The basic residue cluster (55)KKWVR(59) in CCL5 is required for in vivo biologic function
Stephan Segerer1, Zoë Johnson, Angelika Rek
1University Hospital Zürich, Switzerland. Stephan.segerer@usz.ch
Molecular Immunology
|June 16, 2009
Summary
The 50s loop of chemokine CCL5 is crucial for its presentation and function in vivo, impacting leukocyte adhesion and recruitment. This contrasts with the 40s loop
Area of Science:
- Immunology
- Biochemistry
- Cell Biology
Background:
- Chemokine function relies on presentation by extracellular matrix or endothelial surfaces.
- CCL5 has two basic residue clusters ((44)RKNR(47) and (55)KKWVR(59)) involved in protein presentation.
- The role of the 50s loop ((55)KKWVR(59)) in CCL5 presentation was previously uncharacterized.
Purpose of the Study:
- To investigate the role of the 50s loop in CCL5 presentation and function.
- To determine the differential contributions of the 40s and 50s loops to CCL5-mediated biological processes.
Main Methods:
- Ex vivo tissue binding assays.
- In vitro T lymphocyte and monocyte adhesion assays under flow.
- In vivo leukocyte recruitment to the peritoneal cavity.
- Enzyme-linked immunosorbent assay (ELISA) for endothelial cell binding.
Main Results:
- Both 40s and 50s loops are necessary for direct tissue binding.
- The 50s mutant showed reduced T lymphocyte and monocyte adhesion under flow.
- Leukocyte recruitment in vivo was diminished with the 50s mutant.
- Endothelial cell binding was significantly reduced for the 50s mutant compared to wild-type CCL5.
- The 50s mutant had minimal impact on glycosaminoglycan (GAG) binding in vitro.
Conclusions:
- Functional CCL5 presentation involves both the 40s and 50s loops.
- The 40s and 50s loops of CCL5 have distinct roles in mediating its biological functions.
- The 50s loop is critical for CCL5 binding to endothelial cells and subsequent leukocyte recruitment.
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