cAMP-dependent protein kinase activity is essential for preaggregative gene expression in Dictyostelium.
Constitutive inhibition of cAMP-dependent protein kinase (PKA) in Dictyostelium cells blocks cell aggregation and development. We investigated the cause of the aggregation defect in transformants overexpressing dominant-negative PKA regulatory subunits (PKA-RM) under an actin 15 promoter. These mutants could not relay pulses of the chemoattractant cAMP, due to a defect in expression of the aggregative adenylyl cyclase (ACA) gene. Unstimulated and cAMP pulse-induced expression of other aggregative genes encoding the cAMP receptor cAR1, adhesive contact sites A and cAMP-phosphodiesterase were also strongly reduced in the mutants. Additionally, the expression of the discoidin I gene, that is expressed early in development in response to cell density sensing factors, was almost completely absent. These data are in interesting contrast with observations that cAMP relay and aggregative gene expression are normal in null mutants for the PKA catalytic (C) subunit and suggest the presence of multiple C subunit genes in Dictyostelium and an almost universal requirement for PKA activity in developmental gene expression.
Schulkes
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Cell Biology Section, University of Leiden, The Netherlands.
Schaap
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D015105:3',5'-Cyclic-AMP Phosphodiesterases / Q000235:genetics; D000199:Actins / Q000235:genetics; D000262:Adenylyl Cyclases / Q000235:genetics*; D000818:Animals; D015815:Cell Adhesion Molecules / Q000235:genetics; D017868:Cyclic AMP-Dependent Protein Kinases / Q000235:genetics / Q000502:physiology*; D003838:Deoxyadenine Nucleotides / Q000494:pharmacology; D004023:Dictyostelium / Q000201:enzymology* / Q000235:genetics* / Q000254:growth & development; D000070821:Discoidins; D005656:Fungal Proteins / Q000235:genetics; D015966:Gene Expression Regulation, Fungal / Q000502:physiology*; D005800:Genes, Fungal / Q000235:genetics; D037102:Lectins; D011401:Promoter Regions, Genetic / Q000235:genetics; D015800:Protozoan Proteins; D012333:RNA, Messenger / Q000096:biosynthesis; D011953:Receptors, Cyclic AMP / Q000819:agonists / Q000235:genetics; D014158:Transcription, Genetic
D000199:Actins; D015815:Cell Adhesion Molecules; D003838:Deoxyadenine Nucleotides; D000070821:Discoidins; D005656:Fungal Proteins; D037102:Lectins; D015800:Protozoan Proteins; D012333:RNA, Messenger; D011953:Receptors, Cyclic AMP; C052291:cell cohesion molecule, Dictyostelium; C068125:cyclic AMP receptor cAR1; C012873:2'-deoxy-5'-adenosine monophosphate; D017868:Cyclic AMP-Dependent Protein Kinases; D015105:3',5'-Cyclic-AMP Phosphodiesterases; D000262:Adenylyl Cyclases