The novel Nrf2-interacting factor KAP1 regulates susceptibility to oxidative stress by promoting the Nrf2-mediated cytoprotective response.
The transcription factor Nrf2 (nuclear factor-erythroid 2-related factor 2) co-ordinately regulates ARE (antioxidant-response element)-mediated induction of cytoprotective genes in response to electrophiles and oxidative stress; however, the molecular mechanism controlling Nrf2-dependent gene expression is not fully understood. To identify factors that regulate Nrf2-dependent transcription, we searched for proteins that interact with the Nrf2-NT (N-terminal Nrf2 transactivation domain) by affinity purification from HeLa nuclear extracts. In the present study, we identified KAP1 [KRAB (Krüppel-associated box)-associated protein 1] as a novel Nrf2-NT-interacting protein. Pull-down analysis confirmed the interaction between KAP1 and Nrf2 in cultured cells and demonstrated that the N-terminal region of KAP1 binds to Nrf2-NT in vitro. Reporter assays showed that KAP1 facilitates Nrf2 transactivation activity in a dose-dependent manner. Furthermore, the induction of the Nrf2-dependent expression of HO-1 (haem oxygenase-1) and NQO1 [NAD(P)H quinone oxidoreductase 1] by DEM (diethyl maleate) was attenuated by KAP1 knockdown in NIH 3T3 fibroblasts. This finding established that KAP1 acts as a positive regulator of Nrf2. Although Nrf2 nuclear accumulation was unaffected by KAP1 knockdown, the ability of Nrf2 to bind to the regulatory region of HO-1 and NQO1 was reduced. Moreover, KAP1 knockdown enhanced the sensitivity of NIH 3T3 cells to tert-butylhydroquinone, H2O2 and diamide. These results support our contention that KAP1 participates in the oxidative stress response by maximizing Nrf2-dependent transcription.
SciCrunch is a data sharing and display platform. Anyone can create a custom portal where they can select searchable subsets of hundreds of data sources, brand their web pages and create their community. SciCrunch will push data updates automatically to all portals on a weekly basis. User communities can also add their own data to scicrunch, however this is not currently a free service.