Proteoglycans on bone marrow endothelial cells bind and present SDF-1 towards hematopoietic progenitor cells.
Recognition events between hematopoietic progenitor cells (HPC) and bone marrow endothelial cells (BMEC) initiate homing of HPC to the bone marrow. The chemokine SDF-1 is present on BMEC and plays a crucial role in bone marrow engraftment. We studied the role of proteoglycans (PGs) on BMEC in binding and presentation of SDF-1. SDF-1 mRNA was present in three human BMEC cell lines. Competition experiments showed that 125I-SDF-1 alpha binding to the BMEC cell line 4LHBMEC was inhibited by heparins, heparan sulfate (HS) intestinal mucosa, chondroitin and dermatan sulfate (CS/DS), but not by HS bovine kidney. Pretreatment of 4LHBMEC with glycosaminoglycan (GAG)-degrading enzymes or sodium chlorate demonstrated that SDF-1 bound to both HSPGs and CS/DSPGs in a sulfation-dependent manner, as determined with an SDF-1 antibody recognizing the CXCR4-binding site. 4LHBMEC bound four-fold more SDF-1 than HUVEC. Isolated endothelial PGs did not bind SDF-1 in a filter or microplate-binding assay, suggesting the necessity of membrane association. In flow adhesion experiments, endothelial arrest of CXCR4+ KG-1 and not of CXCR4- KG-1a cells increased significantly when SDF-1 was presented on 4LHBMEC. In conclusion, SDF-1 is produced by BMEC and binds to the BMEC cell surface via HS and CS/DS-GAGs, thereby presenting its CXCR4 binding site to HPC contributing to their arrest.
Netelenbos
T
T
Department of Hematology, Vrije Universiteit Medical Center, Amsterdam, The Netherlands.
van den Born
J
J
Kessler
F L
FL
Zweegman
S
S
Merle
P A
PA
van Oostveen
J W
JW
Zwaginga
J J
JJ
Huijgens
P C
PC
Dräger
A M
AM
D000818:Animals; D001854:Bone Marrow Cells / Q000378:metabolism*; D002417:Cattle; D054377:Chemokine CXCL12; D019743:Chemokines, CXC / Q000235:genetics / Q000378:metabolism*; D002704:Chlorates / Q000494:pharmacology; D002809:Chondroitin Sulfates / Q000494:pharmacology; D017931:DNA Primers / Q000737:chemistry; D003871:Dermatan Sulfate / Q000494:pharmacology; D004730:Endothelium, Vascular / Q000378:metabolism*; D005434:Flow Cytometry; D006412:Hematopoietic Stem Cells / Q000378:metabolism*; D019812:Heparan Sulfate Proteoglycans / Q000494:pharmacology / Q000502:physiology*; D006497:Heparan Sulfate / Q000494:pharmacology; D006801:Humans; D016133:Polymerase Chain Reaction; D011485:Protein Binding; D017154:Stromal Cells / Q000378:metabolism
D054377:Chemokine CXCL12; D019743:Chemokines, CXC; D002704:Chlorates; D002809:Chondroitin Sulfates; D017931:DNA Primers; D003871:Dermatan Sulfate; D019812:Heparan Sulfate Proteoglycans; D006497:Heparan Sulfate; C515255:CXCL12 protein, human; C032706:sodium chlorate