The BTB-Kelch protein KLHL20 is a hypoxia-induced CUL3-dependent E3 ligase linked to autophagy, Alzheimer’s disease and cancer. KLHL20 acts to terminate autophagy by promoting the ubiquitination and degradation of ULK1. KLHL20 is also reported as a top 20 biomarker for Alzheimer’s disease progression. Inhibition of KLHL20 may be neuroprotective by extending autophagy for the clearance of neurotoxic proteins aggregates. KLHL20 also promotes cancer through the ubiquitination and degradation of tumour suppressors including PML and DAPK1.

Loss of function mutations in the cohesin subunit gene STAG2 are common in a variety of cancers (1). These cells become dependent on the paralogous cohesin subunit STAG1 (2-4). Mutants of STAG1 that disrupt the binding to the cohesin subunit RAD21 cannot complement the loss of STAG2. This TEP examines the druggability of STAG1 as a synthetic lethal strategy to treat stag2^- cancers.

KEAP1 is a highly redox-sensitive member of the BTB-Kelch family that assembles with the CUL3 protein to form a Cullin-RING E3 ligase complex for the degradation of NRF2. Oxidative stress disables KEAP1 allowing NRF2 protein levels to accumulate for the transactivation of critical stress response genes. Consequently, the KEAP1-NRF2 system is a highly attractive target for the development of protein-protein interaction inhibitors that will stabilise NRF2 for therapeutic effect in conditions of neurodegeneration and inflammation.