Böcker Wolfgang, Docheva Denitsa, Prall Wolf Christian, Egea Virginia, Pappou Emmanouil, Rossmann Oliver, Popov Cvetan, Mutschler Wolf, Ries Christian, Schieker Matthias
Experimental Surgery and Regenerative Medicine, Department of Surgery, University of Munich (LMU), Nussbaumstrasse 20, 80336, Munich, Germany.
J Mol Med (Berl). 2008 Oct;86(10):1183-92. doi: 10.1007/s00109-008-0378-3. Epub 2008 Jul 4.
Mesenchymal stem cells (MSCs) can contribute to tissue repair by actively migrating to sites of tissue injury. However, the cellular and molecular mechanisms of MSC recruitment are largely unknown. The nuclear factor (NF)-kappaB pathway plays a pivotal role in regulating genes that influence cell migration, cell differentiation, inflammation, and proliferation. One of the major cytokines released at sites of injury is tumor necrosis factor-alpha (TNF-alpha), which is known to be a key regulator of the NF-kappaB pathway. Therefore, we hypothesized that TNF-alpha may lead to MSC invasion and proliferation by activation of the NF-kappaB pathway. TNF-receptor 1 and 2, NF-kappaB (p65), and IkappaB kinase 2 (IKK-2) are expressed in human MSCs (hMSCs). Stimulation of hMSCs with TNF-alpha caused a p65 translocation from the cytoplasm to nucleoplasm but did not change the expression profile of MSC markers. TNF-alpha strongly augmented the migration of hMSCs through the human extracellular matrix. Using lentiviral gene transfer, overexpressing a dominant-negative mutant of IKK-2 (dn-IKK-2) significantly blocked this effect. NF-kappaB target genes associated with migration (vascular cell adhesion molecule-1, CD44, and matrix metalloproteinase 9) were upregulated by TNF-alpha stimulation and blocked by dn-IKK-2. Moreover, using the bromodeoxyuridine assay, we showed that the inhibition of the NF-kappaB pathway caused a significant reduction in the basal proliferation rate. TNF-alpha stimulated the proliferation of hMSCs, whereas overexpression of dn-IKK-2 significantly blocked this effect. TNF-alpha led to the upregulated expression of the proliferation-associated gene cyclin D1. In conclusion, we demonstrated that the NF-kappaB pathway components, p65 and IKK-2, are expressed in hMSCs. Our data provide evidence that this signal transduction pathway is implicated in TNF-alpha-mediated invasion and proliferation of hMSCs. Therefore, hMSC recruitment to sites of tissue injury may, at least in part, be regulated by the NF-kappaB signal transduction pathway.
间充质干细胞（MSCs）可通过主动迁移至组织损伤部位来促进组织修复。然而，MSCs募集的细胞和分子机制在很大程度上尚不清楚。核因子（NF）-κB通路在调控影响细胞迁移、细胞分化、炎症和增殖的基因方面起着关键作用。损伤部位释放的主要细胞因子之一是肿瘤坏死因子-α（TNF-α），已知它是NF-κB通路的关键调节因子。因此，我们推测TNF-α可能通过激活NF-κB通路导致MSCs侵袭和增殖。TNF受体1和2、NF-κB（p65）以及IκB激酶2（IKK-2）在人MSCs（hMSCs）中表达。用TNF-α刺激hMSCs导致p65从细胞质转位至核质，但未改变MSC标志物的表达谱。TNF-α强烈增强hMSCs通过人细胞外基质的迁移。使用慢病毒基因转移，过表达IKK-2的显性负突变体（dn-IKK-2）显著阻断了这种效应。与迁移相关的NF-κB靶基因（血管细胞黏附分子-1、CD44和基质金属蛋白酶9）通过TNF-α刺激而上调，并被dn-IKK-2阻断。此外，使用溴脱氧尿苷检测，我们表明抑制NF-κB通路导致基础增殖率显著降低。TNF-α刺激hMSCs的增殖，而dn-IKK-2的过表达显著阻断了这种效应。TNF-α导致增殖相关基因细胞周期蛋白D1的表达上调。总之，我们证明了NF-κB通路成分p65和IKK-2在hMSCs中表达。我们的数据提供了证据表明该信号转导通路与TNF-α介导的hMSCs侵袭和增殖有关。因此，hMSCs募集至组织损伤部位可能至少部分受NF-κB信号转导通路调控。
