5′‐N‐ethylcarboxamide induces IL‐6 expression via MAPKs and NF‐κB activation through Akt, Ca²⁺/PKC, cAMP signaling pathways in mouse embryonic stem cells

Abstract

Many studies suggest that adenosine modulates cell responses in a wide array of tissues through potent and selective regulation of cytokine production. This study examined the effects of adenosine on interleukin (IL)-6 expression and its related signal pathways in mouse embryonic stem (ES) cells. In this study, the adenosine analogue 5'-N-ethylcarboxamide (NECA) increased IL-6 protein expression level. Mouse ES cells expressed the A(1), A(2A), A(2B), and A(3) adenosine receptors (ARs), whose expression levels were increased by NECA and NECA-induced increase of IL-6 mRNA expression or secretion level was inhibited by the non-specific AR inhibitor, caffeine. NECA increased Akt and protein kinase C (PKC) phosphorylation, intracellular Ca(2+) and cyclic adenosine monophosphate (cAMP) levels, which were blocked by caffeine. On the other hand, NECA-induced IL-6 secretion was partially inhibited by Akt inhibitor, bisindolylmaleimide I (PKC inhibitor), SQ 22536 (adenylate cyclate inhibitor) and completely blocked by the 3 inhibitor combination treatment. In addition, NECA increased mitogen activated protein kinase' (MAPK) phosphorylation, which were partially inhibited by the Akt inhibitor, bisindolylmaleimide I, and SQ 22536 and completely blocked by the 3 inhibitor combination treatment. NECA-induced increases of IL-6 protein expression and secretion levels were inhibited by MAPK inhibition. NECA-induced increase of nuclear factor (NF)-kappaB phosphorylation was inhibited by MAPK inhibitors. NECA also increased cAMP response element-binding protein (CREB) phosphorylation, which was blocked by MAPK or NF-kappaB inhibitors. Indeed, NECA-induced increase of IL-6 protein expression and secretion was blocked by NF-kappaB inhibitors. In conclusion, NECA stimulated IL-6 expression via MAPK and NF-kappaB activation through Akt, Ca(2+)/PKC, and cAMP signaling pathways in mouse ES cells. J. Cell. Physiol. 219: 752-759, 2009. (c) 2009 Wiley-Liss, Inc.

Adenosine A2B receptor-mediated leukemia inhibitory factor release from astrocytes protects cortical neurons against excitotoxicity

“…These data are in line with the study of Aloisi and colleagues, which demonstrated that LIF modulation by pro-inflammatory cytokines in human astrocytes was mediated through PKC activation [59]. Moreover, PKC has also been shown to be essential in IL-6 regulation [47,48,62,65], revealing a prominent role for PKC in the signaling pathway controlling LIF gene expression.…”

“…Furthermore, we show here that adenosine-dependent LIF expression in astrocytes is regulated through the NF-κB transcription factor. This observation is in line with several studies showing an NF-κB-dependent regulation of IL-6 gene by this transcription factor in several cell types [38,50,51,65,66]. It has been shown that NECA-induced NF-κB activation and the resultant IL-6 gene expression was abolished by inhibitors of MAPK pathways [65].…”

Musashi-1 regulates AKT-derived IL-6 autocrinal/paracrinal malignancy and chemoresistance in glioblastoma

“…It is noteworthy that Chiou et al reported a paracrine feedback regulatory loop between miR142-3p and IL-6 in GBM cells [33], in which IL-6 suppresses miR142-3p expression through increasing its promoter methylation, while miR142-3p inhibits IL-6 expression and secretion by directly targeting IL-6 3′UTR. Additionally, AKT is previously reported to play positive role in regulating IL-6 biogenesis and secretion by NF-kappaB and MAPK pathway, supporting that AKT may upstream modulator in IL-6 pro-inflammatory pathway [61, 62]. Although the definition of autocrine and paracrine differs from each other, our solid evidence demonstrates the paracrinal effect of DDP-treated GBM cells but the autocrinal effect is unable to be ruled out from our results.…”

“…Regarding the previous studies, the IL-6 regulatory circuit can be jointly categorized as autocrine/paracrine rather than an individual one [63–67]. Additionally, AKT is previously reported to play positive role in regulating IL-6 biogenesis and secretion by NF-kB and MAPK pathway, supporting the notion that AKT may upstream modulator in IL-6 pro-inflammatory pathway [61, 62]. Recently, IL-6 is reported to play a positive role in regulating AKT/PI3K activity to promote tumor cell survival [68].…”

Involvement of Cx43 phosphorylation in 5′‐N‐ethylcarboxamide‐induced migration and proliferation of mouse embryonic stem cells

“…These results indicate that Cx43 phosphorylation is dependent on AR-mediated signaling in mouse ES cells. Previously, we demonstrated that all AR subtype mRNAs can be detected in mouse ES cells (Kim et al, 2009). ARs might function as novel targets in physiology of mouse ES cells.…”