The expression of messenger RNA for ADP-ribosyl cyclase in aldosterone-producing adenomas.
OBJECTIVE
Cyclic ADP-ribose (cADPR) has been reported to be as potent and powerful at releasing intracellular Ca(2+) as inositol triphosphate (IP(3)). To determine whether the cADPR system plays a signalling role in angiotensin II (Ang II)-induced aldosterone synthesis in the human adrenal gland, we investigated the effects of Ang II on ADP-ribosyl cyclase activity in human adrenal cortical tissue. In addition, the expression of ADP-ribosyl cyclase messenger RNA was evaluated in aldosterone-producing adenomas (APAs) and compared with normal adrenal tissue and nonfunctioning adenomas.


METHODS
ADP-ribosyl cyclase activity was measured in crude membrane fractions of human adrenocortical tissues with Ang II or with Ang II plus the Ang II receptor (AT(1)R) antagonist losartan or plus the AT(2)R antagonist PD123319. The effect of 8-bromo-cADPR on Ang II-induced aldosterone production from adrenal tissue was estimated. The expression of ADP-ribosyl cyclase, CYP11B2 and AT(1)R mRNA was measured in APAs, nonfunctioning adenomas, adjacent adrenal tissue and normal adrenal tissue.


METHODS
ADP-ribosyl cyclase activity was measured by using high-performance liquid chromatography (HPLC) and [(3)H] NAD(+). mRNA expression was measured by competitive reverse-transcription polymerase chain reaction (RT-PCR). Results Ang II (10(-7) and 10(-8) mol/l) significantly increased ADP-ribosyl cyclase activity in a dose-dependent manner. This increase was inhibited by pretreatment with losartan but not with PD123319. Treatment with 8-bromo-cADPR (50 micromol/l) reduced Ang II-induced aldosterone secretion. ACTH did not significantly increase the enzyme activity. The expression of ADP-ribosyl cyclase, CYP11B2 and AT(1)R mRNA was increased in APAs compared with that of nonfunctioning adenomas, adjacent adrenal tissue or normal adrenal tissue.


CONCLUSIONS
These results demonstrated the existence of a signalling pathway from the Ang II receptor to ADP-ribosyl cyclase in the human adrenal gland and suggest that the cADP-ribose signalling system might play an important role in the pathogenesis of APAs.
Takeda
Yoshiyu
Y
Molecular Genetics of Cardiovascular Disorders, Graduate School of Medical Science, Kanazawa University, 13-1 Takara-machi, Kanazawa 920-8641, Japan. takeday@im2.m.kanazawa-u.ac.jp
Usukura
Mikiya
M
Yoneda
Takashi
T
Oda
Nobushige
N
Ito
Yoko
Y
Mabuchi
Hiroshi
H
D036541:ADP-ribosyl Cyclase / Q000235:genetics*; D000236:Adenoma / Q000201:enzymology / Q000378:metabolism*; D000306:Adrenal Cortex Neoplasms / Q000201:enzymology / Q000378:metabolism*; D000450:Aldosterone / Q000378:metabolism*; D000809:Angiotensins / Q000494:pharmacology*; D016022:Case-Control Studies; D036563:Cyclic ADP-Ribose / Q000031:analogs & derivatives* / Q000494:pharmacology; D019405:Cytochrome P-450 CYP11B2 / Q000235:genetics / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D015870:Gene Expression; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology; D066298:In Vitro Techniques; D019808:Losartan / Q000494:pharmacology; D011725:Pyridines / Q000494:pharmacology; D012333:RNA, Messenger / Q000032:analysis*; D044140:Receptor, Angiotensin, Type 1 / Q000187:drug effects / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000502:physiology; D014407:Tumor Cells, Cultured
C493642:8-bromo-cyclic-ADP-ribose; D000809:Angiotensins; D007093:Imidazoles; D011725:Pyridines; D012333:RNA, Messenger; D044140:Receptor, Angiotensin, Type 1; D036563:Cyclic ADP-Ribose; C073402:PD 123319; D000450:Aldosterone; D019405:Cytochrome P-450 CYP11B2; D036541:ADP-ribosyl Cyclase; D019808:Losartan