RESUMEN
Persistent infections with some types of human papillomavirus (HPV) constitute the major etiological factor for cervical cancer development. Nanog, a stem cell transcription factor has been shown to increase during cancer progression. We wanted to determine whether Nanog could modulate transcription of E6 and E7 oncogenes. We used luciferase reporters under the regulation of the long control region (LCR) of HPV types 16 and 18 (HPV16/18) and performed RT-qPCR. We found that Nanog increases activity of both viral regulatory regions and elevates endogenous E6/E7 mRNA levels in cervical cancer-derived cells. We demonstrated by in vitro mutagenesis that changes at Nanog-binding sites found in the HPV18 LCR significantly inhibit transcriptional activation. Chromatin immunoprecipitation (ChIP) assays showed that Nanog binds in vivo to the HPV18 LCR, and its overexpression increases its binding as well as that of c-Jun. Surprisingly, we observed that mutation of AP1-binding sites also affect Nanog's ability to activate transcription, suggesting cooperation between the two factors. We searched for putative Nanog-binding sites in the LCR of several HPVs and surprisingly found them only in those types associated with cancer development. Our study shows, for the first time, a role for Nanog in the regulation of E6/E7 transcription of HPV16/18.
Asunto(s)
Proteínas de Unión al ADN/genética , Papillomavirus Humano 16/genética , Papillomavirus Humano 18/genética , Proteína Homeótica Nanog/metabolismo , Proteínas Oncogénicas Virales/genética , Proteínas E7 de Papillomavirus/genética , Infecciones por Papillomavirus/metabolismo , Proteínas Represoras/genética , Línea Celular Tumoral , Proteínas de Unión al ADN/metabolismo , Femenino , Regulación Viral de la Expresión Génica , Interacciones Huésped-Patógeno , Papillomavirus Humano 16/metabolismo , Papillomavirus Humano 18/metabolismo , Humanos , Proteína Homeótica Nanog/genética , Proteínas Oncogénicas Virales/metabolismo , Proteínas E7 de Papillomavirus/metabolismo , Infecciones por Papillomavirus/genética , Infecciones por Papillomavirus/virología , Regiones Promotoras Genéticas , Proteínas Represoras/metabolismo , Factor de Transcripción AP-1/genética , Factor de Transcripción AP-1/metabolismo , Activación Transcripcional , Neoplasias del Cuello Uterino/genética , Neoplasias del Cuello Uterino/metabolismo , Neoplasias del Cuello Uterino/virologíaRESUMEN
Ubiquinone derivatives modulate the mammalian mitochondrial Permeability Transition Pore (PTP). Yeast mitochondria harbor a similar structure: the respiration- and ATP-induced Saccharomyces cerevisiae Mitochondrial Unselective Channel ( Sc MUC). Here we show that decylubiquinone, a well-characterized inhibitor of the PTP, suppresses Sc MUC opening in diverse strains and independently of respiratory chain modulation or redox-state. We also found that naturally occurring derivatives such as hexaprenyl and decaprenyl ubiquinones lacked effects on the Sc MUC. The PTP-inactive ubiquinone 5 (Ub5) promoted the Sc MUC-independent activation of the respiratory chain in most strains tested. In an industrial strain however, Ub5 blocked the protection elicited by dUb. The results indicate the presence of a ubiquinone-binding site in the Sc MUC.