title: p73 supports cellular growth through c-Jun-dependent AP-1 transactivation.
abstract: The cause or consequence of overexpression of p73 (refs 1, 2), the structural and functional homologue of the tumour-suppressor gene product p53 (refs 3, 4), in human cancers is poorly understood. Here, we report a role for p73 in supporting cellular growth through the upregulation of AP-1 transcriptional activity. p73 suppresses growth when overexpressed alone, but synergises with the proto-oncogene c-Jun to promote cellular survival. Conversely, silencing of p73 expression compromises cellular proliferation. Molecular analysis revealed that expression of the AP-1 target-gene product cyclinD1 (ref. 5) is reduced concomitant with p73, but not p53, silencing. Moreover, cyclinD1 was induced by p73 expression in a c-Jun-dependent manner, and was required for p73-mediated cell survival. Furthermore, c-Jun-dependent AP-1 transcriptional activity was augmented by p73 and, consistently, induction of endogenous AP-1 target genes was compromised in the absence of p73. Chromatin immunoprecipitation and electrophoretic mobility shift analysis indicated that p73 enhanced the binding of phosphorylated c-Jun and Fra-1, another AP-1 family member, to AP-1 consensus DNA sequences, by regulating c-Jun phosphorylation and Fra-1 expression. Collectively, our data demonstrates a novel and unexpected role of p73 in augmenting AP-1 transcriptional activity through which it supports cellular growth.
authors.affiliation: Laboratory of Molecular Carcinogenesis, National Cancer Centre, 11 Hospital Drive, Singapore 169610, Singapore.
authors.forename: Faina
authors.initials: F
authors.lastname: Vikhanskaya
authors.forename: Wen Hong
authors.initials: WH
authors.lastname: Toh
authors.forename: Iqbal
authors.initials: I
authors.lastname: Dulloo
authors.forename: Qiang
authors.initials: Q
authors.lastname: Wu
authors.forename: Lakshmanane
authors.initials: L
authors.lastname: Boominathan
authors.forename: Huck Hui
authors.initials: HH
authors.lastname: Ng
authors.forename: Karen H
authors.initials: KH
authors.lastname: Vousden
authors.forename: Kanaga
authors.initials: K
authors.lastname: Sabapathy
mesh_terms: D000818:Animals; D019556:COS Cells; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D002470:Cell Survival / Q000235:genetics; D002471:Cell Transformation, Neoplastic / Q000235:genetics / Q000378:metabolism*; D002478:Cells, Cultured; D002522:Chlorocebus aethiops; D019938:Cyclin D1 / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D015972:Gene Expression Regulation, Neoplastic / Q000235:genetics; D006801:Humans; D051379:Mice; D018345:Mice, Knockout; D041681:NIH 3T3 Cells; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D011485:Protein Binding / Q000235:genetics; D000090063:Proto-Oncogene Mas; D016760:Proto-Oncogene Proteins c-fos / Q000235:genetics / Q000378:metabolism; D016755:Proto-Oncogene Proteins c-jun / Q000235:genetics / Q000378:metabolism*; D018808:Transcription Factor AP-1 / Q000235:genetics / Q000378:metabolism*; D015533:Transcriptional Activation / Q000235:genetics*; D000072160:Tumor Protein p73; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism*; D015854:Up-Regulation / Q000235:genetics; D000099169:Fos-Related Antigen 1
chemical_list: D019938:Cyclin D1; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D000090063:Proto-Oncogene Mas; D016760:Proto-Oncogene Proteins c-fos; D016755:Proto-Oncogene Proteins c-jun; D018808:Transcription Factor AP-1; D000072160:Tumor Protein p73; D025521:Tumor Suppressor Proteins; D000099169:Fos-Related Antigen 1; C000715470:MAS1 protein, human; C000606460:TP73 protein, human; C000606368:Trp73 protein, mouse