Expression of the angiotensinogen gene is synergistically stimulated by 8-BrcAMP and Dex in opossum kidney cells

1995 ◽  
Vol 268 (1) ◽  
pp. R105-R111 ◽  
Author(s):  
M. Ming ◽  
T. T. Wang ◽  
S. Lachance ◽  
A. Delalandre ◽  
S. Carriere ◽  
...  
Keyword(s):  
Fusion Gene ◽  
Dependent Manner ◽  
Fusion Genes ◽  
Opossum Kidney ◽  
Ok Cells ◽  
Angiotensinogen Gene ◽  
Opossum Kidney Cells ◽  
Dependent Protein ◽  
Flanking Region ◽  
Responsive Element

We transiently transfected fusion genes with the 5'-flanking region of the angiotensinogen gene linked to a bacterial chloramphenicol acetyltransferase (CAT) coding sequence as a reporter into opossum kidney (OK) cells. The addition of 8-bromoadenosine 3',5'-cyclic monophosphate (8-BrcAMP) (10(-3)-10(-7) M) or forskolin (10(-9)-10(-5) M) stimulated the expression of the plasmid pOCAT [angiotensinogen nucleotide (N) -1498/+18] fusion gene in OK cells in a dose-dependent manner. The addition of dexamethasone (Dex) (10(-6) M) further enhanced the stimulatory effect of 8-BrcAMP or forskolin, whereas the addition of (R)-p-adenosine 3',5'-cyclic monophosphorothioate [(Rp)-cAMP[S], an inhibitor of cAMP-dependent protein kinase A, I and II] blocked the stimulatory effect of 8-BrcAMP. Furthermore, the addition of 8-BrcAMP (10(-3) M) or Dex (10(-6) M) or a combination of both stimulated the expression of pOCAT (angiotensinogen N -1138/+18), pOCAT (angiotensinogen N -960/+18), pOCAT (angiotensinogen N -814/+18), and pOCAT (angiotensinogen N -688/+18), but had no effect on the expression of pOCAT (angiotensinogen N -280/+18), pOCAT (angiotensinogen N -198/+18), pOCAT (angiotensinogen N -110/+18), pOCAT (angiotensinogen N -53/+18), and pOCAT (angiotensinogen N -35/+18). To further localize the putative cAMP-responsive element (CRE) in the angiotensinogen gene, we constructed fusion genes by inserting the DNA fragments angiotensinogen N -814 to N -689, angiotensinogen N -814 to N -761, and angiotensinogen N -760 to N -689 of the 5'-flanking region of the angiotensinogen gene upstream of the thymidine kinase (TK) promoter fused to a CAT gene and introduced them into OK cells.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Hormonal regulation of expression of the angiotensinogen gene in cultured opossum kidney proximal tubular cells.

1992 ◽  
Vol 2 (10) ◽  
pp. 1516-1522
Author(s):  
J S Chan ◽  
M Ming ◽  
Z R Nie ◽  
R Sikstrom ◽  
S Lachance ◽  
...  
Keyword(s):  
Hormonal Regulation ◽  
Messenger Rna ◽  
Fusion Gene ◽  
Dependent Manner ◽  
Fusion Genes ◽  
Proximal Tubular Cells ◽  
Opossum Kidney ◽  
Tubular Cells ◽  
Ok Cells ◽  
Proximal Tubular

Angiotensinogen (ANG) messenger RNA is expressed in cultured opossum kidney (OK) proximal tubular cells. The aim of these studies was to investigate whether steroid hormones (dexamethasone, estradiol, testosterone, and progesterone) could stimulate the expression of renal ANG gene in vitro. Fusion genes consisting of various lengths of the 5'-flanking region of the rat ANG gene linked to a chloramphenicol acetyl transferase (CAT) reporter gene were constructed and introduced into cultured OK cells. The level of expression of fusion genes was determined by the level of cellular CAT enzymatic activity. The addition of dexamethasone (10(-12) to 10(-6) M) stimulates the expression of the pOCAT (ANG N-1498/+18) fusion gene in OK cells in a dose-dependent manner with a maximum stimulation at 10(-6) M and a half-maximal stimulation at 10(-9) M. Combination of dexamethasone (10(-6) M) and thyroid hormone, L-T3 (10(-6) M), further enhanced the effect of the dexamethasone alone. Testosterone (10(-6) M), estradiol (10(-6) M), and progesterone (10(-6) M) did not have this effect. Moreover, dexamethasone also stimulates the expression of the pOCAT (ANG N-688/+18) but not pOCAT (ANG N-110/+18), pOCAT (ANG N-53/+18) and pOCAT (ANG N-35/+18). These studies demonstrate that the glucocorticoid hormone is effective at stimulating the transcription of the ANG gene in OK cells, but stimulation is not observed from testosterone, estradiol, or progesterone. Moreover, glucocorticoid and L-T3 act synergistically to stimulate the transcription of the ANG gene.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Angiotensinogen gene expression is stimulated by the cAMP-responsive element binding protein in opossum kidney cells.

