The Experts below are selected from a list of 1635 Experts worldwide ranked by ideXlab platform
Jamie A. Davies - One of the best experts on this subject based on the ideXlab platform.
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From organoids to mini-organs: A case study in the kidney
Organs and Organoids, 2018Co-Authors: Melanie L. Lawrence, Christopher G. Mills, Jamie A. DaviesAbstract:Abstract Development of the permanent mammalian kidney, the metanephros, relies on complex reciprocal interactions between two nephrogenic cell populations; the branching ureteric bud and the metanephrogenic mesenchyme. Exploiting these interactions in vitro using murine renal progenitor cells allows the formation of self-organizing organoids of differing levels of complexity. Murine organoids made from dissociated progenitors can be used to probe mammalian kidney development and disease, including patterning, branching morphogenesis, gene function, developmental pathways, and small molecule screening. In addition, they can be used to develop techniques that may eventually lead to the creation of human renal transplant alternatives, model Systems, or screening platforms for toxicology. The simplest of the murine organoids consists of a disorganized mix of immature nephrons and Collecting Ducts, whilst the more advanced organoids contain nephrons arranged around and connected to a single, radially symmetrical Collecting Duct System. Recently, we have taken another step forward by introducing a rudimentary urothelial trunk to the Collecting Duct System, whilst maintaining nephron development. Here, we review the field of murine renal organoids, and include a detailed protocol on how to generate them.
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Node retraction during patterning of the urinary Collecting Duct System
Journal of Anatomy, 2014Co-Authors: Nils O. Lindström, Peter Hohenstein, C-hong Chang, M. Todd Valerius, Jamie A. DaviesAbstract:This report presents a novel mechanism for remodelling a branched epithelial tree. The mouse renal Collecting Duct develops by growth and repeated branching of an initially unbranched ureteric bud: this mechanism initially produces an almost fractal form with young branches connected to the centre of the kidney via a sequence of nodes (branch points) distributed widely throughout the developing organ. The Collecting Ducts of a mature kidney have a different form: from the nephrons in the renal cortex, long, straight lengths of Collecting Duct run almost parallel to one another through the renal medulla, and open together to the renal pelvis. Here we present time-lapse studies of E11.5 kidneys growing in culture: after about 5 days, the Collecting Duct trees show evidence of ‘node retraction’, in which the node of a ‘Y’-shaped branch moves downwards, shortening the stalk of the ‘Y’, lengthening its arms and narrowing their divergence angle so that the ‘Y’ becomes a ‘V’. Computer simulation suggests that node retraction can transform a spread tree, like that of an early kidney, into one with long, almost-parallel medullary rays similar to those seen in a mature real kidney.
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FAK-Src signalling is important to renal Collecting Duct morphogenesis: discovery using a hierarchical screening technique
Biology Open, 2013Co-Authors: Guangping Tai, Peter Hohenstein, Jamie A. DaviesAbstract:This report describes a hierarchical screening technique for identification of pathways that control the morphogenesis of the renal Collecting Duct System. The multi-step screen involves a first round using a 2-dimensional, cell-line-based scrape-healing assay, then a second round using a 3-dimensional tubulogenesis assay; both of these rounds use new cell lines described in this report. The final stage is ex vivo organ culture. We demonstrate the utility of the screen by using it to identify the FAK–Src-pathway signalling as being important for Collecting Duct development, specifically for the cell proliferation on which this development depends.
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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...
Ivana Novak - One of the best experts on this subject based on the ideXlab platform.
