Mazières Julien, Tillement Vanessa, Allal Cuider, Clanet Carine, Bobin Lisbeth, Chen Zhi, Sebti Said M, Favre Gilles, Pradines Anne
Département Innovation Thérapeutique et Oncologie Moléculaire, Centre de Physiopathologie Toulouse Purpan INSERM U563, Institut Claudius Regaud, 20-24 rue du Pont Saint-Pierre, 31052 Toulouse cedex, France.
Exp Cell Res. 2005 Apr 1;304(2):354-64. doi: 10.1016/j.yexcr.2004.10.019. Epub 2004 Dec 28.
RhoB is a low molecular weight GTPase that is both farnesylated (RhoB-F) and geranylgeranylated (RhoB-GG) in cells. Based on data from rodent cell models, it has been suggested that RhoB displays differential effects on cell transformation, according to the nature of its prenylation. To test directly this hypothesis, we generated GTPase-deficient RhoB mutants that are exclusively either farnesylated or geranylgeranylated. We show that in Ras-transformed murine NIH-3T3 cells, RhoB-F enhances, whereas RhoB-GG and RhoB (F/GG) suppresses anchorage-dependent and -independent cell growth as well as tumor growth in nude mice. We then demonstrate that Ras constitutive activation of the tumor survival pathways Akt and NF-kappa B are blocked by RhoB-GG, but not by RhoB-F, providing further support for the opposing role of RhoB-F and RhoB-GG in Ras malignant transformation in NIH-3T3 cells. In addition, both RhoB (F/GG) and RhoB-GG induce apoptosis in Ras-transformed NIH-3T3 cells whereas RhoB-F has no effect. Our data demonstrate that RhoB-F and RhoB-GG which differ only by a 5-carbon isoprene behave differently in rodent cells highlighting the important role of prenyl groups in protein function and emphasize the potency of RhoB to regulate negatively the oncogenic signal.
RhoB是一种低分子量GTP酶，在细胞中可同时被法尼基化（RhoB-F）和香叶基香叶基化（RhoB-GG）。基于啮齿动物细胞模型的数据，有人提出RhoB根据其异戊二烯化的性质对细胞转化具有不同的影响。为了直接验证这一假设，我们生成了仅被法尼基化或仅被香叶基香叶基化的GTP酶缺陷型RhoB突变体。我们发现，在Ras转化的小鼠NIH-3T3细胞中，RhoB-F增强细胞生长，而RhoB-GG和RhoB（F/GG）则抑制贴壁依赖性和非贴壁依赖性细胞生长以及裸鼠体内的肿瘤生长。然后我们证明，RhoB-GG可阻断肿瘤存活途径Akt和NF-κB的Ras组成型激活，但RhoB-F则不能，这进一步支持了RhoB-F和RhoB-GG在NIH-3T3细胞Ras恶性转化中相反的作用。此外，RhoB（F/GG）和RhoB-GG均可诱导Ras转化的NIH-3T3细胞凋亡，而RhoB-F则无此作用。我们的数据表明，仅相差一个5碳异戊二烯的RhoB-F和RhoB-GG在啮齿动物细胞中的行为不同，突出了异戊二烯基团在蛋白质功能中的重要作用，并强调了RhoB对致癌信号进行负调控的能力。
