Cell cycle control of PDGF-induced Ca signaling through modulation of sphingolipid metabolism

The effects of growth factors have been shown to depend on the position of a cell in the cell cycle. However, the physiological basis for this phenomenon remains unclear. Here we show that the majority of both CEINGE clone3 (cl3) and human embryonic kidney 293 cells, when arrested in a quiescent phase (G0), responded to platelet-derived growth factor BB (PDGF-BB) with non-oscillatory Ca signals. Furthermore, the same type of Ca response was also observed in CEINGE cl3 cells (and to a lesser extent in HEK 293 cells) blocked at the G1/S boundary. In contrast, CEINGE cl3 cells synchronized in early G1 or released from G1/S arrest responded in an oscillatory fashion. This cell cycle-dependent modulation of Ca signaling was not observed on epidermal growth factor and G-protein-coupled receptor stimulation and was not due to differences in the expression of PDGF receptors (PDGFRs) during the cell cycle. We demonstrate that inhibition of sphingosine-kinase, which converts sphingosine to sphingosine-1-phosphate, caused G0 as well as G1/S synchronized cells to restore the oscillatory Ca response to PDGF-BB. In addition, we show that the synthesis of sphingosine and sphingosine-1-phosphate is regulated by the cell cycle and may underlie the differences in Ca signaling after PDGFR stimulation.—Fatatis, A., Miller, R. J. Cell cycle control of PDGF-induced Ca signaling through modulation of sphingolipid metabolism. FASEB J. 13, 1291–1301 (1999)