title: Adenylate cyclase A acting on PKA mediates induction of stalk formation by cyclic diguanylate at the Dictyostelium organizer.
abstract: Coordination of cell movement with cell differentiation is a major feat of embryonic development. The Dictyostelium stalk always forms at the organizing tip, by a mechanism that is not understood. We previously reported that cyclic diguanylate (c-di-GMP), synthesized by diguanylate cyclase A (DgcA), induces stalk formation. Here we used transcriptional profiling of dgca- structures to identify target genes for c-di-GMP, and used these genes to investigate the c-di-GMP signal transduction pathway. We found that knockdown of cAMP-dependent protein kinase (PKA) activity in prestalk cells reduced stalk gene induction by c-di-GMP, whereas PKA activation bypassed the c-di-GMP requirement for stalk gene expression. c-di-GMP caused a persistent increase in cAMP, which still occurred in mutants lacking the adenylate cyclases ACG or ACR, or the cAMP phosphodiesterase RegA. However, both inhibition of adenylate cyclase A (ACA) with SQ22536 and incubation of a temperature-sensitive ACA mutant at the restrictive temperature prevented c-di-GMP-induced cAMP synthesis as well as c-di-GMP-induced stalk gene transcription. ACA produces the cAMP pulses that coordinate Dictyostelium morphogenetic cell movement and is highly expressed at the organizing tip. The stalk-less dgca- mutant regained its stalk by expression of a light-activated adenylate cyclase from the ACA promoter and exposure to light, indicating that cAMP is also the intermediate for c-di-GMP in vivo. Our data show that the more widely expressed DgcA activates tip-expressed ACA, which then acts on PKA to induce stalk genes. These results explain why stalk formation in Dictyostelia always initiates at the site of the morphogenetic organizer.
authors.affiliation: Division of Cell and Developmental Biology, School of Life Sciences, University of Dundee, Dundee DD1 5EH, United Kingdom.
authors.forename: Zhi-Hui
authors.initials: ZH
authors.lastname: Chen
authors.affiliation: Division of Cell and Developmental Biology, School of Life Sciences, University of Dundee, Dundee DD1 5EH, United Kingdom.|Division of Computational Biology, School of Life Sciences, University of Dundee, Dundee DD1 5EH, United Kingdom.
authors.forename: Reema
authors.initials: R
authors.lastname: Singh
authors.affiliation: Division of Computational Biology, School of Life Sciences, University of Dundee, Dundee DD1 5EH, United Kingdom.
authors.forename: Christian
authors.initials: C
authors.lastname: Cole
authors.affiliation: Division of Cell and Developmental Biology, School of Life Sciences, University of Dundee, Dundee DD1 5EH, United Kingdom.
authors.forename: Hajara Mohammed
authors.initials: HM
authors.lastname: Lawal
authors.affiliation: Division of Cell and Developmental Biology, School of Life Sciences, University of Dundee, Dundee DD1 5EH, United Kingdom.
authors.forename: Christina
authors.initials: C
authors.lastname: Schilde
authors.affiliation: Division of Molecular Medicine, School of Life Sciences, University of Dundee, Dundee DD1 5EH, United Kingdom.
authors.forename: Melanie
authors.initials: M
authors.lastname: Febrer
authors.affiliation: Division of Computational Biology, School of Life Sciences, University of Dundee, Dundee DD1 5EH, United Kingdom.
authors.forename: Geoffrey J
authors.initials: GJ
authors.lastname: Barton
authors.affiliation: Division of Cell and Developmental Biology, School of Life Sciences, University of Dundee, Dundee DD1 5EH, United Kingdom; p.schaap@dundee.ac.uk.
authors.forename: Pauline
authors.initials: P
authors.lastname: Schaap
mesh_terms: D000262:Adenylyl Cyclases / Q000378:metabolism*; D000242:Cyclic AMP / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D006152:Cyclic GMP / Q000031:analogs & derivatives* / Q000378:metabolism; D004023:Dictyostelium / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D017125:Genes, Protozoan; D009154:Mutation; D019761:Phosphorus-Oxygen Lyases / Q000378:metabolism; D015800:Protozoan Proteins / Q000378:metabolism; D015398:Signal Transduction; D033761:Spores, Protozoan / Q000235:genetics / Q000254:growth & development / Q000378:metabolism
chemical_list: D029968:Escherichia coli Proteins; D015800:Protozoan Proteins; C062025:bis(3',5')-cyclic diguanylic acid; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D019761:Phosphorus-Oxygen Lyases; C060720:diguanylate cyclase; D000262:Adenylyl Cyclases; D006152:Cyclic GMP
keywords: Dictyostelium; adenylate cyclase A; diguanylate cyclase; organizer; stalk differentiation