RESUMO
Ubiquitin domain-containing protein 1 (UBTD1) is highly evolutionary conserved and has been described to interact with E2 enzymes of the ubiquitin-proteasome system. However, its biological role and the functional significance of this interaction remain largely unknown. Here, we demonstrate that depletion of UBTD1 drastically affects the mechanical properties of epithelial cancer cells via RhoA activation and strongly promotes their aggressiveness. On a stiff matrix, UBTD1 expression is regulated by cell-cell contacts, and the protein is associated with ß-catenin at cell junctions. Yes-associated protein (YAP) is a major cell mechano-transducer, and we show that UBTD1 is associated with components of the YAP degradation complex. Interestingly, UBTD1 promotes the interaction of YAP with its E3 ubiquitin ligase ß-TrCP Consequently, in cancer cells, UBTD1 depletion decreases YAP ubiquitylation and triggers robust ROCK2-dependent YAP activation and downstream signaling. Data from lung and prostate cancer patients further corroborate the in cellulo results, confirming that low levels of UBTD1 are associated with poor patient survival, suggesting that biological functions of UBTD1 could be beneficial in limiting cancer progression.
Assuntos
Suscetibilidade a Doenças , Fator de Crescimento Insulin-Like I/metabolismo , Neoplasias/etiologia , Neoplasias/metabolismo , Ubiquitinas/metabolismo , Adesão Celular , Proteínas de Ciclo Celular/metabolismo , Progressão da Doença , Regulação Neoplásica da Expressão Gênica , Via de Sinalização Hippo , Humanos , Mecanotransdução Celular , Modelos Biológicos , Neoplasias/mortalidade , Neoplasias/patologia , Prognóstico , Ligação Proteica , Processamento de Proteína Pós-Traducional , Proteínas Serina-Treonina Quinases/metabolismo , Transdução de Sinais , Fatores de Transcrição/metabolismo , beta Catenina/metabolismo , Proteínas Contendo Repetições de beta-Transducina/metabolismo , Proteína rhoA de Ligação ao GTP/metabolismoRESUMO
The tumour suppressor p53 plays an important role in tumourigenesis. Besides inducing apoptosis, it regulates cellular senescence, which constitutes an important barrier to tumourigenesis. The mechanism of regulation of cellular senescence by p53 and its downstream pathway are poorly understood. Here, we report that the ubiquitin domain-containing 1 (UBTD1) gene, a new downstream target of p53, induces cellular senescence and acts as a novel tumour suppressor by a mechanism that depends on p53. Expression of UBTD1 increased upon cellular senescence induced by serial passageing of cultures, as well as by exposure to DNA-damageing drugs that induce premature senescence. Over-expression of UBTD1 induces senescence in human fibroblasts and cancer cells and attenuation of the transformed phenotype in cancer cells. UBTD1 is down-regulated in gastric and colorectal cancer tissues, and its lower expression correlates with a more aggressive phenotype and worse prognosis. Multivariate analysis revealed that UBTD1 expression was an independent prognostic factor for gastric cancer patients. Furthermore, UBTD1 increased the stability of p53 protein, by promoting the degradation of Mdm2 protein. Importantly, UBTD1 and p53 function mutually depend on each other in regulating cellular senescence and proliferation. Thus, our data suggest that, upon DNA damage, p53 induction by UBTD1 creates a positive feedback mechanism to further increase p53 expression. Our results establish UBTD1 as a regulator of cellular senescence that mediates p53 function, and provide insights into the mechanism of Mdm2 inhibition that impacts p53 dynamics during cellular senescence and tumourigenesis.
Assuntos
Senescência Celular , Neoplasias Colorretais/enzimologia , Fibroblastos/enzimologia , Proteínas Proto-Oncogênicas c-mdm2/metabolismo , Neoplasias Gástricas/enzimologia , Proteína Supressora de Tumor p53/metabolismo , Proteínas Supressoras de Tumor/metabolismo , Ubiquitinas/metabolismo , Antineoplásicos/farmacologia , Sítios de Ligação , Linhagem Celular Tumoral , Proliferação de Células , Transformação Celular Neoplásica/metabolismo , Transformação Celular Neoplásica/patologia , Senescência Celular/efeitos dos fármacos , Neoplasias Colorretais/genética , Neoplasias Colorretais/mortalidade , Neoplasias Colorretais/patologia , Dano ao DNA , Relação Dose-Resposta a Droga , Retroalimentação Fisiológica , Fibroblastos/efeitos dos fármacos , Fibroblastos/patologia , Regulação Neoplásica da Expressão Gênica , Humanos , Masculino , Pessoa de Meia-Idade , Análise Multivariada , Fenótipo , Prognóstico , Regiões Promotoras Genéticas , Estabilidade Proteica , Proteólise , Proteínas Proto-Oncogênicas c-mdm2/genética , Interferência de RNA , Fatores de Risco , Transdução de Sinais , Neoplasias Gástricas/genética , Neoplasias Gástricas/mortalidade , Neoplasias Gástricas/patologia , Fatores de Tempo , Transfecção , Proteína Supressora de Tumor p53/genética , Ubiquitinação , Ubiquitinas/genéticaRESUMO
To adapt in an ever-changing environment, cells must integrate physical and chemical signals and translate them into biological meaningful information through complex signaling pathways. By combining lipidomic and proteomic approaches with functional analysis, we have shown that ubiquitin domain-containing protein 1 (UBTD1) plays a crucial role in both the epidermal growth factor receptor (EGFR) self-phosphorylation and its lysosomal degradation. On the one hand, by modulating the cellular level of ceramides through N-acylsphingosine amidohydrolase 1 (ASAH1) ubiquitination, UBTD1 controls the ligand-independent phosphorylation of EGFR. On the other hand, UBTD1, via the ubiquitination of Sequestosome 1 (SQSTM1/p62) by RNF26 and endolysosome positioning, participates in the lysosomal degradation of EGFR. The coordination of these two ubiquitin-dependent processes contributes to the control of the duration of the EGFR signal. Moreover, we showed that UBTD1 depletion exacerbates EGFR signaling and induces cell proliferation emphasizing a hitherto unknown function of UBTD1 in EGFR-driven human cell proliferation.