Molecular characterization of BRSK2 and BRSK1 kinases as negative regulators of the NRF2 transcription factor

ABSTRACT: NFE2L2/NRF2 is a transcription factor and master regulator of the cellular antioxidant response. Aberrantly high NRF2-dependent transcription is recurrent in human cancer, resulting in increased cellular fitness, chemo-radiation resistance, metabolic reprogramming and immune evasion. NRF2 protein levels and activity is governed primarily by the KEAP1/CUL3 ubiquitin ligase and subsequent proteasomal degradation. To what extent parallel signaling pathways and protein classes impact NRF2 activity remains to be fully explored. Also, because NRF2-directed therapies remain in the discovery and early development stages, continued identification and validation of NRF2 regulators is of potential clinical value. Here we used a gain-of-function genetic screen of the kinome to identify druggable activators and inhibitors of NRF2 signaling. We found that the understudied Brain Selective Kinase 1 and 2 (BRSK1/2) proteins suppress NRF2-dependent transcription and NRF2 protein levels in a kinase-dependent fashion. Integrative phospho-proteomic screens, RNAseq profiling and follow-up validation studies revealed BRSK1/2-driven activation of AMPK and suppression of MTOR signaling. BRSK2 over-expression suppressed global protein synthesis and decreased ribosome-RNA associations, which results in decreased NRF2 protein levels. Overall, our data establish the BRSK1 and BRSK2 kinases as negative regulators of NRF2 via the AMPK/MTOR signaling axis. Strategies which exploit these relationships may prove useful for therapeutically targeting NRF2 in cancer.

INSTRUMENT(S): Orbitrap Fusion Lumos

ORGANISM(S): Homo Sapiens (human)

TISSUE(S): Cell Culture

SUBMITTER: Dennis Goldfarb  

LAB HEAD: Ben Major

PROVIDER: PXD015884 | Pride | 2020-06-24

REPOSITORIES: Pride