Chemokine CXCL1 mediated neutrophil recruitment: Role of glycosaminoglycan interactions.
The chemokine CXCL1/MGSA plays a pivotal role in the host immune response by recruiting and activating neutrophils for microbial killing at the tissue site. CXCL1 exists reversibly as monomers and dimers, and mediates its function by binding glycosaminoglycans (GAG) and CXCR2 receptor. We recently showed that both monomers and dimers are potent CXCR2 agonists, the dimer is the high-affinity GAG ligand, lysine and arginine residues located in two non-overlapping domains mediate GAG interactions, and there is extensive overlap between GAG and receptor-binding domains. To understand how these structural properties influence in vivo function, we characterized peritoneal neutrophil recruitment of a trapped monomer and trapped dimer and a panel of WT lysine/arginine to alanine mutants. Monomers and dimers were active, but WT was more active indicating synergistic interactions promote recruitment. Mutants from both domains showed reduced GAG heparin binding affinities and reduced neutrophil recruitment, providing compelling evidence that both GAG-binding domains mediate in vivo trafficking. Further, mutant of a residue that is involved in both GAG binding and receptor signaling showed the highest reduction in recruitment. We conclude that GAG interactions and receptor activity of CXCL1 monomers and dimers are fine-tuned to regulate neutrophil trafficking for successful resolution of tissue injury.
Department of Biochemistry and Molecular Biology, The University of Texas Medical Branch, Galveston, TX, USA.
Kirti V
KV
Sawant
Department of Biochemistry and Molecular Biology, The University of Texas Medical Branch, Galveston, TX, USA.
Krishna Mohan
KM
Poluri
Department of Biochemistry and Molecular Biology, The University of Texas Medical Branch, Galveston, TX, USA.
Amit K
AK
Dutta
Department of Biochemistry and Molecular Biology, The University of Texas Medical Branch, Galveston, TX, USA.
Krishna Mohan
KM
Sepuru
Department of Biochemistry and Molecular Biology, The University of Texas Medical Branch, Galveston, TX, USA.
Anna
A
Troshkina
Department of Microbiology and Immunology, The University of Texas Medical Branch, Galveston, TX, USA.|Department of Pediatrics, The University of Texas Medical Branch, Galveston, TX, USA.
Roberto P
RP
Garofalo
Department of Biochemistry and Molecular Biology, The University of Texas Medical Branch, Galveston, TX, USA.|Department of Microbiology and Immunology, The University of Texas Medical Branch, Galveston, TX, USA.|Sealy Center for Structural Biology and Molecular Biophysics, The University of Texas Medical Branch, Galveston, TX, USA.
Krishna
K
Rajarathnam
D000818:Animals; D002465:Cell Movement; D054360:Chemokine CXCL1 / Q000235:genetics / Q000378:metabolism*; D005260:Female; D006025:Glycosaminoglycans / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008807:Mice, Inbred BALB C; D009154:Mutation; D009504:Neutrophils / Q000166:cytology / Q000378:metabolism*; D023063:Receptors, Interleukin-8B / Q000235:genetics / Q000378:metabolism*
D054360:Chemokine CXCL1; C475895:Cxcl1 protein, mouse; D006025:Glycosaminoglycans; D023063:Receptors, Interleukin-8B; C020341:glucosaminoglycans