A dual‐functional BODIPY‐based molecular rotor probe reveals different viscosity of protein aggregates in live cells

Abstract

Aberrant protein aggregation leads to various human diseases, but little is known about the physical chemical properties of these aggregated proteins in cells. Herein, we developed a boron-dipyrromethene (BODIPY)-based HaloTag probe, whose conjugation to HaloTag-fused proteins allows us to study protein aggregates using both fluorescence intensity and lifetime. Modulation of BODIPY fluorophore reveals key structural features to attain the dual function. The optimized probe exhibits increased fluorescence intensity and elongated fluorescence lifetime in protein aggregates. Fluorescence lifetime imaging using this probe indicates that protein aggregates afford different viscosity in the forms of soluble oligomers and insoluble aggregates in live cells. The strategy presented in this work can be extended to enable a wide class of HaloTag probes that can be used to study a variety of physical properties of protein aggregates, thus helping unravel the pathogenic mechanism and develop therapeutic strategy.

Aggregation-Induced Emission (AIE), Life and Health

“…Besides, a PS in long-lived T 1 state can also participate in the formation of superoxide (O 2 • – ) or hydroperoxyl radicals (HO 2 • ) through transferring electrons to cellular substrates through a type I reaction. − Different kinds of ROS and radicals generated by those two types of photochemical reactions can kill cancer cells in a PDT therapeutic manner. − Selective and efficient PDT can also be realized by precisely manipulating the light irradiation area, which is an effective way to minimize side effects to healthy tissues . Besides, PDT exhibits several other merits such as noninvasiveness, few side effects, negligible drug resistance and low systemic toxicity, all of which has motivated scientists to work on PDT as a therapeutic modality for disease treatment. , As one of the key elements in PDT, various PSs such as porphyrin, chlorin, phthalocyanine, squaraine, BODIPY derivatives, and transition metal complexes have been explored so far to date. − The development of PSs with a superior organelle targeting capability can help to realize precision PDT toward cancer treatment. , However, most of the existing PSs are still far from the ideal, they should possess characteristics including strong absorption at long wavelengths, efficient photosensitization, negligible dark toxicity, and good photostability and biocompatibility. , In addition, these conventional PSs often possess a rigid planar π-conjugated structure and are prone to aggregate in aqueous media, resulting in significantly decreased photosensitization behavior and emission, which is another critical obstacle for conventional PSs in PDT applications. , In this regard, the discovery and development of PSs with AIE characteristics presents a promising alternative approach. − Herein, the application of AIE PSs in organelle targeted PDT and PDT-induced treatment will be discussed.…”

Microphase Separation Produces Interfacial Environment within Diblock Biomolecular Condensates

“…We constructed diblock peptides with the combination of 30 pentameric repeats of V block and X (A or G) block, namely V 30 A 30 and V 30 G 30 (Experimental Sequences Section in the Supplementary Information). The amino-termini of V 30 A 30 and V 30 G 30 sequences were sub-9 sequently labeled with environmentally sensitive BODIPY or SBD fluorophores, 61,62 whose lifetime could be measured to quantify the viscosity or polarity of the V-end (Fig. 3A, left panel).…”

Micropolarity governs the structural organization of biomolecular condensates

“…A molecular rotor-based boron dipyrromethene (BODIPY) fluorophore was used to measure microviscosity (Fig. 2A, right panel), as its fluorescence lifetime elongates with increasing viscosity (27).…”