Spatiotemporal Aspects of Prolactin-Induced Calcium Signaling

We have examined the spatiotemporal aspects of PRL-induced Ca²⁺ signals using high-speed fluo-3 confocal imaging. We found that PRL stimulated Ca²⁺ entry and intracellular Ca²⁺ mobilization. Ca²⁺ influx was seen as a peripheral increase in Ca²⁺]_i without amplification in the nucleus region. Intracellular Ca²⁺ mobilization was seen as a propagating intracellular calcium wave with a strong amplification in the nuclear region. The amplitude of PRL-induced Ca²⁺ increases would be sufficient to stimulate cell proliferation. Furthermore, PRL induced an increase in ³H]thymidine incorporation. These data suggest that PRL would be able to induce mitogenesis through a Ca²⁺-dependent pathway.