Research ArticlePharmacology

Phenobarbital Indirectly Activates the Constitutive Active Androstane Receptor (CAR) by Inhibition of Epidermal Growth Factor Receptor Signaling

Science Signaling  07 May 2013:
Vol. 6, Issue 274, pp. ra31
DOI: 10.1126/scisignal.2003705

You are currently viewing the abstract.

View Full Text
As a service to the community, AAAS/Science has made this article free with registration.


Phenobarbital is a central nervous system depressant that also indirectly activates nuclear receptor constitutive active androstane receptor (CAR), which promotes drug and energy metabolism, as well as cell growth (and death), in the liver. We found that phenobarbital activated CAR by inhibiting epidermal growth factor receptor (EGFR) signaling. Phenobarbital bound to EGFR and potently inhibited the binding of EGF, which prevented the activation of EGFR. This abrogation of EGFR signaling induced the dephosphorylation of receptor for activated C kinase 1 (RACK1) at Tyr52, which then promoted the dephosphorylation of CAR at Thr38 by the catalytic core subunit of protein phosphatase 2A. The findings demonstrated that the phenobarbital-induced mechanism of CAR dephosphorylation and activation is mediated through its direct interaction with and inhibition of EGFR.

View Full Text