miRNA在Notch信号调控巨噬细胞激活中的作用和机制研究

Macrophages participate in innate immune responses through different activation patterns, resulting in inflammatory reactions, tissue repairs, and other different biological effects. In preliminary studies using tumor models, we found that activating Notch signaling promotes M1 polarization, while blocking Notch signaling promotes M2 polarization, suggesting that Notch signaling is an important factor in the regulation of macrophage activation. However, downstream molecular mechanism of Notch-mediated macrophage polarization is still unclear. miRNA are widely involved in the regulation of cell functions. We found that there were a set of differentially expressed miRNAs between the macrophages obtained from RBP-J, the key transcription factor of Notch signaling, knockout mice and normal mice, which suggested that the regulation of macrophage activation by Notch signaling may work through miRNA. On this basis, this project intends to further characterize macrophage activation regulation by downstream miRNA of Notch signaling, to elucidate the molecular mechanisms of Notch signaling in the regulation of miRNA expression, and to explore the mechanism of Notch signaling-related miRNA in the regulation of macrophage activation. Through the study, we could find the new mechanism on the Notch signaling-mediated regulation of macrophage polarization, and provide a new target for intervention of macrophage polarization, which has an important theoretical significance and potential application value.

巨噬细胞参与天然免疫应答时以不同的方式被激活，产生炎性反应、组织修复等不同的生物学效应。我们在前期采用的肿瘤模型研究中发现，Notch信号是调控巨噬细胞激活的重要因素：激活Notch信号促进M1极化，阻断Notch信号促进M2极化，但其下游分子和机制尚不明确。miRNA广泛参与细胞功能调控，近期我们对Notch信号关键转录因子RBP-J敲除小鼠和正常小鼠巨噬细胞表达的miRNA进行了比对，获得了一组差异表达的miRNA，提示Notch信号可能通过miRNA调控巨噬细胞的激活。在此基础上，本课题拟进一步鉴定巨噬细胞激活调控中Notch信号下游的miRNA，阐明Notch信号调控miRNA表达的分子机制；探究Notch信号下游miRNA对巨噬细胞激活的调控作用和机理。通过本研究可以发现Notch信号调控巨噬细胞极化的新机制，并为巨噬细胞极化的干预提供新的靶点，具有重要的理论意义和潜在应用价值。

巨噬细胞以不同的方式被激活进而参与天然免疫应答，我们在前期研究中证实，Notch信号是调控巨噬细胞激活的重要因素。本研究中我们在Notch信号关键转录因子RBP-J敲除小鼠（RBP-J-/-）和正常小鼠（NC）巨噬细胞表达的miRNA进行了比对，发现miR-125a和miR-148a-3p表达存在明显差异，进一步研究证实：（1）Notch信号通路可促进巨噬细胞表达miR-125a，过表达miR-125a后巨噬细胞大量分泌炎性细胞因子，促进其吞噬杀伤肿瘤细胞和抵抗病原菌入侵能力；miR-125a可靶向性降解FIH1表达，进而增强Hif-1α活性，促进iNOS合成；另一方面其可靶向抑制IRF4翻译，进而抑制MR表达；巨噬细胞过表达miR-125a后检测发现，miR-125a及其宿主基因均表达升高，提示miR-125a可介导自我信号放大，促进自身初级转录本转录；（2）Notch信号通路可促进巨噬细胞表达miR-148a-3p，过表达miR-148a-3p后巨噬细胞大量分泌炎性细胞因子，促进其吞噬和杀伤细菌能力、抗原提呈等巨噬细胞M1型激活的功能；miR-148a-3p可靶向性降解Pten表达，进而使AKT磷酸化水平升高，IKb表达降低，P65表达增加，最终激活Pten/AKT/NF-kB通路，促进炎性因子分泌和ROS表达；通过RBP-JNICD BMDM和RBP-J-/- BMDM的挽救实验进一步证实Notch信号通过miR-148a-3p调节巨噬细胞激活。通过本研究可以发现Notch信号调控巨噬细胞激活的新机制，并为巨噬细胞激活的干预提供新的靶点，具有重要的理论意义和潜在应用价值。