The cyclin-dependent kinase inhibitor R-roscovitine down-regulates Mcl-1 to override pro-inflammatory signalling and drive neutrophil apoptosis.
Successful resolution of inflammation requires inflammatory cells such as neutrophils to undergo apoptosis prior to non-inflammatory phagocytosis by professional phagocytes. Recently, cyclin-dependent kinase (CDK) inhibitors (e.g. R-roscovitine) have been shown to induce neutrophil apoptosis and enhance the resolution of inflammation. Interestingly, NF-kappaB and MAPK pathways and key endogenous survival proteins (typified by Mcl-1) are involved in the regulation of neutrophil apoptosis and, in cancer-cell lines, have been implicated as possible targets of CDK inhibitors. Here, we demonstrate that R-roscovitine over-rides TNF-alpha and LPS-induced survival (determined by morphological examination and binding of fluorescently labelled annexin-V) of isolated peripheral blood neutrophils. This effect did not appear to be mediated via effects on early markers of neutrophil activation (e.g. surface marker expression, shape change, aggregation and superoxide anion generation), by direct inhibition of NF-kappaB activation (assessed by cytoplasmic IkappaBalpha proteolysis and NF-kappaB p65 subunit translocation) and ERK activation (determined by specific ERK phosphorylation) but due to down-regulation (at protein and mRNA level) of the survival protein Mcl-1 but not the pro-apoptotic bcl-2 homologue Bim. These findings suggest that key endogenous survival proteins may be the targets of CDK inhibitors and consequently may be of critical importance in the resolution of inflammation.
Leitch
Andrew E
AE
MRC Centre for Inflammation Research, The Queen's Medical Research Institute, University of Edinburgh Medical School, Edinburgh, Scotland, UK. aleitch3@staffmail.ed.ac.uk
Riley
Nicola A
NA
Sheldrake
Tara A
TA
Festa
Michela
M
Fox
Sarah
S
Duffin
Rodger
R
Haslett
Christopher
C
Rossi
Adriano G
AG
D000328:Adult; D017209:Apoptosis / Q000187:drug effects*; D051017:Apoptosis Regulatory Proteins / Q000096:biosynthesis / Q000235:genetics; D000072224:Bcl-2-Like Protein 11; D002478:Cells, Cultured / Q000166:cytology / Q000187:drug effects / Q000201:enzymology; D018844:Cyclin-Dependent Kinases / Q000037:antagonists & inhibitors* / Q000502:physiology; D015536:Down-Regulation / Q000187:drug effects; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D006801:Humans; D008070:Lipopolysaccharides / Q000494:pharmacology; D008565:Membrane Proteins / Q000096:biosynthesis / Q000235:genetics; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D016328:NF-kappa B / Q000378:metabolism; D009504:Neutrophils / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*; D021381:Protein Transport / Q000187:drug effects; D011518:Proto-Oncogene Proteins / Q000096:biosynthesis / Q000235:genetics; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000096:biosynthesis* / Q000235:genetics; D011687:Purines / Q000494:pharmacology*; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D000077546:Roscovitine; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
D051017:Apoptosis Regulatory Proteins; C000606775:BCL2L11 protein, human; D000072224:Bcl-2-Like Protein 11; D008070:Lipopolysaccharides; D008565:Membrane Proteins; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D016328:NF-kappa B; D047428:Protein Kinase Inhibitors; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D011687:Purines; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D000077546:Roscovitine; D018844:Cyclin-Dependent Kinases; D048049:Extracellular Signal-Regulated MAP Kinases