Overexpression of c-Myc inhibits the appearance of a specific DNase I hypersensitive site in the beta-globin chromatin in murine erythroleukemia cells.

To investigate the molecular mechanism of regulation of differentiation by c-Myc, we examined the acquisition of DNase I hypersensitivity by beta-globin chromatin in an MEL cell transformant (38-2) in which the c-myc gene was placed under the control of a metallothionein gene promoter. Of the three DNase I hypersensitive sites around the beta-globin gene which were detected in MEL cells after DMSO treatment, the appearance of a specific DNase I hypersensitive site near the promoter was greatly reduced by the overexpression of c-Myc. This result suggests that c-Myc regulates beta-globin expression by interfering with the establishment of an active chromatin conformation around the beta-globin gene.