CSM News Electronic Edition Volume 4, number 23 June 24, 1995 Please submit abstracts of your papers as soon as they have been accepted for publication by sending them to CSM-News@worms.cmsbio.nwu.edu. Back issues of CSM-News, the CSM Reference database and other useful information is available by anonymous ftp from worms.cmsbio.nwu.edu [165.124.233.50], via Gopher at the same address, or by World Wide Web at the URL "http://worms.cmsbio.nwu.edu/dicty.html" ============== Announcement ============== Because of Dicty95 there will be no CSM-News next week. Hope to see many of you there! =========== Abstracts =========== cAMP DEPENDENT PROTEIN KINASE ACTIVITY IS ESSENTIAL FOR PREAGGREGATIVE GENE INDUCTION IN DICTYOSTELIUM. Conchita Schulkes and Pauline Schaap Cell Biology Section, Institute for Molecular Plant Sciences, University of Leiden, Wassenaarseweg 64, 2333 AL Leiden, The Netherlands SUMMARY 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 actin15 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. ----------------------------------------------------------------------- [End CSM News, volume 4, number 23]