Long noncoding RNA HOXA‐AS2 mediates microRNA‐106b‐5p to repress sepsis‐engendered acute kidney injury

HOXA cluster antisense RNA 2 (HOXA‐AS2) is a long noncoding RNA associated with the development of numerous cancers. But, whether HOXA‐AS2 exhibits a certain function in sepsis‐engendered acute kidney injury (AKI) remains uninvestigated. We strived to unveil the role of HOXA‐AS2 in sepsis‐engendered AKI. The expression of HOXA‐AS2 in sepsis patients, animal models and lipopolysaccharide (LPS)‐impaired HK‐2 cells was primarily assessed via a real‐time quantitative polymerase chain reaction. The effects of HOXA‐AS2 on cell survival of HK‐2 cells under LPS irritation were evaluated after overexpression of HOXA‐AS2. The correlation between HOXA‐AS2 and microRNA (miR)‐106b‐5p was forecasted via bioinformatics software and verified by using a luciferase report system. Subsequently, the functions of miR‐106b‐5p in LPS‐damaged HK‐2 cells were reassessed. Western blot was used for the determination of Wnt/β‐catenin and nuclear factor‐κB (NF‐κB) pathways. HOXA‐AS2 expression was decreased in sepsis patients, animal operation group and LPS‐irritated HK‐2 cells. Overexpressed HOXA‐AS2 mollified LPS‐triggered impairment in HK‐2 cells. In addition, a negative mediatory relation between HOXA‐AS2 and miR‐106b‐5p was predicated. Synchronously, overexpressed miR‐106b‐5p counteracted the protection of HOXA‐AS2 in LPS‐damaged HK‐2 cells. Ultimately, Wnt/β‐catenin and NF‐κB pathways were hindered by HOXA‐AS2 via targeting miR‐106b‐5p. HOXA‐AS2 exhibited protection in sepsis‐engendered AKI via targeting miR‐106b‐5p and hindering the Wnt/β‐catenin and NF‐κB pathways.     

Silencing of ATP2B1‐AS1 contributes to protection against myocardial infarction in mouse via blocking NFKBIA‐mediated NF‐κB signalling pathway

Myocardial infarction (MI) is an acute coronary syndrome that refers to tissue infarction of the myocardium. This study aimed to investigate the effect of long intergenic non‐protein‐coding RNA (lincRNA) ATPase plasma membrane Ca²⁺ transporting 1 antisense RNA 1 (ATP2B1‐AS1) against MI by targeting nuclear factor‐kappa‐B inhibitor alpha (NFKBIA) and mediating the nuclear factor‐kappa‐B (NF‐κB) signalling pathway. An MI mouse model was established and idenepsied by cardiac function evaluation. It was determined that ATP2B1‐AS1 was highly expressed, while NFKBIA was poorly expressed and NF‐κB signalling pathway was activated in MI mice. Cardiomyocytes were extracted from mice and introduced with a series of mouse ATP2B1‐AS1 vector, NFKBIA vector, siRNA‐mouse ATP2B1‐AS1 and siRNA‐NFKBIA. The expression of NF‐κBp50, NF‐κBp65 and IKKβ was determined to idenepsy whether ATP2B1‐AS1 and NFKBIA affect the NF‐κB signalling pathway, the results of which suggested that ATP2B1‐AS1 down‐regulated the expression of NFKBIA and activated the NF‐κB signalling pathway in MI mice. Based on the data from assessment of cell viability, cell cycle, apoptosis and levels of inflammatory cytokines, either silencing of mouse ATP2B1‐AS1 or overexpression of NFKBIA was suggested to result in reduced cardiomyocyte apoptosis and expression of inflammatory cytokines, as well as enhanced cardiomyocyte viability. Our study provided evidence that mouse ATP2B1‐AS1 silencing may have the potency to protect against MI in mice through inhibiting cardiomyocyte apoptosis and inflammation, highlighting a great promise as a novel therapeutic target for MI.     

p97/VCP promotes Cullin‐RING‐ubiquitin‐ligase/proteasome‐dependent degradation of IκBα and the preceding liberation of RelA from ubiquitinated IκBα

Cullin‐RING‐ubiquitin‐ligase (CRL)‐dependent ubiquitination of the nuclear factor kappa B (NF‐κB) inhibitor IκBα and its subsequent degradation by the proteasome usually precede NF‐κB/RelA nuclear activity. Through removal of the CRL‐activating modification of their cullin subunit with the ubiquitin (Ub)‐like modifier NEDD8, the COP9 signalosome (CSN) opposes CRL Ub‐ligase activity. While RelA phosphorylation was observed to mediate NF‐κB activation independent of Ub‐proteasome‐pathway (UPP)‐dependent turnover of IκBα in some studies, a strict requirement of the p97/VCP ATPase for both, IκBα degradation and NF‐κB activation, was reported in others. In this study, we thus aimed to reconcile the mechanism for tumour necrosis factor (TNF)‐induced NF‐κB activation. We found that inducible phosphorylation of RelA is accomplished in an IKK‐complex‐dependent manner within the NF‐κB/RelA‐IκBα‐complex contemporaneous with the phosphorylation of IκBα, and that RelA phosphorylation is not sufficient to dissociate NF‐κB/RelA from IκBα. Subsequent to CRL‐dependent IκBα ubiquitination functional p97/VCP is essentially required for efficient liberation of (phosphorylated) RelA from IκBα, preceding p97/VCP‐promoted timely and efficient degradation of IκBα as well as simultaneous NF‐κB/RelA nuclear translocation. Collectively, our data add new facets to the knowledge about maintenance of IκBα and RelA expression, likely depending on p97/VCP‐supported scheduled basal NF‐κB activity, and the mechanism of TNF‐induced NF‐κB activation.     

