: Lusche, Daniel F, Malchow, D
• Format: Journal Article
• Language: English
• Published: Netherlands 01-01-2005
• Subjects: 3',5'-Cyclic-GMP Phosphodiesterases - genetics; 3',5'-Cyclic-GMP Phosphodiesterases - metabolism; Animals; Arachidonic Acid - pharmacology; Calcium - metabolism; Calcium Channels - drug effects; Calcium Channels - metabolism; Calcium Signaling - drug effects; Calcium Signaling - genetics; Cell Membrane - drug effects; Cell Membrane - metabolism; Cyclic AMP - metabolism; Cyclic AMP - pharmacology; Cyclic GMP - analogs & derivatives; Cyclic GMP - metabolism; Cyclic Nucleotide Phosphodiesterases, Type 5; Dictyostelium - genetics; Dictyostelium - growth & development; Dictyostelium - metabolism; Dose-Response Relationship, Drug; Extracellular Fluid - drug effects; Extracellular Fluid - metabolism; Mutation - genetics; Photic Stimulation; Up-Regulation - drug effects; Up-Regulation - genetics
• ISSN: 0143-4160
• DOI: 10.1016/j.ceca.2004.06.005

It was previously shown that cGMP enhances cAMP-induced Ca2+-influx in Dictyostelium discoideum. This finding is based on experiments done with strains defective in cGMP-hydrolysis, the streamer F cells. In this work, we show that these chemically mutagenized cells display different properties in their cAMP-induced light-scattering response and cAMP-induced Ca2+-influx compared with a cGMP-phosphodiesterase knock-out strain, pdeD KO, generated by homologous recombination. PdeD KO cells possess a reduced Ca2+-influx that is developmentally regulated. This finding contradicts the result of streamer F cells, where cAMP-induced Ca2+-influx is prolonged and elevated. Both mutants, however, showed a three to four-fold delayed response to cAMP at 3-4h of starvation. Thus, the consequence of an elevated cGMP concentration is a delay and an inhibition of Ca2+-influx and not an enhancement. Results obtained with streamer F cells should therefore be interpreted with caution because the mutation(s) responsible for the divergent phenotype to pdeD KO cells has not been identified. We show by the use of membrane-permeant cGMP-analogues in wild type (wt) cells, permeabilized cells and measurements on isolated vesicles that the cause for the reduced Ca2+-influx seems to be due to developmentally regulated Ca2+-channel inhibition by cGMP.