CYTOCHROME P450(11-BETA) - ECTOPIC EXPRESSION IN OOCYTE AND ITS PHYSIOLOGICAL IMPLICATION

Cytochrome P450(11 beta) (steroid 11 beta-hydroxylase) catalyzes an es sential step for biosynthesis of glucocorticoid as well as mineralocor ticoid, and therefore is believed to exist specifically in the adrenoc ortical mitochondria. We previously isolated a complementary DNA clone encoding this enzyme from bullfrog (Rana catesbeiana) adrenal tissues and characterized the enzyme expressed in COS cells. To explore the t issue distribution of the enzyme we performed Northern blot analysis. Unexpectedly we found that a large amount of the mRNA exists in the ov ary as well as the adrenal gland. It was present in oocytes, but not i n follicular cells. The P450 protein was not found during early stages of oocyte development, and at the final stage of maturation the messa ge appeared to be translated. Evidence was obtained that the stage-dep endent translation of the mRNA was due to the regulated polyadenylatio n at its 3'-end. In oocytes of various organisms several maternal mRNA s are known to add poly(A) tails in the cytoplasm during the progester one-induced maturation.