AJP - Regulatory, Integrative and Comparative Physiology, Vol 271, Issue 3 519-R527, Copyright © 1996 by American Physiological Society
Dopaminergic receptors and angiotensinogen gene expression in opossum kidney cells
T. T. Wang, S. Lachance, A. Delalandre, S. Carriere and J. S. Chan
University of Montreal, Maisonneuve-Rosemont Hospital, Research Center, Quebec, Canada.
To investigate whether expression of the renal angiotensinogen gene is
regulated by dopaminergic receptors, we used opossum kidney (OK 27) cells
with a fusion gene containing the 5'- flanking regulatory sequence of the
rat angiotensinogen gene fused with a human growth hormone (hGH) gene as a
reporter [pOGH, angiotensinogen nucleotide (N) -1498/+18], permanently
integrated into their genomes. The level of expression of pOGH
(angiotensinogen N-1498/+18) in OK 27 was evaluated by the amount of
immunoreactive hGH (ir-hGH) secreted into the culture medium. In the
absence of 3-isobutyl-1-methylxanthine (IBMX), addition of dopamine
(10(-13) to 10(-5)M) had minimal effect on the expression of the pOGH
(angiotensinogen N-1498/+18) in OK 27 cells. In the presence of IBMX,
addition of low concentrations (10(-13) and 10(-7) M) of dopamine
stimulated the expression of pOGH angiotensinogen N-1498/+18) in OK 27
cells in a dose-dependent manner, whereas high concentrations (i.e., >
10(-7) M) had minimal effect. The stimulatory effect of dopamine on the
expression of pOGH (angiotensinogen N-1498/+18) was inhibited by the
presence of SCH-23390 (D1-dopaminergic receptor antagonist) and spiperone
(D2-dopaminergic receptor antagonist), but not by ketanserin (5
HT2/5HT1c-serotonergic receptor antagonist). Moreover, the stimulatory
effect of dopamine was inhibited by the presence of U-73122 (an inhibitor
of phospholipase C and phospholipase A2) or staurosporine (an inhibitor of
protein kinase C) or (R)-p-adenosine 3',5'-cyclic monophosphorothioate
(Rp-cAMP[S]; an inhibitor of cAMP-dependent protein kinase AI and II).
Addition of low concentrations (10(-13) to 10(-9)M) of SKF-82958
(D1-dopaminergic receptor agonist) or PPHT (D2-dopaminergic receptor
agonist) also stimulated the expression of pOGH (angiotensinogen
N-1498/+18). The stimulatory effect of SKF-82958 was inhibited by the
presence of SCH-23390 or Rp-cAMP[S], whereas the effect of PPHT was
inhibited by the presence of spiperone or staurosporine. These studies
demonstrate that the expression of pOGH (angiotensinogen N-1498/+18) in OK
27 cells is modulated by dopaminergic receptor agonists.
