Proximal proteomics reveals a landscape of human nuclear condensates

Nuclear condensates (NCs) are membraneless organelles that enable spatial and functional compartmentalization in the nucleus. Yet, the components and functional co-organization of NCs have been poorly studied. Here, we used PhastID to explore the proximal interactome of 18 NCs in HeLa cells. Our data revealed the organizational flow of gene control among these NCs. Crucially, we developed an algorithm to dissect the intricate internal relations of NCs. This algorithm led to key discoveries: the identification of an uncharacterized BUD13 condensate, and the recognition of specific co-organizations between nuclear gems and Cajal bodies for telomerase maturation, and between nuclear gems and histone locus bodies for histone gene pre-mRNA processing. We also created a global reference map to understand NC dynamics under stresses and how disease-related mutations differentially affect NC interactomes. Overall, our work provides a proximal proteome-based atlas for human NCs, substantially advancing our spatiotemporal understanding of nuclear biological events.