Roles of IκB kinase ε in the innate immune defense and beyond.

IκB kinase ε (IKKε) is a non-canonical IκB kinase that is extensively studied in the context of innate immune response. Recently, significant progress has been made in understanding the role of IKKε in interferon (IFN) signaling. In addition to its roles in innate immunity, recent studies also demonstrate that IKKε is a key regulator of the adaptive immune response. Specifically, IKKε functions as a negative feedback kinase to curtail CD8 T cell response, implying that it can be a potential therapeutic target to boost antiviral and antitumor T cell immunity. In this review, we highlight the roles of IKKε in regulating IFN signaling and T cell immunity, and discuss a few imminent questions that remain to be answered.