Intracellular calcium dynamics and expression of P2Y and IP₃ receptors in a cycling G₁-phase cell

摘要

The regulation of intracellular events is of critical importance in proliferating cells. These events may be altered by signaling molecules linked through cell-cycle regulatory mechanisms. Recent advances have linked the calcium ion (Ca~(2+)) with the progression of the cell cycle through interphase and the different phases of mitosis. However, there has been little explanation on the fundamental relationship of calcium signals and their associated receptors with the interphase subphases. In the present study, to clarify this possible relationship, we investigated how calcium signaling and its associated purinergic receptors are related to the cell cycle between the nucleoplasm and cytoplasm in cultured G_(1)-interphase cells of HeLa.S-Fucci2 and fucci/mouse fibroblasts. Ratiometric fluorescence and reverse transcriptase polymerase chain reaction (RT-PCR) techniques were employed to assess the intracellular Ca~(2+) concentrations (_(i)) and the expression of purinergic and inositol trisphosphate receptors, respectively. The results obtained revealed the existence of two distinct subcellular increases in _(i) in a single individual G_(1)-phase cell, suggesting variations between the early and late G_(1)-phases of the cell cycle. In addition to the Ca~(2+) wave, the RT-PCR results indicated variability in the purinergic receptors and inositol 1,4,5-trisphosphate receptor subtypes within G_(1)-phase cells. Based on these results, we propose that receptor expression and calcium signals are functionally distinct within individual interphase subphases.