Cell‐cell contact mediates cAMP secretion in Dictyostelium discoideum

Abstract

Cyclic adenosine 3':5' monophosphate (cAMP) and cell-cell contact regulate developmental gene expression in Dictyostelium discoideum. Developing D. discoideum amoebae synthesize and secrete cAMP following the binding of cAMP to their surface cAMP receptor, a response called cAMP signaling. We have demonstrated two responses of developing D. discoideum amoebae to cell-cell contact. Cell-cell contact elicits cAMP secretion and alters the amount of cAMP secreted in a subsequent cAMP signaling response. Depending upon experimental conditions, bacterial-amoebal contact and amoebal-amoebal contact can enhance or diminish the amount of cAMP secreted during a subsequent cAMP signaling response. We have hypothesized that cell-cell contact regulates D. discoideum development by altering cellular and extracellular levels of cAMP. To begin testing this hypothesis, these responses were further characterized. The two responses to cell-cell contact are independent, i.e., they can each occur in the absence of the other. The responses to cell-cell contact also have unique temperature dependences when compared to each other, cAMP signaling, and phagocytosis. This suggests that these four responses have unique steps in their transduction mechanisms. The secretion of cAMP in response to cell-cell contact appears to be a non-specific response; contact between D. discoideum amoebae and Enterobacter aerogenes, latex beads, or other amoebae elicits cAMP secretion. Despite the apparent similarities of the effects of bacterial-amoebal and amoebal-amoebal contact on the cAMP signaling response, this contact-induced response appears to be specific. Latex beads addition does not alter the magnitude of a subsequent cAMP signaling response.(ABSTRACT TRUNCATED AT 250 WORDS)

Regulation of spatiotemporal expression of cell–cell adhesion molecules during development of Dictyostelium discoideum

“…1992). Since the formation of cell–cell contacts affects cAMP metabolism and cAMP signaling (Fontana & Price 1988; Fontana et al. 1991a,b), it is possible that the loss of DdCAD‐1 expression may somehow enhance cAMP signaling and stimulate a higher level of csA/gp80 expression.…”

Molecular Cloning and Characterization of DdCAD-1, a Ca2+-dependent Cell-Cell Adhesion Molecule, in

“…In addition to intercellular adhesion, there is increasing evidence that the classic cadherins are involved in signal transduction (72). In Dictyostelium, several recent reports have shown that cell-cell contact can elicit cAMP secretion and modulate cAMP signaling in Dictyostelium (73)(74)(75). Recent studies in our laboratory have demonstrated a role for cell-cell contact in a cAMP-dependent pathway that regulates gene expression, as well as in the cAMP signal relay system (19).…”

Synthesis of the Ca2+-dependent cell adhesion molecule DdCAD-1 is regulated by multiple factors during Dictyostelium development

“…Several recent reports suggest that an interdependent relationship exists between cell-cell contact and cAMP signaling [15][16][17]. We have previously shown that cellcell contact is required for the stimulation of csaA expression [10].…”