Kerst J M, Sanders J B, Slaper-Cortenbach I C, Doorakkers M C, Hooibrink B, van Oers R H, von dem Borne A E, van der Schoot C E
Central Laboratory, Red Cross Blood Transfusion Service, Amsterdam, The Netherlands.
Blood. 1993 Jan 15;81(2):344-51.
To study the receptors involved in the interaction between extracellular matrix proteins and hematopoietic progenitor cells, we analyzed the expression of beta 1 integrins on CD34+ bone marrow cells by means of immunoflowcytometry. Alpha 4 beta 1 and alpha 5 beta 1 were expressed, whereas alpha 1 beta 1, alpha 2 beta 1, alpha 3 beta 1, alpha 6 beta 1, and alpha v beta 1 were virtually absent. Furthermore, we assessed the alpha 4 and alpha 5 expression on committed myeloid progenitor cells. These colony-forming cells were detected in the alpha 4 dull fraction and the alpha 5 dull fraction. During myeloid differentiation, both in vivo and in vitro, a differential expression of alpha 4 beta 1 and alpha 5 beta 1 was observed. alpha 5 beta 1 was found to be lost at the myelocytic-metamyelocytic stage, before the loss of alpha 4 beta 1, at the band stage. Functional studies showed no binding of erythroid progenitor-depleted, CD34+ bone marrow cells to fibronectin. However, protein kinase C activation strongly induced fibronectin binding (68% of the cells). Inhibition experiments with specific antibodies and peptides showed the binding to be mediated by both alpha 4 beta 1 and alpha 5 beta 1. Also, colony-forming cells of granulocytes and macrophages were demonstrated to adhere to fibronectin in an activation-dependent way. During granulocyte colony-stimulating factor-induced in vitro maturation, the activation-dependent fibronectin binding capacity is gradually lost. We conclude that: (1) CD34+ bone marrow cells express alpha 4 beta 1 and alpha 5 beta 1; (2) the expression of alpha 4 beta 1 and alpha 5 beta 1 is differentially expressed during myeloid differentiation; and (3) binding of CD34+ bone marrow cells to fibronectin is activation dependent.
为研究细胞外基质蛋白与造血祖细胞相互作用中涉及的受体，我们通过免疫流式细胞术分析了CD34⁺骨髓细胞上β1整合素的表达。α4β1和α5β1表达，而α1β1、α2β1、α3β1、α6β1和αvβ1几乎不存在。此外，我们评估了定向髓系祖细胞上α4和α5的表达。这些集落形成细胞在α4低表达部分和α5低表达部分被检测到。在体内和体外的髓系分化过程中，观察到α4β1和α5β1的差异表达。发现α5β1在髓细胞-晚幼粒细胞阶段丢失，早于α4β1在杆状核阶段的丢失。功能研究表明，去除红系祖细胞的CD34⁺骨髓细胞与纤连蛋白无结合。然而，蛋白激酶C激活强烈诱导纤连蛋白结合（68%的细胞）。用特异性抗体和肽进行的抑制实验表明，结合是由α4β1和α5β1介导的。此外，粒细胞和巨噬细胞的集落形成细胞被证明以激活依赖的方式黏附于纤连蛋白。在粒细胞集落刺激因子诱导的体外成熟过程中，激活依赖的纤连蛋白结合能力逐渐丧失。我们得出结论：（1）CD34⁺骨髓细胞表达α4β1和α5β1；（2）α4β1和α5β1的表达在髓系分化过程中存在差异；（3）CD34⁺骨髓细胞与纤连蛋白的结合是激活依赖的。
