Sharma M, Afrin F, Tripathi Rp, Gangenahalli G
Stem Cell & Gene Therapy Research Group, Institute of Nuclear Medicine & Allied Sciences , Delhi-110054, India.
Department of Biotechnology, Jamia Hamdard University , New Delhi-110062, India.
J Stem Cells Regen Med. 2013 Apr 30;9(1):19-27. doi: 10.46582/jsrm.0901005. eCollection 2013.
SDF-1/CXCR4 axis plays a principle role in the homing and engraftment of hematopoietic stem/progenitor cells (HSPCs), a process that defines cells ability to reach and seed recipient bone marrow niche following their intravenous infusion. However, the proper functioning of CXCR4 downstream signaling depends upon consistent optimal expression of both SDF-1 ligand and its receptor CXCR4, which in turn is variable and regulated by several factors. The constitutive active mutants of CXCR4 (N119A and N119S) being able to induce autonomous downstream signaling, overcome the limitation of ligand-receptor interaction for induction of CXCR4 signaling. Therefore, we intended to explore their potential in Chemotaxis; a key cellular process which crucially regulates cells homing to bone marrow. In present study, Tet-on inducible gene expression vector system was used for doxycycline inducible regulated transgene expression of CXCR4 active mutants in hematopoietic stem progenitor cell line K-562. Both of these mutants revealed significantly enhanced Chemotaxis to SDF-1 gradient as compared to wild type. Furthermore, gene expression profiling of these genetically engineered cells as assessed by microarray analysis revealed the up-regulation of group of genes that are known to play a crucial role in CXCR4 mediated cells homing and engraftment. Hence, this study suggest the potential prospects of CXCR4 active mutants in research and development aimed to improve the efficiency of cells in the mechanism of homing and engraftment process.
基质细胞衍生因子-1（SDF-1）/CXC趋化因子受体4（CXCR4）轴在造血干/祖细胞（HSPCs）的归巢和植入过程中起主要作用，该过程决定了细胞静脉输注后到达并定植于受体骨髓微环境的能力。然而，CXCR4下游信号的正常功能取决于SDF-1配体及其受体CXCR4的持续最佳表达，而这又受到多种因素的影响且具有变异性。CXCR4的组成型活性突变体（N119A和N119S）能够诱导自主下游信号，克服了配体-受体相互作用对CXCR4信号诱导的限制。因此，我们旨在探索它们在趋化作用中的潜力；趋化作用是一个关键的细胞过程，对细胞归巢至骨髓起着至关重要的调节作用。在本研究中，采用Tet-on诱导型基因表达载体系统，在造血干祖细胞系K-562中进行强力霉素诱导的CXCR4活性突变体转基因表达调控。与野生型相比，这两种突变体对SDF-1梯度的趋化作用均显著增强。此外，通过微阵列分析评估这些基因工程细胞的基因表达谱，发现一组已知在CXCR4介导的细胞归巢和植入中起关键作用的基因上调。因此，本研究提示CXCR4活性突变体在旨在提高细胞归巢和植入机制效率的研发中具有潜在前景。
