A pleiotropic defect in cAMP-regulated gene expression in the Dictyostelium agg- mutant synag 7.
During differentiation of Dictyostelium discoideum, cAMP functions as a diffusible, extracellular signal to direct chemotaxis and regulate developmental gene expression. The availability of signal-transduction mutants of Dictyostelium now makes it feasible to pursue a genetic analysis of cAMP signaling. The synag 7 mutant is defective in receptor-mediated adenylate cyclase stimulation and cannot relay a cAMP signal. To further characterize this mutant, mRNA levels of several cAMP-regulated genes were measured during development. cAMP-regulated gene expression was found to be dramatically altered in synag 7:several different genes which require cAMP for expression in wild-type cells were induced in synag 7 in the absence of cAMP. In addition, the gene-encoding discoidin I, which is normally expressed in starved cells and repressed by cAMP, is expressed at very low levels in starved synag 7 cells, possibly due to precocious repression. These results suggest that a pleiotropic regulator of cAMP-regulated gene expression is uncoupled from its normal controls during development in synag 7.
Drummond
I A
IA
Department of Cell, Molecular, and Structural Biology, Northwestern University Medical School, Chicago, Illinois 60611.
Chisholm
R L
RL
D000199:Actins / Q000096:biosynthesis; D000242:Cyclic AMP / Q000502:physiology*; D004023:Dictyostelium / Q000254:growth & development*; D000070821:Discoidins; D005656:Fungal Proteins / Q000096:biosynthesis; D015966:Gene Expression Regulation, Fungal; D037102:Lectins; D015800:Protozoan Proteins; D011953:Receptors, Cyclic AMP; D015398:Signal Transduction
D000199:Actins; D000070821:Discoidins; D005656:Fungal Proteins; D037102:Lectins; D015800:Protozoan Proteins; D011953:Receptors, Cyclic AMP; D000242:Cyclic AMP