Profiling of the Golgi Apparatus Proteome in Living Cells Using Nanophotosensitizer-Mediated Photocatalytic Proximity Labeling

Eukaryotic cells are characterized by a high degree of compartmentalization, wherein the function of proteins is intricately tied to their subcellular localization, as distinct compartments provide specialized microenvironments. The Golgi apparatus serves as a critical hub for the processing and sorting of proteins within intracellular trafficking pathways. The identification of the Golgi apparatus proteome in living cells is of great significance for understanding both intercellular and intracellular communication networks. However, this still poses a significant challenge because of the scarcity of targeted labeling strategies, which is attributed to the fact that the stacked structure of the Golgi apparatus membrane hinders the access of traditional organic molecule photosensitizers. Inspired by the mechanism of chondroitin sulfate accumulation in the Golgi apparatus of living cells, we prepared the Golgi apparatus-targeting nanophotosensitizer by combination of chondroitin sulfate and photosensitizers. The nanophotosensitizer enabled photocatalytic proximity labeling of the Golgi apparatus proteome with high spatiotemporal precision under native conditions. After validation in living HeLa cells, which demonstrated that more than 400 Golgi apparatus-annotated proteins were identified, we applied the strategy to dynamic Golgi apparatus proteome mapping of brain metastatic lung cancer cells. We found that Golgi apparatus proteins played a role in signal transduction and extracellular matrix organization during cancer metastasis. Overall, this study not only significantly advanced the identification of the Golgi apparatus proteome but also provided new insights into the potential functions of the Golgi apparatus.