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Physiological and molecular mechanisms of inorganic phosphate handling in the toad Bufo bufo
Pflügers Archiv - European Journal of Physiology, 2007Co-Authors: Nadja Møbjerg, Andreas Werner, Sofie M. Hansen, Ivana NovakAbstract:The aim of this study was to elucidate mechanisms of P_i handling in toads ( Bufo bufo ). We introduced toads to experimental solutions of various [P_i] and high P_i diets and measured urine and lymph [P_i]. Both lymph and urine [P_i] increased with increasing P_i loads, indicating P_i absorption across skin and intestine. An initial fragment of a NaPi-II type transporter was amplified from kidney, and the full-length sequence was obtained. The protein showed the molecular hallmarks of NaPi-IIb transporters. When expressed in Xenopus oocytes the clone showed unusual pH dependence, but apparent affinity constants for P_i and Na^+ were in the range of other NaPi-II transporters. Expression profiling showed that the transporter was present in skin, intestine and kidney. Reverse transcription–polymerase chain reaction assays on dissected renal tubules indicated expression in the Collecting Duct System. Collecting tubules and Ducts were isolated, perfused and microelectrode recordings showed electrogenic P_i transport in apical and basolateral membranes. Taken together, our results show that P_i is handled by intestine, kidney and skin. The presently cloned NaPi-IIb is a likely candidate involved in P_i absorption across these epithelia. In addition, electrophysiological experiments suggest that the Collecting Duct System plays an important role in P_i homeostasis.
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Physiological and molecular mechanisms of inorganic phosphate handling in the toad Bufo bufo
Pflügers Archiv - European Journal of Physiology, 2006Co-Authors: Nadja Møbjerg, Andreas Werner, Sofie M. Hansen, Ivana NovakAbstract:The aim of this study was to elucidate mechanisms of Pi handling in toads (Bufo bufo). We introduced toads to experimental solutions of various [Pi] and high Pi diets and measured urine and lymph [Pi]. Both lymph and urine [Pi] increased with increasing Pi loads, indicating Pi absorption across skin and intestine. An initial fragment of a NaPi-II type transporter was amplified from kidney, and the full-length sequence was obtained. The protein showed the molecular hallmarks of NaPi-IIb transporters. When expressed in Xenopus oocytes the clone showed unusual pH dependence, but apparent affinity constants for Pi and Na+ were in the range of other NaPi-II transporters. Expression profiling showed that the transporter was present in skin, intestine and kidney. Reverse transcription–polymerase chain reaction assays on dissected renal tubules indicated expression in the Collecting Duct System. Collecting tubules and Ducts were isolated, perfused and microelectrode recordings showed electrogenic Pi transport in apical and basolateral membranes. Taken together, our results show that Pi is handled by intestine, kidney and skin. The presently cloned NaPi-IIb is a likely candidate involved in Pi absorption across these epithelia. In addition, electrophysiological experiments suggest that the Collecting Duct System plays an important role in Pi homeostasis.
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Ion transport mechanisms in the mesonephric Collecting Duct System of the toad Bufo bufo: microelectrode recordings from isolated and perfused tubules
Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, 2004Co-Authors: Nadja Møbjerg, Erik Larsen, Ivana NovakAbstract:It is not clear how and whether terrestrial amphibians handle NaCl transport in the distal nephron. Therefore, we studied ion transport in isolated perfused Collecting tubules and Ducts from toad, Bufo bufo, by means of microelectrodes. No qualitative difference in basolateral cell membrane potential (Vbl) was observed between tubules and Ducts in response to ion substitutions, inhibitor and agonist applications. Cl- substitution experiments indicated a small Cl- conDuctance in the basolateral membrane. The apical membrane did not have a significant Cl- conDuctance. Luminal [Na+] steps and amiloride application showed a small apical Na+ conDuctance. Arginine vasotocin depolarized Vbl. The small apical Na+ conDuctance indicates that the Collecting Duct System contributes little to NaCl reabsorption when compared to aquatic amphibians. In contrast, Vbl rapidly depolarized upon lowering of [Na+] in the bath, demonstrating the presence of a Na+-coupled anion transporter. [HCO3-] steps revealed that this transporter is not a Na+-HCO3- cotransporter. Together, our results indicate that a major task of the Collecting Duct System in B. bufo is not conDuctive NaCl transport but rather K+ secretion, as shown by our previous studies. Moreover, our results indicate the presence of a novel basolateral Na+-coupled anion transporter, the identity of which remains to be elucidated.
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K(+) transport in the mesonephric Collecting Duct System of the toad Bufo bufo: microelectrode recordings from isolated and perfused tubules.
