The protective role of a small GTPase RhoE against UVB-induced DNA damage in keratinocytes
The protective role of a small GTPase RhoE against UVB-induced DNA damage in keratinocytes
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DOI：
10.1074/jbc.m610532200
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发表时间：
2007-02-16
影响因子：
4.8
通讯作者：
Lee, Sam W.
中科院分区：
文献类型：
--
作者：
Boswell, Sarah A.;Ongusaha, Pat P.;Lee, Sam W.
RhoE是一个P53靶基因，被认为是中波紫外线诱导角质形成细胞存活的关键因素。Rho家族的GTP酶通过改变肌动蛋白细胞骨架来调节细胞行为的许多方面，作为分子开关在活跃的、GTP结合的构象和不活跃的、GDP结合的构象之间循环。与典型的Rho家族蛋白不同，RhoE(也称为RND3)是GTPase缺陷的，因此预计具有结构性活性。在这项研究中，我们研究了培养的人角质形成细胞对UVB辐射的反应。RhoE蛋白水平在UVB照射后升高，通过小干扰RNA阻断RhoE诱导后，与对照细胞相比，细胞凋亡显著增加，促生存靶标p21、COX-2和细胞周期蛋白D1水平降低，活性氧水平升高。这些数据表明，RhoE是一个作用于p38、JNK、p21和细胞周期蛋白D1上游的促生存因子。表达对P53的小干扰RNA的HaCat细胞表明，RhoE的功能独立于其已知的伙伴P53和Rho相关激酶I(ROCK I)。利用皮肤特异性转基因小鼠模型在表皮中靶向表达RhoE导致UVB照射后凋亡细胞数量显著减少。因此，RhoE的诱导可以抵消UVB诱导的细胞凋亡，并且可以作为一个新的靶点来预防UVB诱导的光损伤，而不考虑P53的状态。
RhoE, a p53 target gene, was identified as a critical factor for the survival of human keratinocytes in response to UVB. The Rho family of GTPases regulates many aspects of cellular behavior through alterations to the actin cytoskeleton, acting as molecular switches cycling between the active, GTP-bound and the inactive, GDP-bound conformations. Unlike typical Rho family proteins, RhoE (also known as Rnd3) is GTPase-deficient and thus expected to be constitutively active. In this study, we investigated the response of cultured human keratinocyte cells to UVB irradiation. RhoE protein levels increase upon exposure to UVB, and ablation of RhoE induction through small interfering RNA resulted in a significant increase in apoptosis and a reduction in the levels of the pro-survival targets p21, Cox-2, and cyclin D1, as well as an increase of reactive oxygen species levels when compared with control cells. These data indicate that RhoE is a pro-survival factor acting upstream of p38, JNK, p21, and cyclin D1. HaCat cells expressing small interfering RNA to p53 indicate that RhoE functions independently of its known associates, p53 and Rho-associated kinase I (ROCK I). Targeted expression of RhoE in epidermis using skin-specific transgenic mouse model resulted in a significant reduction in the number of apoptotic cells following UVB irradiation. Thus, RhoE induction counteracts UVB-induced apoptosis and may serve as a novel target for the prevention of UVB-induced photodamage regardless of p53 status.