Department of Cellular Biology, University of Georgia, Athens, GA.
Bioinformatics, University of Freiburg, Freiburg, Germany.
J Cell Biol. 2020 Sep 7;219(9). doi: 10.1083/jcb.202002077.
Not much is known about how organelles organize into patterns. In ciliates, the cortical pattern is propagated during "tandem duplication," a cell division that remodels the parental cell into two daughter cells. A key step is the formation of the division boundary along the cell's equator. In Tetrahymena thermophila, the cdaA alleles prevent the formation of the division boundary. We find that the CDAA gene encodes a cyclin E that accumulates in the posterior cell half, concurrently with accumulation of CdaI, a Hippo/Mst kinase, in the anterior cell half. The division boundary forms between the margins of expression of CdaI and CdaA, which exclude each other from their own cortical domains. The activities of CdaA and CdaI must be balanced to initiate the division boundary and to position it along the cell's equator. CdaA and CdaI cooperate to position organelles near the new cell ends. Our data point to an intracellular positioning mechanism involving antagonistic Hippo signaling and cyclin E.
关于细胞器如何形成模式，人们知之甚少。在纤毛虫中，皮质模式是在“串联复制”过程中传播的，这是一种细胞分裂过程，将亲代细胞重塑为两个子细胞。关键步骤是沿着细胞赤道形成分裂边界。在嗜热四膜虫中，cdaA 等位基因阻止了分裂边界的形成。我们发现 CDAA 基因编码一种细胞周期蛋白 E，它在后半细胞中积累，同时 Hippo/Mst 激酶 CdaI 在细胞前半部分积累。CdaI 和 CdaA 的表达边界之间形成了分裂边界，它们将彼此排除在自己的皮质区域之外。CdaA 和 CdaI 的活性必须平衡，才能启动分裂边界，并使其沿着细胞赤道定位。CdaA 和 CdaI 合作将细胞器定位在新细胞末端附近。我们的数据表明，一种涉及拮抗 Hippo 信号和细胞周期蛋白 E 的细胞内定位机制。