The Journal of Experimental Biology, 2002Co-Authors: Nadja Møbjerg, Erik Larsen, Ivana NovakAbstract:SUMMARY We studied the mechanisms of K+ transport in cells from isolated and perfused Collecting tubules and Ducts from the mesonephric kidney of the toad Bufo bufo. Cells were impaled with microelectrodes across the basal cell membrane. The basolateral membrane potential (Vbl) depolarized upon change of bath [K+] from 3 to 20 mmol l-1 demonstrating a large K+ conDuctance in this membrane. In Collecting tubules and Collecting Ducts a Vbl of -66±2 mV and -74±4 mV depolarized by 30±2 mV and 36±3 mV, respectively (N=23; 15). The K+ channel inhibitor Ba2+ (1 mmol l-1) inhibited the basolateral K+ conDuctance and depolarized a Vbl of -64±4 mV by 30±6 mV (N=8). Luminal K+ steps (3 to 20 mmol l-1) demonstrated a K+ conDuctance in the apical cell membrane. In Collecting tubules and Collecting Ducts a Vbl of -70±3 mV and -73±3 mV depolarized by 11±3 mV and 16±3 mV, respectively (N=11; 11). This conDuctance could also be inhibited by Ba2+, which depolarized a Vbl of -71±5 mV by 9±3 mV (N=5). The pump inhibitor ouabain (1 mmol l-1) depolarized Vbl, but addition of furosemide to bath solution did not affect Vbl. The [K+] in urine varied from 1.3 to 22.8 mmol l-1. In conclusion, we propose that the Collecting Duct System of B. bufo secretes K+ into the urine via luminal K+ channels.
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k transport in the mesonephric Collecting Duct System of the toad bufo bufo microelectrode recordings from isolated and perfused tubules
The Journal of Experimental Biology, 2002Co-Authors: Nadja Møbjerg, Erik Larsen, Ivana NovakAbstract:SUMMARY We studied the mechanisms of K+ transport in cells from isolated and perfused Collecting tubules and Ducts from the mesonephric kidney of the toad Bufo bufo. Cells were impaled with microelectrodes across the basal cell membrane. The basolateral membrane potential (Vbl) depolarized upon change of bath [K+] from 3 to 20 mmol l-1 demonstrating a large K+ conDuctance in this membrane. In Collecting tubules and Collecting Ducts a Vbl of -66±2 mV and -74±4 mV depolarized by 30±2 mV and 36±3 mV, respectively (N=23; 15). The K+ channel inhibitor Ba2+ (1 mmol l-1) inhibited the basolateral K+ conDuctance and depolarized a Vbl of -64±4 mV by 30±6 mV (N=8). Luminal K+ steps (3 to 20 mmol l-1) demonstrated a K+ conDuctance in the apical cell membrane. In Collecting tubules and Collecting Ducts a Vbl of -70±3 mV and -73±3 mV depolarized by 11±3 mV and 16±3 mV, respectively (N=11; 11). This conDuctance could also be inhibited by Ba2+, which depolarized a Vbl of -71±5 mV by 9±3 mV (N=5). The pump inhibitor ouabain (1 mmol l-1) depolarized Vbl, but addition of furosemide to bath solution did not affect Vbl. The [K+] in urine varied from 1.3 to 22.8 mmol l-1. In conclusion, we propose that the Collecting Duct System of B. bufo secretes K+ into the urine via luminal K+ channels.
Roger G Oneil - One of the best experts on this subject based on the ideXlab platform.
