Richter Rudolf, Jochheim-Richter Andrea, Ciuculescu Felicia, Kollar Katarina, Seifried Erhard, Forssmann Ulf, Verzijl Dennis, Smit Martine J, Blanchet Xavier, von Hundelshausen Philipp, Weber Christian, Forssmann Wolf-Georg, Henschler Reinhard
1 Institute of Transfusion Medicine and Immune Hematology , Blood Donation Service of the German Red Cross, Frankfurt, Germany .
Stem Cells Dev. 2014 Aug 15;23(16):1959-74. doi: 10.1089/scd.2013.0524. Epub 2014 May 27.
Mobilization of hematopoietic stem and progenitor cells (HPCs) is induced by treatment with granulocyte-colony stimulating factor, chemotherapy, or irradiation. We observed that these treatments are accompanied by a release of chemotactic activity into the blood. This plasma activity is derived from the bone marrow, liver, and spleen and acts on HPCs via the chemokine receptor CXCR4. A human blood peptide library was used to characterize CXCR4-activating compounds. We identified CXCL12[22-88] and N-terminally truncated variants CXCL12[24-88], CXCL12[25-88], CXCL12[27-88], and CXCL12[29-88]. Only CXCL12[22-88] could effectively bind to CXCR4 and induce intracellular calcium flux and chemotactic migration of HPCs. CXCL12[25-88] and CXCL12[27-88] revealed neither agonistic nor antagonistic activities in vitro, whereas CXCL12[29-88] inhibited CXCL12[22-88]-induced chemotactic migration. Since binding to glycosaminoglycans (GAG) modulates the function of CXCL12, binding to heparin was analyzed. Surface plasmon resonance kinetic analysis showed that N-terminal truncation of Arg22-Pro23 increased the dissociation constant KD by one log10 stage ([22-88]: KD: 5.4 ± 2.6 μM; [24-88]: KD: 54 ± 22.4 μM). Further truncation of the N-terminus decreased the KD ([25-88] KD: 30 ± 4.8 μM; [27-88] KD: 23 ± 1.6 μM; [29-88] KD: 19 ± 5.4 μM), indicating increasing competition for heparin binding. Systemic in vivo application of CXCL12[22-88] as well as CXCL12[27-88] or CXCL12[29-88] induced a significant mobilization of HPCs in mice. Our findings indicate that plasma-derived CXCL12 variants may contribute to the regulation of HPC mobilization by modulating the binding of CXCL12[22-88] to GAGs rather than blocking the CXCR4 receptor and, therefore, may have a contributing role in HPC mobilization.
造血干细胞和祖细胞（HPCs）的动员可通过粒细胞集落刺激因子、化疗或放疗诱导产生。我们观察到，这些治疗会伴随着趋化活性释放到血液中。这种血浆活性源自骨髓、肝脏和脾脏，并通过趋化因子受体CXCR4作用于HPCs。利用人血肽库对CXCR4激活化合物进行了表征。我们鉴定出CXCL12[22 - 88]以及N端截短变体CXCL12[24 - 88]、CXCL12[25 - 88]、CXCL12[27 - 88]和CXCL12[29 - 88]。只有CXCL12[22 - 88]能够有效结合CXCR4并诱导HPCs的细胞内钙流和趋化迁移。CXCL12[25 - 88]和CXCL12[27 - 88]在体外既无激动活性也无拮抗活性，而CXCL12[29 - 88]抑制CXCL12[22 - 88]诱导的趋化迁移。由于与糖胺聚糖（GAG）结合会调节CXCL12的功能，因此分析了其与肝素的结合情况。表面等离子体共振动力学分析表明，Arg22 - Pro23的N端截短使解离常数KD增加了一个对数级（[22 - 88]：KD：5.4±2.6μM；[24 - 88]：KD：54±22.4μM）。N端的进一步截短降低了KD（[25 - 88] KD：30±4.8μM；[27 - 88] KD：23±1.6μM；[29 - 88] KD：19±5.4μM），表明对肝素结合的竞争增加。CXCL12[22 - 88]以及CXCL12[27 - 88]或CXCL12[29 - 88]的全身体内应用均诱导了小鼠体内HPCs的显著动员。我们的研究结果表明，血浆来源的CXCL12变体可能通过调节CXCL12[22 - 88]与GAGs的结合而非阻断CXCR4受体来参与HPCs动员的调节，因此可能在HPCs动员中发挥作用。
