Project description:Vasopressin, the antidiuretic hormone, acts on the renal collecting duct. In this experiment both vasopressin (AVP) and the V2R specific agonist dDAVP were infused into Aquaporin 1 knockout animals for 7 days. The aim of the experiment was to identify genes increased by vasopressin receptors in the renal medullary collecting ducts, in the absence of an increase in renal medullary osmolarity (the AQP1 knockouts are concentrating mechanism knockouts). All experiments used inner medulla tissue for the RNA isolation. Hybridizations were performed that compared kidney inner medulla total RNA from three control mice against kidney medulla total RNA from 3 mice infused with either arginine vasopressin (AVP) or des-amino-D-arginine vasopressin (dDAVP).
Project description:Vasopressin, the antidiuretic hormone, acts on the renal collecting duct. In this experiment both vasopressin (AVP) and the V2R specific agonist dDAVP were infused into Aquaporin 1 knockout animals for 7 days. The aim of the experiment was to identify genes increased by vasopressin receptors in the renal medullary collecting ducts, in the absence of an increase in renal medullary osmolarity (the AQP1 knockouts are concentrating mechanism knockouts). All experiments used inner medulla tissue for the RNA isolation. Keywords: Vasopressin treatment study
Project description:Activation of ERK1 and ERK2 is essential in regulation of a wide variety of cellular and physiological processes. In native inner medullary collecting ducts, vasopressin (AVP) working through the V2 subtype vasopressin receptor (V2R)-mediated activation of Gαs, inhibits ERK1 and ERK2 activity. However, it has been reported that V2R can signal independently of Gαs through the activation of β-arrestin, which activates ERK1 and ERK2. Vaptans, V2R antagonists that function as so-called “inverse agonists”, have the potential of promoting cell proliferation via β-arrestin-dependent ERK activation. Here we use the mpkCCD cell line which natively expresses V2R to investigate the effects of AVP, the V2-selective analog dDAVP, and tolvaptan on ERK1 and ERK2 phosphorylation and activation. We demonstrated that ERK1 and ERK2 phosphorylation in mpkCCD cells was significantly reduced by either AVP or dDAVP, in contrast to the increases seen in non-collecting duct cells overexpressing V2R. We also found that tolvaptan has a strong effect to increase ERK1 and ERK2 phosphorylation in the presence of dDAVP and that the tolvaptan effect to increase ERK1 and ERK2 phosphorylation is absent in PKA-null mpkCCD cells. Thus, it appears that the tolvaptan effect to increase ERK activation is PKA-dependent and, therefore, not mediated by the β-arrestin pathway. Overall, the studies show that AVP decreases and that tolvaptan increases ERK1 and ERK2 activation in cells expressing V2R at endogenous levels, and provide no evidence for a role for β-arrestin in the regulation of ERK1 and ERK2 activity.
Project description:Activation of ERK1 and ERK2 is essential in regulation of a wide variety of cellular and physiological processes. In native inner medullary collecting ducts, vasopressin (AVP) working through the V2 subtype vasopressin receptor (V2R)-mediated activation of Gαs, inhibits ERK1 and ERK2 activity. However, it has been reported that V2R can signal independently of Gαs through the activation of β-arrestin, which activates ERK1 and ERK2. Vaptans, V2R antagonists that function as so-called “inverse agonists”, have the potential of promoting cell proliferation via β-arrestin-dependent ERK activation. Here we use the mpkCCD cell line which natively expresses V2R to investigate the effects of AVP, the V2-selective analog dDAVP, and tolvaptan on ERK1 and ERK2 phosphorylation and activation. We demonstrated that ERK1 and ERK2 phosphorylation in mpkCCD cells was significantly reduced by either AVP or dDAVP, in contrast to the increases seen in non-collecting duct cells overexpressing V2R. We also found that tolvaptan has a strong effect to increase ERK1 and ERK2 phosphorylation in the presence of dDAVP and that the tolvaptan effect to increase ERK1 and ERK2 phosphorylation is absent in PKA-null mpkCCD cells. Thus, it appears that the tolvaptan effect to increase ERK activation is PKA-dependent and, therefore, not mediated by the β-arrestin pathway. Overall, the studies show that AVP decreases and that tolvaptan increases ERK1 and ERK2 activation in cells expressing V2R at endogenous levels, and provide no evidence for a role for β-arrestin in the regulation of ERK1 and ERK2 activity.
Project description:This series of microarray data contain transcript intensity of mpkCCD cells. Experiment Overall Design: The mpkCCDc14 cells were cloned into colonies with varying aquaporin 2 (AQP2) expression levels in the presence of vasopressin analogy dDAVP. Transcript profiling was done for the original cells and cell clones 2, 3, 9, 10, and 11. By studying transcripts that correlate with AQP2 mRNA levels among cell clones, the objective was to identify transcripts responsible for cell-specific expression of AQP2.
Project description:Activation of the renal urine concentrating mechanism by vasopressin requires the coordinated regulation of multiple gene products including ion transporters, and water channels as well as regulatory proteins like protein kinases and phosphatases or enzymes involved in the energy-metabolism of the cells. We used microarray analysis of AVP-regulated gene products in a rat model of central diabetes insipidus (DI) to generate a comprehensive database documenting these changes. For microarray studies young (8 weeks) adult male Brattleboro rats were randomly divided into 2 groups (n = 3 per group) and treated for 3 days with either 1-desamino-8-D-Arg vasopressin (dDAVP; 5ng/h; Sigma Aldrich, Germany) or vehicle via osmotic minipump (ALZET minipump model 2001, Charles River, Sulzfeld, Germany). At the end of the treatment period animals were sacrificed and the kidneys removed. The outer medulla was isolated and used for cDNA generation and subsequent microarray analysis using [Rat230_2] Affymetrix Rat Genome 230 2.0 Array.