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expression of a diverse array of ca2 activated k channels sk1 3 ik1 bk that functionally couple to the mechanosensitive trpv4 channel in the Collecting Duct System of kidney
PLOS ONE, 2016Co-Authors: Michael B. Butterworth, Michael X. Zhu, Jin Bin Tian, Roger G OneilAbstract:The voltage- and Ca2+-activated, large conDuctance K+ channel (BK, maxi-K) is expressed in the Collecting Duct System of kidney where it underlies flow- and Ca2+-dependent K+ excretion. To determine if other Ca2+-activated K+ channels (KCa) may participate in this process, mouse kidney and the K+-secreting mouse cortical Collecting Duct (CCD) cell line, mCCDcl1, were assessed for TRPV4 and KCa channel expression and cross-talk. qPCR mRNA analysis and immunocytochemical staining demonstrated TRPV4 and KCa expression in mCCDcl1 cells and kidney connecting tubule (CNT) and CCD. Three subfamilies of KCa channels were revealed: the high Ca2+-binding affinity small-conDuctance SK channels, SK1and SK3, the intermediate conDuctance channel, IK1, and the low Ca2+-binding affinity, BK channel (BKα subunit). Apparent expression levels varied in CNT/CCD where analysis of CCD principal cells (PC) and intercalated cells (IC) demonstrated differential staining: SK1:PC IC, IK1:PC>IC, BKα:PC = IC, and TRPV4:PC>IC. Patch clamp analysis and fluorescence Ca2+ imaging of mCCDcl1 cells demonstrated potent TRPV4-mediated Ca2+ entry and strong functional cross-talk between TRPV4 and KCa channels. TRPV4-mediated Ca2+ influx activated each KCa channel, as evidenced by selective inhibition of KCa channels, with each active KCa channel enhancing Ca2+ entry (due to membrane hyperpolarization). Transepithelial electrical resistance (TEER) analysis of confluent mCCDcl1 cells grown on permeable supports further demonstrated this cross-talk where TRPV4 activation induce a decrease in TEER which was partially restored upon selective inhibition of each KCa channel. It is concluded that SK1/SK3 and IK1 are highly expressed along with BKα in CNT and CCD and are closely coupled to TRPV4 activation as observed in mCCDcl1 cells. The data support a model in CNT/CCD segments where strong cross talk between TRPV4-mediated Ca2+ influx and each KCa channel leads to enhance Ca2+ entry which will support activation of the low Ca2+-binding affinity BK channel to promote BK-mediated K+ secretion.
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function of transient receptor potential cation channel subfamily v member 4 trpv4 as a mechanical transducer in flow sensitive segments of renal Collecting Duct System
Journal of Biological Chemistry, 2012Co-Authors: Jonathan Berrout, Min Jin, Mykola Mamenko, Oleg Zaika, Oleh Pochynyuk, Roger G OneilAbstract:Abstract The TRPV4 Ca2+-permeable channel is sensitive to mechanical stimuli. In the current study we have employed immunocytochemical staining in kidney slices and functional assessments (Ca2+ imaging) in isolated, split-open, tubule segments to define TRPV4 sites of expression and flow-dependent function in the Collecting Duct System. Staining patterns revealed strong expression of TRPV4 along the entire Collecting Duct System with highest levels at the apical (luminal)/sub-apical region of the principal cells (PC), the dominant cell type, with more diffuse staining in intercalated cells (IC). Using fluorescence Ca2+ imaging and the selective TRPV4 agonist, GSK1016790A, we demonstrated functional TRPV4 channels in PC and IC of split-opened cortical Collecting Ducts (CCD) and connecting tubules (CNT). The agonist was ineffective in inducing a rise in [Ca2+]i in the absence of extracellular Ca2+ or in tubules from TRPV4 deficient animals. Most importantly, a 10-fold elevation in luminal (apical) fluid flow induced a rapid and sustained influx of Ca2+ that was abolished by the TRPV channel inhibitor, ruthenium red, or in tubules isolated from TRPV4 deficient animals. We concluded that TRPV4 is highly expressed along the entire Collecting Duct System where it appears to function as a sensor/transducer of flow-induce mechanical stresses.
Nadja Møbjerg - One of the best experts on this subject based on the ideXlab platform.
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Physiological and molecular mechanisms of inorganic phosphate handling in the toad Bufo bufo
Pflügers Archiv - European Journal of Physiology, 2007Co-Authors: Nadja Møbjerg, Andreas Werner, Sofie M. Hansen, Ivana NovakAbstract:The aim of this study was to elucidate mechanisms of P_i handling in toads ( Bufo bufo ). We introduced toads to experimental solutions of various [P_i] and high P_i diets and measured urine and lymph [P_i]. Both lymph and urine [P_i] increased with increasing P_i loads, indicating P_i absorption across skin and intestine. An initial fragment of a NaPi-II type transporter was amplified from kidney, and the full-length sequence was obtained. The protein showed the molecular hallmarks of NaPi-IIb transporters. When expressed in Xenopus oocytes the clone showed unusual pH dependence, but apparent affinity constants for P_i and Na^+ were in the range of other NaPi-II transporters. Expression profiling showed that the transporter was present in skin, intestine and kidney. Reverse transcription–polymerase chain reaction assays on dissected renal tubules indicated expression in the Collecting Duct System. Collecting tubules and Ducts were isolated, perfused and microelectrode recordings showed electrogenic P_i transport in apical and basolateral membranes. Taken together, our results show that P_i is handled by intestine, kidney and skin. The presently cloned NaPi-IIb is a likely candidate involved in P_i absorption across these epithelia. In addition, electrophysiological experiments suggest that the Collecting Duct System plays an important role in P_i homeostasis.
