the chicken cerba alphaproduct induces expression of thyroid hormoneresponsive genes in 353triiodothyronine receptordeficient rat hepatoma cells to determine the capacity of the chicken cerba ctralpha gene product in regulating expression of known thyroid hormoneresponsive genes both the ctralpha and the viral verba genes were expressed in fao cells a rat hepatoma cell line defective for functional thyroid hormone receptors upon nuclear expression of the ctralpha protein the cells become responsive to thyroid hormone as detected by expression of a number of genes malic enzyme phosphoenolpyruvate carboxykinase and nakatpase reported to be indirectly induced by the hormone in vivo in addition our data show that the cerba product directly activates the moloney murine leukemia virus promoter in a liganddependent manner the data show that the chicken cerbaalpha protein can modulate the expression of rat genes under either direct or indirect control by thyroid hormone