The Experts below are selected from a list of 11634 Experts worldwide ranked by ideXlab platform
Mark A Knepper - One of the best experts on this subject based on the ideXlab platform.
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pka independent vasopressin signaling in renal Collecting Duct
The FASEB Journal, 2020Co-Authors: Chunglin Chou, Markus M. Rinschen, Viswanathan Raghuram, Arnab Datta, Chinrang Yang, Kavee Limbutara, Mark A KnepperAbstract:Vasopressin regulates renal water excretion by binding to a Gα s-coupled receptor (V2R) in Collecting Duct cells, resulting in increased water permeability through regulation of the aquaporin-2 (AQP2) water channel. This action is widely accepted to be associated with cAMP-mediated activation of protein kinase A (PKA). Here, we use phosphoproteomics in Collecting Duct cells in which PKA has been deleted (CRISPR-Cas9) to identify PKA-independent responses to vasopressin. The results show that V2R-mediated vasopressin signaling is predominantly, but not entirely, PKA-dependent. Upregulated sites in PKA-null cells include Ser256 of AQP2, which is critical to regulation of AQP2 trafficking. In addition, phosphorylation changes in the protein kinases Stk39 (SPAK) and Prkci (an atypical PKC) are consistent with PKA-independent regulation of these protein kinases. Target motif analysis of the phosphopeptides increased in PKA-null cells indicates that vasopressin activates one or more members of the AMPK/SNF1-subfamily of basophilic protein kinases. In vitro phosphorylation assays using recombinant, purified SNF1-subfamily kinases confirmed postulated target specificities. Of interest, measured IBMX-dependent cAMP levels were an order of magnitude higher in PKA-null than in PKA-intact cells, indicative of a PKA-dependent feedback mechanism. Overall, the findings support the conclusion that V2-receptor mediated signaling in Collecting Duct cells is in part PKA-independent.
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phosphoproteomic identification of vasopressin v2 receptor dependent signaling in the renal Collecting Duct
American Journal of Physiology-renal Physiology, 2019Co-Authors: Venkatesh Deshpande, Chunglin Chou, Viswanathan Raghuram, Arnab Datta, Anika R Kao, Mark A KnepperAbstract:Vasopressin controls water balance largely through PKA-dependent effects to regulate the Collecting Duct water channel aquaporin-2 (AQP2). Although considerable information has accrued regarding th...
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identification of ut a1 and aqp2 interacting proteins in rat inner medullary Collecting Duct
American Journal of Physiology-cell Physiology, 2018Co-Authors: Chunglin Chou, Trairak Pisitkun, Gloria Hwang, Daniel J Hageman, Lichy Han, Prashasti Agrawal, Mark A KnepperAbstract:The urea channel UT-A1 and the water channel aquaporin-2 (AQP2) mediate vasopressin-regulated transport in the renal inner medullary Collecting Duct (IMCD). To identify the proteins that interact w...
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identification of β catenin interacting proteins in nuclear fractions of native rat Collecting Duct cells
American Journal of Physiology-renal Physiology, 2017Co-Authors: Jacqueline R Hwang, Chunglin Chou, Mark A Knepper, Barbara Medvar, Hyun Jun JungAbstract:The gene encoding the aquaporin-2 water channel is regulated transcriptionally in response to vasopressin. In the renal Collecting Duct, vasopressin stimulates the nuclear translocation and phospho...
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serine threonine phosphatases and aquaporin 2 regulation in renal Collecting Duct
American Journal of Physiology-renal Physiology, 2017Co-Authors: Chunglin Chou, Sophia M Lemaire, Viswanathan Raghuram, Cameron R Grady, Christina M Pickering, Ezigbobiara N Umejiego, Mark A KnepperAbstract:Phosphorylation of the aquaporin-2 (AQP2) water channel at four COOH-terminal serines plays a central role in the regulation of water permeability of the renal Collecting Duct. The level of phosphorylation at these sites is determined by a balance between phosphorylation by protein kinases and dephosphorylation by phosphatases. The phosphatases that dephosphorylate AQP2 have not been identified. Here, we use large-scale data integration techniques to identify serine-threonine phosphatases likely to interact with AQP2 in renal Collecting Duct principal cells. As a first step, we have created a comprehensive list of 38 S/T phosphatase catalytic subunits present in the mammalian genome. Then we used Bayes' theorem to integrate available information from large-scale data sets from proteomic and transcriptomic studies to rank the known S/T phosphatases with regard to the likelihood that they interact with AQP2 in renal Collecting Duct cells. To broaden the analysis, we have generated new proteomic data (LC-MS/MS) identifying 4538 distinct proteins including 22 S/T phosphatases in cytoplasmic fractions from native inner medullary Collecting Duct cells from rats. The official gene symbols corresponding to the top-ranked phosphatases (common names in parentheses) were: Ppp1cb (PP1-β), Ppm1g (PP2C), Ppp1ca (PP1-α), Ppp3ca (PP2-B or calcineurin), Ppp2ca (PP2A-α), Ppp1cc (PP1-γ), Ppp2cb (PP2A-β), Ppp6c (PP6C), and Ppp5c (PP5). This ranking correlates well with results of prior reDuctionist studies of ion and water channels in renal Collecting Duct cells.
