Analysis of the DNA-binding activities of Myc/Max/Mad network complexes during induced differentiation of U-937 monoblasts and F9 teratocarcinoma cells

• Published in: Oncogene Vol. 15; no. 6; pp. 737 - 748
• Main Authors: LARSSON, L.-G, BAHRAM, F, BURKHARDT, H, LÜSCHER, B
• Format: Journal Article
• Language: English
• Published: Basingstoke Nature Publishing 07.08.1997; Nature Publishing Group
• Subjects: Animals; Antigen-Antibody Complex - immunology; Antigen-Antibody Complex - isolation & purification; Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; Basic-Leucine Zipper Transcription Factors; Biological and medical sciences; c-Myc protein; Carrier Proteins; Cell Cycle Proteins; Cell Differentiation; Cell differentiation, maturation, development, hematopoiesis; Cell physiology; Cell proliferation; Chickens; Deoxyribonucleic acid; DNA; DNA - metabolism; DNA-Binding Proteins - immunology; DNA-Binding Proteins - isolation & purification; DNA-Binding Proteins - metabolism; Fundamental and applied biological sciences. Psychology; Gene expression; Gene regulation; Humans; Kinetics; Mice; Molecular and cellular biology; Monocytes; Myc protein; Nuclear Proteins - immunology; Nuclear Proteins - isolation & purification; Nuclear Proteins - metabolism; Nucleotide sequence; Phosphoproteins - immunology; Phosphoproteins - isolation & purification; Phosphoproteins - metabolism; Post-translation; Protein Binding; Protein Biosynthesis; Proto-Oncogene Proteins c-myc - immunology; Proto-Oncogene Proteins c-myc - isolation & purification; Proto-Oncogene Proteins c-myc - metabolism; Repressor Proteins; Teratocarcinoma; Teratocarcinoma cells; Transcription; Transcription Factors; Tumor Cells, Cultured; Human; Ligand binding; Teratoma; Induction; Rodentia; DNA binding protein; Molecular interaction; Cell differentiation; Lymphoma; Heterodimer; Vertebrata; Regulation(control); Mammalia; Cell line; Monoblast; Mouse; C-Onc gene; Molecular complex
• ISSN: 0950-9232; 1476-5594
• DOI: 10.1038/sj.onc.1201390

The bHLHZip protein Max interacts with both the Myc and Mad family proteins forming heterodimers which specifically bind certain E-box DNA recognition sequences, thereby regulating transcription. Whereas Myc proteins actively promote cell proliferation, Mad complexes have the opposite function. Although the main regulation of this network seems to be the control of myc- and mad family gene expression, regulation at the level of DNA-binding and transactivation may also be in operation. Few studies on the DNA-binding activity of native Myc:Max or Max:Mad complexes have been reported mainly due to technical difficulties. To overcome these problems we have developed a specific and sensitive solid phase DNA-binding assay based on partial purification of native Myc, Max and Mad1 complexes by immunological methods. Using this technique we report that the DNA-binding activity of c-Myc-containing complexes is reduced during induced differentiation of U-937 monoblasts and F9 embryonic teratocarcinoma cells. In contrast, the DNA-binding of Mad1-containing complexes increases during monocytic differentiation. In general, the DNA-binding activity of c-Myc and Mad1 correlate with their expression. However, our studies of early kinetics of TPA-induced differentiation of U-937 cells as well as of late events during F9 differentiation suggest that post-translational regulation of Myc and Max DNA-binding may also occur. The solid phase DNA-binding assay may thus provide a tool to study the regulation of DNA-binding in more detail.