Fushimi Kazuo, Ray Payal, Kar Amar, Wang Lei, Sutherland Leslie C, Wu Jane Y
Department of Neurology, Center for Genetic Medicine, Northwestern University Feinberg School of Medicine, 303 East Superior Street, Chicago, IL 60611, USA.
Proc Natl Acad Sci U S A. 2008 Oct 14;105(41):15708-13. doi: 10.1073/pnas.0805569105. Epub 2008 Oct 7.
Similar to many genes involved in programmed cell death (PCD), the caspase 2 (casp-2) gene generates both proapoptotic and antiapoptotic isoforms by alternative splicing. Using a yeast RNA-protein interaction assay, we identified RBM5 (also known as LUCA-15) as a protein that binds to casp-2 pre-mRNA. In both transfected cells and in vitro splicing assay, RBM5 enhances the formation of proapoptotic Casp-2L. RBM5 binds to a U/C-rich sequence immediately upstream of the previously identified In100 splicing repressor element. Our mutagenesis experiments demonstrate that RBM5 binding to this intronic sequence regulates the ratio of proapoptotic/antiapoptotic casp-2 splicing isoforms, suggesting that casp-2 splicing regulation by RBM5 may contribute to its tumor suppressor activity. Our work has uncovered a player in casp-2 alternative splicing regulation and revealed a link between the alternative splicing regulator and the candidate tumor suppressor gene. Together with previous studies, our work suggests that splicing control of cell death genes may be an important aspect in tumorigenesis. Enhancing the expression or activities of splicing regulators that promote the production of proapoptotic splicing isoforms might provide a therapeutic approach to cancer.
与许多参与程序性细胞死亡（PCD）的基因相似，半胱天冬酶2（casp-2）基因通过可变剪接产生促凋亡和抗凋亡异构体。利用酵母RNA-蛋白质相互作用试验，我们鉴定出RBM5（也称为LUCA-15）是一种与casp-2前体mRNA结合的蛋白质。在转染细胞和体外剪接试验中，RBM5均增强促凋亡Casp-2L的形成。RBM5与先前鉴定的In100剪接抑制元件上游紧邻的富含U/C的序列结合。我们的诱变实验表明，RBM5与这个内含子序列的结合调节促凋亡/抗凋亡casp-2剪接异构体的比例，这表明RBM5对casp-2剪接的调节可能有助于其肿瘤抑制活性。我们的工作发现了casp-2可变剪接调节中的一个作用因子，并揭示了可变剪接调节因子与候选肿瘤抑制基因之间的联系。与先前的研究一起，我们的工作表明细胞死亡基因的剪接控制可能是肿瘤发生的一个重要方面。增强促进促凋亡剪接异构体产生的剪接调节因子的表达或活性可能为癌症提供一种治疗方法。
