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

ABSTRACT: 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, DSP1? and DSP1?. Unlike DSP1?, DSP1? is not required for presnRNA 3'-end cleavage. Rather, it competes with DSP1? 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.

SUBMITTER: Wang W 

PROVIDER: S-EPMC7443885 | biostudies-literature | 2020 Aug

REPOSITORIES: biostudies-literature