Downregulation of vasopressin V2 receptor promoter activity via V1a receptor pathway

2007 ◽  
Vol 292 (5) ◽  
pp. F1418-F1426 ◽  
Author(s):  
Yuichiro Izumi ◽  
Yushi Nakayama ◽  
Tomohiko Mori ◽  
Hiroki Miyazaki ◽  
Hideki Inoue ◽  
...  
Keyword(s):  
Promoter Region ◽  
Promoter Activity ◽  
Collecting Duct ◽  
V1a Receptor ◽  
Antidiuretic Effect ◽  
Collecting Ducts ◽  
V2 Receptor ◽  
Flanking Region ◽  
Pka Pathway

Vasopressin V1a and V2 receptors (V1aR and V2R, respectively) distribute in the collecting duct of the kidney. Although the function of V2R mediating the antidiuretic effect of AVP has been investigated in detail, the role of V1aR in the collecting ducts has not been elucidated. In the present study, we have investigated the role of the V1aR pathway in V2R promoter activity. We cloned the 5′-flanking region of rat V2R (rV2R) and investigated rV2R promoter activity in the LLC-PK1 cell line transfected to express rat V1aR (rV1aR) dominantly (LLC-PK1/rV1aR). AVP induced a transient increase, followed by a sustained decrease, of rV2R promoter activity in these cells. This AVP-induced decrease of rV2R promoter activity was inhibited by V1aR, but not V2R, antagonist. PMA mimicked this decrease of rV2R promoter activity. On the contrary, 8-(4-chlorophenylthio)-cAMP increased rV2R promoter activity. These PMA- and 8-(4-chlorophenylthio)-cAMP-induced effects were not observed on the deletion segment of the 5′-flanking region lacking CAAT and SP1 sites. In conclusion, 1) expression of the V2R is downregulated via the V1aR pathway in LLC-PK1/rV1aR cells, and 2) expression of the V2R is downregulated by the PMA-induced PKC pathway and upregulated by the cAMP-PKA pathway. These opposite effects of PKC and PKA appear to be regulated by the same promoter region of CAAT and SP1.

Low pH stimulates vasopressin V2 receptor promoter activity and enhances downregulation induced by V1a receptor stimulation

2009 ◽  
Vol 297 (3) ◽  
pp. F620-F628 ◽  
Author(s):  
Hasiyet Memetimin ◽  
Yuichiro Izumi ◽  
Yushi Nakayama ◽  
Yukimasa Kohda ◽  
Hideki Inoue ◽  
...  
Keyword(s):  
Promoter Activity ◽  
Urine Concentration ◽  
Low Ph ◽  
Dependent Manner ◽  
V1a Receptor ◽  
Vasopressin V2 Receptor ◽  
Basolateral Side ◽  
Collecting Ducts ◽  
V2 Receptor ◽  
Ph Conditions

Arginine vasopressin (AVP) plays a key role in the urine concentration mechanism via the vasopressin V2 receptor (V2R) and aquaporin 2 (AQP2) in the kidney. It is well known that V2R is localized on the basolateral side and the V1a receptor (V1aR) is distributed on the luminal side of the collecting ducts. Previously, we reported an increase of V1aR mRNA and a decrease of V2R mRNA in the collecting ducts under chronic metabolic acidosis. However, the regulatory mechanism of V2R in acidic conditions has not yet been determined. In the present study, we investigated the effect of changes in pH on V2R promoter activity, using the LLC-PK1 cell line stably expressing rat V1aR (LLC-PK1/rV1aR). The rV2R promoter activity was significantly increased at 12 h after the incubation in low-pH conditions, which was sustained for 24 h. mRNA and protein expressions of V2R were also increased in low-pH conditions. V1aR stimulation suppressed rV2R promoter activity in a pH-dependent manner. PKA and JNK inhibitors suppressed rV2R promoter activity in both neutral and low-pH conditions without FBS. However, a JNK inhibitor prevented the increase of V2R promoter activity only in low-pH conditions in the presence of FBS. In summary, V2R expression is increased at transcriptional, mRNA, and protein levels in LLC-PK1/rV1aR cells under low-pH conditions. Acidic condition-induced V2R enhancement was suppressed by V1aR stimulation, suggesting the crucial role of V1aR in water and electrolyte homeostasis in acidosis.

