title: Characterization of hematopoietic progenitor mobilization in protease-deficient mice.
abstract: Recent evidence suggests that protease release by neutrophils in the bone marrow may contribute to hematopoietic progenitor cell (HPC) mobilization. Matrix metalloproteinase-9 (MMP-9), neutrophil elastase (NE), and cathepsin G (CG) accumulate in the bone marrow during granulocyte colony-stimulating factor (G-CSF) treatment, where they are thought to degrade key substrates including vascular cell adhesion molecule-1 (VCAM-1) and CXCL12. To test this hypothesis, HPC mobilization was characterized in transgenic mice deficient in one or more hematopoietic proteases. Surprisingly, HPC mobilization by G-CSF was normal in MMP-9-deficient mice, NE x CG-deficient mice, or mice lacking dipeptidyl peptidase I, an enzyme required for the functional activation of many hematopoietic serine proteases. Moreover, combined inhibition of neutrophil serine proteases and metalloproteinases had no significant effect on HPC mobilization. VCAM-1 expression on bone marrow stromal cells decreased during G-CSF treatment of wild-type mice but not NE x CG-deficient mice, indicating that VCAM-1 cleavage is not required for efficient HPC mobilization. G-CSF induced a significant decrease in CXCL12 alpha protein expression in the bone marrow of Ne x CG-deficient mice, indicating that these proteases are not required to down-regulate CXCL12 expression. Collectively, these data suggest a complex model in which both protease-dependent and -independent pathways may contribute to HPC mobilization.
authors.affiliation: Stem Cell Biology Laboratory, Peter MacCallum Cancer Institute, Melbourne, Victoria, Australia.
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Levesque
authors.forename: Fulu
authors.initials: F
authors.lastname: Liu
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Simmons
authors.forename: Tomoko
authors.initials: T
authors.lastname: Betsuyaku
authors.forename: Robert M
authors.initials: RM
authors.lastname: Senior
authors.forename: Christine
authors.initials: C
authors.lastname: Pham
authors.forename: Daniel C
authors.initials: DC
authors.lastname: Link
mesh_terms: D000818:Animals; D001853:Bone Marrow / Q000378:metabolism / Q000648:ultrastructure; D020789:Cathepsin C / Q000172:deficiency / Q000235:genetics; D056649:Cathepsin G; D002403:Cathepsins / Q000172:deficiency / Q000235:genetics; D054377:Chemokine CXCL12; D019743:Chemokines, CXC / Q000096:biosynthesis; D003114:Colony-Forming Units Assay; D010450:Endopeptidases / Q000172:deficiency* / Q000235:genetics; D016179:Granulocyte Colony-Stimulating Factor / Q000494:pharmacology; D019650:Hematopoietic Stem Cell Mobilization; D006412:Hematopoietic Stem Cells / Q000166:cytology* / Q000187:drug effects / Q000201:enzymology; D006801:Humans; D016209:Interleukin-8 / Q000235:genetics / Q000494:pharmacology; D020780:Matrix Metalloproteinase 9 / Q000097:blood / Q000172:deficiency / Q000235:genetics; D061965:Matrix Metalloproteinase Inhibitors; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic; D009504:Neutrophils / Q000187:drug effects / Q000201:enzymology / Q000502:physiology; D011480:Protease Inhibitors / Q000494:pharmacology; D019707:Receptors, Chemokine / Q000096:biosynthesis; D011994:Recombinant Proteins / Q000494:pharmacology; D012697:Serine Endopeptidases; D019010:Vascular Cell Adhesion Molecule-1 / Q000378:metabolism
chemical_list: C515255:CXCL12 protein, human; D054377:Chemokine CXCL12; D019743:Chemokines, CXC; C515256:Cxcl12 protein, mouse; D016209:Interleukin-8; D061965:Matrix Metalloproteinase Inhibitors; D011480:Protease Inhibitors; D019707:Receptors, Chemokine; D011994:Recombinant Proteins; D019010:Vascular Cell Adhesion Molecule-1; D016179:Granulocyte Colony-Stimulating Factor; D002403:Cathepsins; D010450:Endopeptidases; D020789:Cathepsin C; D012697:Serine Endopeptidases; C534094:CTSG protein, human; D056649:Cathepsin G; C534096:Ctsg protein, mouse; D020780:Matrix Metalloproteinase 9