Onset of endoreplication through the regulation of G2/M phase during the cell cycle

在植物发育期间，植物细胞经常通过DNA复制重复发生而不干预细胞分裂的细胞周期来增加其细胞DNA含量(倍性)。尽管人们普遍认为细胞倍性增加对控制细胞大小、代谢活动和细胞分化可能是重要的，但对这些过程的调控机制知之甚少。在这项研究中，我们主要关注两个因素，GIG1和SCL，这两个因素可能在增加细胞倍性方面发挥重要作用。我们发现GIG1可能通过抑制G2期和有丝分裂期间特定的蛋白质降解系统来负向调节倍性的增加。另一方面，SCL可能通过转录抑制参与DNA复制的基因来加速倍性的增加，可能是在细胞周期的M期。

Plant cells often increase their cellular DNA content (ploidy) during plant development, through the modified cell cycle where DNA replication occurs repeatedly without intervening cell division. Although it has been generally believed that increased cellular ploidy may be important for the control of cell size, metabolic activity, and cell differentiation, little is known about the regulatory mechanisms of this processes. In this study, we have focused on the two factors, GIG1 and SCL, that may have important roles in increasing cellular ploidy. We showed that GIG1 may negatively regulate ploidy increase by inhibiting a specific protein degradation system acing during G2 and mitosis. On the other hand, SCL may accelerate increasing ploidy by transcriptional repression of genes involved in DNA replication, possibly during M phase in the cell cycle.