Regulation of XXXX adrenal P450c21 messenger RNA, protein and activity by @entity3927 .

@entity1880 @entity840 @entity3927 @entity1928 @entity7410
The role of ACTH, @entity1928 and @entity7410 on the regulation of mRNA abundance, protein levels and enzymatic activity of cytochrome P450 21-hydroxylase (P450c21, CYP21) were investigated in @entity840 adrenal cell cultures. In untreated cells, 21-hydroxylase activity was diminished throughout a 48 h period of incubation. Although incubation with @entity1928 and @entity7410 restored 21-hydroxylase activity to normal levels, the addition of ACTH did not prevent the decrease of 21-hydroxylase activity. Treatment of cells with @entity3927 for 24 h inhibited 21-hydroxylase activity by 93%; however, after removal of the drug a slight increase of enzyme activity was observed; this rise was enhanced by the addition of ACTH. @entity1928 and @entity7410 increased the levels of 21-hydroxylase activity to the same range as seen in untreated cells. In cells that were not pretreated with @entity3927 , incubation with @entity1880 for 1 h had no effect on 21-hydroxylase activity and could not prevent the modest increase of 21-hydroxylase activity induced by @entity1928 or @entity7410 after 48 h of incubation. In @entity3927 -treated cells, @entity1880 blocks the stimulation of enzyme activity induced by ACTH, @entity1928 and @entity7410 . Our findings indicate that 21-hydroxylase activity can be stimulated by ACTH, @entity1928 or @entity7410 solely in the presence of reduced enzymatic activity. Western immunoblot analysis of P450c21 protein levels in untreated or @entity3927 -treated adrenal cells indicate that P450c21 protein levels were in the same range and further incubation with ACTH caused a similar elevation of P450c21 protein levels in both the untreated and @entity3927 -treated cells. Northern blot analysis on RNA isolated from adrenal cells showed that @entity3927 did not alter the basal steady state levels of P450c21 mRNA. As well, incubation with ACTH or @entity7410 increased the levels of P450c21 transcript to the same extent in both untreated and @entity3927 -treated cells. These results taken together provide additional evidence for the presence of an adrenal specific protein factor(s) modulating 21-hydroxylase activity.
