Lysosomal targeting with stable and sensitive fluorescent probes (Superior LysoProbes): applications for lysosome labeling and tracking during apoptosis.

Xin Chen,Lanrong Bi,Pengfei Li,Xin Yan,Yue Bi,K Michael Gibson,Catherine E Bammert,Tianyang Wang,William J Pavan,Jingfang Ju,Shanshan Hou

doi:10.1038/srep09004

Abstract

Intracellular pH plays an important role in the response to cancer invasion. We have designed and synthesized a series of new fluorescent probes (Superior LysoProbes) with the capacity to label acidic organelles and monitor lysosomal pH. Unlike commercially available fluorescent dyes, Superior LysoProbes are lysosome-specific and are highly stable. The use of Superior LysoProbes facilitates the direct visualization of the lysosomal response to lobaplatin elicited in human chloangiocarcinoma (CCA) RBE cells, using confocal laser scanning microscopy. Additionally, we have characterized the role of lysosomes in autophagy, the correlation between lysosome function and microtubule strength, and the alteration of lysosomal morphology during apoptosis. Our findings indicate that Superior LysoProbes offer numerous advantages over previous reagents to examine the intracellular activities of lysosomes.

Highlights

Intracellular pH plays an important role in the response to cancer invasion
These acidotropic probes are comparable to LysoTrackers in that they label compartments based upon their pKa values, thereby decreasing their specificity for lysosomes
The spirocyclic structures of the rhodamine lactam-type derivatives were confirmed by NMR

Summary

Introduction

Intracellular pH plays an important role in the response to cancer invasion. We have designed and synthesized a series of new fluorescent probes (Superior LysoProbes) with the capacity to label acidic organelles and monitor lysosomal pH. Most commercially available lysosome probes require a short excitation wavelength, which considerably restricts the use of these probes in tissue imaging associated with low penetration depth, decreased solubility, and poor photostability due to wavelength restrictions[17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32] To address this problem, Belfield et al recently developed a novel, two-photon absorbing fluorescence derivatives exhibiting selectivity for the lysosomes of HCT 116 colon cancer cells[26]. We developed alternative lysosome-specific probes that manifest advantages for short- and long-term studies of lysosome structure and function

Methods

Results

Conclusion