Astrocytes express gap junction proteins and multiple types of P2Y receptors (P2YRs) that contribute to the propagation of intercellular Ca 2+ waves (ICW). To gain access to the role played by gap junctional communication in ICW propagation generated by P2YR activation, we selectively expressed P2Y1,2,4R subtypes and Cx43 in the human 1321N1 astrocytoma cell line, which lacks endogenous P2 receptors. Fluorescence recovery after photobleaching revealed that 1321N1 cells are poorly dye-coupled and do not propagate ICW. Forced expression of Cx43 in 1321N1 cells (which did not show functional hemichannels) increased dye coupling and allowed short-range ICW transmission that was mainly mediated by intercellular diffusion of Ca 2+ generated in the stimulated cells. Astrocytoma clones expressing each of the P2YR subtypes were also able to propagate ICWs that were likely dependent on IP3 generation. These waves exhibited properties particular to each P2YR subtype. Co-expression of eGFP-hCx43 and P2Y 1R modified the properties of P2Y1R-generated ICW to those characteristics of P2Y2R. Increased coupling in P2Y4R clones induced by expression of eGFP-hCx43 abolished the ICWs observed in uncoupled P2Y4R clones. No changes in the behavior of ICWs generated in P2Y2R clones were observed after forced expression of Cx43. These data indicate that in 1321N1 cells gap junctional communication provides intercellular integration of Ca2+ signals generated by P2YR activation, thus coordinating the propagation of intercellular calcium waves.
- Calcium waves
- Dye coupling
- Purinergic receptors
ASJC Scopus subject areas
- Cellular and Molecular Neuroscience