Transient Zn2+deficiency induces replication stress and compromises daughter cell proliferation

Abstract

AbstractCells must replicate their genome quickly and accurately, and they require metabolites and cofactors to do so. Ionic zinc (Zn2+) is an essential micronutrient that is required for hundreds of cellular processes, including DNA synthesis and adequate proliferation. Deficiency in this micronutrient impairs DNA synthesis and inhibits proliferation, but the mechanism is unknown. Using fluorescent reporters to track single cells via long-term live-cell imaging, we find that Zn2+is required at the G1/S transition and during S-phase for timely completion of S-phase. A short pulse of Zn2+deficiency impairs DNA synthesis and increases markers of replication stress. These markers of replication stress are reversed upon resupply of Zn2+. Finally, we find that if Zn2+is removed during the mother cell’s S-phase, daughter cells enter a transient quiescent state, maintained by sustained expression of p21, which disappears upon reentry into the cell cycle. In summary, short pulses of mild Zn2+deficiency in S-phase specifically induce replication stress, which causes downstream proliferation impairments in daughter cells.SignificanceZinc is an essential micronutrient required for cells to grow and proliferate. However, the mechanism of how zinc influences proliferation is unknown. We show that short exposure to mild zinc deficiency in S-phase impairs DNA synthesis and induces replication stress, leading to pauses in daughter cell proliferation. However, pulses of low zinc during other phases of the cell cycle don’t affect mother cell cycle progression or daughter cell proliferation. These results indicate that while zinc is important for many proteins, during the cell cycle short pulses of mild zinc deficiency have the biggest impact on a cell’s ability to synthesize DNA, suggesting that DNA polymerase complex acts as a gate keeper, sensing zinc status in the cell.