Golgi Apparatus‐Associated Secretome Deciphering in Living Cells Enabled by Aggregation‐Induced Emission Luminogen‐Mediated Photocatalytic Proximity Labeling

ABSTRACT Golgi apparatus (GA)‐associated secretome runs through the endomembrane system and is critical for inter‐ and intracellular communication networks. However, achieving in situ dissection of the GA‐associated secretome remains challenging owing to the scarcity of specific labeling methods. This work develops an aggregation‐induced emission (AIE) luminogen‐mediated photocatalytic proximity labeling strategy that allows profiling of the GA‐associated secretome with high spatiotemporal precision. Leveraging an AIE luminogen‐derived GA‐targeting photocatalyst, this strategy achieves efficient labeling of proteins in minutes within the Golgi lumen upon light activation, which enables spatiotemporally resolved modification of histidine and tyrosine residues. We succeed in profiling secretome in both living HeLa cells and hard‐to‐transfect macrophage HMC3 cells, and a significant subset of GA‐associated secretome with 80% specificity is determined, linking the distinct GA‐associated secretory profiles to cellular characteristics. The method is further applied to proteome mapping of brain and bone metastatic lung cancer cells, which reveals the underlying roles the GA‐associated secretome plays in extracellular matrix organization during metastasis. This work delivers a robust tool to break the dilemma of chemical labeling of GA‐associated secretome in living cells, and provides mechanistic insights into secretion regulation at the subcellular level.