Extracellular cAMP can restore development in Dictyostelium cells lacking one, but not two subtypes of early cAMP receptors (cARs). Evidence for involvement of cAR1 in aggregative gene expression

Ron D.M. Soede, Robert H. Insall, Peter N. Devreotes, Pauline Schaap

Research output: Contribution to journalArticlepeer-review

Abstract

Extracellular cAMP induces expression of several classes of developmentally regulated genes in Dictyostelium Four highly homologous surface cAMP receptors (cARs) were identified earlier, but involvement of specific cARs in gene regulation has not been clarified. Cells lacking the chemotactic receptor, cAR1, neither aggregate nor express developmentally regulated genes. Expression of aggregative genes is in wild-type cells induced by nanomolar cAMP pulses and repressed by persistent micromolar cAMP stimuli, which induce expression of prespore and prestalk-enriched genes during the postaggregative stages of development. We show here that in cell lines carrying a cAR1 gene disruption, nanomolar pulses cannot induce aggregative gene expression. Remarkably, micromolar cAMP can induce expression of aggregative genes in car1- cells as well as expression of prespore and prestalk-enriched genes, and furthermore restores their ability to form normal slugs and fruiting bodies. These data indicate that cAR1 mediates aggregative but not postaggregative gene expression and morphogenesis, and suggest that after gene disruption, its function is partially taken over by a lower affinity receptor that is not subjected to desensitisation. The absence of another early cAMP receptor, cAR3, does not affect development. However, in a car1-/car3- double mutant, cAMP stimulation cannot restore any developmental gene expression, indicating that cAR3 may have substituted for cAR1 in car1- cell lines.

Original languageEnglish (US)
Pages (from-to)1997-2002
Number of pages6
JournalDevelopment
Volume120
Issue number7
StatePublished - Jul 1994

Keywords

  • Adaptation
  • Developmental gene expression
  • Dictyostelium discoideum
  • Gene disruption
  • cAMP receptor plasticity

ASJC Scopus subject areas

  • Molecular Biology
  • Developmental Biology

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