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Licensed Unlicensed Requires Authentication Published by De Gruyter August 19, 2008

Specific inhibition of transcriptional activity of the constitutive androstane receptor (CAR) by the splicing factor SF3a3

Hye Jin Yun, Jungsun Kwon and Wongi Seol
From the journal


The constitutive androstane receptor (CAR) is a member of the nuclear receptor superfamily and plays an important role in the degradation of xenobiotics in the liver. Using yeast two-hybrid screening, we identified SF3a3, a 60-kDa subunit of the splicing factor 3a complex, as a specific CAR-interacting protein. We further confirmed their interaction by both co-immunoprecipitation and GST pull-down assay. Functional studies showed that overexpression of SF3a3 inhibited the reporter activity driven by a promoter containing CAR binding sequences by up to 50%, whereas reduced expression of SF3a3 activated the same reporter activity by approximately three-fold. The inhibitory function of SF3a3 is independent of the presence of TCPOBOP, a CAR ligand. These data suggest that SF3a3 functions as a co-repressor of CAR transcriptional activity, in addition to its canonical function.

Corresponding author

Received: 2008-1-16
Accepted: 2008-5-29
Published Online: 2008-08-19
Published in Print: 2008-10-01

©2008 by Walter de Gruyter Berlin New York