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

在植物发育过程中，植物细胞通过修饰的细胞周期，在不干预细胞分裂的情况下反复进行DNA复制，从而增加细胞DNA含量（倍性）。尽管人们普遍认为细胞倍性的增加可能对细胞大小、代谢活性和细胞分化的控制很重要，但对这一过程的调节机制知之甚少。在本研究中，我们重点研究了两个因子，GIG1和SCL，它们可能在增加细胞倍性中起重要作用。我们发现GIG1可能通过抑制G2和有丝分裂期间发生的特定蛋白质降解系统来负性调节倍性增加。另一方面，SCL可能通过抑制参与DNA复制的基因的转录来加速倍性的增加，这可能发生在细胞周期的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.