Diverse roles of the ubiquitin system in NF-κB activation.

NF-κB is a transcription factor known to be involved in pleomorphic biological phenomena such as inflammation and immune responses. Abnormal activation of NF-κB has been reported in many pathological conditions, including allergic and auto-inflammatory diseases and malignancies. Therefore, the NF-κB activation pathway has been extensively studied and involvement of the ubiquitin conjugation system in the NF-κB activation pathways has been shown. Also non-degradable roles of the ubiquitin system have been revealed, recently. Several types of polyubiquitin chains exist and the type of chain seems to determine how ubiquitinated proteins are regulated. Roles of non-degradable types of polyubiquitin chains such as K63, linear and K11 chains in NF-κB activation is one of the big issues in NF-κB research. Thus, this short article discusses the differential roles of those polyubiquitin chains in NF-κB activation. This article is part of a Special Issue entitled: Ubiquitin-Proteasome System. Guest Editors: Thomas Sommer and Dieter H. Wolf.