Dissection of the cAMP induced cytosolic calcium response in Dictyostelium discoideum: the role of cAMP receptor subtypes and G protein subunits

AbstractThe cAMP signaling cascade leading to changes in [Ca2+]i in Dictyostelium discoideum was analyzed using cell lines overexpressing single cAMP receptor subtypes (cAR1–cAR3) or lacking the Gα2 or Gβ subunit of the G protein. Imaging of fura2-dextran-loaded amoebae revealed cAMP-induced [Ca2+]i changes characteristic for each receptor subtype activated. Cells expressing distinct subtypes sort to defined zones during multicellular development suggesting involvement of the specific [Ca2+]i transients in patterning processes. Whereas generation of the [Ca2+]i increase was Gα2-independent, only few cells devoid of Gβ displayed a [Ca2+]i change after stimulation indicating its participation in the regulation of the calcium homeostasis