Cytoplasmic-to-nuclear volume ratio affects AP-1 complex formation as an indicator of cell cycle responsiveness.

Cytoplasmic volume undergoes a series of changes during mitosis in eukaryotes; in turn, signaling events such as osmotic stress can regulate the cytoplasmic volume in cells. In some organisms, increase in cytoplasmic-to-nuclear volume ratio was seen to affect the growth potential in cells, however, the mechanistics of such a regulation, if at all present, was unclear. In a computational model, we have constructed a growth factor-induced signaling pathway leading to AP-1 heterodimer formation through transcriptional regulation, and analyzed the effects of increasing the cytoplasmic-to-nuclear ratio on c-jun transcription and AP-1 complex. We have observed that larger cytoplasmic volumes caused both an increase in the final AP-1 product and a delay in the time of AP-1 accumulation.