Identification of the NF-κB inhibitor A20 as a key regulator for human adipogenesis

Abstract

The zinc-finger protein A20 is a key player in the negative feedback regulation of the nuclear factor kappa-light-chain-enhancer of activated B-cell (NF-κB) pathway in response to multiple stimuli. Tumor necrosis factor alpha (TNFα), a cytokine with pleiotropic effects on cellular proliferation and differentiation, dramatically increases A20 expression in all tissues. As TNFα inhibits adipocyte differentiation, we have determined the contribution of A20 to the adipogenic capacity of human mesenchymal stromal cells (MSCs). Here we show that A20 is constitutively expressed in MSCs, which previously has been observed only in cells that are either tumor or immune cells (T/B lymphocytes). TNFα stimulation induced a rapid degradation of A20 protein mediated exclusively by the proteasome in MSCs and not by caspases. This degradation is concomitant to the induction of its own mRNA, which suggests that a tight regulation of NF-κB signaling in MSCs is fundamental. On one hand, we demonstrate that the knockdown of A20-mediated transcript dramatically decreases the adipogenic capacity of MSCs, which correlates with the phenotype observed in the presence of TNFα. On the other hand, A20 overexpression blocks NF-κB activation and drives to increased adipogenesis, even in the presence of TNFα treatment. In conclusion, our data demonstrate that the presence of A20 allows MSCs to differentiate into adipocytes by maintaining NF-κB signaling at a basal state.

A20 plays a critical role in the immunoregulatory function of mesenchymal stem cells

“…Here, we found that shA20 MSCs exhibit an enhanced proliferative capacity as has been demonstrated for other immune cells, which is possibly as a result of increased expression of NF-jB-dependent, anti-apoptotic proteins. Dorronsoro et al reported that A20 is a key regulator in human adipogenesis [35]. In this study, we showed that the adipogenic differentiation capacity was dramatically decreased in shA20 C3 MSCs.…”

“…Dorronsoro et al . reported that A20 is a key regulator in human adipogenesis . In this study, we showed that the adipogenic differentiation capacity was dramatically decreased in shA20 C3 MSCs.…”

Deubiquitinases A20 and CYLD modulate costimulatory signaling via CD137 (4–1BB)

“…Lentivirus encoding shRNA to silence endogenous A20 expression and EGFP were produced by the Viral Vector Platform at Inbiomed Foundation as described previously. 72,73 Purified human CD8 T cells were preactivated 24 hours with CD3/ CD28 magnetics beads prior lentiviral infection, which was performed at a multiplicity of infection of 10 overnight. After, cells were incubated with plated bound anti-CD3 (OKT3) and anti-CD137 (6B4) or mIgG1 mAbs for 48 hours and Bcl-xL expression levels were monitored by flow cytometry.…”

Mesenchymal stem cell deficiency influences megakaryocytopoiesis through the TNFAIP3/NF‐κB/SMAD pathway in patients with immune thrombocytopenia

“…Activation of the NF‐κB/SMAD7 pathway can lead to MSC differentiation deficiency (Wang et al , ). Dorronsoro et al () demonstrated that the presence of TNFAIP3 allows MSCs to differentiate into adipocytes by maintaining NF‐κB signalling at a basal level. Activated NF‐κB inhibits osteogenic differentiation in bone marrow mesenchymal stem cells (Tang et al , ).…”