AVP-induced VIT32 gene expression in collecting duct cells occurs via trans-activation of a CRE in the 5′-flanking region of the VIT32 gene

2004 ◽  
Vol 287 (3) ◽  
pp. F460-F468 ◽  
Author(s):  
Christie P. Thomas ◽  
Randy W. Loftus ◽  
Kang Z. Liu
Keyword(s):  
Gene Expression ◽  
Promoter Region ◽  
Collecting Duct ◽  
Airway Epithelial Cells ◽  
Proximal Promoter ◽  
Xenopus Laevis Oocytes ◽  
Proximal Promoter Region ◽  
Duct Cells ◽  
Collecting Duct Cells ◽  
Flanking Region

VIT32, a vasopressin-induced transcript, inhibits Na+ transport when coexpressed with the epithelial sodium channel in Xenopus laevis oocytes ( EMBO J 21: 5109–5117, 2002). To understand the mechanism of VIT32 gene regulation, we examined the effect of DDAVP and cAMP stimulation on VIT32 expression in M-1 mouse collecting duct cells and in H441 human airway epithelial cells. Elevation of cAMP with forskolin and IBMX increased VIT32 gene expression with a peak effect at 2 h. The increase in gene expression was abolished by H89 and by actinomycin D, suggesting that cAMP stimulates VIT32 mRNA expression by a PKA-mediated increase in gene transcription. An ∼1.5-kb fragment of the 5′-flanking region of VIT32 was cloned and was able to confer cAMP-stimulated reporter gene activity when transfected into M-1 and H441 cells. By deletion analysis and site-directed mutagenesis, a cAMP response element (CRE) was identified within the proximal promoter region that was sufficient to account for the increase in VIT32 gene expression seen with DDAVP and elevation of cAMP. Furthermore, DDAVP-stimulated VIT32 promoter-reporter activity was inhibited by H89 and by a dominant negative CREB construct. Finally, we were able to identify CREB as a nuclear protein that bound to the VIT32 CRE in gel mobility shift assays. In summary, DDAVP stimulates transcription of VIT32 via a CRE within the proximal promoter region of the VIT32 gene.

Evidence of corticosteroid action along the nephron

1984 ◽  
Vol 246 (2) ◽  
pp. F111-F123 ◽  
Author(s):  
D. Marver
Keyword(s):  
Collecting Duct ◽  
Type I ◽  
Type Ii ◽  
Cortical Collecting Duct ◽  
Distal Nephron ◽  
Type Iii ◽  
Collecting Ducts ◽  
Collecting Tubule ◽  
Cortical Collecting Tubule

The kidney contains three classes of corticosteroid-binding proteins receptors. They include a mineralocorticoid-specific (Type I), a glucocorticoid-specific (Type II), and a corticosterone-specific (Type III) site. The Type I and Type III sites roughly parallel each other along the nephron, with maximal binding occurring in the late distal convoluted or connecting segment and the cortical and medullary collecting ducts. Type II sites occur throughout the nephron, with maximal concentrations appearing in the proximal tubule and the late distal convoluted-cortical collecting duct region. The function of the Type I sites in the connecting segment is unclear since chronic mineralocorticoid therapy does not influence the potential difference in this segment as it does in the cortical collecting tubule. Furthermore, the specific role of Type II versus Type III sites in the distal nephron is unknown. Finally, the possible influence of sodium on both latent and steroid-induced renal cortical and medullary Na-K-ATPase is discussed.

Deoxycorticosterone-stimulated bicarbonate secretion in rabbit cortical collecting ducts: effects of luminal chloride removal and in vivo acid loading

1985 ◽  
Vol 249 (2) ◽  
pp. F205-F212 ◽  
Author(s):  
J. Garcia-Austt ◽  
D. W. Good ◽  
M. B. Burg ◽  
M. A. Knepper
Keyword(s):  
Collecting Duct ◽  
High Rate ◽  
Bicarbonate Secretion ◽  
Cortical Collecting Duct ◽  
Acid Base ◽  
Urinary Ph ◽  
Collecting Ducts ◽  
Acid Loading

