The alpha-fetoprotein promoter is the target of Afr1-mediated postnatal repression

The alpha-fetoprotein (AFP) gene is transcribed at high levels in the fetal liver and is repressed at birth, leading to low but detectable levels of A FP mRNA in the adult liver. This repression is regulated, in part, by a loc us that is unlinked to AFP called Alpha-fetoprotein regulator I (Afr1). Pre vious studies showed that Afr1 regulation is independent of the AFP enhance rs but requires the 1-kb AFP promoter/repressor region. Here, we demonstrat e that a transgene with the 250-bp AFP promoter region linked to AFP enhanc er element EII is expressed in the fetal liver and is postnatally repressed . In addition, this transgene is regulated by Afr1. These data indicate tha t the promoter is involved in postnatal AFP repression. Furthermore, we pro vide a high-resolution map of the Afr1 locus on mouse chromosome 15. (C) 20 00 Academic Press.