The essential role of U4 snRNP in pre-messenger RNA (mRNA) splicing has been well established. In this study, we utilized an antisense morpholino oligonucleotide (AMO) specifically targeting U4 snRNA to achieve functional knockdown of U4 snRNP in HeLa cells. Our results showed that this knockdown resulted in global intronic premature cleavage and polyadenylation (PCPA) events, comparable to the effects observed with U1 AMO treatment, as demonstrated by mRNA 3′-seq analysis. Furthermore, our study suggested that this may be a common phenomenon in both human and mouse cell lines. Additionally, we showed that U4 AMO treatment disrupted transcription elongation, as evidenced by chromatin immunoprecipitation sequencing (ChIP-seq) analysis for RNAPII. Collectively, our results identified a unique role for U4 snRNP in the inhibition of PCPA and indicated a model wherein splicing intrinsically inhibits intronic cleavage and polyadenylation in the context of cotranscriptional mRNA processing.

中文翻译：

---

U4 snRNP 抑制前 mRNA 的过早裂解和聚腺苷酸化


U4 snRNP 在前信使 RNA (mRNA) 剪接中的重要作用已得到充分证实。在本研究中，我们利用特异性靶向 U4 snRNA 的反义吗啉寡核苷酸 (AMO) 来实现 HeLa 细胞中 U4 snRNP 的功能性敲低。我们的结果表明，这种敲低导致了整体内含子过早裂解和多腺苷酸化 (PCPA) 事件，与 U1 AMO 处理观察到的效果相当，如 mRNA 3'-seq 分析所证明的。此外，我们的研究表明这可能是人类和小鼠细胞系中的常见现象。此外，我们发现 U4 AMO 处理会破坏转录延伸，RNAPII 的染色质免疫沉淀测序 (ChIP-seq) 分析证明了这一点。总的来说，我们的结果确定了 U4 snRNP 在抑制 PCPA 中的独特作用，并表明了一个模型，其中剪接本质上抑制共转录 mRNA 加工背景下的内含子切割和多腺苷酸化。