5-Azacytidine and Sodium Butyrate Induce Expression of Aromatase in Fibroblasts from Chickens Carrying the Henny Feathering Trait but Not from Wild-type Chickens

Male chickens with the henny feathering trait have a female feathering pattern. In two henny-feathered breeds, the Sebright bantam and the Golden Campine, the synthesis of estrogen is increased as a consequence of increased activity of aromatase, a cytochrome P-450 enzyme that converts androgen to estrogen. The activity of the enzyme is elevated in tissue slices and in cultured fibroblasts from heterozygous and homozygous birds of both breeds. In contrast, aromatase activity is very low in extraglandular tissues from control chickens and is undetectable in fibroblasts cultured from these tissues. The current studies show that two agents known to alter gene expression--5-azacytidine and sodium butyrate--markedly induce expression of aromatase activity in Sebright and Campine fibroblasts but have no effect on aromatase activity in fibroblasts from wild-type chickens. Induction of aromatase is specific since two other microsomal enzymes in chicken fibroblasts--one, a component of the aromatase enzyme complex and the other a cytochrome P-450 oxidase distinct from the aromatase--are not significantly affected by these agents. Further study of this unique mutation should provide insight into the mechanisms by which genes are switched to an uninducible state during differentiation.