Endoplasmic reticulum targeting fluorescent probes to image mobile Zn²⁺

Abstract

Zn 2+ plays an important role in the normal function of the endoplasmic reticulum (ER) and its deficiency can cause ER stress, which is related to a wide range of diseases. In order to provide tools to better understand the role of mobile Zn 2+ in ER processes, the first custom designed ER-localised fluorescent Zn 2+ probes have been developed through the introduction of a cyclohexyl sulfonylurea as an ER-targeting unit with different Zn 2+ receptors. Experiments in vitro and in cellulo show that both probes have a good fluorescence switch on response to Zn 2+ , high selectivity over other cations, low toxicity, ER-specific targeting ability and are efficacious imaging agents for mobile Zn 2+ in four different cell lines. Probe 9 has been used to detect mobile Zn 2+ changes under ER stress induced by both tunicamycin or thapsigargin, which indicates that the new probes should allow a better understanding of the mechanisms cells use to respond to dysfunction of zinc homeostasis in the ER and its role in the initiation and progression of diseases to be developed.

Protect to Detect: A Golgi Apparatus Targeted Probe to Image Mobile Zinc Through the Use of a Lipophilic Cell-Labile Protecting Group Strategy

“…The restriction of intramolecular rotations can also hinder the access to low energy conical intersections associated with ultrafast decay to the ground state. This theory was used to explain similar previous findings by us 6,22,31 and has been discussed elsewhere. 33,34…”

“…S3 and Table S1, ESI), which is consistent with previous values we have observed in related probes with this zinc-binding motif and fluorophore. 6,22 A titration of probe 1 with different equivalents of Zn 2+ by 1 H NMR spectroscopy ( Fig. S4-S6, ESI) was performed to further demonstrate the Zn 2+ association.…”

“…2b), which is much lower than that of the similar probes we have previously reported. 6,22 This is likely to be due to the large amplitude vibrations of the trityl group, which increase non-radiative decay pathways. It is therefore unsurprising that when the trityl protecting group was removed, the quantum yield increased significantly and the quantum yield of probe 2 reached 0.046 and that of its complex with 1 equivalent of Zn 2+ became 0.092 (Fig.…”

Subcellular localised small molecule fluorescent probes to image mobile Zn2+

“…Glibenclamide functions as the ER targeting group in the commercial ER tracker red and ER tracker green, and using a sulfonyl urea analogue, we developed two probes 25 and 26 as ER targeting probes. 66 It was shown that both probes accumulated in the ER in a number of cell lines, and displayed a good switch on uorescence response to Zn 2+ . Probe 25 was used to demonstrate that a decrease of mobile Zn 2+ concentration in the ER occurs under conditions of ER stress induced by tunicamycin and thapsigargin.…”

A FRET-based fluorescent Zn2+sensor: 3D ratiometric imaging, flow cytometric tracking and cisplatin-induced Zn2+fluctuation monitoring

“…[6][7][8][9][10][11] As a powerful technology which can provide spatiotemporal information on Zn 2+ , uorescence imaging has been applied in living cells, tissues and model animals. [12][13][14][15][16] Imaging and monitoring labile Zn 2+ uctuation is intriguing yet challenging since the deviation of endogenous labile Zn 2+ homeostasis might be very small and dynamic. Moreover, interference from photobleaching, sensor concentration variation, and light scattering may result in misleading information.…”