Cell and Developmental Biology, John Innes Centre, Norwich NR4 7UH, UK.
Centro de Biología Molecular Severo Ochoa, CSIC-UAM, Cantoblanco, 28049 Madrid, Spain.
Science. 2021 Jun 11;372(6547):1176-1181. doi: 10.1126/science.abb4348.
How eukaryotic cells assess and maintain sizes specific for their species and cell type remains unclear. We show that in the shoot stem cell niche, cell size variability caused by asymmetric divisions is corrected by adjusting the growth period before DNA synthesis. KIP-related protein 4 (KRP4) inhibits progression to DNA synthesis and associates with mitotic chromosomes. The F BOX-LIKE 17 (FBL17) protein removes excess KRP4. Consequently, daughter cells are born with comparable amounts of KRP4. Inhibitor dilution models predicted that KRP4 inherited through chromatin would robustly regulate size, whereas inheritance of excess free KRP4 would disrupt size homeostasis, as confirmed by mutant analyses. We propose that a cell cycle regulator, stabilized by association with mitotic chromosomes, reads DNA content as a cell size-independent scale.
真核细胞如何评估和维持其物种和细胞类型特有的大小尚不清楚。我们表明，在 茎尖干细胞龛中，通过不对称分裂引起的细胞大小可变性通过调整 DNA 合成前的生长周期来纠正。与 KIP 相关的蛋白 4（KRP4）抑制向 DNA 合成的进展，并与有丝分裂染色体结合。F BOX-LIKE 17（FBL17）蛋白去除多余的 KRP4。因此，子细胞产生的 KRP4 量相当。抑制剂稀释模型预测，通过染色质继承的 KRP4 将稳健地调节大小，而继承多余的游离 KRP4 将破坏大小的动态平衡，这一点通过突变分析得到了证实。我们提出，一种细胞周期调节剂，通过与有丝分裂染色体的结合而稳定，将 DNA 含量作为与细胞大小无关的尺度进行读取。
