title: RPAP3 splicing variant isoform 1 interacts with PIH1D1 to compose R2TP complex for cell survival.
abstract: We previously characterized RNA polymerase II-associated protein 3 (RPAP3) as a cell death enhancer. Here we report the identification and characterization of splicing isoform of RPAP3, isoform 1 and 2. We investigated the interaction between RPAP3 and PIH1 domain containing protein 1 (PIH1D1), and found that RPAP3 isoform 1, but not isoform 2, interacted with PIH1D1. Furthermore, knockdown of RPAP3 isoform 1 by small interfering RNA down-regulated PIH1D1 protein level without affecting PIH1D1 mRNA. RPAP3 isoform 2 potentiated doxorubicin-induced cell death in human breast cancer T-47 cells although isoform 1 showed no effect. These results suggest that R2TP complex is composed of RPAP3 isoform 1 for its stabilization, and that RPAP3 isoform 2 may have a dominant negative effect on the survival potency of R2TP complex.
authors.affiliation: Department of Pharmacology, Graduate School of Dentistry, Osaka University, Suita, Osaka 565-0871, Japan.
authors.forename: Miki
authors.initials: M
authors.lastname: Yoshida
authors.forename: Makio
authors.initials: M
authors.lastname: Saeki
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Egusa
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Irie
authors.forename: Yuya
authors.initials: Y
authors.lastname: Kamano
authors.forename: Shinya
authors.initials: S
authors.lastname: Uraguchi
authors.forename: Maki
authors.initials: M
authors.lastname: Sotozono
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Niwa
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Kamisaki
mesh_terms: D000595:Amino Acid Sequence; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism*; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D045744:Cell Line, Tumor; D002470:Cell Survival; D015536:Down-Regulation; D004317:Doxorubicin / Q000494:pharmacology; D055785:Gene Knockdown Techniques; D057809:HEK293 Cells; D006801:Humans; D008969:Molecular Sequence Data; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics; D015398:Signal Transduction; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism
chemical_list: D051017:Apoptosis Regulatory Proteins; D002352:Carrier Proteins; C555143:PIH1D1 protein, human; D020033:Protein Isoforms; D012333:RNA, Messenger; D034741:RNA, Small Interfering; C472351:RPAP3 protein, human; D004317:Doxorubicin; D058570:TOR Serine-Threonine Kinases