Barr Keaton, He Kevin L, Krumbein Andreas J, Chanfreau Guillaume F
Department of Chemistry and Biochemistry and the Molecular Biology Institute, University of California, Los Angeles CA 90095-1569.
Proc Natl Acad Sci U S A. 2025 Aug 12;122(32):e2507187122. doi: 10.1073/pnas.2507187122. Epub 2025 Aug 5.
Splicing of terminal introns is coupled to 3'-end processing by cleavage and polyadenylation (CPA) in mammalian genes. Whether this functional coupling is universally conserved across eukaryotes is unclear. Here, we show using long read RNA sequencing in that splicing inactivation does not result in widespread CPA impairment, and that inactivation of CPA has limited impact on splicing efficiency. The negative impact of CPA inactivation on splicing is mainly due to transcription termination defects that promote readthrough transcription, leading to splicing inhibition for downstream intron-containing genes. The deleterious effect of 5' extensions on splicing is length-dependent and can be detected independently from CPA inactivation for endogenous or synthetic genes. Deficient termination can also promote usage of cryptic splice sites and long-range intergenic splicing events. These results argue against a broad coupling between splicing and CPA in but show that efficient CPA-mediated transcription termination is critical for splicing fidelity and efficiency in a compact genome.
在哺乳动物基因中，末端内含子的剪接与通过切割和聚腺苷酸化（CPA）进行的3'端加工相偶联。这种功能偶联在真核生物中是否普遍保守尚不清楚。在这里，我们通过长读长RNA测序表明，剪接失活不会导致广泛的CPA损伤，并且CPA失活对剪接效率的影响有限。CPA失活对剪接的负面影响主要是由于转录终止缺陷促进了通读转录，导致下游含内含子基因的剪接受到抑制。5'端延伸对剪接的有害影响是长度依赖性的，并且可以独立于内源性或合成基因的CPA失活而被检测到。终止缺陷还可以促进隐蔽剪接位点的使用和长距离基因间剪接事件。这些结果反对在[具体物种或情况未提及]中剪接与CPA之间存在广泛的偶联，但表明有效的CPA介导的转录终止对于紧凑基因组中的剪接保真度和效率至关重要。
