Sensitive imaging of Endoplasmic reticulum (ER) autophagy with an acidity-reporting ER-Tracker

Yilong Shi; Xiaoxue Zou; Xianghui Zheng; Yimin Wu; Jiahuai Han; Shoufa Han

doi:10.1080/15548627.2023.2165759

Sensitive imaging of Endoplasmic reticulum (ER) autophagy with an acidity-reporting ER-Tracker

Autophagy. 2023 Jul;19(7):2015-2025. doi: 10.1080/15548627.2023.2165759. Epub 2023 Jan 12.

Authors

Yilong Shi¹, Xiaoxue Zou¹, Xianghui Zheng², Yimin Wu¹, Jiahuai Han³, Shoufa Han¹

Affiliations

¹ State Key Laboratory for Physical Chemistry of Solid Surfaces, the Key Laboratory for Chemical Biology of Fujian Province, the MOE Key Laboratory of Spectrochemical Analysis & Instrumentation, and Department of Chemical Biology, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, China.
² Bioluminor Biotech Ltd, Xiamen, China.
³ State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signalling Network, School of Life Sciences, Xiamen University, Xiamen, China.

Abstract

Macroautophagic/autophagic turnover of endoplasmic reticulum (reticulophagy) is critical for cell health. Herein we reported a sensitive fluorescence-on imaging of reticulophagy using a small molecule probe (ER-proRed) comprised of green-emissive fluorinated rhodol for ER targeting and nonfluorescent rhodamine-lactam prone to lysosome-triggered red fluorescence. Partitioned in ER to exhibit green fluorescence, ER-proRed gives intense red fluorescence upon co-delivery with ER into acidic lysosomes. Serving as the signal of reticulophagy, the turning on of red fluorescence enables discernment of reticulophagy induced by starvation, varied levels of reticulophagic receptors, and chemical agents such as etoposide and sodium butyrate. These results show ER probes optically activatable in lysosomes, such as ER-proRed, offer a sensitive and simplified tool for studying reticulophagy in biology and diseases.Abbreviations: Baf-A1, bafilomycin A₁; CCCP, carbonyl cyanide m-chlorophenyl hydrazone; CQ, chloroquine diphosphate; ER, endoplasmic reticulum; FHR, fluorinated hydrophobic rhodol; GFP, green fluorescent protein; Reticulophagy, selective autophagy of ER; RFP, red fluorescent protein; ROX, X-rhodamine; UPR, unfolded protein response.

Keywords: Autophagy imaging; endoplasmic reticulum; fluorescence-on; lysosomal acidity; reticulophagy.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Autophagy*
Carrier Proteins / metabolism
Endoplasmic Reticulum / metabolism
Endoplasmic Reticulum Stress
Unfolded Protein Response*

Substances

Carrier Proteins

Grants and funding

This work was supported by grants from National Natural Science Foundation of China (NSFC) (22177096), NSFC (81788101), National Key R&D Program of China (2020YFA0803500), and the CAMS Innovation Fund for Medical Science (2019-I2M-5-062).