lncRNA通过串联不同剪接因子调控可变剪接的作用机制研究

The great majority of human multi-exon-containing genes undergo alternative splicing, which has been increasingly appreciated as a major post-transcriptional mechanism to generate structural and functional diversity of gene products in higher eukaryotic cells. Long noncoding RNA (lncRNA) can act as a “molecular sponge” by interacting with splicing factors, and thereby modulate the concentration of splicing factors in cells and influence alternative splicing patterns. However, other mechanisms employed by lncRNAs to regulate alternative splicing remain to be elucidated. hnRNP I and PSF are two important splicing factors, which are thought to function in determining the splicing site and smoothing early and late steps of the splicing reaction respectively. We have isolated an lncRNA that coordinately interact with both hnRNP I and PSF. Our results show that hnRNP I and PSF are tethered together by this lncRNA. The ability of this lncRNA to tether two different splicing factors not only facilitates, but also couples, the regulatory function of hnRNP I and PSF in alternative splicing. Furthermore, it seems likely that this lncRNA also serves as a scaffold to maintain the integrity of spliceosome. In addition to hnRNP I, the other members of hnRNP family also function in regulating pre-mRNA splicing. We have demonstrated the role of the lncRNA in maintaining the PSF-hnRNP F interaction, suggesting that the lncRNA may interact with certain other hnRNP proteins. With these preliminary results, we plan to further investigate role of lncRNA-splicing factor interactions in the control of alternative splicing.

可变剪接是真核生物基因产物多样性的主要产生机制。长非编码RNA（lncRNA）可作为“分子海绵”吸附剪接因子，从而影响剪接因子的细胞内浓度并调控可变剪接。然而，lncRNA是否还通过其他机制调控可变剪接尚不清楚。PSF和hnRNP I是两个重要的剪接因子。在前期工作中我们筛选到一条与PSF和hnRNP I均发生相互作用的lncRNA；该lncRNA参与了对PSF-hnRNP I相互作用及剪接体完整性的维持，并与PSF、hnRNP I协同调节了前体mRNA的可变剪接。除了hnRNP I，hnRNP 家族的其他成员也与RNA剪接密切相关。我们证实该lncRNA也参与了对PSF-hnRNP F相互作用的维持，推测该lncRNA还能够与其他的hnRNP蛋白相互作用。基于前期基础，本项目旨在研究该lncRNA通过串联不同剪接因子参与可变剪接调控的作用机制。

可变剪接是真核生物基因产物多样性的主要产生机制。长非编码RNA（lncRNA）可作为“分子海绵”吸附剪接因子，从而影响剪接因子的细胞内浓度并调控可变剪接。然而，lncRNA是否还通过其他机制调控可变剪接尚不清楚。在本项目中，我们发现lncRNA MALAT1能够同时结合剪接因子PTBP1、PSF并形成MALAT1/PTBP1/PSF复合物，从而协同调节pre-mRNA的可变剪接。MALAT1/PTBP1/PSF复合物在多种细胞环境中均可形成，具有生物学普遍性。较之于MALAT1这一单因子，MALAT1与PTBP1、PSF形成的复合物在肝癌中更加具有生物学重要性和病理学显著性。此外，除了PTBP1，其他的hnRNP蛋白，如hnRNP A1、hnRNP F和hnRNP U均可与MALAT1和PSF互作，说明MALAT1可能具有协调多种剪接因子活性的能力，从而广泛参与pre-mRNA的可变剪接调控。.此外，我们不仅揭示了lncRNA 通过调节蛋白质泛素化修饰参与基因表达调控的新机制，还发现定位于不同亚细胞区域的lncRNA 可通过偶联不同的效应机制同时在表观遗传修饰及翻译层面调节基因表达，为其他具有不同亚细胞区域共分布的lncRNA 提供了研究范例。对RNA 结合蛋白的研究中，发现凝血因子FVII、FIX、FX 这类RNA结合蛋白不仅参与了凝血级联反应，还能够杀灭革兰氏阴性“超级细菌”。在基础研究方面，该工作发现凝血因子具有杀灭细菌的新功能，更新了对凝血因子的传统认知，提示需重新认识血栓形成在脓毒症、脑卒中、心梗等重大疾病发生中的作用；在应用研究方面，为干预“超级细菌”感染等重大疾病提供了新方案。.目前，本项目已发表SCI论文4篇[Chen et al., Cell Res., 2019 (IF=25.617)；Lan et al., Nucleic Acids Res., 2018 (IF=16.971); Li et al., Semin Cancer Biol., 2021 (IF=15.707); Miao et al., PLoS Genet., 2019 (IF=5.917)]。