Down‐regulation of mitogen‐activated protein kinases and nuclear factor‐κB signaling is involved in rapamycin suppression of TLR2‐induced inflammatory response in monocytic THP‐1 cells

Tripalmitoyl‐S‐glycero‐Cys‐(Lys) 4 (Pam3CSK4) interacted with TLR2 induces inflammatory responses through the mitogen‐activated protein kinases (MAPKs) and nuclear factor‐κB (NF‐κB) signal pathway. Rapamycin can suppress TLR‐induced inflammatory responses; however, the detailed molecular mechanism is not fully understood. Here, the mechanism by which rapamycin suppresses TLR2‐induced inflammatory responses was investigated. It was found that Pam3CSK4‐induced pro‐inflammatory cytokines were significantly down‐regulated at both the mRNA and protein levels in THP‐1 cells pre‐treated with various concentrations of rapamycin. Inhibition of phosphatidylinositol 3‐kinase/protein kinase‐B (PI3K/AKT) signaling did not suppress the expression of pro‐inflammatory cytokines, indicating that the immunosuppression mediated by rapamycin in THP1 cells is independent of the PI3K/AKT pathway. RT‐PCR showed that Erk and NF‐κB signal pathways are related to the production of pro‐inflammatory cytokines. Inhibition of Erk or NF‐κB signaling significantly down‐regulated production of pro‐inflammatory cytokines. Additionally, western blot showed that pre‐treatment of THP‐1 cells with rapamycin down‐regulates MAPKs and NF‐κB signaling induced by Pam3CSK4 stimulation, suggesting that rapamycin suppresses Pam3CSK4‐induced pro‐inflammatory cytokines via inhibition of TLR2 signaling. It was concluded that rapamycin suppresses TLR2‐induced inflammatory responses by down‐regulation of Erk and NF‐κB signaling.     

Negative regulation of NF‐κB action by Set9‐mediated lysine methylation of the RelA subunit

Proper regulation of NF‐κB activity is critical to maintain and balance the inflammatory response. Inactivation of the NF‐κB complex relies in part on the proteasome‐mediated degradation of promoter‐bound NF‐κB, but the detailed molecular mechanism initiating this process remains elusive. Here, we show that the methylation of the RelA subunit of NF‐κB has an important function in this process. Lysine methyltransferase Set9 physically associates with RelA in vitro and in vivo in response to TNF‐α stimulation. Mutational and mass spectrometric analyses reveal that RelA is monomethylated by Set9 at lysine residues 314 and 315 in vitro and in vivo. Methylation of RelA inhibits NF‐κB action by inducing the proteasome‐mediated degradation of promoter‐associated RelA. Depletion of Set9 by siRNA or mutation of the RelA methylation sites prolongs DNA binding of NF‐κB and enhances TNF‐α‐induced expression of NF‐κB target genes. Together, these findings unveil a novel mechanism by which methylation of RelA dictates the turnover of NF‐κB and controls the NF‐κB‐mediated inflammatory response.     

Concurrent inhibition of NF‐κB,cyclooxygenase‐2, and epidermal growth factor receptor leads to greater anti‐tumor activity in pancreatic cancer

Inactivation of survival pathways such as NF‐κB, cyclooxygenase (COX‐2), or epidermal growth factor receptor (EGFR) signaling individually may not be sufficient for the treatment of advanced pancreatic cancer (PC) as suggested by recent clinical trials. 3,3′‐Diindolylmethane (B‐DIM) is an inhibitor of NF‐κB and COX‐2 and is a well‐known chemopreventive agent. We hypothesized that the inhibition of NF‐κB and COX‐2 by B‐DIM concurrently with the inhibition of EGFR by erlotinib will potentiate the anti‐tumor effects of cytotoxic drug gemcitabine, which has been tested both in vitro and in vivo. Inhibition of viable cells in seven PC cell lines treated with B‐DIM, erlotinib, or gemcitabine alone or their combinations was evaluated using 3‐(4,5‐dimetylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide (MTT) assay. Significant inhibition in cell viability was observed in PC cells expressing high levels of COX‐2, EGFR, and NF‐κB proteins. The observed inhibition was associated with an increase in apoptosis as assessed by ELISA. A significant down‐regulation in the expression of COX‐2, NF‐κB, and EGFR in BxPC‐3, COLO‐357, and HPAC cells was observed, suggesting that simultaneous targeting of EGFR, NF‐κB, and COX‐2 is more effective than targeting either signaling pathway separately. Our in vitro results were further supported by in vivo studies showing that B‐DIM in combination with erlotinib and gemcitabine was significantly more effective than individual agents. Based on our preclinical in vitro and in vivo results, we conclude that this multi‐targeted combination could be developed for the treatment of PC patients whose tumors express high levels of COX‐2, EGFR, and NF‐κB. J. Cell. Biochem. 110: 171–181, 2010. © 2010 Wiley‐Liss, Inc.