Institute for Research in Immunology and Cancer, Université de Montréal, Montréal, QC, H3T 1J4, Canada.
Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, ON, M5G 1X5, Canada.
Nat Commun. 2022 Aug 5;13(1):4562. doi: 10.1038/s41467-022-32335-8.
AFDN/Afadin is required for establishment and maintenance of cell-cell contacts and is a unique effector of RAS GTPases. The biological consequences of RAS complex with AFDN are unknown. We used proximity-based proteomics to generate an interaction map for two isoforms of AFDN, identifying the polarity protein SCRIB/Scribble as the top hit. We reveal that the first PDZ domain of SCRIB and the AFDN FHA domain mediate a direct but non-canonical interaction between these important adhesion and polarity proteins. Further, the dual RA domains of AFDN have broad specificity for RAS and RAP GTPases, and KRAS co-localizes with AFDN and promotes AFDN-SCRIB complex formation. Knockout of AFDN or SCRIB in epithelial cells disrupts MAPK and PI3K activation kinetics and inhibits motility in a growth factor-dependent manner. These data have important implications for understanding why cells with activated RAS have reduced cell contacts and polarity defects and implicate AFDN as a genuine RAS effector.
AFDN/Afadin 对于细胞-细胞接触的建立和维持是必需的，并且是 RAS GTPases 的独特效应物。RAS 复合物与 AFDN 的生物学后果尚不清楚。我们使用基于邻近的蛋白质组学生成了两种 AFDN 同工型的相互作用图谱，鉴定出极性蛋白 SCRIB/Scribble 为首要命中物。我们揭示 SCRIB 的第一个 PDZ 结构域和 AFDN FHA 结构域介导这些重要的粘附和极性蛋白之间的直接但非典型相互作用。此外，AFDN 的双重 RA 结构域对 RAS 和 RAP GTPases 具有广泛的特异性，并且 KRAS 与 AFDN 共定位并促进 AFDN-SCRIB 复合物的形成。上皮细胞中 AFDN 或 SCRIB 的敲除破坏了 MAPK 和 PI3K 的激活动力学，并以生长因子依赖性方式抑制迁移。这些数据对于理解为什么激活的 RAS 细胞具有减少的细胞接触和极性缺陷具有重要意义，并暗示 AFDN 是真正的 RAS 效应物。
