Leukocyte elastase negatively regulates Stromal cell-derived factor-1 (SDF-1)/CXCR4 binding and functions by amino-terminal processing of SDF-1 and CXCR4.
Activation of CXCR4 by the CXC chemokine stromal cell-derived factor-1 (SDF-1) requires interaction of the amino-terminal domains of both molecules. We report that proteinases released from either mononucleated blood cells or polymorphonuclear neutrophils degranulated by inflammatory stimuli generate an SDF-1 fragment that is deleted from amino-terminal residues Lys(1)-Pro(2)-Val(3), as characterized by mass spectrometry analysis. The proteolyzed chemokine fails to induce agonistic functions and is unable to prevent the fusogenic capacity of CXCR4-tropic human immunodeficiency viruses. Furthermore, we observed that exposure of CXCR4-expressing cells to leukocyte proteinases results in the proteolysis of the extracellular amino-terminal domain of the receptor, as assessed by flow cytometry analysis and electrophoretic separation of immunoprecipitated CXCR4. Blockade of SDF-1 and CXCR4 proteolysis by the specific leukocyte elastase inhibitor, N-methoxysuccinyl-alanine-alanine-proline-valine-chloromethyl ketone, identified elastase as the major enzyme among leukocyte-secreted proteinases that accounts for inactivation of both SDF-1 and CXCR4. Indeed, purified leukocyte elastase generated in either SDF-1 or CXCR4 a pattern of cleavage indistinguishable from that observed with leukocyte-secreted proteinases. Our findings suggest that elastase-mediated proteolysis of SDF-1/CXCR4 is part of a mechanism regulating their biological functions in both homeostatic and pathologic processes.
Valenzuela-Fernández
Agustín
A
Unité d'Immunologie Virale, INSERM U485 de l'Institut Pasteur, 28 Rue du Dr. Roux, 75724 Paris Cedex 15, France.
Planchenault
Thierry
T
Baleux
Françoise
F
Staropoli
Isabelle
I
Le-Barillec
Karine
K
Leduc
Dominique
D
Delaunay
Thierry
T
Lazarini
Françoise
F
Virelizier
Jean-Louis
JL
Chignard
Michel
M
Pidard
Dominique
D
Arenzana-Seisdedos
Fernando
F
D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D001665:Binding Sites; D002118:Calcium / Q000378:metabolism; D002459:Cell Fusion; D054377:Chemokine CXCL12; D019743:Chemokines, CXC / Q000378:metabolism* / Q000494:pharmacology; D003600:Cytosol / Q000378:metabolism; D015497:HIV-1 / Q000502:physiology; D006801:Humans; D019169:Jurkat Cells; D019272:Leukocyte Elastase / Q000378:metabolism*; D007963:Leukocytes, Mononuclear / Q000201:enzymology / Q000502:physiology; D051379:Mice; D009842:Oligopeptides / Q000378:metabolism / Q000494:pharmacology; D019718:Receptors, CXCR4 / Q000378:metabolism*; D017384:Sequence Deletion; D021241:Spectrometry, Mass, Electrospray Ionization; D017154:Stromal Cells / Q000378:metabolism; D013379:Substrate Specificity
D000911:Antibodies, Monoclonal; C515255:CXCL12 protein, human; D054377:Chemokine CXCL12; D019743:Chemokines, CXC; C515256:Cxcl12 protein, mouse; D009842:Oligopeptides; D019718:Receptors, CXCR4; D019272:Leukocyte Elastase; D002118:Calcium