MT1-MMP association with membrane lipid rafts facilitates G-CSF--induced hematopoietic stem/progenitor cell mobilization.
OBJECTIVE
Soluble matrix metalloproteinases (MMPs) facilitate the egress of hematopoietic stem/progenitor cells (HSPC) from the bone marrow (BM) during granulocyte colony-stimulating factor (G-CSF)-induced mobilization. Because membrane-type (MT)1-MMP, which is localized on the leading edge of migrating cells, activates the latent forms of soluble MMPs, we investigated its role in HSPC mobilization.


METHODS
We examined the effect of G-CSF on the expression of MT1-MMP and its activities (proMMP-2 activation and migration) in hematopoietic cells. We also investigated the subcellular localization of MT1-MMP and the signaling pathways that regulate its expression and function in hematopoietic cells after exposure to G-CSF.


RESULTS
We found that G-CSF increases MT1-MMP transcription and protein synthesis in hematopoietic cells; proMMP-2 activation in cocultures of HSPC with BM fibroblasts; chemoinvasion across reconstituted basement membrane Matrigel toward a stromal cell-derived factor-1 gradient, which is reduced by small interfering RNA silencing of MT1-MMP; and localization of MT1-MMP to membrane lipid rafts through a mechanism that is regulated by the phosphatidylinositol 3-kinase signaling pathway. Disruption of raft formation (by the cholesterol-sequestering agent methyl-beta-cyclodextrin) abrogated phosphatidylinositol 3-kinase phosphorylation and MT1-MMP incorporation into lipid rafts resulting in reduced proMMP-2 activation and HSPC migration.


CONCLUSIONS
G-CSF-induced upregulation of MT1-MMP in hematopoietic cells and its enhanced incorporation into membrane lipid rafts contributes to proMMP-2 activation, which facilitates mobilization of HSPC.
Shirvaikar
Neeta
N
Department of Medicine, University of Alberta, Edmonton, Alberta, Canada.
Marquez-Curtis
Leah A
LA
Shaw
Andrew R
AR
Turner
A Robert
AR
Janowska-Wieczorek
Anna
A
D002465:Cell Movement; D002478:Cells, Cultured; D018920:Coculture Techniques; D004789:Enzyme Activation / Q000187:drug effects; D004792:Enzyme Precursors / Q000378:metabolism; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism; D018093:Gelatinases / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects*; D016179:Granulocyte Colony-Stimulating Factor / Q000494:pharmacology*; D019650:Hematopoietic Stem Cell Mobilization; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000201:enzymology*; D006801:Humans; D053511:Matrix Metalloproteinase 14 / Q000096:biosynthesis*; D021962:Membrane Microdomains / Q000201:enzymology*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D015398:Signal Transduction / Q000187:drug effects; D017154:Stromal Cells / Q000166:cytology / Q000378:metabolism; D015854:Up-Regulation / Q000187:drug effects*; D047392:beta-Cyclodextrins / Q000494:pharmacology
D004792:Enzyme Precursors; D047392:beta-Cyclodextrins; C108732:methyl-beta-cyclodextrin; D016179:Granulocyte Colony-Stimulating Factor; D019869:Phosphatidylinositol 3-Kinases; D018093:Gelatinases; C069860:progelatinase; C507086:MMP14 protein, human; D053511:Matrix Metalloproteinase 14