1997 ◽  
Vol 8 (7) ◽  
pp. 1072-1079
Author(s):  
J F Qian ◽  
T T Wang ◽  
X H Wu ◽  
J Wu ◽  
C Ge ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Thymidine Kinase ◽  
Fusion Gene ◽  
Dependent Protein Kinase ◽  
Opossum Kidney ◽  
Element Binding Protein ◽  
Dependent Protein ◽  
Responsive Element ◽  
Camp Responsive Element Binding ◽  
Kinase A

It has been reported previously that the addition of isoproterenol or forskolin stimulates the expression of the angiotensinogen (ANG) gene in opossum kidney (OK) 27 cells, an OK cell line with a fusion gene containing the 5'-flanking regulatory sequence of the rat ANG gene fused with a human growth hormone (hGH) gene as a reporter, pOGH (ANG N-1498/+18), permanently integrated into their genomes. To investigate whether the effect of isoproterenol or forskolin on the expression of the ANG gene is mediated via the nuclear 43-kD cAMP-responsive element binding protein (CREB), OK 27 cells were transiently transfected with an expression plasmid containing the cDNA for the 43-kD CREB (pRSV/CREB). The level of expression of the pOGH (ANG N-1498/+18) in OK 27 cells was estimated by the amount of immunoreactive hGH secreted into the culture medium. Transfection of pRSV/CREB alone stimulated the expression of pOGH (ANG N-1498/+18). The addition of isoproterenol or forskolin further enhanced the stimulatory effect of pRSV/ CREB on the expression of pOGH (ANG N-1498/+18). The enhancing effect of isoproterenol was inhibited by the presence of propranolol (an inhibitor of beta-adrenoceptors) and (R)-p-adenosine 3'5'-cyclic monophospho-orthioate (Rp)-cAMP (an inhibitor of cAMP-dependent protein kinase A I and II). Transfection of pRSV/CREB had no effect on the expression of thymidine kinase growth hormone in OK 13 cells, an OK cell line with a fusion gene containing the promoter/enhancer DNA sequence of the viral thymidine-kinase gene fused with an hGH gene as a reporter, thymidine kinase growth hormone, permanently integrated into their genomes. These studies demonstrate that isoproterenol stimulates the expression of ANG gene via the cAMP-dependent protein kinase A and probably via the interaction of the 43-kD CREB with the 5'-flanking region of the ANG gene. Our data indicate that the nuclear 43-kD CREB may have a modulatory role on the expression of the ANG gene in OK cells.

scholarly journals Thyroid hormone, L-T3, stimulates the expression of the angiotensinogen gene in cultured opossum kidney (OK) cells.

1992 ◽  
Vol 2 (8) ◽  
pp. 1360-1367 ◽  
Author(s):  
J S Chan ◽  
A H Chan ◽  
Z R Nie ◽  
R Sikstrom ◽  
S Lachance ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Thyroid Hormone ◽  
Human Growth ◽  
Fusion Genes ◽  
Proximal Tubular Cells ◽  
Opossum Kidney ◽  
Tubular Cells ◽  
Ok Cells ◽  
Angiotensinogen Gene ◽  
Proximal Tubular

