Faculty Collaboration Database

The C-terminal peptide of CCL21 drastically augments CCL21 activity through the dendritic cell lymph node homing receptor CCR7 by interaction with the receptor N-terminus. Cell Mol Life Sci 2021 Nov;78(21-22):6963-6978

Date

09/30/2021

Pubmed ID

34586443

Pubmed Central ID

PMC8558179

DOI

10.1007/s00018-021-03930-7

Scopus ID

2-s2.0-85116031161 (requires institutional sign-in at Scopus site)   11 Citations

Abstract

The endogenous chemokines CCL19 and CCL21 signal via their common receptor CCR7. CCL21 is the main lymph node homing chemokine, but a weak chemo-attractant compared to CCL19. Here we show that the 41-amino acid positively charged peptide, released through C-terminal cleavage of CCL21, C21TP, boosts the immune cell recruiting activity of CCL21 by up to 25-fold and the signaling activity via CCR7 by ~ 100-fold. Such boosting is unprecedented. Despite the presence of multiple basic glycosaminoglycan (GAG) binding motifs, C21TP boosting of CCL21 signaling does not involve interference with GAG mediated cell-surface retention. Instead, boosting is directly dependent on O-glycosylations in the CCR7 N-terminus. As dictated by the two-step binding model, the initial chemokine binding involves interaction of the chemokine fold with the receptor N-terminus, followed by insertion of the chemokine N-terminus deep into the receptor binding pocket. Our data suggest that apart from a role in initial chemokine binding, the receptor N-terminus also partakes in a gating mechanism, which could give rise to a reduced ligand activity, presumably through affecting the ligand positioning. Based on experiments that support a direct interaction of C21TP with the glycosylated CCR7 N-terminus, we propose that electrostatic interactions between the positively charged peptide and sialylated O-glycans in CCR7 N-terminus may create a more accessible version of the receptor and thus guide chemokine docking to generate a more favorable chemokine-receptor interaction, giving rise to the peptide boosting effect.

Author List

Jørgensen AS, Brandum EP, Mikkelsen JM, Orfin KA, Boilesen DR, Egerod KL, Moussouras NA, Vilhardt F, Kalinski P, Basse P, Chen YH, Yang Z, Dwinell MB, Volkman BF, Veldkamp CT, Holst PJ, Lahl K, Goth CK, Rosenkilde MM, Hjortø GM

Authors

Michael B. Dwinell PhD Director, Professor in the Microbiology and Immunology department at Medical College of Wisconsin
Brian F. Volkman PhD Professor in the Biochemistry department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Animals
CHO Cells
Cells, Cultured
Chemokine CCL21
Cricetulus
Dendritic Cells
Glycosylation
Humans
Ligands
Lymph Nodes
Peptides
Protein Binding
Receptors, CCR7
Receptors, Lymphocyte Homing
Signal Transduction
Static Electricity