Tailoring the Amphiphilicity of Fluorescent Protein Chromophores to Detect Intracellular Proteome Aggregation in Diverse Biological Samples

Unraveling Intracellular Protein Corona Components of Nanoplastics via Photocatalytic Protein Proximity Labeling

Bioaccumulation of nanoplastic particles has drawn increasing attention regarding environmental sustainability and biosafety. How nanoplastic particles interact with the cellular milieu still remains elusive. Herein, we exemplify a general approach to profile the composition of a "protein corona" interacting with nanoparticles via the photocatalytic protein proximity labeling method. To enable photocatalytic proximity labeling of the proteome interacting with particles, iodine-substituted BODIPY (I-BODIPY) is selected as the photosensitizer and covalently conjugated onto amino-polystyrene nanoparticles as a model system. Next, selective proximity labeling of interacting proteins is demonstrated using I-BODIPY-labeled nanoplastic particles in both Escherichia coli lysate and live alpha mouse liver 12 cells. Mechanistic studies reveal that the covalent modifications of proteins by an aminoalkyne substrate are conducted via a reactive oxygen species photosensitization pathway. Further proteomic analysis uncovers that mitochondria-related proteins are intensively involved in the protein corona, indicating substantial interactions between nanoplastic particles and mitochondria. In addition, proteostasis network components are also identified, accompanied by consequent cellular proteome aggregation confirmed by fluorescence imaging. Together, this work exemplifies a general strategy to interrogate the composition of the protein corona of nanomaterials by endowing them with photooxidation properties to enable photocatalytic protein proximity labeling function.

Dual-environment-sensitive probe to detect protein aggregation in stressed laryngeal carcinoma cells and tissues

The interplay between protein folding and biological activity is crucial, with the integrity of the proteome being paramount to ensuring effective biological function execution. In this study, we report a dual-environment-sensitive probe A1, capable of selectively binding to protein aggregates and dynamically monitoring their formation and degradation. Through in vitro, cellular, and tissue assays, A1 demonstrated specificity in distinguishing aggregated from folded protein states, selectively partitioning into aggregated proteins. Thermal shift assays revealed A1 could monitor the process of protein aggregation upon binding to misfolded proteins and preceding to insoluble aggregate formation. In cellular models, A1 detected stress-induced proteome aggregation in TU212 cells (laryngeal carcinoma cells), revealing a less polar microenvironment within the aggregated proteome. Similarly, tissue samples showed more severe proteome aggregation in cancerous tissues compared to paracancerous tissues. Overall, A1 represents a versatile tool for probing protein aggregation with significant implications for both fundamental research and clinical diagnostics.