Donald E Kohan - One of the best experts on this subject based on the ideXlab platform.
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identification of nfat5 as a transcriptional regulator of the edn1 gene in Collecting Duct
American Journal of Physiology-renal Physiology, 2019Co-Authors: Jayalakshmi Lakshmipathi, Donald E Kohan, Will Wheatley, Anil Kumar, Gaelle Mercenne, Aylin R RodanAbstract:The inner medullary Collecting Duct (IMCD) produces very high levels of endothelin-1 (ET-1) that acts as an autocrine inhibitor of IMCD Na+ and water reabsorption. Recent studies suggest that IMCD ...
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Collecting Duct principal but not intercalated cell prorenin receptor regulates renal sodium and water excretion
American Journal of Physiology-renal Physiology, 2018Co-Authors: Nirupama Ramkumar, James D Stockand, Elena Mironova, Donald E Kohan, Deborah Stuart, Nikita Abraham, Yang Gao, Shuping Wang, Jayalakshmi LakshmipathiAbstract:The Collecting Duct is the predominant nephron site of prorenin and prorenin receptor (PRR) expression. We previously demonstrated that the Collecting Duct PRR regulates epithelial Na+ channel (ENa...
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role of the Collecting Duct renin angiotensin system in regulation of blood pressure and renal function
Current Hypertension Reports, 2016Co-Authors: Nirupama Ramkumar, Donald E KohanAbstract:Recent evidence suggests that the renal tubular renin angiotensin system regulates urinary Na+ and water excretion and blood pressure. Three key components of the tubular renin angiotensin system, namely renin, prorenin receptor, and angiotensin-II type 1 receptor, are localized to the Collecting Duct. This system may modulate Collecting Duct Na+ and water reabsorption via angiotensin-II-dependent and angiotensin-II-independent pathways. Further, the system may be of greatest relevance in hypertensive states and particularly those characterized by high circulating angiotensin-II. In this review, we summarize the current knowledge on the synthesis, regulation, and function of Collecting Duct-derived renin angiotensin system components and examine recent developments with regard to regulation of blood pressure and renal fluid and Na+ excretion.
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Collecting Duct principal cell transport processes and their regulation
Clinical Journal of The American Society of Nephrology, 2015Co-Authors: David Pearce, Rama Soundararajan, Christiane Trimpert, Ossama B Kashlan, Peter M T Deen, Donald E KohanAbstract:The principal cell of the kidney Collecting Duct is one of the most highly regulated epithelial cell types in vertebrates. The effects of hormonal, autocrine, and paracrine factors to regulate principal cell transport processes are central to the maintenance of fluid and electrolyte balance in the face of wide variations in food and water intake. In marked contrast with the epithelial cells lining the proximal tubule, the Collecting Duct is electrically tight, and ion and osmotic gradients can be very high. The central role of principal cells in salt and water transport is reflected by their defining transporters-the epithelial Na(+) channel (ENaC), the renal outer medullary K(+) channel, and the aquaporin 2 (AQP2) water channel. The coordinated regulation of ENaC by aldosterone, and AQP2 by arginine vasopressin (AVP) in principal cells is essential for the control of plasma Na(+) and K(+) concentrations, extracellular fluid volume, and BP. In addition to these essential hormones, additional neuronal, physical, and chemical factors influence Na(+), K(+), and water homeostasis. Notably, a variety of secreted paracrine and autocrine agents such as bradykinin, ATP, endothelin, nitric oxide, and prostaglandin E2 counterbalance and limit the natriferic effects of aldosterone and the water-retaining effects of AVP. Considerable recent progress has improved our understanding of the transporters, receptors, second messengers, and signaling events that mediate principal cell responses to changing environments in health and disease. This review primarily addresses the structure and function of the key transporters and the complex interplay of regulatory factors that modulate principal cell ion and water transport.
