IKK-2 is required for TNF-α-induced invasion and proliferation of human mesenchymal stem cells

Abstract

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.

Harnessing and Modulating Inflammation in Strategies for Bone Regeneration

“…14,81 Exposure to TNF-a significantly affects the in vitro protein expression, proliferation, and migration of undifferentiated human MSCs, but has not been reported to induce differentiation. 11,82 Thus, to study the effects of TNF-a on osteogenically differentiating MSCs, supplements must be added to induce MSC osteogenic differentiation. Studies of the effects of TNF-a on osteogenic differentiation have been complicated by the fact that two supplements typically used to stimulate in vitro MSC osteogenic differentiation, dexamethasone and ascorbic acid, antagonize TNF-a signaling.…”

Fetal Liver-Derived Mesenchymal Stem Cell Engraftment After Allogeneic In Utero Transplantation into Rabbits

“…Indeed, tissue injury seems to release soluble factors (TNF-alpha, SDF-1, etc.) capable of attracting and facilitating the homing of MSCs, which would enhance their repair/regeneration capabilities [40,41], and there are already a variety of preclinical studies and clinical trials exploring the repair/regeneration potential of MSCs in injured tissues (eg, sepsis, acute myocardial infarction, graft-versus-host disease, Crohn's disease, and acute lung injury). However, fetal intervention into uninjured fetal organs seeks to prevent diseases before the onset of irreversible damage.…”

LYG-202 Augments Tumor Necrosis Factor-α-Induced Apoptosis via Attenuating Casein Kinase 2-Dependent Nuclear Factor-κB Pathway in HepG2 Cells

“…The facts that TNF-␣-induced IB␣ phosphorylation requires IKK␤ (Hayden and Ghosh, 2004;Böcker et al, 2008;Schmid and Birbach, 2008) and is inhibited by LYG-202 prompted us to determine the effect of LYG-202 on IKK␤ activation. Results from the IKK␤ kinase assay showed that LYG-202 obviously suppressed IKK␤ activity in a dose-dependent manner (Fig.…”