title: Carboxypeptidase M expressed by human bone marrow cells cleaves the C-terminal lysine of stromal cell-derived factor-1alpha: another player in hematopoietic stem/progenitor cell mobilization?
abstract: Carboxypeptidase M (CPM) is a membrane-bound zinc-dependent protease that cleaves C-terminal basic residues, such as arginine or lysine, from peptides/proteins. We examined whether CPM is expressed by hematopoietic and stromal cells and could degrade stromal cell-derived factor (SDF)-1alpha, a potent chemoattractant for hematopoietic stem/progenitor cells (HSPC). We found that (a) CPM transcript is expressed by bone marrow (BM) and mobilized peripheral blood CD34(+) cells, myeloid, erythroid, and megakaryocytic cell progenitors, mononuclear cells (MNC), polymorphonuclear cells (PMN), and stromal cells, including mesenchymal stem cells; and that (b) granulocyte-colony-stimulating factor (G-CSF) significantly increases its expression at the gene and protein levels in MNC and PMN. Moreover, we found that recombinant CPM cleaves full-length SDF-1alpha (1-68) rapidly, removing the C-terminal lysine and yielding des-lys SDF-1alpha (1-67). We demonstrated that such CPM treatment of SDF-1alpha reduced the in vitro chemotaxis of HSPC, which, however, was preserved when the CPM was exposed to the carboxypeptidase inhibitor dl-2-mercaptomethyl-3-guanidino-ethylthiopropanoic acid. Thus, we present evidence that CPM is expressed by cells occurring in the BM microenvironment and that the mobilizing agent G-CSF strongly upregulates it in MNC and PMN. We suggest that cleavage of the C-terminal lysine residue of SDF-1alpha by CPM leads to attenuated chemotactic responses and could facilitate G-CSF-induced mobilization of HSPC from BM to peripheral blood.
authors.affiliation: Research and Development, Canadian Blood Services, Edmonton, Alberta, Canada.
authors.forename: Leah
authors.initials: L
authors.lastname: Marquez-Curtis
authors.forename: Ali
authors.initials: A
authors.lastname: Jalili
authors.forename: Kathleen
authors.initials: K
authors.lastname: Deiteren
authors.forename: Neeta
authors.initials: N
authors.lastname: Shirvaikar
authors.forename: Anne-Marie
authors.initials: AM
authors.lastname: Lambeir
authors.forename: Anna
authors.initials: A
authors.lastname: Janowska-Wieczorek
mesh_terms: D001854:Bone Marrow Cells / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*; D002460:Cell Line; D054377:Chemokine CXCL12 / Q000737:chemistry* / Q000378:metabolism*; D002633:Chemotaxis / Q000187:drug effects; D058851:GPI-Linked Proteins; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D016179:Granulocyte Colony-Stimulating Factor / Q000494:pharmacology; D019650:Hematopoietic Stem Cell Mobilization; D006413:Hematopoietic System / Q000166:cytology / Q000187:drug effects; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000166:cytology / Q000187:drug effects / Q000201:enzymology; D008239:Lysine / Q000378:metabolism*; D008666:Metalloendopeptidases / Q000235:genetics / Q000378:metabolism*; D009504:Neutrophils / Q000166:cytology / Q000187:drug effects / Q000201:enzymology; D011485:Protein Binding / Q000187:drug effects; D019718:Receptors, CXCR4 / Q000378:metabolism; D015854:Up-Regulation / Q000187:drug effects
chemical_list: D054377:Chemokine CXCL12; D058851:GPI-Linked Proteins; D019718:Receptors, CXCR4; D016179:Granulocyte Colony-Stimulating Factor; C058479:carboxypeptidase M; D008666:Metalloendopeptidases; D008239:Lysine