title: Perturbation of 60 S ribosomal biogenesis results in ribosomal protein L5- and L11-dependent p53 activation.
abstract: Ribosomal proteins play an important role in p53 activation in response to nucleolar stress. Multiple ribosomal proteins, including L5, L11, L23, and S7, have been shown to bind to and inhibit MDM2, leading to p53 activation. However, it is not clear whether ribosomal protein regulation of MDM2 is specific to some, but not all ribosomal proteins. Here we show that L29 and L30, two ribosomal proteins from the 60 S ribosomal subunit, do not bind to MDM2 and do not inhibit MDM2-mediated p53 suppression, indicating that the ribosomal protein regulation of the MDM2-p53 feedback loop is specific. Interestingly, direct perturbation of the 60 S ribosomal biogenesis by knocking down either L29 or L30 drastically induced the level and activity of p53, leading to p53-depedent cell cycle arrest. This p53 activation was drastically inhibited by knockdown of L11 or L5. Consistently, knockdown of L29 or L30 enhanced the interaction of MDM2 with L11 and L5 and markedly inhibited MDM2-mediated p53 ubiquitination, suggesting that direct perturbation of 60 S ribosomal biogenesis activates p53 via L11- and L5-mediated MDM2 suppression. Mechanistically, knockdown of L30 or L29 significantly increased the NEDDylation and nuclear retention of L11. Knocking down endogenous NEDD8 suppressed p53 activation induced by knockdown of L30. These results demonstrate that NEDDylation of L11 plays a critical role in mediating p53 activation in response to perturbation of ribosomal biogenesis.
authors.affiliation: Department of Molecular and Medical Genetics, School of Medicine, Oregon Health & Science University, Portland, Oregon 97239, USA.
authors.forename: Xiao-Xin
authors.initials: XX
authors.lastname: Sun
authors.forename: Yue-Gang
authors.initials: YG
authors.lastname: Wang
authors.forename: Dimitris P
authors.initials: DP
authors.lastname: Xirodimas
authors.forename: Mu-Shui
authors.initials: MS
authors.lastname: Dai
mesh_terms: D001779:Blood Coagulation Factors / Q000235:genetics / Q000378:metabolism; D002453:Cell Cycle / Q000235:genetics / Q000502:physiology; D045744:Cell Line, Tumor; D002466:Cell Nucleolus / Q000235:genetics / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D006801:Humans; D015151:Immunoblotting; D047468:Immunoprecipitation; D011485:Protein Binding; D051736:Proto-Oncogene Proteins c-mdm2 / Q000378:metabolism; D034622:RNA Interference; D016601:RNA-Binding Proteins; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012269:Ribosomal Proteins / Q000235:genetics / Q000378:metabolism*; D054683:Ribosome Subunits, Large, Eukaryotic / Q000235:genetics / Q000378:metabolism*; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism*; D054875:Ubiquitination / Q000235:genetics / Q000502:physiology
chemical_list: D001779:Blood Coagulation Factors; D016601:RNA-Binding Proteins; C104946:RPL29 protein, human; D012269:Ribosomal Proteins; D016159:Tumor Suppressor Protein p53; C027624:ribosomal protein L11; C035201:ribosomal protein L30; C029742:ribosomal protein L5; C497206:MDM2 protein, human; D051736:Proto-Oncogene Proteins c-mdm2