Project description:Vasopressin is the major hormone that regulates renal water excretion. It does so by binding to a receptor in renal collecting duct cells, triggering signaling pathways that ultimately regulate the abundance, location, and activity of the water channel protein aquaporin 2. We took an advantage of quantitative large scale proteomic technologies and oligonucleotide microarrays to quantify steady state changes in protein and transcript abundances in response to vasopressin in a collecting duct cell line, mpkCCD clone 11 (Yu et al. PNAS 2009, 106:2441-2446). This cell line originally developed by Alan Vandewalle’s group recapitulates vasopressin-mediated AQP2 expression and phosphorylation as seen in native colleting duct cells. The mpkCCD cells were grown on membrane supports to permit polarization. Once transepithelial resistance reached 5kohm per centimeter square and higher, the cells were exposed to the vasopressin V2 receptor analog, dDAVP, at a physiological concentration, 0.1nM, for 5 days. Control experiments were done with cells exposed to vehicle alone. Total RNA was harvested and processed for transcript expression analysis using Affymetrix GeneChip Mouse Genome 430 2.0 Arrays. Each experimental treatment, vehicle and dDAVP, was repeated 3 times.
Project description:Introduction. States of vasopressin excess can exist either with or without hyponatremia, depending on water intake. Here, we set up a mouse model of vasopressin-excess without hyponatremia to address the consequences of vasopressin excess that are independent of serum sodium. Methods. A mouse vasopressin-excess model was created by infusing desmopressin for 5 days without a forced water load. Control mice were infused with vehicle. Results. RNA-seq in microdissected cortical collecting ducts (CCDs) from vasopressin-excess mice showed significant changes in 153 transcripts including the expected increases in aquaporin-2 (AQP2) and AQP3 along with increases in several other targets of V2-receptor-mediated signaling in principal cells. In addition, there were decreases in abundances of many transcripts known to be targets of regulation by the Wnt/frizzled/β-catenin pathway. The vasopressin-excess model also manifested marked increases in phosphorylation of β-catenin at a known protein kinase A (PKA) site, viz. Ser552. CRISPR-mediated mutation of this PKA-target site in mice resulted in extensive changes in the transcriptomes of microdissected CCDs after desmopressin-infusion, heavily weighted toward increases in known transcriptional targets of the Wnt/β-catenin pathway. ATAC-seq in microdissected CCDs from DDAVP-infused mice revealed decreases in chromatin accessibility at promoters of many genes regulated in the Wnt/β-catenin pathway. Conclusion. We conclude that vasopressin-excess is associated with vasopressin/PKA-dependent repression of Wnt/Frizzled/β-catenin target gene expression, mediated in part by PKA-dependent phosphorylation of Ser552 of β-catenin. The repression is associated with decreasing chromatin accessibility in the promoter-TSS regions of target genes. The findings suggest that normonatremic vasopressin-excess is not necessarily benign.
Project description:Water homeostasis is regulated by the peptide hormone arginine vasopressin (AVP), which promotes water reabsorption in the renal collecting duct. The regulation of Aqp2 gene transcription is a key mechanism through which AVP modulates water transport as disruption of this mechanism leads to water balance disorders. Therefore, an important goal is to understand the regulatory processes that control Aqp2 gene transcription. While CREB (CREB1) has been proposed as the primary transcription factor responsible for Aqp2 transcription, recent evidence challenges this view, suggesting that other CREB-like transcription factors, including ATF1 and CREM, may play a role. We employed the CRISPR/Cas9 gene-editing system to delete Atf1, Creb1, and Crem in mpkCCD cells, an immortalized collecting duct cell line. These cell lines were then exposed to the vasopressin analog dDAVP to assess the role of these transcription factors in regulating Aqp2 expression. Deletion of all three transcription factors (ATF1, CREB1, and CREM) led to a significant reduction in the vasopressin-induced upregulation of AQP2 protein, confirming their role in regulating Aqp2 expression. Rescue experiments in triple knockout cells showed that expressing any of the three transcription factors restored the response to vasopressin. RNA-seq data showed that Aqp2 mRNA levels mirrored changes in protein abundance, supporting the idea that these transcription factors affect Aqp2 transcription. Our findings demonstrate that ATF1, CREB1, and CREM have redundant roles in regulating Aqp2 transcription. Our results suggest that these transcription factors might regulate the expression of other unidentified transcription factors involved in Aqp2 regulation.
Project description:Copeptin, the c-terminal fragment of arginine vasopressin (AVP), is considered a useful biomarker for the secretion of AVP. Preeclampsia, a cardiovascular disorder of pregnancy, has been associated with elevated maternal plasma copeptin concentrations. These findings led us to hypothesize that AVP secretion is elevated during preeclampsia, and may contribute to the pathogenesis of this disorder. To examine the effect of increased circulating AVP upon placental development, exogenous AVP was infused into pregnant wildtype C57BL/6J mice, and the transcriptome of a single placenta per dam was assessed at gestational day 12.5 by RNAseq.