Stromal cell-derived factor 1 alpha-induced chemotaxis in T cells is mediated by nitric oxide signaling pathways

Stromal cell-derived factor 1 alpha (SDF1 alpha) and its cognate chemokine receptor CXCR4 act as potent chemoattractants and regulate trafficking and homing of hematopoietic progenitor cells and lymphocytes. However, the molecular mechanisms regulating SDF1 alpha-driven cell migration are not well defined. In this study, we have explored the roles of the second messenger NO and the transcription factor NF-kappa B in SDF1 alpha-induced T cell migration. SDF1 alpha treatment of Jurkat T cells increased the activity of NO synthase, which catalyzes the generation of NO. We observed that pretreatment of Jurkat cells or activated PBLs with several NO donors significantly enhanced the SDF1 alpha-induced migration, whereas various inhibitors of NO synthase markedly abrogated the chemotactic response in a concentration-dependent manner. Furthermore, we observed that inhibitors of the transcription factor NF-kappa B, which is linked to NO signaling pathways, also significantly blocked the SDF1 alpha-induced chemotactic response. However, these compounds did not have a significant effect on SDF1 alpha-induced mitogen-activated protein kinase activity. In addition, the MAP/Erk kinase kinase inhibitor PD98059 did not abrogate SDF1 alpha-induced chemotaxis. AKT, which has been shown to mediate NO production, was also phosphorylated upon SDF1 alpha stimulation. These studies suggest that NO-related signaling pathways may mediate SDF1 alpha-induced chemotaxis, but not mitogen-activated protein kinase activation.