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renal Collecting Duct nos1 maintains fluid electrolyte homeostasis and blood pressure
Hypertension, 2013Co-Authors: Kelly A. Hyndman, Donald E Kohan, Erika I. Boesen, Ahmed A. Elmarakby, Michael W. Brands, Paul L. Huang, David M. Pollock, Jennifer S. PollockAbstract:Nitric oxide is a pronatriuretic and prodiuretic factor. The highest renal NO synthase (NOS) activity is found in the inner medullary Collecting Duct. The Collecting Duct (CD) is the site of daily fine-tune regulation of sodium balance, and led us to hypothesize that a CD-specific deletion of NOS1 would result in an impaired ability to excrete a sodium load leading to a salt-sensitive blood pressure phenotype. We bred AQP2-CRE mice with NOS1 floxed mice to produce flox control and CD-specific NOS1 knockout (CDNOS1KO) littermates. CDs from CDNOS1KO mice produced 75% less nitrite, and urinary nitrite+nitrate (NOx) excretion was significantly blunted in the knockout genotype. When challenged with high dietary sodium, CDNOS1KO mice showed significantly reduced urine output, sodium, chloride, and NOx excretion, and increased mean arterial pressure relative to flox control mice. In humans, urinary NOx is a newly identified biomarker for the progression of hypertension. These findings reveal that NOS1 in the CD is critical in the regulation of fluid–electrolyte balance, and this new genetic model of CD NOS1 gene deletion will be a valuable tool to study salt-dependent blood pressure mechanisms.
Chunglin Chou - One of the best experts on this subject based on the ideXlab platform.
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pka independent vasopressin signaling in renal Collecting Duct
The FASEB Journal, 2020Co-Authors: Chunglin Chou, Markus M. Rinschen, Viswanathan Raghuram, Arnab Datta, Chinrang Yang, Kavee Limbutara, Mark A KnepperAbstract:Vasopressin regulates renal water excretion by binding to a Gα s-coupled receptor (V2R) in Collecting Duct cells, resulting in increased water permeability through regulation of the aquaporin-2 (AQP2) water channel. This action is widely accepted to be associated with cAMP-mediated activation of protein kinase A (PKA). Here, we use phosphoproteomics in Collecting Duct cells in which PKA has been deleted (CRISPR-Cas9) to identify PKA-independent responses to vasopressin. The results show that V2R-mediated vasopressin signaling is predominantly, but not entirely, PKA-dependent. Upregulated sites in PKA-null cells include Ser256 of AQP2, which is critical to regulation of AQP2 trafficking. In addition, phosphorylation changes in the protein kinases Stk39 (SPAK) and Prkci (an atypical PKC) are consistent with PKA-independent regulation of these protein kinases. Target motif analysis of the phosphopeptides increased in PKA-null cells indicates that vasopressin activates one or more members of the AMPK/SNF1-subfamily of basophilic protein kinases. In vitro phosphorylation assays using recombinant, purified SNF1-subfamily kinases confirmed postulated target specificities. Of interest, measured IBMX-dependent cAMP levels were an order of magnitude higher in PKA-null than in PKA-intact cells, indicative of a PKA-dependent feedback mechanism. Overall, the findings support the conclusion that V2-receptor mediated signaling in Collecting Duct cells is in part PKA-independent.
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phosphoproteomic identification of vasopressin v2 receptor dependent signaling in the renal Collecting Duct
American Journal of Physiology-renal Physiology, 2019Co-Authors: Venkatesh Deshpande, Chunglin Chou, Viswanathan Raghuram, Arnab Datta, Anika R Kao, Mark A KnepperAbstract:Vasopressin controls water balance largely through PKA-dependent effects to regulate the Collecting Duct water channel aquaporin-2 (AQP2). Although considerable information has accrued regarding th...
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identification of ut a1 and aqp2 interacting proteins in rat inner medullary Collecting Duct
American Journal of Physiology-cell Physiology, 2018Co-Authors: Chunglin Chou, Trairak Pisitkun, Gloria Hwang, Daniel J Hageman, Lichy Han, Prashasti Agrawal, Mark A KnepperAbstract:The urea channel UT-A1 and the water channel aquaporin-2 (AQP2) mediate vasopressin-regulated transport in the renal inner medullary Collecting Duct (IMCD). To identify the proteins that interact w...