Angiotensinogen (ANG) messenger RNA is expressed in opossum kidney (OK) proximal tubular cells. To examine whether thyroid hormone, L-T3, could stimulate the expression of the ANG gene in OK proximal tubular cells, fusion genes, consisting of various lengths of the 5'-flanking region of the rat angiotensinogen gene linked to a human growth hormone reporter gene, were constructed and introduced into OK cells. As a negative control, they were introduced into a nonkidney cell line, a human choriocarcinoma cell line (JEG-3). The level of the expression of fusion genes in these cells were determined by the level of immunoreactive human growth hormone secreted into the culture medium. The expression of ANG-growth hormone (ANG-GH) fusion genes pOGH (ANG N-1498/+18), pOGH (ANG N-688/+18), pOGH (ANG N-110/+18), pOGH (ANG N-53/+18), and pOGH (ANG N-35/+18) was 226-, 4.5-, 1.0-, 12-, and 2.5-fold higher than promoterless pOGH in the expression of growth hormone activity in OK cells. No significant expression of any of these ANG-GH fusion genes over the promoterless pOGH was observed in JEG-3 cells. The addition of L-T3 stimulates the expression of pOGH (ANG N-1498/+18) in a dose-dependent manner with a maximal and half-maximal effect at 10(-7) M and at 10(-8) to 10(-9) M, respectively. Thyroid hormone (10(-7) M) also stimulates the expression of pOGH (ANG N-688/+18) but not pOGH (ANG N-110/+18), pOGH (ANG N-53/+18), or pOGH (ANG N-35/+18).(ABSTRACT TRUNCATED AT 250 WORDS)

Transcriptional activation of the rat glucagon gene by the cyclic AMP-responsive element in pancreatic islet cells

1990 ◽  
Vol 10 (12) ◽  
pp. 6799-6804
Author(s):  
W Knepel ◽  
J Chafitz ◽  
J F Habener
Keyword(s):  
Cyclic Amp ◽  
Pancreatic Islet ◽  
Transcriptional Activation ◽  
Islet Cells ◽  
Pancreatic Islet Cell ◽  
Heterologous Promoter ◽  
Dependent Protein Kinase ◽  
Dependent Protein ◽  
Flanking Region ◽  
Responsive Element

The 5'-flanking region of the rat glucagon gene contains, from nucleotides -291 to -298, a sequence (TGA CGTCA) which mediates cyclic AMP (cAMP) responsiveness in several genes (cAMP-responsive element [CRE]). However, because of nonpermissive bases surrounding the CRE octamer, the glucagon CRE does not confer cAMP responsiveness to an inert heterologous promoter in placental JEG cells that do not express the glucagon gene. This report describes transient transfection experiments with glucagon-reporter fusion genes that show that glucagon gene expression is activated by cAMP-dependent protein kinase A in a glucagon-expressing pancreatic islet cell line. This activation is mediated through the glucagon CRE.

scholarly journals Transcriptional activation of the rat glucagon gene by the cyclic AMP-responsive element in pancreatic islet cells.

1990 ◽  
Vol 10 (12) ◽  
pp. 6799-6804 ◽  
Author(s):  
W Knepel ◽  
J Chafitz ◽  
J F Habener
Keyword(s):  
Cyclic Amp ◽  
Pancreatic Islet ◽  
Transcriptional Activation ◽  
Islet Cells ◽  
Pancreatic Islet Cell ◽  
Heterologous Promoter ◽  
Dependent Protein Kinase ◽  
Dependent Protein ◽  
Flanking Region ◽  
Responsive Element

The 5'-flanking region of the rat glucagon gene contains, from nucleotides -291 to -298, a sequence (TGA CGTCA) which mediates cyclic AMP (cAMP) responsiveness in several genes (cAMP-responsive element [CRE]). However, because of nonpermissive bases surrounding the CRE octamer, the glucagon CRE does not confer cAMP responsiveness to an inert heterologous promoter in placental JEG cells that do not express the glucagon gene. This report describes transient transfection experiments with glucagon-reporter fusion genes that show that glucagon gene expression is activated by cAMP-dependent protein kinase A in a glucagon-expressing pancreatic islet cell line. This activation is mediated through the glucagon CRE.

scholarly journals β-Adrenoceptors and dexamethasone synergistically stimulate the expression of the angiotensinogen gene in opossum kidney cells

