The DNA damage pathway regulates innate immune system ligands for the NKG2D receptor

摘要

Some stimulatory receptors of the innate immune system, such as the NKG2D receptor expressed by NK cells and activated CD8⁺ T cells, recognize self-molecules that are upregulated in diseased cells by poorly understood mechanisms. Here we show that mouse and human NKG2D ligands are upregulated in non-tumor cell lines by genotoxic stress and stalled DNA replication, conditions known to activate a major DNA damage checkpoint pathway initiated by ATM (Ataxia telangiectasia, mutated) or ATR (ATM- and Rad3-related) protein kinases. Ligand upregulation was prevented by pharmacological or genetic inhibition of ATR, ATM or Chk1, the latter a downstream transducer kinase in the pathway. Furthermore, constitutive ligand expression by a tumor cell line was inhibited by ATM siRNA, suggesting that ligand expression in established tumor cells, which often harbor genomic irregularities, may be due to chronic activation of the DNA damage response pathway. Thus, the DNA damage response, previously shown to arrest the cell cycle and enhance DNA repair functions or to trigger apoptosis, may also participate in alerting the immune system to the presence potentially dangerous cells.