title: Ribosomal proteins L11 and L5 activate TAp73 by overcoming MDM2 inhibition.
abstract: Over the past decade, a number of ribosomal proteins (RPs) have been found to have a role in activating the tumor suppressor p53 by directly binding to MDM2 and impeding its activity toward p53. Herein, we report that RPL5 and RPL11 can also enhance the transcriptional activity of a p53 homolog TAp73, but through a distinct mechanism. Interestingly, even though RPL5 and RPL11 were not shown to bind to p53, they were able to directly associate with the transactivation domain of TAp73 independently of MDM2 in response to RS. This association led to perturbation of the MDM2-TAp73 interaction, consequently preventing MDM2 from its association with TAp73 target gene promoters. Furthermore, ectopic expression of RPL5 or RPL11 markedly induced TAp73 transcriptional activity by antagonizing MDM2 suppression. Conversely, ablation of either of the RPs compromised TAp73 transcriptional activity, as evident by the reduction of p21 and Puma expression, in response to 5-fluorouracil (5-FU). Consistently, overexpression of RPL5 or RPL11 enhanced, but knockdown of either of them hampered, TAp73-mediated apoptosis. Intriguingly, simultaneous knockdown of TAp73 and either of the RPs was required for rescuing the 5-FU-triggered S-phase arrest of p53-null tumor cells. These results demonstrate a novel mechanism underlying the inhibition of tumor cell proliferation and growth by these two RPs via TAp73 activation.
authors.affiliation: Department of Biochemistry & Molecular Biology, Tulane Cancer Center; Tulane University School of Medicine; New Orleans, Louisiana, USA.
authors.forename: X
authors.initials: X
authors.lastname: Zhou
authors.affiliation: Department of Biochemistry & Molecular Biology, Tulane Cancer Center; Tulane University School of Medicine; New Orleans, Louisiana, USA.
authors.forename: Q
authors.initials: Q
authors.lastname: Hao
authors.affiliation: Department of Biochemistry & Molecular Biology, Tulane Cancer Center; Tulane University School of Medicine; New Orleans, Louisiana, USA.
authors.forename: Q
authors.initials: Q
authors.lastname: Zhang
authors.affiliation: Department of Biochemistry & Molecular Biology, Tulane Cancer Center; Tulane University School of Medicine; New Orleans, Louisiana, USA.
authors.forename: J-M
authors.initials: JM
authors.lastname: Liao
authors.affiliation: 1] Department of Biochemistry & Molecular Biology, Tulane Cancer Center; Tulane University School of Medicine; New Orleans, Louisiana, USA [2] Department of Laboratory Medicine; Jiangxi Children's Hospital, Nanchang, Jiangxi, China.
authors.forename: J-W
authors.initials: JW
authors.lastname: Ke
authors.affiliation: Department of Biochemistry & Molecular Biology, Tulane Cancer Center; Tulane University School of Medicine; New Orleans, Louisiana, USA.
authors.forename: P
authors.initials: P
authors.lastname: Liao
authors.affiliation: Department of Biochemistry & Molecular Biology, Tulane Cancer Center; Tulane University School of Medicine; New Orleans, Louisiana, USA.
authors.forename: B
authors.initials: B
authors.lastname: Cao
authors.affiliation: Department of Biochemistry & Molecular Biology, Tulane Cancer Center; Tulane University School of Medicine; New Orleans, Louisiana, USA.
authors.forename: H
authors.initials: H
authors.lastname: Lu
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000235:genetics; D051017:Apoptosis Regulatory Proteins / Q000235:genetics / Q000378:metabolism; D045744:Cell Line, Tumor; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D051379:Mice; D018345:Mice, Knockout; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism; D051736:Proto-Oncogene Proteins c-mdm2 / Q000235:genetics / Q000378:metabolism*; D012269:Ribosomal Proteins / Q000235:genetics / Q000378:metabolism*; D059807:S Phase Cell Cycle Checkpoints / Q000235:genetics; D014158:Transcription, Genetic; D000072160:Tumor Protein p73; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D051017:Apoptosis Regulatory Proteins; C438378:BBC3 protein, human; C493956:CDKN1A protein, human; C493957:Cdkn1a protein, mouse; D050759:Cyclin-Dependent Kinase Inhibitor p21; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; C488588:PUMA protein, mouse; D011518:Proto-Oncogene Proteins; D012269:Ribosomal Proteins; C000606368:Trp73 protein, mouse; D000072160:Tumor Protein p73; D025521:Tumor Suppressor Proteins; C454920:delta Np73, mouse; C027624:ribosomal protein L11; C497206:MDM2 protein, human; C497207:Mdm2 protein, mouse; D051736:Proto-Oncogene Proteins c-mdm2