1996 ◽  
Vol 50 (1) ◽  
pp. 94-101 ◽  
Author(s):  
Ming Ming ◽  
Wynnie Chan ◽  
Tian T. Wang ◽  
Kenneth D. Roberts ◽  
Michel Bouvier ◽  
...  
Keyword(s):  
Kidney Cells ◽  
Opossum Kidney ◽  
Angiotensinogen Gene ◽  
Opossum Kidney Cells

Binding and degradation of NH2-terminal parathyroid hormone by opossum kidney cells

1991 ◽  
Vol 260 (4) ◽  
pp. E544-E552 ◽  
Author(s):  
R. C. Brown ◽  
A. C. Silver ◽  
J. S. Woodhead
Keyword(s):  
Specific Binding ◽  
Ligand Complex ◽  
Receptor Ligand ◽  
Opossum Kidney ◽  
Ok Cells ◽  
Opossum Kidney Cells ◽  
Acid Washing ◽  
Cellular Processing ◽  
Cell Medium ◽  
Chymotrypsin Inhibitors

The binding and cellular processing of NH2-terminal parathyroid (PTH) hormone by confluent monolayers of opossum kidney (OK) cells was characterized using radiolabeled PTH peptide analogues. Time- and temperature-dependent specific binding of 125I-labeled (Nle-8,18, Tyr-34)-NH2-bovine(b)PTH-(1-34) was accompanied by the appearance of degraded radiolabel in the cell medium. Degrading activity was observed to be a specific consequence of binding by PTH receptors. Degrading activity was inhibited by monensin, chloroquine, and NH4+ but not by chymotrypsin inhibitors. Acid washing demonstrated that greater than 80% of total cell-associated specific binding at equilibrium was located in a rapidly internalized (acid-resistant) pool. Monensin pretreatment led to increased acid-resistant binding, presumably through inhibition of turnover of internalized receptor ligand and indicated that the degradation of radiolabel was probably associated with processing of the receptor-ligand complex. Release of intact radiolabel from the acid-resistant pool indicated that some of the internalized peptide was recycled out of the cell in an undegraded form (retroendocytosis). Acid-resistant binding and degradation of 125I-(Nle-8,18, Tyr-34)-NH2-bPTH-(3-34) was minimal, indicating that this ligand was not internalized. It is concluded that the binding and internalization of PTH-(1-34) fragment by confluent OK cells is a specific receptor-mediated process. Cellular processing of PTH-(1-34) conforms to established models of internalization by receptor-mediated endocytosis.

Dual action of phosphonoformic acid on Na(+)-phosphate cotransport in opossum kidney cells

1992 ◽  
Vol 263 (2) ◽  
pp. F301-F310 ◽  
Author(s):  
M. Loghman-Adham ◽  
T. P. Dousa
Keyword(s):  
Prolonged Exposure ◽  
Apical Membrane ◽  
Competitive Inhibition ◽  
Membrane Vesicles ◽  
Opossum Kidney ◽  
Ok Cells ◽  
Phosphonoformic Acid ◽  
Opossum Kidney Cells ◽  
Dependent Inhibition ◽  
Dual Action

Phosphonoformic acid (PFA, foscarnet) was found to exert both an inhibitory and a stimulatory effect on Na(+)-dependent Pi transport in opossum kidney (OK) cells. When added in the uptake media, PFA produced a dose-dependent inhibition of Na(+)-Pi cotransport. PFA had no effect on the Na(+)-dependent transports of methyl-alpha-D-glucopyranoside (AMG) or L-alanine or on amiloride-sensitive Na(+)-H+ antiport. The inhibition of Na(+)-Pi cotransport was competitive [inhibitory constant (Ki) = 6.0 mM], reversible by dilution, and solute specific. When OK cells were incubated with PFA for longer time periods (1–15 h), the Na(+)-Pi uptake measured after removal of PFA was significantly increased, i.e., “upregulated.” The extent of Na(+)-Pi cotransport upregulation was dependent on time (greater than or equal to 30 min) and dose of PFA (2–10 mM). The increase in Na(+)-Pi cotransport by upregulation with PFA was due to higher apparent Vmax with no change in apparent Michaelis constant (Km) for Pi and was solute specific: uptakes of AMG or L-proline were not changed. Removal of PFA from culture medium resulted in a fast reversal of upregulation. Upregulation was not inhibited by cycloheximide, actinomycin D, or cordycepin. Solute-specific increase of Na(+)-Pi cotransport was also found when measured in apical membrane vesicles isolated from OK cells. Thus PFA exerts a dual action on the Na(+)-Pi cotransporter of OK cells: 1) acute, competitive inhibition and 2) after prolonged exposure it increases Na(+)-Pi uptake, probably by insertion of Na(+)-Pi cotransporters into apical membrane.

