Nucleolin Mediates LPS-induced Expression of Inflammatory Mediators and Activation of Signaling Pathways

Abstract

In this study, we investigated the effects of nucleolin on lipopolysaccharide (LPS)induced activation of MAPK and NF-KappaB (NF-κB) signaling pathways and secretion of TNF-α, IL-1β and HMGB1 in THP-1 monocytes. Immunofluorescence assay and Western blotting were used to identify the nucleolin expression in cell membrane, cytoplasm and nucleus of THP-1 monocytes. Inactivation of nucleolin was induced by neutralizing antibody against nucleolin. THP-1 monocytes were pretreated with anti-nucleolin antibody for 1 h prior to LPS challenge. The irrelevant IgG group was used as control. Secretion of inflammatory mediators (TNF-α, IL-1β and HMGB1) and activation of MAPK and NF-κB/I-κB signaling pathways were examined to assess the effects of nucleolin on LPS-mediated inflammatory response. Nucleolin existed in cell membrane, cytoplasm and nucleus of THP-1 monocytes. Pretreatment of anti-nucleolin antibody significantly inhibited the LPS-induced secretion of TNF-α, IL-1β and HMGB1. P38, JNK, ERK and NF-κB subunit p65 inhibitors could significantly inhibit the secretion of IL-1β, TNF-α and HMGB1 induced by LPS. Moreover, the phosphorylation of p38, JNK, ERK and p65 (or nuclear translocation of p65) was significantly increased after LPS challenge. In contrast, pretreatment of anti-nucleolin antibody could significantly inhibit the LPS-induced phosphorylation of p38, JNK, ERK and p65 (or nuclear translocation of p65). However, the irrelevant IgG, as a negative control, had no effect on LPS-induced secretion of TNF-α and IL-1β and phosphorylation of p38, JNK, ERK and p65 (or nuclear translocation of p65). We demonstrated that nucleolin mediated the LPS-induced activation of MAPK and NF-κB signaling pathways, and regulated the secretion of inflammatory mediators (TNF-α, IL-1β and HMGB1).

Anti-nucleolin aptamer, iSN04, inhibits the inflammatory responses in myoblasts by modulating the β-catenin/NF-κB signaling pathway

“…Accordingly, nucleolin knockdown inhibits GSK-3β phosphorylation and reduces β-catenin protein [50]. A recent study showed that anti-nucleolin neutralizing antibody inhibits NF-κB nuclear translocation and inflammatory gene expression induced by lipopolysaccharide, a TLR4 ligand [51]. These findings suggest that nucleolin antagonism by iSN04 inhibits GSK-3β phosphorylation, which leads to β-catenin degradation and NF-κB inactivation, eventually exerting an anti-inflammatory effect.…”

TLR4 TIR domain and nucleolin GAR domain synergistically mediate RSV infection and induce neuronal inflammatory damage in SH‐SY5Y cells

“…Although there are clinical reports of acute neurological complications associated with RSV, the adverse effects of such complications have often been previously underestimated. In recent years, with the widespread reports of RSV‐related encephalopathy, an increasing number of scholars have realized that RSV‐related neurological symptoms are important clinical manifestations, and the possibility of RSV infection should be considered when children present with acute neurological symptoms 36 . The pathogenesis of RSV‐related encephalopathy may vary, and our previous studies have shown that TLR4 and NCL co‐mediate the infection of neurons by the virus, but the specific mechanism remains to be further studied.…”

“…The above studies suggest that the GAR domain of NCL may be an important receptor domain of RSV‐infected nerve cells. The M protein is a non‐glycosylated structural protein lining the inner leaflet of the viral envelope that binds to the cytoplasmic structural domains of F proteins 36 . Here, we examined M protein mRNA expression to reflect the effects of TIR and GAR on RSV replication.…”

Efficient In Vitro and In Vivo Anti-Inflammatory Activity of a Diamine-PEGylated Oleanolic Acid Derivative

“…The NF-κB and MAPK pathways are essential in regulating the production of inflammatory cytokines in activated macrophages such as TNF-α, IL-1β, and IL-6. TNF-α participates in various processes such as cell survival, apoptosis, and necrosis, by stimulating TNF receptors and related pathways, such as NF-κB and MAPKs [ 33 ]. The LPS-induced pattern of macrophage activation leads to high production of inflammatory mediators, such as TNF-α, IL-1β, and IL-6.…”