Genetic Control of Cellular Quiescence in S. pombe

Transition from proliferation to quiescence brings about extensive changes in cellular behavior and structure. However, genes critical for establishing and/or for maintaining quiescence are largely unknown. The fission yeast S. pombe is found as an excellent model for studying this problem, because it becomes quiescent under nitrogen starvation. Here we characterize 610 temperature-sensitive (ts) mutants, and identify 33 genes required for entry into and the maintenance of quiescence. These genes cover a broad range of cellular functions in the cytoplasm, membrane and the nucleus, encoding proteins for stress-responsive and cell cycle kinase signaling pathway, actin-bound and osmo-controlling endosome formation, RNA transcription, splicing and ribosome biogenesis, chromatin silencing, biosynthesis of lipid and ATP, cell wall and membrane morphogenesis, protein trafficking and vesicle fusion. We specifically highlight Fcp1, CTD phosphatase of RNA polymerase II, which differentially affects transcription of genes involved in quiescence and proliferation. We propose that the transcriptional role of Fcp1 is central to differentiate quiescence from proliferation. Keywords: cell cycle control, protein trafficking, cortex actin, RNA polymerase II, protein phosphatase Gene expression profile under nitrogen rich or starved condition at 26ºC or 37ºC in WT (L972) or fcp1-452 ts mutant strain of fission yeast.