To assess the role of cortical collecting duct bicarbonate secretion in the regulation of net acid excretion, we have sought to identify what factors influence the secretion rate. Net and unidirectional bicarbonate fluxes were measured in isolated perfused cortical collecting ducts from deoxycorticosterone-treated rabbits. The collecting ducts secreted bicarbonate at 11-24 pmol X mm-1 X min-1, confirming the high rate seen in earlier studies. Oral acid loading (50 mM NH4Cl drinking water) completely inhibited the net bicarbonate secretion. The bath-to-lumen flux was markedly reduced with acid loading, but the lumen-to-bath flux changed very little. In tubules from rabbits treated with deoxycorticosterone (but not NH4Cl), luminal chloride replacement with either sulfate or gluconate completely and reversibly inhibited the net bicarbonate secretion. The bath-to-lumen flux was greatly inhibited, but there was little change in the lumen-to-bath flux. We conclude: 1) High rates of bicarbonate secretion can be induced in rabbit cortical collecting ducts by chronic treatment of the animals with deoxycorticosterone. 2) When deoxycorticosterone-treated rabbits were made acidotic by oral administration of NH4Cl, the bicarbonate secretion was prevented, indicating that the systemic acid-base state of the animal may be an important factor regulating bicarbonate secretion. 3) Replacement of chloride in the lumen with sulfate inhibits bicarbonate secretion in the cortical collecting duct, an effect which may explain in part the decrease in urinary pH in response to sulfate infusions in mineralocorticoid-stimulated animals.

scholarly journals Renal compensation to chronic hypoxic hypercapnia: downregulation of pendrin and adaptation of the proximal tubule

2007 ◽  
Vol 292 (4) ◽  
pp. F1256-F1266 ◽  
Author(s):  
Sophie de Seigneux ◽  
Hans Malte ◽  
Henrik Dimke ◽  
Jørgen Frøkiær ◽  
Søren Nielsen ◽  
...  
Keyword(s):  
Proximal Tubule ◽  
Collecting Duct ◽  
Chloride Concentration ◽  
Respiratory Acidosis ◽  
Plasma Bicarbonate ◽  
Arterial Ph ◽  
Collecting Ducts ◽  
Chloride Excretion ◽  
Plasma Chloride

The molecular basis for the renal compensation to respiratory acidosis and specifically the role of pendrin in this condition are unclear. Therefore, we studied the adaptation of the proximal tubule and the collecting duct to respiratory acidosis. Male Wistar-Hannover rats were exposed to either hypercapnia and hypoxia [8% CO2 and 13% O2 (hypercapnic, n = 6) or normal air (controls, n = 6)] in an environmental chamber for 10 days and were killed under the same atmosphere. In hypercapnic rats, arterial pH was lower than controls (7.31 ± 0.01 vs. 7.39 ± 0.01, P = 0.03), blood HCO3− concentration was increased (42 ± 0.9 vs. 32 ± 0.24 mM, P < 0.001), arterial Pco2 was increased (10.76 ± 0.4 vs. 7.20 ± 0.4 kPa, P < 0.001), and plasma chloride concentration was decreased (92.2 ± 0.7 vs. 97.2 ± 0.5 mM, P < 0.001). Plasma aldosterone levels were unchanged. In the proximal tubule, immunoblotting showed an increased expression of sodium/bicarbonate exchanger protein (188 ± 22 vs. 100 ± 11%, P = 0.005), confirmed by immunohistochemistry. Total Na/H exchanger protein expression in the cortex was unchanged by immunoblotting (119 ± 10 vs. 100 ± 11%, P = 0.27) and immunohistochemistry. In the cortex, the abundance of pendrin was decreased (51 ± 9 vs. 100 ± 7%, P = 0.003) by immunoblotting. Immunohistochemistry revealed that this decrease was clear in both cortical collecting ducts (CCDs) and connecting tubules (CNTs). This demonstrates that pendrin expression can be regulated in acidotic animals with no changes in aldosterone levels and no external chloride load. This reduction of pendrin expression may help in redirecting the CNT and CCD toward chloride excretion and bicarbonate reabsorption, contributing to the increased plasma bicarbonate and decreased plasma chloride of chronic respiratory acidosis.

scholarly journals Aldosterone-sensitive repression of ENaCα transcription by a histone H3 lysine-79 methyltransferase

2006 ◽  
Vol 290 (3) ◽  
pp. C936-C946 ◽  
Author(s):  
Wenzheng Zhang ◽  
Xuefeng Xia ◽  
Diana I. Jalal ◽  
Teresa Kuncewicz ◽  
William Xu ◽  
...  
Keyword(s):  
Collecting Duct ◽  
Histone H3 ◽  
Gene Promoter ◽  
Negative Regulator ◽  
Mrna Levels ◽  
Methyltransferase Activity ◽  
Α Subunit ◽  
Collecting Ducts ◽  
Flanking Region ◽  
Increased Activity

