The role of protein kinase CK2 in intestinal epithelial cell inflammatory signaling.
BACKGROUND
The transcription factor NF-kappaB is believed to play a key pathophysiological role in chronic intestinal inflammation. Further characterization of its mechanism of regulation, predominantly through cell signaling pathways, may provide clues as to the means of its intervention. One such potential signaling candidate is the protein kinase CK2. Despite its known ability to influence NF-kappaB activation, it has received no attention in this particular setting.


OBJECTIVE
To characterize the aspects of its activation in response to IL-1beta in the colonic cell lines Caco2 and HCT116.


METHODS
A biochemical analysis of kinase activation was performed using phospho-specific antibodies as well as immune complex kinase assays; transcription factor activity was measured by transient transfection and luciferase-based NF-kappaB reporter assays; pro-inflammatory molecule expression was determined using RT-PCR.


RESULTS
In this report, we show an enhanced activation of CK2 bound to IKKgamma or the p65 subunit of the NF-kappaB in response to IL-1beta stimulation of intestinal epithelial cells. Using two established NF-kappaB reporters, we demonstrate that CK2 is involved in NF-kappaB regulation through the p65 serine 529 site. Using co-immunoprecipitation studies, we also show that p65 is bound to CK2 predominantly in the nucleus. From a functional perspective, two CK2 specific inhibitors were then shown to attenuate IL-8 reporter activation. Finally, the expression of a series of pro-inflammatory molecules including IL-8, GRO-alpha, MCP-1, TNFalpha and iNOS were variably affected in response to CK2 inhibition.


CONCLUSIONS
CK2 plays an active role in NF-kappaB signaling in intestinal epithelial cell lines and may represent a possible target for intervention.
Parhar
Kuljit
K
The Jack Bell Research Center, 2660 Oak Street, V6H 3Z6, Vancouver, British Columbia, Canada.
Morse
Jennifer
J
Salh
Baljinder
B
D047390:Casein Kinase II / Q000037:antagonists & inhibitors / Q000378:metabolism*; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism; D004847:Epithelial Cells / Q000187:drug effects / Q000201:enzymology* / Q000473:pathology*; D045325:HCT116 Cells; D006801:Humans; D051550:I-kappa B Kinase / Q000378:metabolism; D007249:Inflammation; D018836:Inflammation Mediators / Q000378:metabolism; D053583:Interleukin-1beta / Q000494:pharmacology; D016209:Interleukin-8 / Q000235:genetics; D007422:Intestines / Q000187:drug effects / Q000201:enzymology* / Q000473:pathology*; D007700:Kinetics; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding / Q000187:drug effects; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects; D051996:Transcription Factor RelA / Q000235:genetics / Q000378:metabolism; D015533:Transcriptional Activation / Q000187:drug effects
D018836:Inflammation Mediators; D053583:Interleukin-1beta; D016209:Interleukin-8; D047428:Protein Kinase Inhibitors; D051996:Transcription Factor RelA; D047390:Casein Kinase II; D051550:I-kappa B Kinase