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transcriptomes of major renal Collecting Duct cell types in mouse identified by single cell rna seq
Proceedings of the National Academy of Sciences of the United States of America, 2017Co-Authors: Lihe Chen, Jae Wook Lee, Chunglin Chou, Anil V Nair, Maria A Battistone, Teodor G Păunescu, Maria Merkulova, Sylvie Breton, Jill W Verlander, Susan M WallAbstract:Prior RNA sequencing (RNA-seq) studies have identified complete transcriptomes for most renal epithelial cell types. The exceptions are the cell types that make up the renal Collecting Duct, namely intercalated cells (ICs) and principal cells (PCs), which account for only a small fraction of the kidney mass, but play critical physiological roles in the regulation of blood pressure, extracellular fluid volume, and extracellular fluid composition. To enrich these cell types, we used FACS that employed well-established lectin cell surface markers for PCs and type B ICs, as well as a newly identified cell surface marker for type A ICs, c-Kit. Single-cell RNA-seq using the IC- and PC-enriched populations as input enabled identification of complete transcriptomes of A-ICs, B-ICs, and PCs. The data were used to create a freely accessible online gene-expression database for Collecting Duct cells. This database allowed identification of genes that are selectively expressed in each cell type, including cell-surface receptors, transcription factors, transporters, and secreted proteins. The analysis also identified a small fraction of hybrid cells expressing aquaporin-2 and anion exchanger 1 or pendrin transcripts. In many cases, mRNAs for receptors and their ligands were identified in different cells (e.g., Notch2 chiefly in PCs vs. Jag1 chiefly in ICs), suggesting signaling cross-talk among the three cell types. The identified patterns of gene expression among the three types of Collecting Duct cells provide a foundation for understanding physiological regulation and pathophysiology in the renal Collecting Duct.
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transcriptomes of major renal Collecting Duct cell types in mouse identified by single cell rna seq
bioRxiv, 2017Co-Authors: Lihe Chen, Jae Wook Lee, Chunglin Chou, Anil V Nair, Maria A Battistone, Teodor G Păunescu, Maria Merkulova, Sylvie Breton, Jill W Verlander, Susan M WallAbstract:Prior RNA sequencing (RNA-Seq) studies have identified complete transcriptomes for most renal epithelial cell types. The exceptions are the cell types that make up the renal Collecting Duct, namely intercalated cells (ICs) and principal cells (PCs), which account for only a small fraction of the kidney mass, but play critical physiological roles in the regulation of blood pressure, extracellular fluid volume and extracellular fluid composition. To enrich these cell types, we used fluorescence-activated cell sorting (FACS) that employed well established lectin cell surface markers for PCs and type B ICs, as well as a newly identified cell surface marker for type A ICs, viz. c-Kit. Single-cell RNA-Seq using the IC- and PC-enriched populations as input enabled identification of complete transcriptomes of A-ICs, B-ICs and PCs. The data were used to create a freely-accessible online gene-expression database for Collecting Duct cells. This database allowed identification of genes that are selectively expressed in each cell type including cell-surface receptors, transcription factors, transporters and secreted proteins. The analysis also identified a small fraction of hybrid cells expressing both aquaporin-2 and either anion exchanger 1 or pendrin transcripts. In many cases, mRNAs for receptors and their ligands were identified in different cells (e.g. Notch2 chiefly in PCs vs Jag1 chiefly in ICs) suggesting signaling crosstalk among the three cell types. The identified patterns of gene expression among the three types of Collecting Duct cells provide a foundation for understanding physiological regulation and pathophysiology in the renal Collecting Duct.
Jamie A. Davies - One of the best experts on this subject based on the ideXlab platform.