Aldosterone is a major regulator of epithelial Na+ absorption. One of its principal targets is the epithelial Na+ channel α-subunit (ENaCα), principally expressed in the kidney collecting duct, lung, and colon. Models of aldosterone-mediated trans-activation of the ENaCα gene have focused primarily on interactions of liganded nuclear receptors with the ENaCα gene promoter. Herein, we demonstrate that the murine histone H3 lysine-79 methyltransferase, murine disruptor of telomeric silencing alternative splice variant “a” (mDot1a), is a novel component in the aldosterone signaling network controlling transcription of the ENaCα gene. Aldosterone downregulated mDot1a mRNA levels in murine inner medullary collecting ducts cells, which was associated with histone H3 K79 hypomethylation in bulk histones and at specific sites in the ENaCα 5′-flanking region, and trans-activation of ENaCα. Knockdown of mDot1a by RNA interference increased activity of a stably integrated ENaCα promoter-luciferase construct and expression of endogenous ENaCα mRNA. Conversely, overexpression of EGFP-tagged mDot1a resulted in hypermethylation of histone H3 K79 at the endogenous ENaCα promoter, repression of endogenous ENaCα mRNA expression, and decreased activity of the ENaCα promoter-luciferase construct. mDot1a-mediated histone H3 K79 hypermethylation and repression of ENaCα promoter activity was abolished by mDot1a mutations that eliminate its methyltransferase activity. Collectively, our data identify mDot1a as a novel aldosterone-regulated histone modification enzyme, and, through binding the ENaCα promoter and hypermethylating histone H3 K79 associated with the ENaCα promoter, a negative regulator of ENaCα transcription.

scholarly journals Regulation of the Human MSH6 Gene by the Sp1 Transcription Factor and Alteration of Promoter Activity and Expression by Polymorphisms

2003 ◽  
Vol 23 (22) ◽  
pp. 7992-8007 ◽  
Author(s):  
Isabella Gazzoli ◽  
Richard D. Kolodner
Keyword(s):  
Dna Methylation ◽  
Transcription Factor ◽  
Promoter Region ◽  
Promoter Activity ◽  
Dna Mismatch ◽  
Msh6 Gene ◽  
Sp1 Transcription Factor ◽  
Human Dna ◽  
Promoter Allele ◽  
Flanking Region

ABSTRACT Defects in human DNA mismatch repair have been reported to underlie a variety of hereditary and sporadic cancer cases. We characterized the structure of the MSH6 promoter region to examine the mechanisms of transcriptional regulation of the MSH6 gene. The 5′-flanking region of the MSH6 gene was found to contain seven functional Sp1 transcription factor binding sites that each bind Sp1 and Sp3 and contribute to promoter activity. Transcription did not appear to require a TATA box and resulted in multiple start sites, including two major start sites and at least nine minor start sites. Three common polymorphisms were identified in the promoter region (−557 T→G, −448 G→A, and −159 C→T): the latter two were always associated, and each of these functionally inactivated a different Sp1 site. The polymorphic allele −448 A −159 T was demonstrated to be a common Caucasian polymorphism found in 16% of Caucasians and resulted in a five-Sp1-site promoter that had 50% less promoter activity and was more sensitive to inactivation by DNA methylation than the more common seven Sp1 site promoter allele, which was only partially inactivated by DNA methylation. In cell lines, this five-Sp1-site polymorphism resulted in reduced MSH6 expression at both the mRNA and protein level. An additional 2% of Caucasians contained another polymorphism, −210 C→T, which inactivated a single Sp1 site that also contributes to promoter activity.

Regulation of V2R transcription by hypertonicity and V1aR-V2R signal interaction

2008 ◽  
Vol 295 (4) ◽  
pp. F1170-F1176 ◽  
Author(s):  
Yuichiro Izumi ◽  
Yushi Nakayama ◽  
Hasiyet Memetimin ◽  
Takeaki Inoue ◽  
Yukimasa Kohda ◽  
...  
Keyword(s):  
Promoter Region ◽  
Promoter Activity ◽  
Urine Volume ◽  
Renal Medulla ◽  
Urine Concentration ◽  
Isotonic Condition ◽  
Intracellular Ca ◽  
Hypertonic Condition ◽  
V2 Receptor ◽  
Vasopressin V1a Receptor

