Thesis

The role of purinergic receptors in the modulation of JNK signalling endothelial and cancer cells

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Awarding institution
  • University of Strathclyde
Date of award
  • 2012
Thesis identifier
  • T13208
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Department, School or Faculty
Abstract
  • Purinergic receptors (P2YR) are a family of G-protein coupled receptors (GPCRs) which have been shown to regulate MAPK (mitogen activated protein kinase) signalling to elicit pro-inflammatory responses in diseases such as atherosclerosis.1,2 Within the MAPK family, JNK (c-Jun NH2-terminal kinase) is strongly activated by pro-inflammatory cytokines, including tumour necrosis factor-α (TNF-α) and interleukin-1β (IL-1β).3,4 Thus, this project examined the potential for purinergic and cytokine receptors to interact at the signalling level. In particular, it was hypothesised that purinoceptors could inhibit cytokine induced JNK signalling. In human umbilical vein endothelial cells (HUVECs), activation of P2YR by ATP produced a concentration dependent inhibition of TNF-α and IL-1β mediated JNK activity, as measured by Western blotting and in vitro kinase assays. This inhibitory effect was cytokine specific, as neither sorbitol nor anisomycin dependent JNK activity was affected. Furthermore, ATP altered neither cytokine mediated p38 MAPK nor NF-κB signalling, indicating that the effect was pathway specific. In order to identify the P2YR involved, HUVECs were pre-treated with antagonists for P2Y11 (NF340) or P2Y1 (MRS2179), but only NF340 reversed the inhibitory effect of ATP. The signalling pathways involved were also studied using the Gq/11 inhibitor YM254890 and the PKA inhibitor H89, which produced a partial and complete reversal of ATP mediated inhibition respectively. ATP mediated JNK inhibition was also translated into a physiological outcome via a reduction in IL-1β dependent cyclo-oxygenase 2 expression. In MDA-MB-231 breast cancer cells, ATP and adenosine also inhibited cytokine dependent JNK signaling. Surprisingly, ATP inhibited the UVC-mediated JNK signalling, which was completely reversed by the Gq/11 inhibitor YM254890. The JNK dependent apoptotic effect of UVC was also examined, but neither the JNK inhibitor SP600125, nor ATP had a significant effect on apoptosis. In conclusion, this study supported an emerging signalling paradigm that GPCR activation can negatively modulate JNK signalling in endothelial and cancer cells.
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DOI
Date Created
  • 2012
Former identifier
  • 947894

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