The role of HIV-related chemokine receptors and chemokines in human erythropoiesis in vitro.
In order to better define the role of HIV-related chemokines in human erythropoiesis we studied: A) the expression of chemokine receptors, both on human CD34(+) cells which include erythroid progenitors and on more mature erythroid cells; B) the functionality of these receptors by calcium flux, chemotaxis assay and phosphorylation of mitogen-activated protein kinases (MAPK) p42/44 (ERK1/ERK2) and AKT, and finally C) the influence of chemokines on BFU-E formation. We found that HIV-related chemokine receptor CXCR4, but not CCR5, is detectable on human CD34(+) BFU-E cells. CXCR4 surface expression decreased during erythroid maturation, although CXCR4 mRNA was still present in cells isolated from differentiated erythroid colonies. SDF-1, a CXCR4 ligand, induced calcium flux and phosphorylation of MAPK (p42/44) and AKT in CD34(+)KIT(+) bone marrow mononuclear cells which contain BFU-E, as well as chemotactic activity of both human CD34(+) BFU-E progenitors and erythroid cells isolated from day 2-6 BFU-E colonies. Responsiveness to SDF-1 decreased when the cells differentiated to the point of surface expression of the erythroid-specific marker Glycophorin-A. In contrast, the CCR5 ligands (macrophage inflammatory protein-1alpha [MIP-1alpha], MIP-1beta, and RANTES) did not activate calcium flux, MAPK and AKT phosphorylation or chemotaxis of CD34(+)KIT(+) cells or cells isolated from the BFU-E colonies. Interestingly, none of the chemokines tested in this study had any effect on BFU-E colony formation. In conclusion, only CXCR4 is functional, and its specific ligand SDF-1 may therefore play an important role in the homing and/or retention of early erythroid precursors in the bone marrow environment.
Majka
M
M
Department of Pathology & Laboratory Medicine, Children's Hospital of Philadelphia, PA 19104, USA.
Ratajczak
J
J
Lee
B
B
Honczarenko
M
M
Douglas
R
R
Kowalska
M A
MA
Silberstein
L
L
Gewirtz
A M
AM
Ratajczak
M Z
MZ
D018952:Antigens, CD34; D002118:Calcium / Q000378:metabolism; D002455:Cell Division; D002478:Cells, Cultured; D018925:Chemokines / Q000502:physiology*; D002633:Chemotaxis; D016895:Culture Media, Serum-Free; D015672:Erythroid Precursor Cells / Q000166:cytology / Q000378:metabolism; D004920:Erythropoiesis / Q000502:physiology*; D015870:Gene Expression; D006678:HIV / Q000378:metabolism*; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000378:metabolism; D006801:Humans; D008024:Ligands; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D010766:Phosphorylation; D019707:Receptors, Chemokine / Q000235:genetics / Q000502:physiology*
D018952:Antigens, CD34; D018925:Chemokines; D016895:Culture Media, Serum-Free; D008024:Ligands; D019707:Receptors, Chemokine; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D002118:Calcium