A Multivalent Ligand for the Mannose-6-Phosphate Receptor for Endolysosomal Targeting of an Activity-Based Probe

• Published in: Angewandte Chemie International Edition 2014-10, Vol.53 (41), p.10975-10978
• Main Authors: Hoogendoorn, Sascha, van Puijvelde, Gijs H. M., Kuiper, Johan, van der Marel, Gijs A., Overkleeft, Herman S.
• Format: Article
• Language: English
• Subjects: activity-based protein profiling; Animals; Boron Compounds - chemistry; Cathepsins - chemistry; Cathepsins - metabolism; Cercopithecus aethiops; Clusters; Compartments; Conjugation; COS Cells; Covalence; Dendritic Cells - cytology; Dendritic Cells - metabolism; drug delivery; endolysosomal pathway; Endosomes - metabolism; Fluorescent Dyes - chemistry; fluorescent probes; Glycopeptides; Glycopeptides - chemical synthesis; Glycopeptides - chemistry; Leucine - analogs & derivatives; Leucine - chemistry; Ligands; mannose-6-phosphate; Mannosephosphates - chemistry; Mice; Pathways; Phosphates; Protein Binding; Receptor, IGF Type 2 - chemistry; Receptors; Uptakes
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.201406842

The ubiquitously expressed mannose‐6‐phosphate receptors (MPRs) are a promising class of receptors for targeted compound delivery into the endolysosomal compartments of a variety of cell types. The development of a synthetic, multivalent, mannose‐6‐phosphate (M6P) glycopeptide‐based MPR ligand is described. The conjugation of this ligand to fluorescent DCG‐04, an activity‐based probe for cysteine cathepsins, enabled fluorescent readout of its receptor‐targeting properties. The resulting M6P‐cluster–BODIPY–DCG‐04 probe was shown to efficiently label cathepsins in cell lysates as well as in live cells. Furthermore, the introduction of the 6‐O‐phosphates leads to a completely altered uptake profile in COS and dendritic cells compared to a mannose‐containing ligand. Competition with mannose‐6‐phosphate abolished all uptake of the probe in COS cells, and we conclude that the mannose‐6‐phosphate cluster targets the MPR and ensures the targeted delivery of cargo bound to the cluster into the endolysosomal pathway. On target: A synthetic glycopeptide (P) that contains six mannose‐6‐phosphate residues was covalently attached to a fluorescent activity‐based probe for cathepsins. The construct was internalized in live cells through binding to the mannose‐6‐phosphate receptor (MPR), thus validating the cluster as an MPR‐targeting ligand that can be used to deliver cargo into the endolysosomal pathway.