RESUMEN
Recent genetic studies have documented a pivotal growth-regulatory role played by the Cullin 7 (CUL7) E3 ubiquitin ligase complex containing the Fbw8-substrate-targeting subunit, Skp1, and the ROC1 RING finger protein. In this report, we identified insulin receptor substrate 1 (IRS-1), a critical mediator of the insulin/insulin-like growth factor 1 signaling, as a proteolytic target of the CUL7 E3 ligase in a manner that depends on mammalian target of rapamycin and the p70 S6 kinase activities. Interestingly, while embryonic fibroblasts of Cul7-/- mice were found to accumulate IRS-1 and exhibit increased activation of IRS-1's downstream Akt and MEK/ERK pathways, these null cells grew poorly and displayed phenotypes reminiscent of those associated with oncogene-induced senescence. Taken together, our findings demonstrate a key role for the CUL7 E3 in targeting IRS-1 for degradation, a process that may contribute to the regulation of cellular senescence.
Asunto(s)
Proteínas Adaptadoras Transductoras de Señales/metabolismo , Proteínas Cullin/metabolismo , Ubiquitina/metabolismo , Proteínas Adaptadoras Transductoras de Señales/genética , Animales , Línea Celular , Senescencia Celular , Proteínas Cullin/genética , Activación Enzimática , Quinasas MAP Reguladas por Señal Extracelular/genética , Quinasas MAP Reguladas por Señal Extracelular/metabolismo , Proteínas F-Box/genética , Proteínas F-Box/metabolismo , Humanos , Proteínas Sustrato del Receptor de Insulina , Ratones , Ratones Noqueados , Fenotipo , Proteínas Quinasas/genética , Proteínas Quinasas/metabolismo , ARN Interferente Pequeño/genética , ARN Interferente Pequeño/metabolismo , Proteínas Recombinantes de Fusión/genética , Proteínas Recombinantes de Fusión/metabolismo , Transducción de Señal/fisiología , Serina-Treonina Quinasas TORRESUMEN
BACKGROUND/AIM: Immunotherapy has been considered a promising approach for brain tumor treatment since the discovery of the brain lymphatic system. Glioblastoma (GBM), the most aggressive type of brain tumor, is associated with poor prognosis and a lack of effective treatment options. MATERIALS AND METHODS: To test the efficacy of human anti-PD-1, we used a humanized PD-1 knock-in mouse to establish an orthotopic GBM-bearing model. RESULTS: Nivolumab, a human anti-PD-1, effectively inhibited tumor growth, increased the survival rate of mice, enhanced the accumulation and function of cytotoxic T cells, reduced the accumulation and function of immunosuppressive cells and their related factors, and did not induce tissue damage or biochemical changes. The treatment also induced the accumulation and activation of CD8+ cytotoxic T cells, while reducing the accumulation and activation of myeloid-derived suppressor cells, regulatory T cells, and tumor-associated macrophages in the immune microenvironment. CONCLUSION: Nivolumab has the potential to be a treatment for GBM.
Asunto(s)
Neoplasias Encefálicas , Glioblastoma , Humanos , Animales , Ratones , Glioblastoma/tratamiento farmacológico , Glioblastoma/genética , Nivolumab/farmacología , Receptor de Muerte Celular Programada 1 , Neoplasias Encefálicas/tratamiento farmacológico , Neoplasias Encefálicas/genética , Encéfalo/patología , Inmunoterapia , Línea Celular Tumoral , Microambiente TumoralRESUMEN
p193/CUL7 is an E3 ubiquitin ligase initially identified as an SV40 Large T Antigen binding protein. Expression of a dominant interfering variant of mouse p193/CUL7 (designated 1152stop) conferred resistance to MG132- and etoposide-induced apoptosis in U2OS cells. Immune precipitation/Western analyses revealed that endogenous p193/CUL7 formed a complex with Parc (a recently identified parkin-like ubiquitin ligase) and p53. Apoptosis resistance did not result from 1152stop-mediated disruption of the endogenous p193/CUL7 binding partners. Moreover, 1152stop molecule did not directly bind to endogenous p193/CUL7, Parc or p53. These data suggested a role for p193/CUL7 in the regulation of apoptosis independently of p53 and Parc activity.
Asunto(s)
Apoptosis/efectos de los fármacos , Proteínas Cullin/metabolismo , Resistencia a Medicamentos , Etopósido/farmacología , Expresión Génica/efectos de los fármacos , Leupeptinas/farmacología , Animales , Anticuerpos Monoclonales/inmunología , Línea Celular , Proteínas Cullin/genética , Proteínas Cullin/inmunología , Citoplasma/metabolismo , Topoisomerasa de ADN IV/metabolismo , Activación Enzimática/efectos de los fármacos , Humanos , Ratones , Mutación/genética , Complejo de la Endopetidasa Proteasomal/metabolismo , Inhibidores de Proteasoma , Unión Proteica , Proteína p53 Supresora de Tumor/genética , Proteína p53 Supresora de Tumor/metabolismoRESUMEN
Previous studies have demonstrated that expression of p193 and p53 mutants with dominant-interfering activities renders embryonic stem cell-derived cardiomyocytes responsive to the growth promoting activities of the E1A viral oncoproteins. In this study, the effects of p53 and p193 antagonization on cardiomyocyte cell cycle activity in normal and infarcted hearts were examined. Transgenic mice expressing the p193 and/or the p53 dominant-interfering mutants in the heart were generated. Transgene expression had no effect on cardiomyocyte cell cycle activity in uninjured adult hearts. In contrast expression of either transgene resulted in a marked induction of cardiomyocyte cell cycle activity at the infarct border zone at 4 weeks after permanent coronary artery occlusion. Expression of the p193 dominant-interfering mutant was also associated with an induction of cardiomyocyte DNA synthesis in the interventricular septa of infarcted hearts. A concomitant and marked reduction in hypertrophic cardiomyocyte growth was observed in the septa of hearts expressing the p193 dominant-interfering transgene, suggesting that cell cycle activation might partially counteract the adverse ventricular remodeling that occurs after infarction. Collectively these data suggest that antagonization of p193 and p53 activity relaxes the otherwise stringent regulation of cardiomyocyte cell cycle reentry in the injured adult heart.