Immune responses to invading pathogens are mediated largely through a family of 
transmembrane Toll-like receptors and modulated by a number of downstream 
effectors. In particular, a family of four interleukin 1 receptor-associated 
kinases (IRAK) regulates responsiveness to bacterial endotoxins. Pharmacological 
targeting of particular IRAK components may be beneficial for treatment of 
bacterial infections. Here, we studied transcriptional regulation of the human 
IRAK2 gene. Analysis of the IRAK2 promoter region reveals putative binding sites 
for several transcriptional factors, including ZIP (EGR1 and SP1), CTCF and 
AP-2beta. Deletion of the ZIP or AP-2 sites did not significantly affect IRAK2 
promoter activity in naive and endotoxin-treated mononuclear cells, in dormant 
and activated Jurkat T-cells, in lung and kidney cells. In contrast, we found 
that CTCF plays a major role in IRAK2 transcription. An electrophoretic mobility 
shift assay of the DNA fragments containing the IRAK2 CpG island, revealed a 
single high-affinity binding site for the transcriptional regulator and a 
chromatin insulator protein, CTCF. This assay revealed a CTCF-binding site 
within the mouse Irak2 promoter. The presence of the CTCF protein in human IRAK2 
promoter was confirmed by chromatin immunoprecipitation assay. Specific residues 
that interacted with the CTCF protein, were identified by methylation 
interference assay. In all cell lines analyzed, including cells of lung, renal, 
monocytic and T-cell origin, the IRAK2 luciferase reporter construct, containing 
an intact CTCF-binding site, showed strong promoter activity. However, IRAK2 
promoter activity was decreased dramatically for the constructs with a mutated 
CTCF-binding site.