DNA-PKcs, but not TLR9, is required for activation of Akt by CpG-DNA.
CpG-DNA and its related synthetic CpG oligodeoxynucleotides (CpG-ODNs) play an important role in immune cell survival. It has been suggested that Akt is one of the CpG-DNA-responsive serine/threonine kinases; however, the target protein of CpG-DNA that leads to Akt activation has not been elucidated. Here, we report that ex vivo stimulation of bone marrow-derived macrophages (BMDMs) from mice lacking the catalytic subunit of DNA-dependent protein kinase (DNA-PKcs) results in defective phosphorylation and activation of Akt by CpG-DNA. Unexpectedly, loss of the Toll-like receptor 9 has a minimal effect on Akt activation in response to CpG-DNA. Further in vitro analysis using purified DNA-PK and recombinant Akt proteins reveals that DNA-PK directly induces phosphorylation and activation of Akt. In addition, in BMDMs, DNA-PKcs associates with Akt upon CpG-DNA stimulation and triggers transient nuclear translocation of Akt. Thus, our findings establish a novel role for DNA-PKcs in CpG-DNA signaling and define a CpG-DNA/DNA-PKcs/Akt pathway.
Dragoi
Ana-Maria
AM
Department of Molecular Microbiology and Immunology, Brown University, Providence, RI 02912, USA.
Fu
Xiaoying
X
Ivanov
Stanimir
S
Zhang
Ping
P
Sheng
Linbo
L
Wu
Dianqing
D
Li
Gloria C
GC
Chu
Wen-Ming
WM
D021581:Active Transport, Cell Nucleus / Q000187:drug effects; D000818:Animals; D001853:Bone Marrow / Q000187:drug effects / Q000201:enzymology; D002478:Cells, Cultured; D051747:DNA-Activated Protein Kinase; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004789:Enzyme Activation; D008264:Macrophages / Q000187:drug effects / Q000201:enzymology; D051379:Mice; D018345:Mice, Knockout; D009838:Oligodeoxyribonucleotides / Q000494:pharmacology*; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt; D011956:Receptors, Cell Surface / Q000378:metabolism; D051217:Toll-Like Receptor 9
C408982:CPG-oligonucleotide; D004268:DNA-Binding Proteins; D009838:Oligodeoxyribonucleotides; D011518:Proto-Oncogene Proteins; D011956:Receptors, Cell Surface; C495370:Tlr9 protein, mouse; D051217:Toll-Like Receptor 9; D051747:DNA-Activated Protein Kinase; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt