Abberant chemotaxis and differentiation in Dictyostelium mutant fgdC with a defective regulation of receptor-stimulated phosphoinositidase C.
Dictyostelium cells use extracellular cyclic AMP both as a chemoattractant and as a morphogen inducing cell-type-specific gene expression. Cyclic AMP binds to surface receptors, activates one or more G-proteins, and stimulates adenylate cyclase, guanylate cyclase and phosphoinositidase C. Mutant fgdC showed aberrant chemotaxis, and was devoid of cyclic AMP-induced gene expression and differentiation. Both the receptor- and G-protein-mediated stimulation of adenylate cyclase and guanylate cyclase were unaltered in mutant fgdC as compared to wild-type cells. In wild-type cells phosphoinositidase C was activated about twofold by the cyclic AMP receptor. In mutant fgdC cells, however, the enzyme was inhibited by about 60%. These results suggest that phosphoinositidase C is regulated by a receptor-operated activation/inhibition switch that is defective in mutant fgdC. We conclude that activation of phosphoinositidase C is essential for Dictyostelium development.
Bominaar
A A
AA
Department of Biochemistry, University of Groningen, The Netherlands.
Kesbeke
F
F
Snaar-Jagalska
B E
BE
Peters
D J
DJ
Schaap
P
P
Van Haastert
P J
PJ
D000818:Animals; D002633:Chemotaxis / Q000502:physiology*; D000242:Cyclic AMP / Q000378:metabolism / Q000494:pharmacology*; D004023:Dictyostelium / Q000502:physiology*; D019204:GTP-Binding Proteins / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects*; D009154:Mutation; D010727:Phosphoric Diester Hydrolases / Q000378:metabolism*; D011953:Receptors, Cyclic AMP / Q000378:metabolism; D015290:Second Messenger Systems
D011953:Receptors, Cyclic AMP; D000242:Cyclic AMP; D010727:Phosphoric Diester Hydrolases; C021491:glycerophosphoinositol glycerophosphodiesterase; D019204:GTP-Binding Proteins