Yoshimoto Takanobu, Boehm Manfred, Olive Michelle, Crook Martin F, San Hong, Langenickel Thomas, Nabel Elizabeth G
Cardiovascular Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, 31 Center Dr., 31/5A48, Bethesda, MD 20892, USA.
Exp Cell Res. 2006 Jul 1;312(11):2040-53. doi: 10.1016/j.yexcr.2006.03.001. Epub 2006 Apr 17.
The retinoblastoma gene product (RB) is an important regulator of E2F activity. RB recruits a number of proteins, including HDACs, SWI/SNF complex, lysine methyl transferase (SUV39H1) and DNA methyltransferase (DNMT1), all of which negatively regulate E2F activity with RB. Here, we show that RB interacts with PRMT2, a member of the protein arginine methyltransferase family, to regulate E2F activity. PRMT2 directly bound and interacted with RB through its AdoMet binding domain, in contrast to other PRMT proteins, including PRMT1, PRMT3 and PRMT4. In reporter assays, PRMT2 repressed E2F1 transcriptional activity in an RB-dependent manner. PRMT2 formed a ternary complex with E2F1 in the presence of RB. To further explore the role of endogenous PRMT2 in the regulation of E2F activity, the PRMT2 gene was ablated in mice by gene targeting. Compared with PRMT2(+/+) mouse embryonic fibroblasts (MEFs), PRMT2(-/-) MEFs demonstrated increased E2F activity and early S phase entry following release of serum starvation. Vascular injury to PRMT2(-/-) arteries results in a hyperplastic response, consistent with increased G1-S phase progression. Taken together, these findings demonstrate a novel mechanism for the regulation of E2F activity by a member of the protein arginine methyltransferase family.
视网膜母细胞瘤基因产物（RB）是E2F活性的重要调节因子。RB招募多种蛋白质，包括组蛋白去乙酰化酶（HDACs）、SWI/SNF复合物、赖氨酸甲基转移酶（SUV39H1）和DNA甲基转移酶（DNMT1），所有这些蛋白质都与RB一起对E2F活性进行负调控。在此，我们表明RB与蛋白质精氨酸甲基转移酶家族成员PRMT2相互作用，以调节E2F活性。与其他PRMT蛋白（包括PRMT1、PRMT3和PRMT4）不同，PRMT2通过其AdoMet结合域直接与RB结合并相互作用。在报告基因检测中，PRMT2以RB依赖的方式抑制E2F1转录活性。在存在RB的情况下，PRMT2与E2F1形成三元复合物。为了进一步探究内源性PRMT2在E2F活性调节中的作用，通过基因靶向在小鼠中敲除了PRMT2基因。与PRMT2(+/+)小鼠胚胎成纤维细胞（MEFs）相比，PRMT2(-/-) MEFs在血清饥饿解除后表现出E2F活性增加和早期S期进入。对PRMT2(-/-)动脉的血管损伤导致增生反应，这与G1-S期进程增加一致。综上所述，这些发现证明了蛋白质精氨酸甲基转移酶家族成员调节E2F活性的新机制。
