GM-CSF is an important haematopoietic growth factor and immune modulator. Studies on T cells revealed that efficient activation of the human GM-CSF gene is dependent upon the activation of an enhancer located 3 kb upstream of the promoter, inducible by phorbol myristate acetate and calcium ionophore (PMNI) via kinase-and Ca\(^2\)\(^+\) -dependent signalling pathways, respectively. This enhancer is often aberrantly remodelled as a constitutive DNase hypersensitive site (DHS) in acute myeloid leukaemia (AML). To investigate the role of MAPKs in enhancer activity and chromatin remodelling, I used activated T blasts and human leukaemic cell lines as inducible model systems. The combination of MEK and p38 MAPK inhibitors reduced PMNI-induced GM-CSF gene expression and the DHS at the enhancer. This was associated with a reduction in DNA-binding activity for the MAPK-inducible AP-1 and in the phosphorylation of MSK1, which in turn stimulates NF-κB transcriptional activity by phosphorylating p65 at Ser276. The combination of MEK and p38 inhibitors also reduced the PMNI-mediated recruitment of AP-1, MSK1 and NF-κB at the enhancer. These data demonstrate a cross-talk between the MAPK and NF-κB signalling pathways in regulating GM-CSF gene transcription and therefore represent potential targets for the treatment of AML cases where aberrant chromatin remodelling occurs.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:642369 |
| Date | January 2015 |
| Creators | Canestraro, Martina |
| Publisher | University of Birmingham |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://etheses.bham.ac.uk//id/eprint/5720/ |
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