RESUMEN
Yin-Yang-1 (YY1) regulates the transcription of many genes, including the oncogenes c-fos and c-myc. Depending on the context, YY1 acts as a transcriptional repressor, a transcriptional activator, or a transcriptional initiator. The yeast two-hybrid system was used to screen a human complementary DNA (cDNA) library for proteins that associate with YY1, and a c-myc cDNA was isolated. Affinity chromatography confirmed that YY1 associates with c-Myc but not with Max. In cotransfections, c-Myc inhibits both the repressor and the activator functions of YY1, which suggests that one way c-Myc acts is by modulating the activity of YY1.
Asunto(s)
Proteínas de Unión al ADN/metabolismo , Proteínas Proto-Oncogénicas c-myc/metabolismo , Factores de Transcripción/metabolismo , Dedos de Zinc , Células 3T3 , Proteínas E1A de Adenovirus/metabolismo , Animales , Factores de Transcripción Básicos con Cremalleras de Leucinas y Motivos Hélice-Asa-Hélice , Factores de Transcripción con Cremalleras de Leucina de Carácter Básico , Proteínas de Unión al ADN/antagonistas & inhibidores , Proteínas de Unión al ADN/genética , Proteínas de Unión al ADN/farmacología , Factores de Unión al ADN Específico de las Células Eritroides , Secuencias Hélice-Asa-Hélice , Humanos , Ratones , Proteínas Proto-Oncogénicas c-myc/farmacología , Proteínas Recombinantes de Fusión/metabolismo , Factores de Transcripción/antagonistas & inhibidores , Factores de Transcripción/genética , Factores de Transcripción/farmacología , Transfección , Células Tumorales Cultivadas , Factores Estimuladores hacia 5' , Factor de Transcripción YY1RESUMEN
Previous studies on the murine c-myc promoter demonstrated that a ubiquitously present protein, common factor 1 (CF1), bound at two sites located -260 and -390 bp from the P1 transcription start site. CF1 has been purified to near homogeneity and shown to be identical to the zinc finger protein Yin-yang 1 (YY1) as judged by similarity of molecular weight and other biochemical properties, immunological cross-reactivity, and the ability of recombinant YY1 to bind to CF1 sites. In cotransfection experiments, YY1 is a strong activator of transcription from c-myc promoter-based reporters. Furthermore, in murine erythroleukemia cells, overexpressed YY1 causes increased levels of c-myc mRNA initiated from both major transcription initiation sites of the endogenous c-myc gene.