Neural Stem Cell Laboratory, Institute of Medical Biology, Singapore, Singapore.
PLoS One. 2011 Feb 2;6(2):e16603. doi: 10.1371/journal.pone.0016603.
Adenomatous Polyposis Coli (APC) is a tumor suppressor gene product involved in colon cancer. APC is a large multidomain molecule of 2843 amino acid residues and connects cell-cell adhesion, the F-actin/microtubule cytoskeleton and the nucleus. Here we show that Cdc42 interacts directly with the first three armadillo repeats of APC by yeast two-hybrid screens. We confirm the Cdc42-APC interaction using pulldown assays in vitro and FRET assays in vivo. Interestingly, Cdc42 interacts with APC at leading edge sites where F-actin is enriched. In contrast, Cdc42 interacts with the truncated mutant APC¹⁻¹⁶³⁸ in cellular puncta associated with the golgi-lysozome pathway in transfected CHO cells. In HCT116 and SW480 cells, Cdc42 induces the relocalization of endogenous APC and the mutant APC¹⁻¹³³⁸ to the plasma membrane and cellular puncta, respectively. Taken together, these data indicate that the Cdc42-APC interaction induces localization of both APC and mutant APC and may thus play a direct role in the functions of these proteins.
腺瘤性结肠息肉病（APC）是一种参与结肠癌的肿瘤抑制基因产物。APC 是一种含有 2843 个氨基酸残基的大型多结构域分子，连接细胞-细胞黏附、F-肌动蛋白/微管细胞骨架和细胞核。在这里，我们通过酵母双杂交筛选发现 Cdc42 与 APC 的前三个角蛋白重复序列直接相互作用。我们通过体外下拉测定和体内 FRET 测定证实了 Cdc42-APC 相互作用。有趣的是，Cdc42 在富含 F-肌动蛋白的前沿部位与 APC 相互作用。相比之下，Cdc42 在转染的 CHO 细胞中与高尔基溶酶体途径相关的细胞内点状与截断突变体 APC¹⁻¹⁶³⁸相互作用。在 HCT116 和 SW480 细胞中，Cdc42 诱导内源性 APC 和突变体 APC¹⁻¹³³⁸分别向质膜和细胞内点状结构的重新定位。总之，这些数据表明 Cdc42-APC 相互作用诱导 APC 和突变体 APC 的定位，因此可能直接参与这些蛋白的功能。
