The microRNA-30e as a decision maker in stress-induced signaling pathways

基于它们转录后调节大部分蛋白质组表达的能力，小的（19-23个核苷酸）非编码RNA分子，即所谓的microrna (miRs)，在多种细胞过程中发挥着核心作用。由于miRs能够靶向许多mrna，到目前为止，这些mrna在很大程度上仍是未知的，我们远未完全了解单个miRs的特定功能。通过微阵列分析，我们发现除了众所周知的p53靶点miR-34a之外，还有其他几种mir，包括miR-30c和miR-30e，它们以p53依赖的方式被电离照射诱导。虽然miR-30家族的5个成员含有相同的种子序列，因此应该识别相似的靶mrna，但只有miR-30e的异位表达，而miR-30c的异位表达不能拯救肿瘤细胞免受电离照射、依托opo苷或miR-34a过表达诱导的凋亡。有趣的是，miR-30e不仅能够保护细胞免受应激诱导的凋亡，而且还能诱导强烈的永久性细胞周期阻滞，称为衰老。与这些过程一致，miR-30e被发现调节caspase-3和周期蛋白依赖性激酶抑制剂p21的表达。在对这些问题进行深入分析之后，我们将不仅仔细研究miR-30e表达对p53的依赖性，而且反过来研究它们对p53依赖性和非依赖性应激诱导信号通路的影响。使用各种生物信息学和实验方法，我们将确定其他miR-30e靶点，如p21，我们将深入研究它们对miR-30e调节的应激反应的影响。

Based on their capability to post-transcriptionally modulate expression of a large portion of the proteome, small (19-23 nucleotides) non-coding RNA molecules, so-called microRNAs (miRs), play a central role in diverse cellular processes. As miRs are able to target numerous mRNAs, that up to now remain largely unknown, we are far from fully understanding specific functions of individual miRs. By means of microarray analyses we identified besides the well-known p53 target miR-34a also several other miRs including miR-30c and miR-30e that were induced by ionizing irradiation in a p53-dependent manner. Although the five members of the miR-30 family contain an identical seed sequence and thus should recognize similar target mRNAs, only ectopic expression of miR-30e, but not of miR-30c rescues tumor cells from apoptosis induced by ionizing irradiation, etoposide or overexpression of miR-34a. Interestingly, miR-30e was not only able to protect the cells from stress-induced apoptosis, but in addition, induced a strong and permanent cell cycle arrest called senescence. Consistent with these processes, miR-30e was found to modulate expression of caspase-3 and the cyclin-dependent kinase inhibitior p21. Following an in-depth analysis of these issues, we will then closely examine not only the putative p53 dependency of miR-30e expression, but conversely investigate their impact on p53-dependent and -independent stress-induced signaling pathways. Using various bioinformatical and experimental approaches, we will identify additional miR-30e targets that like p21 will be thoroughly investigated with regard to their influence on miR-30e-regulated stress responses.