Asymmetric cell division results in two distinctly fated daughter cells. A molecular hallmark of asymmetric division is the unequal partitioning of cell fate determinants. We have previously established that growth factor signaling promotes protein depalmitoylation to foster polarized protein localization, which, in turn, drives migration and metastasis. We report protein palmitoylation as a key mechanism for the asymmetric partitioning of the cell fate determinants Numb and β-catenin through the activity of the depalmitoylating enzyme APT1. Using point mutations, we showed that specific palmitoylated residues on Numb were required for its asymmetric localization. By live-cell imaging, we showed that reciprocal interactions between APT1 and the Rho family GTPase CDC42 promoted the asymmetric localization of Numb and β-catenin to the plasma membrane. This, in turn, restricted Notch- or Wnt-responsive transcriptional activity to one daughter cell. Moreover, we showed that altering APT1 abundance changed the transcriptional signatures of MDA-MB-231 triple receptor–negative breast cancer cells, similar to changes in Notch and β-catenin–mediated Wnt signaling. We also showed that loss of APT1 depleted a specific subpopulation of tumorigenic cells in colony formation assays. Together, our findings suggest that APT1-mediated depalmitoylation is a major mechanism of asymmetric cell division that maintains Notch- and Wnt-associated protein dynamics, gene expression, and cellular functions.

不对称细胞分裂产生两个命运截然不同的子细胞。不对称分裂的分子标志是细胞命运决定因素的不平等分配。我们之前已经确定，生长因子信号传导促进蛋白质去棕榈酰化，以促进极化蛋白质定位，进而驱动迁移和转移。我们报告蛋白质棕榈酰化是通过去棕榈酰化酶 APT1 的活性不对称分配细胞命运决定因素 Numb 和 β-连环蛋白的关键机制。通过点突变，我们发现 Numb 上的特定棕榈酰化残基是其不对称定位所必需的。通过活细胞成像，我们发现 APT1 和 Rho 家族 GTPase CDC42 之间的相互作用促进了 Numb 和 β-catenin 在质膜上的不对称定位。这反过来又限制了一个子细胞的 Notch 或 Wnt 反应性转录活性。此外，我们发现改变 APT1 丰度会改变 MDA-MB-231 三受体阴性乳腺癌细胞的转录特征，类似于 Notch 和 β-catenin 介导的 Wnt 信号传导的变化。我们还表明，在集落形成测定中，APT1 的缺失会耗尽特定的致瘤细胞亚群。总之，我们的研究结果表明，APT1 介导的去棕榈酰化是不对称细胞分裂的主要机制，可维持 Notch 和 Wnt 相关蛋白动力学、基因表达和细胞功能。