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an improved kidney dissociation and reaggregation culture system results in nephrons arranged organotypically around a single Collecting Duct system
Organogenesis, 2011Co-Authors: Veronika V Ganeva, Mathieu Unbekandt, Jamie A. DaviesAbstract:Recently, we published a method for reconstruction of embryonic kidney tissues from suspensions of cells. 5 For this method, cell suspensions are obtained by enzyme-assisted disaggregation of E11.5 mouse kidney rudiments, followed by temporary pharmacological inhibition of ROCK to reduce loss of cells during this single-cell suspension phase of the experiment. The suspended cells are reaggregated, and they form tubes that express markers typical of ureteric bud/Collecting Duct. Near these tubes, nephron progenitors form from the mesenchyme and go through their normal morphological sequence of development to produce nephrons with defined Bowman’s capsules, proximal tubules and distal tubules; each expresses specific markers in their usual stages and places. The nephrons connect to the nearby ureteric bud/Collecting Duct structures to make a continuous lumen, as Methods for constructing engineered “tissues” from simple suspensions of cells are valuable for investigations into basic developmental biology and for tissue engineering. We recently published a method for producing embryonic renal tissues from suspensions of embryonic mouse renal cells. this method reproduced the anatomies and differentiation states of nephrons and stroma very well; it had the limitation, however, that what would, in normal development, be a single, highly branched Collecting Duct tree leading to a ureter developed, in the engineered system, as a multitude of very small Collecting Duct trees. the se were isolated from each other and therefore would not be effective for draining urine to a common exit, were the tissue to be supplied with blood and physiologically active. her e, we report an improvement on the original method; it results in the formation of nephrons arranged around one single Collecting Duct tree as would happen in a normal kidney.
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an improved kidney dissociation and reaggregation culture system results in nephrons arranged organotypically around a single Collecting Duct system
Organogenesis, 2011Co-Authors: Veronika V Ganeva, Mathieu Unbekandt, Jamie A. DaviesAbstract:Methods for constructing engineered “tissues” from simple suspensions of cells are valuable for investigations into basic developmental biology and for tissue engineering. We recently published a method for producing embryonic renal tissues from suspensions of embryonic mouse renal cells. This method reproduced the anatomies and differentiation states of nephrons and stroma very well; it had the limitation, however, that what would, in normal development, be a single, highly branched Collecting Duct tree leading to a ureter developed, in the engineered system, as a multitude of very small Collecting Duct trees. These were isolated from each other and therefore would not be effective for draining urine to a common exit, were the tissue to be supplied with blood and physiologically active. Here, we report an improvement on the original method; it results in the formation of nephrons arranged around one single Collecting Duct tree as would happen in a normal kidney.
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dact2 is expressed in the developing ureteric bud Collecting Duct system of the kidney and controls morphogenetic behavior of Collecting Duct cells
American Journal of Physiology-renal Physiology, 2010Co-Authors: Wen-chin Lee, Melinda T. Hough, Weijia Liu, Robert Ekiert, Nils O. Lindström, Peter Hohenstein, Jamie A. DaviesAbstract:The overall pattern of the developing kidney is set in large part by the developing ureteric bud/Collecting Duct system, and dysgenesis of this system accounts for a variety of clinically significa...
Jennifer S. Pollock - One of the best experts on this subject based on the ideXlab platform.
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nos1 dependent negative feedback regulation of the epithelial sodium channel in the Collecting Duct
American Journal of Physiology-renal Physiology, 2015Co-Authors: Kelly A. Hyndman, Vladislav Bugaj, James D Stockand, Elena Mironova, Jennifer S. PollockAbstract:With an increase in urine flow there is a significant increase in shear stress against the renal epithelium including the inner medullary Collecting Duct, resulting in an increase in nitric oxide (...
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renal Collecting Duct nos1 maintains fluid electrolyte homeostasis and blood pressure
Hypertension, 2013Co-Authors: Kelly A. Hyndman, Donald E Kohan, Erika I. Boesen, Ahmed A. Elmarakby, Michael W. Brands, Paul L. Huang, David M. Pollock, Jennifer S. PollockAbstract:Nitric oxide is a pronatriuretic and prodiuretic factor. The highest renal NO synthase (NOS) activity is found in the inner medullary Collecting Duct. The Collecting Duct (CD) is the site of daily fine-tune regulation of sodium balance, and led us to hypothesize that a CD-specific deletion of NOS1 would result in an impaired ability to excrete a sodium load leading to a salt-sensitive blood pressure phenotype. We bred AQP2-CRE mice with NOS1 floxed mice to produce flox control and CD-specific NOS1 knockout (CDNOS1KO) littermates. CDs from CDNOS1KO mice produced 75% less nitrite, and urinary nitrite+nitrate (NOx) excretion was significantly blunted in the knockout genotype. When challenged with high dietary sodium, CDNOS1KO mice showed significantly reduced urine output, sodium, chloride, and NOx excretion, and increased mean arterial pressure relative to flox control mice. In humans, urinary NOx is a newly identified biomarker for the progression of hypertension. These findings reveal that NOS1 in the CD is critical in the regulation of fluid–electrolyte balance, and this new genetic model of CD NOS1 gene deletion will be a valuable tool to study salt-dependent blood pressure mechanisms.