Majka M, Ratajczak J, Lee B, Honczarenko M, Douglas R, Kowalska M A, Silberstein L, Gewirtz A M, Ratajczak M Z
Department of Pathology & Laboratory Medicine, Children's Hospital of Philadelphia, PA 19104, USA.
Stem Cells. 2000;18(2):128-38. doi: 10.1634/stemcells.18-2-128.
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.
为了更好地确定与HIV相关的趋化因子在人类红细胞生成中的作用，我们进行了以下研究：A）趋化因子受体在包括红系祖细胞的人类CD34(+)细胞以及更成熟的红系细胞上的表达；B）通过钙流、趋化性测定以及丝裂原活化蛋白激酶（MAPK）p42/44（ERK1/ERK2）和AKT的磷酸化来检测这些受体的功能，最后C）趋化因子对爆式红系集落形成单位（BFU-E）形成的影响。我们发现，在人类CD34(+) BFU-E细胞上可检测到与HIV相关的趋化因子受体CXCR4，而不是CCR5。尽管从分化的红系集落中分离出的细胞中仍存在CXCR4 mRNA，但在红系成熟过程中CXCR4的表面表达下降。CXCR4的配体基质细胞衍生因子-1（SDF-1）可诱导含有BFU-E的CD34(+)KIT(+)骨髓单个核细胞中的钙流以及MAPK（p42/44）和AKT的磷酸化，同时还可诱导人类CD34(+) BFU-E祖细胞以及从第2 - 6天的BFU-E集落中分离出的红系细胞的趋化活性。当细胞分化到表达红系特异性标志物血型糖蛋白-A时，对SDF-1的反应性降低。相反CCR5的配体（巨噬细胞炎性蛋白-1α [MIP-1α]、MIP-一β和调节激活正常T细胞表达和分泌因子 [RANTES]）不会激活CD34(+)KIT(+)细胞或从BFU-E集落中分离出的细胞的钙流、MAPK和AKT磷酸化或趋化性。有趣的是，本研究中测试的任何趋化因子对BFU-E集落形成均无影响。总之，只有CXCR4具有功能，因此其特异性配体SDF-1可能在早期红系前体细胞归巢和/或保留于骨髓环境中发挥重要作用。
