Hybridization-proximity labeling reveals spatially ordered interactions of nuclear RNA compartments

The ability of RNAs to form specific contacts with other macromolecules provides an important mechanism for subcellular compartmentalization. Here we describe a suite of hybridization-proximity (HyPro) labeling technologies for unbiased discovery of proteins (HyPro-MS) and transcripts (HyPro-seq) associated with RNAs of interest in genetically unperturbed cells. As a proof of principle, we show that HyPro-MS and HyPro-seq can identify both known and previously unexplored spatial neighbors of the noncoding RNAs 45S, NEAT1, and PNCTR expressed at markedly different levels. Notably, HyPro-seq uncovers an extensive repertoire of incompletely processed, adenosine-to-inosine-edited transcripts accumulating at the interface between their encoding chromosomal regions and the NEAT1-containing paraspeckle compartment. At least some of these targets require NEAT1 for their optimal expression, Overall, this study provides a versatile tool-kit for dissecting RNA interactomes in diverse biomedical contexts and expands our understanding of the functional architecture of the mammalian nucleus.

Automated summary

This study introduces a set of labeling technologies for the unbiased discovery of proteins and transcripts associated with specific RNAs. These technologies can identify both known and unknown molecules that interact with the RNA of interest. The study also reveals a large repertoire of incompletely processed, edited transcripts accumulating between chromosomal regions and RNA-containing compartments. Overall, this versatile tool-kit expands our understanding of the functional architecture of the mammalian nucleus.