Rap1-mediated nuclear factor-kappaB (NF-κB) activity regulates the paracrine capacity of mesenchymal stem cells in heart repair following infarction

Abstract

Paracrine effect is the major mechanism that underlies mesenchymal stem cells (MSC)-based therapy. This study aimed to examine how Rap1, telomeric repeat-binding factor 2-interacting protein 1 (Terf2IP), which is a novel modulator involved in the nuclear factor-kappaB (NF-κB) pathway, regulates the paracrine effects of MSC-mediated heart repair following infarction. NF-κB activity of stromal cells was increased by Rap1 as measured by pNF-κB-luciferase reporter activity, and this was abolished by IkB-dominant-negative protein. Knockdown of Rap1 with shRap1 resulted in diminished translocation of p65-NF-κB from the cytoplasm to nuclei in response to tumor necrosis factor-α (TNF-α) stimulation. Compared with BM-MSCs, Rap1−/−-BM-MSCs displayed a significantly reduced ratio of phosphorylated NF-κB to NF-κB-p65 and of Bax to Bcl-2, and increased resistance to hypoxia-induced apoptosis by the terminal deoxynucleotidal transferase-mediated dUTP nick end labeling (TUNEL) assay. In contrast, re-expression of Rap1 in Rap1−/−-BM-MSCs resulted in loss of resistance to apoptosis in the presence of hypoxia. Moreover, absence of Rap1 in BM-MSCs led to downregulation of NF-κB activity accompanied by reduced pro-inflammatory paracrine cytokines TNF-α, IL (interleukin)-6 and monocyte chemotactic protein-1 in Rap1−/−-BM-MSCs compared with BM-MSCs. The apoptosis of neonatal cardiomyocytes (NCMCs) induced by hypoxia was significantly reduced when cocultured with Rap1−/−-BM-MSC hypoxic-conditioned medium (CdM). The increased cardioprotective effects of Rap1−/−-BM-MSCs were reduced when Rap1−/−-BM-MSCs were reconstituted with Rap1 re-expression. Furthermore, in vivo study showed that transplantation of Rap1−/−-BM-MSCs significantly improved heart function, decreased infarct size, prevented cardiomyocyte apoptosis and inhibited inflammation compared with controls and BM-MSCs (P<0.01). This study reveals that Rap1 has a critical role in the regulation of MSC paracrine actions. Compared with BM-MSCs, Rap1−/−-BM-MSCs decreased NF-κB sensitivity to stress-induced pro-inflammatory cytokine production and reduced apoptosis. Selective inhibition of Rap1 in BM-MSCs may be a novel strategy to enhance MSC-based therapeutic efficacy in myocardial infarction.

Intravenous Anesthetics Enhance the Ability of Human Bone Marrow-Derived Mesenchymal Stem Cells to Alleviate Hepatic Ischemia-Reperfusion Injury in a Receptor-Dependent Manner

“…For instance, NF-κB contributes to the production of growth factors (VEGF, FGF2, HGF, and IGF-1) by human MSCs under stimulation with TNF-α, LPS, or hypoxia [36]. In addition, in a hypoxic environment, the decreased activation of NF-κB contributes to a better outcome for myocardial infarction [37,38]. Thus, we hypothesized that NF-κB also participates in the ability of hBM-MSCs to alleviate HIRI.…”

Preconditioning strategies for improving the survival rate and paracrine ability of mesenchymal stem cells in acute kidney injury

“…In contrast, decreased NF-κB activity was observed in Rap1-/-BMSCs, which displayed more resistance to apoptosis and presented better cardioprotective effects in myocardial infarction mice than wild-type BMSCs. 90 Similarly, the results from mice fed a high fat diet (HFD) identified HFD-induced activation of NF-κB in MSCs, contributing to the reduced expression of VEGFA and bFGF. 91 In conclusion, the exact role NF-κB plays in other routes of delivery in AKI models.…”

“…These studies confirmed that the activation of NF‐κB might be involved in the cytoprotective, migratory and paracrine processes of MSCs. In contrast, decreased NF‐κB activity was observed in Rap1‐/‐BMSCs, which displayed more resistance to apoptosis and presented better cardioprotective effects in myocardial infarction mice than wild‐type BMSCs . Similarly, the results from mice fed a high fat diet (HFD) identified HFD‐induced activation of NF‐κB in MSCs, contributing to the reduced expression of VEGFA and bFGF .…”

The role of telomere-binding modulators in pluripotent stem cells

“…Cytoplasmic Rap1 is an inhibitor kinase (IKK) adaptor that controls NFκB pathway (Teo et al, 2010). Suppression of NFκB pathway through knockdown RAP1 is benefit for atherosclerotic lesions and myocardial infarction (Cai et al, 2015;Zhang et al, 2015b). To further investigate the telomeric and extra-telomeric functions of RAP1 should help shed more light on its possible role in pluripotency maintenance.…”