Involvement of cyclic AMP cell surface receptors and G-proteins in signal transduction during slug migration of Dictyostelium discoideum.
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.
Schenk
P W
PW
Cell Biology and Genetics Unit, Zoological Laboratory, Leiden University, The Netherlands.
Van Es
S
S
Kesbeke
F
F
Snaar-Jagalska
B E
BE
D000262:Adenylyl Cyclases / Q000378:metabolism; D001667:Binding, Competitive; D002462:Cell Membrane / Q000502:physiology; D002465:Cell Movement; D000242:Cyclic AMP / Q000031:analogs & derivatives / Q000378:metabolism / Q000494:pharmacology; D004023:Dictyostelium / Q000502:physiology*; D020558:GTP Phosphohydrolases / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000502:physiology*; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism; D007700:Kinetics; D011953:Receptors, Cyclic AMP / Q000378:metabolism / Q000502:physiology*; D015398:Signal Transduction
D011953:Receptors, Cyclic AMP; D015544:Inositol 1,4,5-Trisphosphate; D000242:Cyclic AMP; D020558:GTP Phosphohydrolases; D019204:GTP-Binding Proteins; D000262:Adenylyl Cyclases