Oberman Froma, Rand Kinneret, Maizels Yael, Rubinstein Ariel M, Yisraeli Joel K
Department of Anatomy and Cell Biology, Hebrew University, Hadassah Medical School, Jerusalem, Israel.
RNA. 2007 Sep;13(9):1558-69. doi: 10.1261/rna.559507. Epub 2007 Jul 24.
The highly conserved, RNA binding VICKZ proteins help regulate RNA localization, stability, and translation in many eukaryotes. These proteins are also required for cell migration in embryos and cultured cells. In adults, many tumors overexpress VICKZ homologs, and it has been hypothesized that the proteins can mediate cell motility and invasion. How these proteins facilitate cell movement and, in particular, whether their ability to bind RNA plays a role in their function remain unclear. Using HPLC and mass spectrometry to identify a region of Xenopus Vg1 RBP (xVICKZ3) that binds the vegetal localization element of Vg1 RNA, we generated a deletion construct that functions in a dominant-negative manner. The construct associates with full-length xVICKZ3 and severely reduces binding to target RNAs. This dominant-negative construct phenocopies the effect of down-regulating xVICKZ3 in Xenopus embryos. A corresponding deletion in the human homolog hVICKZ1 similarly functions in a dominant-negative fashion to reduce the ability of full-length hVICKZ protein to bind RNA. Expression of the dominant-negative construct in human carcinoma cells inhibits cell movement by several criteria. We conclude that the ability of VICKZ proteins to mediate cell migration, in vitro and in vivo, requires their RNA binding activity.
高度保守的RNA结合蛋白VICKZ有助于调控许多真核生物中的RNA定位、稳定性及翻译过程。这些蛋白对于胚胎和培养细胞中的细胞迁移也是必需的。在成体中，许多肿瘤过度表达VICKZ同源物，并且据推测这些蛋白可介导细胞运动性和侵袭。这些蛋白如何促进细胞运动，尤其是它们结合RNA的能力在其功能中是否起作用仍不清楚。利用高效液相色谱法（HPLC）和质谱法鉴定非洲爪蟾Vg1 RBP（xVICKZ3）中与Vg1 RNA植物定位元件结合的区域，我们构建了一种以显性负性方式发挥作用的缺失构建体。该构建体与全长xVICKZ3结合，并严重降低与靶RNA的结合。这种显性负性构建体模拟了在非洲爪蟾胚胎中下调xVICKZ3的效果。人类同源物hVICKZ1中的相应缺失同样以显性负性方式发挥作用以降低全长hVICKZ蛋白结合RNA的能力。通过多项标准评估，显性负性构建体在人癌细胞中的表达抑制细胞运动。我们得出结论，VICKZ蛋白在体外和体内介导细胞迁移的能力需要其RNA结合活性。
