Alternative splicing of DSP1 enhances snRNA accumulation by promoting transcription termination and recycle of the processing complex.

Weili Wang, Xuepiao Pu, Siyu Yang, Yujie Feng, Chan Lin, Mu Li, Xi Li, Huali Li, Chunmei Meng, Qingjun Xie, Bin Yu, Yunfeng Liu

Proceedings of the National Academy of Sciences of the United States of America 2020 Aug 18

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Small nuclear RNAs (snRNAs) are the basal components of the spliceosome and play crucial roles in splicing. Their biogenesis is spatiotemporally regulated. However, related mechanisms are still poorly understood. Defective in snRNA processing (DSP1) is an essential component of the DSP1 complex that catalyzes plant snRNA 3'-end maturation by cotranscriptional endonucleolytic cleavage of the primary snRNA transcripts (presnRNAs). Here, we show that DSP1 is subjected to alternative splicing in pollens and embryos, resulting in two splicing variants, DSP1α and DSP1β. Unlike DSP1α, DSP1β is not required for presnRNA 3'-end cleavage. Rather, it competes with DSP1α for the interaction with CPSF73-I, the catalytic subunit of the DSP1 complex, which promotes efficient release of CPSF73-I and the DNA-dependent RNA polymerease II (Pol II) from the 3' end of snRNA loci thereby facilitates snRNA transcription termination, resulting in increased snRNA levels in pollens. Taken together, this study uncovers a mechanism that spatially regulates snRNA accumulation.

Citation

Weili Wang, Xuepiao Pu, Siyu Yang, Yujie Feng, Chan Lin, Mu Li, Xi Li, Huali Li, Chunmei Meng, Qingjun Xie, Bin Yu, Yunfeng Liu. Alternative splicing of DSP1 enhances snRNA accumulation by promoting transcription termination and recycle of the processing complex. Proceedings of the National Academy of Sciences of the United States of America. 2020 Aug 18;117(33):20325-20333