| HC11 mouse mammary epithelial cells grown to confluency and treated with a combination of dexamethasone, insulin, and prolactin exhibited a substantial increase in EGF mRNA content. This same hormone combination was capable of inducing expression of a reporter gene consisting of ;Deletions of the 5;Even though hormone treatment did not show a detectable effect on YY1 proteins and YY1 binding to the DNA element in HC11 cells, lactation event significant reduced the nuclear YY1 concentration and YY1-DNA complex formation in mammary tissues. Results from these studies show that expression of the EGF gene in mammary epithelium is repressed by YY1, and the removal of that repression via reduced YY1 content and/or YY1-DNA interaction may play a role in hormone-induced expression of the EGF gene in lactating mammary tissue. |
