ABSTRACT
Aberrant autophagy of the endoplasmic reticulum (reticulophagy) is engaged in diverse pathological disorders. Herein, we reported sensitive imaging of reticulophagy with ER-Green-proRed, a diad combining a solvatochromic entity of trifluoromethylated naphthalimide for long-term ER tracking by green fluorescence and an entity of rhodamine-lactam fluorogenic to lysosomal acidity. Stringently accumulated in the ER to give green fluorescence, ER-Green-proRed exhibits robust red fluorescence upon codelivery with the ER subdomain into lysosomes. The relevance of turn-on red fluorescence to reticulophagy was validated by reticulophagy modulated by starvation, reticulophagic receptors, and autophagy inhibition. This imaging method was successfully employed to discern reticulophagy induced by various pharmacological agents. These results show the potential of ER-targeted pH probes, as exemplified by ER-Green-proRed, to image reticulophagy and to identify reticulophagy inducers.
Subject(s)
Autophagy , Endoplasmic Reticulum , Fluorescence , Endoplasmic Reticulum Stress , Carrier ProteinsABSTRACT
Siglecs that binds cell surface sialoglycans are a family of immunomodulatory receptors, of which, Siglec-7 expressed on natural killer (NK) cells promotes tumor immunoevation while the role of Siglec-1 expressed on macrophages on tumor development remains largely unexplored. Herein, we selectively introduced high affinity sialoside ligands of Siglec-1 and Siglec-7 to tumor cell surface via in vivo Strain-promoted Azide-Alkyne cyclization of TCCSiaα2,3-Lactose or FITCSiaα2,6-Lactose with 9-azido sialic acid (AzSia) metabolically installed on tumor cell surface. We found that TCCSiaα2,3-Lactose conjugated on tumor surface moderately inhibited tumor growth while FITCSiaα2,6-Lactose promote tumor growth. These results suggest high-affinity ligand of Siglec-1 dispalyed on tumors surface provide a new perspective for tumor immunotherapy.
