Key Laboratory of Bioresources and Ecoenvironment (Ministry of Education), College of Life Sciences, Sichuan University, Chengdu, PR China.
Jiangsu Key Laboratory of Biological Cancer Therapy, Xuzhou Medical College, Xuzhou 221002, PR China.
Biochem Biophys Res Commun. 2014 Feb 14;444(3):445-50. doi: 10.1016/j.bbrc.2014.01.102. Epub 2014 Jan 29.
RBM5 is a known putative tumor suppressor gene that has been shown to function in cell growth inhibition by modulating apoptosis. RBM5 also plays a critical role in alternative splicing as an RNA binding protein. However, it is still unclear which domains of RBM5 are required for RNA binding and related functional activities. We hypothesized the two putative RNA recognition motif (RRM) domains of RBM5 spanning from amino acids 98-178 and 231-315 are essential for RBM5-mediated cell growth inhibition, apoptosis regulation, and RNA binding. To investigate this hypothesis, we evaluated the activities of the wide-type and mutant RBM5 gene transfer in low-RBM5 expressing A549 cells. We found that, unlike wild-type RBM5 (RBM5-wt), a RBM5 mutant lacking the two RRM domains (RBM5-ΔRRM), is unable to bind RNA, has compromised caspase-2 alternative splicing activity, lacks cell proliferation inhibition and apoptosis induction function in A549 cells. These data provide direct evidence that the two RRM domains of RBM5 are required for RNA binding and the RNA binding activity of RBM5 contributes to its function on apoptosis induction and cell growth inhibition.
RBM5 是一种已知的假定肿瘤抑制基因，通过调节细胞凋亡来抑制细胞生长。RBM5 作为一种 RNA 结合蛋白，在剪接体的选择性剪接中也起着至关重要的作用。然而，目前尚不清楚 RBM5 的哪些结构域是 RNA 结合和相关功能活动所必需的。我们假设 RBM5 中从氨基酸 98-178 和 231-315 跨越的两个假定 RNA 识别基序 (RRM) 结构域对于 RBM5 介导的细胞生长抑制、凋亡调控和 RNA 结合是必需的。为了验证这一假说，我们评估了在低表达 RBM5 的 A549 细胞中转染野生型和突变型 RBM5 基因的活性。我们发现，与野生型 RBM5 (RBM5-wt) 不同，缺乏两个 RRM 结构域的 RBM5 突变体 (RBM5-ΔRRM) 无法结合 RNA，其半胱天冬酶-2 选择性剪接活性受损，在 A549 细胞中缺乏增殖抑制和诱导凋亡的功能。这些数据提供了直接证据，证明 RBM5 的两个 RRM 结构域是 RNA 结合所必需的，并且 RBM5 的 RNA 结合活性有助于其诱导凋亡和抑制细胞生长的功能。