Albumin endocytosis is regulated by heterotrimeric GTP-binding protein G alpha i-3 in opossum kidney cells

1996 ◽  
Vol 271 (2) ◽  
pp. F356-F364 ◽  
Author(s):  
N. J. Brunskill ◽  
N. Cockcroft ◽  
S. Nahorski ◽  
J. Walls
Keyword(s):  
G Protein ◽  
Pertussis Toxin ◽  
Protein G ◽  
Dependent Manner ◽  
Protein Subunit ◽  
Apparent Dissociation Constant ◽  
Opossum Kidney ◽  
Ok Cells ◽  
Proximal Tubular ◽  
Albumin Endocytosis

Proteinuria is an adverse feature in patients with renal disease, possibly due to toxicity of albumin to proximal tubular cells. Albumin is reabsorbed from tubular fluid by receptor-mediated endocytosis. The mechanism of regulation of the endocytosis is unknown. The large quantities of G proteins in proximal tubular cell apical membranes suggests that they may have a regulatory role in endocytosis. 125I-labeled albumin uptake was measured in opossum kidney (OK) cells. This is a saturable process with high-affinity [apparent dissociation constant (Kd) = 24.3 mg/l] and low-affinity (Kd = 15.9 g/l) components. The endocytic uptake of gold-albumin into OK cells was confirmed by electron microscopy. 125I-albumin endocytosis in OK cells was inhibited by pertussis toxin, but cholera toxin had no effect. Pertussis toxin also inhibited uptake of [3H]inulin. OK cells were stably transfected with a cDNA for the G protein subunit G alpha i-3 and transfectants were screened by immunoblotting. Several G alpha i-3-overexpressing clones were detected. OK cells overexpressing G alpha i-3 demonstrate increased 125I-albumin uptake, which is abolished by pertussis toxin, in both a concentration- and time-dependent manner. These results suggest that albumin endocytosis in OK cells is regulated by the G protein G alpha i-3.

Modulation of Na-H exchange activity by angiotensin II in opossum kidney cells

1992 ◽  
Vol 263 (6) ◽  
pp. C1141-C1146 ◽  
Author(s):  
M. Jourdain ◽  
C. Amiel ◽  
G. Friedlander
Keyword(s):  
Angiotensin Ii ◽  
Ang Ii ◽  
Camp Content ◽  
Opossum Kidney ◽  
Ok Cells ◽  
Camp Generation ◽  
Opossum Kidney Cells ◽  
Different Sources ◽  
Pkc Activation ◽  
Exchange Activity

Angiotensin II (ANG II) was shown to modulate transport in the renal proximal tubule through both inhibition of adenylate cyclase and protein kinase C (PKC) activation. We evaluated the effects of ANG II on adenosine 3',5'-cyclic monophosphate (cAMP) content and Na-H exchange activity (amiloride-sensitive Na influx) in two strains of opossum kidney (OK) cells originating from different sources, OK-VD and OK-RR cells. In OK-VD cells, ANG II inhibited basal and parathyroid hormone (PTH)-induced cAMP generation in a pertussis toxin-sensitive manner and reversed PTH inhibition of Na-H exchange. These effects of ANG II were prevented by PD 123319, a selective nonpeptide antagonist of AT2 receptors. In contrast, DuP 753, which antagonizes selectively AT1 receptors, had no effect. In OK-RR cells, ANG II had no effect on cAMP content and decreased Na-H exchange activity. The effect of ANG II persisted in the presence of PTH but was abolished by PKC downregulation and by DuP 753, but not by PD 123319. In conclusion, two types of ANG II receptors, coupled to distinct signaling pathways, were expressed independently in OK cells originating from two different sources and mediated opposite effects of ANG II on Na-H exchange activity. Those models provide a powerful tool for studying the intracellular steps involved in the tubular effects of ANG II and to evaluate the effect of pharmacological inhibitors of ANG II binding to its receptors.

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