PERINATAL ACTIVATION OF A TYROSINE AMINOTRANSFERASE FUSION GENE DOES NOT OCCUR IN ALBINO LETHAL MICE

To investigate developmental expression of the rat tyrosine aminotransferase (TAT) gene in normal and in albino lethal mice we generated transgenic mice carrying a fusion gene of TAT 5'-sequences (11 kb) and the bacterial chloramphenicol acetyltransferase (CAT) gene. In four lines, CAT activity was found only in liver. RNA analyses on a high-expressing line showed that transgenic expression follows expression of mouse TAT mRNA: it is inducible by glucocorticoids and activated perinatally. This perinatal activation of transgene expression does not occur in lethal albino mice (c14CoS/c14CoS) which are characterized by reduced mRNA levels of several liver-specific enzymes involved in gluconeogenesis. In conclusion, the data show that the 5'-flanking region of the rat TAT gene contains elements specifying regulated expression and establish that the 5'-flanking region of the TAT gene is responsive to the enzyme deficiency characteristic of the albino lethal mice.