Eukaryotic Cell Cycle Control

点击翻译按钮获取中文摘要

The goal of this research is to understand the molecular mechanism controlling the cell cycle "start" and the cell differentiation "start". To this end, fission yeast has been studied as a model organism because this organism is closely related to higher eukaryotes. During the past 3 years, we have discovered 4 novel factors controlling the onset of differentiation and 5 new factors controlling the cell cycle "start". Among the 4 factors are a B-type cyclin that negatively controls the onset of differentiation and positively controls the start of the cell cycle ; a stress signal MAP kinase called Phh1 that positively controls the onset of differentiation ; a novel protein named Rcd1 that is essential for nitrogen-starvation-induced start of differentiation ; Nrd1, a RNA binding protein that negatively controls the onset of differentiation. They have mammalian homologues, raising the possibility that the differentiation control system found in fission yeast may be conserved up to mammals.Among the 5 cell cycle "start" factors are Res2, a DNA binding subunit that forms a transcriptional factor complex with Cdc10 ; Rep1 and Rep2, two transcriptional activator subunits that act by forming a complex with Res2-Cdc10 ; the new cyclin Pas1 that associates with Cdc2 kinase and activates Res2/Cdc10/Rep2 ; Spt1 a novel factor that binds Cdc18 and critically controls the onset and progression of S phase. Spt1 might form a control cascade independent of the Cdc2/Pas1-Res/Cdc10/Rep-Cdc18 cascade.