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

A dual-labeling fluorescent probe to track lysosomal polarity and endoplasmic reticulum dynamics during ferroptosis

“…20 To date, only four fluorescent probes for ER/lysosome dual-labeling have been successfully developed (Table S3 and Scheme S3, ESI†). 21–24 Nevertheless, these pH-sensitive lipophilic probes cannot detect polarity and tend to transfer into the newborn LDs in ferroptosis. To the best of our knowledge, no probe has been reported that simultaneously detects polarity and discriminates between the ER and lysosomes (Scheme 1).…”

Fluorescence-On Imaging of Reticulophagy Enabled by an Acidity-Reporting Solvatochromic Probe

“…Autophagy is hallmarked by the delivery of cargo-enclosed autophagosomes into acidic lysosomes . This process has been employed to detect the autophagy of mitochondria (mitophagy) with mitochondria-targeted pH sensors by sensing lysosomal acidity. − By contrast, there remains a paucity of suitable small-molecular probes for reticulophagy imaging. − …”

“…We recently reported a rhodol-conjugated pH sensor for reticulophagy imaging by sensing pH acidification in reticulophagy . However, this approach is limited by the always-on green fluorescence of the rhodol entity and susceptibility of probe loss from the ER.…”

“…44−49 We recently reported a rhodol-conjugated pH sensor for reticulophagy imaging by sensing pH acidification in retic-ulophagy. 46 However, this approach is limited by the always-on green fluorescence of the rhodol entity and susceptibility of probe loss from the ER. To overcome these limitations and to override the need for plasmid transfection and generation of a stable cell line expressing protein reporters, we herein report ER-Green-proRed, a small-molecular probe for long-term highfidelity imaging of reticulophagy.…”