title: A novel function of caspase-8 in the regulation of androgen-receptor-driven gene expression.
abstract: Transcriptional regulation by the androgen receptor (AR) is critical for male sexual development and prostate cancer. In this study, we used an expression cloning strategy to identify molecules that regulate AR-driven transcription. Screening of a human cDNA library resulted in isolation of caspase-8 (Casp8), an initiator caspase that mediates death-receptor-induced apoptosis. Casp8 repressed AR-dependent gene expression independently of its apoptotic protease activity by disrupting AR amino-terminal and carboxy-terminal (N/C) interaction and inhibiting androgen-induced AR nuclear localization. Protein-protein interaction analysis revealed that three motifs in Casp8 specifically interacted with the motifs that are known to be involved in AR N/C interaction. Substitutions of the amino-acid residues critical for AR-Casp8 interactions abolished the Casp8-mediated inhibition of AR transactivation. In addition, knockdown of Casp8 by RNA interference specifically affected the androgen-dependent expression of AR-targeting genes in LNCaP cells. These results indicate that Casp8 has a novel function beyond its known role in the mediation of apoptosis.
authors.affiliation: Department of Cancer Biology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.
authors.forename: Wei
authors.initials: W
authors.lastname: Qi
authors.forename: Hong
authors.initials: H
authors.lastname: Wu
authors.forename: Lin
authors.initials: L
authors.lastname: Yang
authors.forename: Douglas D
authors.initials: DD
authors.lastname: Boyd
authors.forename: Zhengxin
authors.initials: Z
authors.lastname: Wang
mesh_terms: D020816:Amino Acid Motifs; D017209:Apoptosis; D053181:Caspase 8 / Q000378:metabolism / Q000502:physiology*; D002467:Cell Nucleus / Q000378:metabolism; D005786:Gene Expression Regulation; D015723:Gene Library; D006801:Humans; D008957:Models, Genetic; D010447:Peptide Hydrolases / Q000378:metabolism; D011485:Protein Binding; D025941:Protein Interaction Mapping; D017434:Protein Structure, Tertiary; D034622:RNA Interference; D011944:Receptors, Androgen / Q000378:metabolism*; D015533:Transcriptional Activation
chemical_list: D011944:Receptors, Androgen; D010447:Peptide Hydrolases; D053181:Caspase 8