Preprint identifies transient RNA dicing as a post-transcriptional switch during immune cell activation

A bioRxiv preprint describes RNA dicing as a regulated, transient post-transcriptional process that remodels the mature mRNA landscape during macrophage polarisation — the transition of immune cells between distinct activation states.

RNA dicing, as previously characterised by the same research group, is a post-transcriptional mechanism that cleaves mature mRNAs into stable, uncapped fragments that retain the capacity for translation. The current preprint extends this work by showing that dicing is not a constitutive or stochastic process but is temporally controlled: it peaks during early cell-state transitions in macrophages and then subsides, acting more like a switch than a steady-state modifier.

Using long-read transcriptomics, the authors map dicing events transcriptome-wide and find that cleavage preferentially occurs at boundaries between protein domains, preserving downstream coding modules. This positional preference suggests the process is not simply degradative but may generate functional protein isoforms or alter translational output in a domain-aware manner. The authors identify fate-specific patterns — different dicing programmes associated with different polarisation outcomes — consistent with a role in shaping cell identity.

The findings add a layer to the post-transcriptional regulation of gene expression in innate immunity and raise questions about whether dicing contributes to the rapid, large-scale gene expression changes characteristic of macrophage activation. Independent replication and functional validation of the proposed protein isoforms will be important next steps. The preprint has not yet been peer-reviewed.