Stability of the human pregnane X receptor is regulated by E3 ligase UBR5 and serine/threonine kinase DYRK2.
The hPXR (human pregnane X receptor), a major chemical toxin sensor, is a ligand-induced transcription factor activated by various xenobiotics and toxins, resulting in the transcriptional up-regulation of detoxifying enzymes. To date, little is known about the upstream regulation of hPXR. Using MS analysis and a kinome-wide siRNA screen, we report that the E3 ligase UBR5 (ubiquitin protein ligase E3 component n-recognin 5) and DYRK2 (dual-specificity tyrosine-phosphorylation-regulated kinase 2) regulate hPXR stability. UBR5 knockdown resulted in accumulation of cellular hPXR and a concomitant increase in hPXR activity, whereas the rescue of UBR5 knockdown decreased the cellular hPXR level and activity. Importantly, UBR5 exerted its effect in concert with the serine/threonine kinase DYRK2, as the knockdown of DYRK2 phenocopied UBR5 knockdown. hPXR was shown to be a substrate for DYRK2, and DYRK2-dependent phosphorylation of hPXR facilitated its subsequent ubiquitination by UBR5. This is the first report of the post-translational regulation of hPXR via phosphorylation-facilitated ubiquitination by DYRK2 and UBR5. The results of the present study reveal the role of the ubiquitin-proteasomal pathway in modulating hPXR activity and indicate that pharmacological inhibitors of the ubiquitin-proteasomal pathway that regulate hPXR stability may negatively affect treatment outcome from unintended hPXR-mediated drug-drug interactions.
*Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, U.S.A.
Su Sien
SS
Ong
*Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, U.S.A.
Asli N
AN
Goktug
*Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, U.S.A.
Ayesha
A
Elias
*Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, U.S.A.
Jing
J
Wu
†Cancer Research Program, Garvan Institute of Medical Research, 384 Victoria Street, Darlinghurst NSW 2010, Australia.
Darren
D
Saunders
*Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, U.S.A.
Taosheng
T
Chen
D002478:Cells, Cultured; D057809:HEK293 Cells; D056945:Hep G2 Cells; D022781:Hepatocytes / Q000378:metabolism; D006801:Humans; D000077297:Pregnane X Receptor; D017346:Protein Serine-Threonine Kinases / Q000502:physiology*; D055550:Protein Stability; D011505:Protein-Tyrosine Kinases / Q000502:physiology*; D011987:Receptors, Steroid / Q000737:chemistry / Q000378:metabolism*; D044767:Ubiquitin-Protein Ligases / Q000502:physiology*; D054875:Ubiquitination / Q000502:physiology; D000097603:Dyrk Kinases
D000077297:Pregnane X Receptor; D017346:Protein Serine-Threonine Kinases; D011505:Protein-Tyrosine Kinases; D011987:Receptors, Steroid; D044767:Ubiquitin-Protein Ligases; D000097603:Dyrk Kinases; C117617:UBR5 protein, human