2X6G | pdb_00002x6g

Polymerization of Mip-1 Chemokine (Ccl3 and Ccl4) and Clearance of Mip-1 by Insulin-Degrading Enzyme.

(2010) EMBO J 29: 3952

• PubMed: 20959807 Search on PubMedSearch on PubMed Central
• DOI: https://doi.org/10.1038/emboj.2010.256
• Primary Citation Related Structures: 
  2X69, 2X6G, 2X6L


• PubMed Abstract: 
  

  Macrophage inflammatory protein-1 (MIP-1), MIP-1α (CCL3) and MIP-1β (CCL4) are chemokines crucial for immune responses towards infection and inflammation. Both MIP-1α and MIP-1β form high-molecular-weight aggregates. Our crystal structures reveal that MIP-1 aggregation is a polymerization process and human MIP-1α and MIP-1β form rod-shaped, double-helical polymers. Biophysical analyses and mathematical modelling show that MIP-1 reversibly forms a polydisperse distribution of rod-shaped polymers in solution. Polymerization buries receptor-binding sites of MIP-1α, thus depolymerization mutations enhance MIP-1α to arrest monocytes onto activated human endothelium. However, same depolymerization mutations render MIP-1α ineffective in mouse peritoneal cell recruitment. Mathematical modelling reveals that, for a long-range chemotaxis of MIP-1, polymerization could protect MIP-1 from proteases that selectively degrade monomeric MIP-1. Insulin-degrading enzyme (IDE) is identified as such a protease and decreased expression of IDE leads to elevated MIP-1 levels in microglial cells. Our structural and proteomic studies offer a molecular basis for selective degradation of MIP-1. The regulated MIP-1 polymerization and selective inactivation of MIP-1 monomers by IDE could aid in controlling the MIP-1 chemotactic gradient for immune surveillance.

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Organizational Affiliation: 
• Ben-May Department for Cancer Research, The University of Chicago, Chicago, IL 60637, USA.