Ca ²⁺ -Induced Ca ²⁺ Release in Sea Urchin Egg Homogenates: Modulation by Cyclic ADP-Ribose

Abstract

Calcium-induced calcium release (CICR) may function widely in calcium-mediated cell signaling, but has been most thoroughly characterized in muscle cells. In a homogenate of sea urchin eggs, which display transients in the intracellular free calcium concentration ([Ca2+]i) during fertilization and anaphase, addition of Ca2+ triggered CICR. Ca2+ release was also induced by the CICR modulators ryanodine and caffeine. Responses to both Ca2+ and CICR modulators (but not Ca2+ release mediated by inositol 1,4,5-trisphosphate) were inhibited by procaine and ruthenium red, inhibitors of CICR. Intact eggs also displayed transients of [Ca2+]i when microinjected with ryanodine. Cyclic ADP-ribose, a metabolite with potent Ca(2+)-releasing properties, appears to act by way of the CICR mechanism and may thus be an endogenous modulator of CICR. A CICR mechanism is present in these nonmuscle cells as is assumed in various models of intracellular Ca2+ wave propagation.

Involvement of P2X receptors in the NAD+-induced rise in [Ca2+]i in human monocytes

“…cADPR, NAADP, and ADPR are involved in the regulation of cellular Ca 2+ homeostasis. While cADPR and NAADP trigger Ca 2+ -release from intracellular stores [5][6][7], ADPR controls calcium entry through the plasma membrane channel TRPM2 [8,9]. It is difficult to envision how cADPR and NAADP can function inside the cell if they are generated by ectoenzymes.…”

Nitric oxide and cGMP activate Ca2+-release processes in rat parotid acinar cells

“…A product of NAD + metabolism, cADPR was discovered by Clapper et al [4] in extracts from sea urchin eggs and was shown to release Ca# + from intracellular stores distinct from the Ins(1,4,5)P $ -sensitive stores. cADPR has since been suggested as an endogenous ligand for the ryanodine receptor (RyR) [5]. In permeabilized rat parotid and lacrimal acinar cells, cADPR releases Ca# + from Ins(1,4,5)P $ -insensitive stores [6,7].…”

Functional Characterization of the Recombinant Type 3 Ca2+ Release Channel (Ryanodine Receptor) Expressed in HEK293 Cells

“…Effect of Cyclic ADP-ribose-Recent studies suggest that cyclic ADP-ribose (cADPr) is a second messenger capable of triggering intracellular Ca 2ϩ release in a variety of cell types (42,43). The cADPr-induced Ca 2ϩ release is thought to be mediated by ryanodine receptors and requires CaM (44,45).…”