Arginine vasopressin (AVP) and hypertonicity in the renal medulla play a major role in the urine concentration mechanism. Previously, we showed that rat vasopressin V2 receptor (rV2R) promoter activity was increased by vasopressin V2R stimulation and decreased by vasopressin V1a receptor (V1aR) stimulation in a LLC-PK1 cell line stably expressing rat V1aR (LLC-PK1/rV1aR). In the present study, we investigated the effects of hypertonicity on the rV2R promoter activity and on the suppression of rV2R promoter activity by V1aR stimulation in LLC-PK1/rV1aR cells. rV2R promoter activity was increased in NaCl- or mannitol-induced hypertonicity. The hypertonicity-responsive site in the rV2R promoter region was limited to 10 bp, including the Sp1 motif. The increase of V2R promoter activity by hypertonicity was significantly inhibited by a JNK inhibitor (SP600125) and PKA inhibitor (H89). In contrast, rV2R promoter activity was remarkably suppressed by V1aR stimulation in the hypertonic condition rather than in the isotonic condition. The AVP-stimulated intracellular Ca2+ concentration was increased in the hypertonic condition, suggesting the functional activation of V1aR by hypertonicity. In conclusion, 1) V2R promoter activity is increased by hypertonicity via the JNK and PKA pathways, 2) suppression of V2R expression by the V1aR-Ca2+ pathway is enhanced by hypertonicity, and 3) hypertonicity enhances the V1aR-Ca2+ pathway. The counteractivity of V2R and V1aR could be required to maintain minimum urine volume in the dehydrated state.

The effects of collecting duct active NaCl reabsorption and inner medulla anatomy on renal concentrating mechanism

1996 ◽  
Vol 270 (5) ◽  
pp. F900-F911 ◽  
Author(s):  
X. Wang ◽  
A. S. Wexler
Keyword(s):  
Collecting Duct ◽  
Three Dimensional ◽  
Hydraulic Permeability ◽  
Three Dimensional Model ◽  
Duct Epithelium ◽  
Collecting Ducts ◽  
Renal Concentrating Mechanism ◽  
Medullary Collecting Duct ◽  
Collecting Duct Epithelium

First, the representation of the inner medulla incorporates an exaggerated radial separation between tubules, vessels, and collecting ducts; and, second, the hydraulic permeability in the upper portion of the inner medullary collecting ducts was erroneously set to zero. In the current work, we explore the role of collecting duct hydraulic permeability and anatomical heterogeneity via mathematical modeling. The model predicts concentrated urine for measured values of the hydraulic permeability and homogeneous lower inner medulla as long as net active NaCl reabsorption is incorporated in the upper inner medullary collecting duct epithelium. This new three-dimensional model results in two recycling paths. The upper portion of the inner medulla recycles NaCl, whereas the lower portion recycles urea.

Evidence for dual signaling pathways for V2 vasopressin receptor in rat inner medullary collecting duct

1996 ◽  
Vol 270 (4) ◽  
pp. F623-F633 ◽  
Author(s):  
C. A. Ecelbarger ◽  
C. L. Chou ◽  
S. J. Lolait ◽  
M. A. Knepper ◽  
S. R. DiGiovanni
Keyword(s):  
Arginine Vasopressin ◽  
Receptor Agonist ◽  
Collecting Duct ◽  
Calcium Mobilization ◽  
Mrna Levels ◽  
Inner Medullary Collecting Duct ◽  
Receptor Mrna ◽  
V1a Receptor ◽  
V2 Receptor ◽  
Medullary Collecting Duct

Previous studies have demonstrated that both the V2-receptor agonist, 1-desamino-8-D-arginine vasopressin (dDAVP), and the V1a-receptor agonist, [Phe2, Orn8]vasotocin (PO-VT), increase intracellular calcium concentration ([Ca2+]i) in the rat inner medullary collecting duct (IMCD). The present studies were done to clarify the receptor subtype(s) responsible for calcium mobilization. Measurements of [Ca2+]i, using fura 2 in microdissected IMCD segments, confirmed that arginine vasopressin (AVP), dDAVP, and PO-VT stimulate an increase in [Ca2+]i and that the response to all three agents could be blocked by the specific V2-receptor antagonist, [d(CH2)5(1),D-Ile2, Ile4, Arg8]vasopressin (II-VP). These results would suggest that all three agents acted through the V2 receptor. Furthermore, we showed that PO-VT increased cAMP production in IMCD suspensions and water permeability in isolated perfused tubules. These responses were also blocked by II-VP, indicating that PO-VT is also a V2 agonist in the IMCD. Finally, we utilized the quantitative reverse transcription-polymerase chain reaction technique of Wiesner (Nucleic Acids Res. 20: 5863-5864, 1992) to evaluate V1a and V2 mRNA levels in rat collecting duct. In terminal IMCD, we estimated > 30 copies/cell for V2 receptor mRNA but less than 1 copy/cell of V1a receptor mRNA, thus there is littler or no V1a mRNA expression in the terminal IMCD. These results suggest that calcium mobilization in response to vasopressin analogues is associated with the V2 receptor and that the V2 receptor is linked to both adenylyl cyclase and calcium mobilization in the rat IMCD.

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