The interactions between different organelles are ubiquitous and crucial for life activities. Thus, development of a single fluorescent probe enabling the simultaneous two-color visualization of two organelles is of great significance for the study of organelle interplay. Herein, using the reversible ringopening/closing reactions of rhodamine dyes, we have fabricated a robust fluorescent probe to distinguish lipid droplets (LDs) and the endoplasmic reticulum (ER) in dual-emission channels with negligible crosstalk. The probe 6′-which was sensitive to the changes in the water content in the organism, displayed strong green fluorescence in the hydrophobic LDs from its ring-closed form, while it existed in a ring-opened form in the ER to illuminate a strong near-infrared emission. Importantly, the spectral difference was up to 320 nm, and thus the crosstalk between two channels was negligible. With the unique probe, the lipid accumulation in cells treated with different concentrations of oleic acid, cholesterol, and stearic acid has been successfully observed. The changes of LDs and the ER in living cells stimulated by temperature changes and hypoxia stimulation have also been revealed. Meanwhile, the different sizes and distribution of LDs and the ER in various tissues were also studied using the robust probe. This work provides a new approach to the design of dual-emissive probes and contributes to a significant molecular tool to promote the study of organelle interactions.
Autophagy and apoptosis play a central role in maintaining
homeostasis
in mammals. Therefore, discriminative visualization of the two cellular
processes is an important and challenging task. However, fluorescent
probes enabling ratiometric visualization of both autophagy and apoptosis
with different sets of fluorescence signals have not been developed
yet. In this work, we constructed a versatile single fluorescent probe
(NKLR) based on the aggregation/monomer principle for
the ratiometric and discriminative visualization of autophagy and
apoptosis. NKLR can simultaneously perform two-color
imaging of RNA (deep red channel) and lysosomes (yellow channel) in
aggregation and monomer states, respectively. During autophagy, NKLR migrated from cytoplasmic RNA and nuclear RNA to lysosomes,
showing enhanced yellow emission and sharply decreased deep red fluorescence.
Moreover, this migration process was reversible upon the recovery
of autophagy. Comparatively, during apoptosis, NKLR immigrated
from lysosomes to RNA, and the yellow emission decreased and even
disappeared, while the fluorescence of the deep red channel slightly
increased. Overall, autophagy and apoptosis could be discriminatively
visualized via the fluorescence intensity ratios
of the two channels. Meanwhile, the cells in three different states
(healthy, autophagic, apoptotic) could be distinguished by three point-to-point
fluorescence images via the localization and emission
color of NKLR. Therefore, the probe NKLR can serve as a desirable molecular tool to reveal the in-depth relation
between autophagy and apoptosis and facilitate the study on the two
cellular processes.
Mitochondria supply the majority of energy to sustain the biological activities in living cells, and mitochondria dysfunction would lead to serious diseases. Mitochondrial depolarization is a sign of mitochondrial dysfunction,...
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