CRL2-KLHDC3 E3 ubiquitin ligase complex suppresses ferroptosis through promoting p14 degradation.

The cystine/glutamate antiporter SLC7A11 (commonly known as xCT) functions to import cystine for glutathione biosynthesis, thereby protecting cells from oxidative stress and ferroptosis, a regulated form of non-apoptotic cell death driven by the accumulation of lipid-based reactive oxygen species (ROS). p14, a well-established tumor suppressor, promotes ferroptosis by inhibiting NRF2-mediated SLC7A11 transcription. Here, we demonstrate the crucial role of Cullin 2 RING E3 ligase (CRL2)-KLHDC3 E3 ubiquitin ligase complex in regulating p14 protein stability. KLHDC3 acts as a CRL2 adaptor that specifically recognizes a C-terminal degron in p14 and triggers p14 for ubiquitin-proteasomal degradation. This regulation mode is absent in the murine p14 homolog, p19 which lacks the C-terminal degron. We also show that KLHDC3 suppresses ferroptosis in vitro and supports tumor growth in vivo by relieving p14-mediated suppression of SLC7A11 transcription. Overall, these findings reveal that the protein stability and pro-ferroptotic function of p14 are controlled by a CRL2 E3 ubiquitin ligase complex, and suggest that suppression of the p14NRF2-SLC7A11 regulatory pathway by KLHDC3 overexpression likely contributes to cancer progression.