Photocatalytic labelling-enabled subcellular-resolved RNA profiling and synchronous multi-omics investigation.

Understanding cellular functions in health and disease requires dissecting spatiotemporal variations in the subcellular transcriptome. Existing methods for mitochondrial RNA profiling suffer from limitations, including low resolution, contamination and dependence on genetic manipulation. Here we present a bioorthogonal photocatalytic labelling and sequencing strategy (CAT-seq) that enables high-resolution, in situ profiling of mitochondrial RNA in living cells without genetic manipulation. We identified a quinone methide probe for efficient RNA labelling. Rigorous validation and optimization enabled CAT-seq to successfully profile mitochondrial RNA and track RNA dynamics in HeLa cells. We further applied CAT-seq to the challenging RAW 264.7 macrophages, revealing an underlying mitochondrial translational remodelling pathway. By leveraging the chemistry of quinone methide warheads, we established an orthogonal labelling system enabling synchronous RNA and protein multi-omics profiling within the same sample. Together, assisted by bioorthogonal photocatalytic chemistry, CAT-seq offers a general, non-genetic and well-compatible approach for subcellular-resolved RNA and multi-omics investigations, particularly in studies of intact primary living samples that are otherwise challenging to access.