Temporal order of chromatin structural changes associated with activation of the major chicken vitellogenin gene.

The major chicken vitellogenin (VTG II) gene is marked at the chromatin level in hormone-responsive cells by a set of nuclease-hypersensitive sites that exist prior to hormone-mediated expression. When the gene is transcriptionally activated in the liver by treatment with 17 beta-estradiol, three additional hypersensitive sites are induced, which map near the 5' end of the gene. Two of these sites are stable and, moreover, appear to be propagated to daughter cells after hormone is withdrawn. In contrast, the third site (located 0.7 kb upstream from the gene) is observed only during periods of hormone treatment, perhaps due to a transient interaction with hormone receptor complex at this site. Whereas none of these nuclease-hypersensitive sites is observed in erythrocytes, brain, or fibroblasts, a subset is present in differentiated oviduct cells that have estrogen receptors, but do not express VTG II.