Baboon Cyp11b1: The Localization and Catalytic Activity in Baboon Adrenal Tissue

Abstract

A third gene encoding baboon CYP11B1 was isolated and was shown to catalyze only the metabolism of deoxycorticosterone (DOC) to corticosterone. The investigation into the localization of CYP11B1 in the baboon adrenal tissue, using in situ hybridization, showed that mRNA transcripts were predominantly present in the zona reticularis (ZR) and zona fasciculata (ZF). Signal was also observed in the zona glomerulosa (ZG) and scattered within the medulla. Immunohistochemical studies, using rabbit anti-sheep CYP11B1 IgG, indicated that CYP11B1 was expressed only in the zona fasciculata, zona reticularis and in the medulla. CYP11B1 was not detected in the zona glomerulosa. Subsequent Western Blot investigations into the presence of CYP11B1 in baboon adrenal cortex and medullary homogenates indicated CYP11B1 as a single band in the cortex and as two distinct bands in the medulla. CYP11A was present only in the baboon adrenal cortex. The metabolism of deoxycorticosterone and corticosterone was subsequently investigated in the baboon adrenal cortex and medulla. In cortex homogenates, deoxycorticosterone was converted to corticosterone, and neither 18-hydroxycorticosterone nor aldosterone was detected. In medulla homogenates, however, corticosterone was metabolized to aldosterone, as confirmed by APcI-MS.

Isolation of marinobufotoxin from the supernatant of cultured PC12 cells

“…27 There are a few reports suggesting the existence of these enzymes in the adrenal medulla. 28,29 Murrell et al 27 reported that PC12 cells expressed d5,3b-hydroxysteroid dehydrogenase isomerase mRNA, as determined by quantitative polymerase chain reaction, which further supports the possible production of cardenolides and bufadienolides in the adrenal medulla and PC12 cells. We reported that a substance with OL-IR was secreted from PC12 cells and that the addition of progesterone to the culture increased OL-IR content.…”

“…The adrenal cortex is the main tissue for steroidogenesis and the adrenal medulla requires 11β‐hydroxysteroid dehydrogenase 26 and δ5,3β‐hydroxysteroid dehydrogenase for steroidogenesis to occur 27 . There are a few reports suggesting the existence of these enzymes in the adrenal medulla 28,29 . Murrell et al.…”