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Physiological and molecular mechanisms of inorganic phosphate handling in the toad Bufo bufo
Pflügers Archiv - European Journal of Physiology, 2006Co-Authors: Nadja Møbjerg, Andreas Werner, Sofie M. Hansen, Ivana NovakAbstract:The aim of this study was to elucidate mechanisms of Pi handling in toads (Bufo bufo). We introduced toads to experimental solutions of various [Pi] and high Pi diets and measured urine and lymph [Pi]. Both lymph and urine [Pi] increased with increasing Pi loads, indicating Pi absorption across skin and intestine. An initial fragment of a NaPi-II type transporter was amplified from kidney, and the full-length sequence was obtained. The protein showed the molecular hallmarks of NaPi-IIb transporters. When expressed in Xenopus oocytes the clone showed unusual pH dependence, but apparent affinity constants for Pi and Na+ were in the range of other NaPi-II transporters. Expression profiling showed that the transporter was present in skin, intestine and kidney. Reverse transcription–polymerase chain reaction assays on dissected renal tubules indicated expression in the Collecting Duct System. Collecting tubules and Ducts were isolated, perfused and microelectrode recordings showed electrogenic Pi transport in apical and basolateral membranes. Taken together, our results show that Pi is handled by intestine, kidney and skin. The presently cloned NaPi-IIb is a likely candidate involved in Pi absorption across these epithelia. In addition, electrophysiological experiments suggest that the Collecting Duct System plays an important role in Pi homeostasis.
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Ion transport mechanisms in the mesonephric Collecting Duct System of the toad Bufo bufo: microelectrode recordings from isolated and perfused tubules
Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, 2004Co-Authors: Nadja Møbjerg, Erik Larsen, Ivana NovakAbstract:It is not clear how and whether terrestrial amphibians handle NaCl transport in the distal nephron. Therefore, we studied ion transport in isolated perfused Collecting tubules and Ducts from toad, Bufo bufo, by means of microelectrodes. No qualitative difference in basolateral cell membrane potential (Vbl) was observed between tubules and Ducts in response to ion substitutions, inhibitor and agonist applications. Cl- substitution experiments indicated a small Cl- conDuctance in the basolateral membrane. The apical membrane did not have a significant Cl- conDuctance. Luminal [Na+] steps and amiloride application showed a small apical Na+ conDuctance. Arginine vasotocin depolarized Vbl. The small apical Na+ conDuctance indicates that the Collecting Duct System contributes little to NaCl reabsorption when compared to aquatic amphibians. In contrast, Vbl rapidly depolarized upon lowering of [Na+] in the bath, demonstrating the presence of a Na+-coupled anion transporter. [HCO3-] steps revealed that this transporter is not a Na+-HCO3- cotransporter. Together, our results indicate that a major task of the Collecting Duct System in B. bufo is not conDuctive NaCl transport but rather K+ secretion, as shown by our previous studies. Moreover, our results indicate the presence of a novel basolateral Na+-coupled anion transporter, the identity of which remains to be elucidated.
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K(+) transport in the mesonephric Collecting Duct System of the toad Bufo bufo: microelectrode recordings from isolated and perfused tubules.
The Journal of Experimental Biology, 2002Co-Authors: Nadja Møbjerg, Erik Larsen, Ivana NovakAbstract:SUMMARY We studied the mechanisms of K+ transport in cells from isolated and perfused Collecting tubules and Ducts from the mesonephric kidney of the toad Bufo bufo. Cells were impaled with microelectrodes across the basal cell membrane. The basolateral membrane potential (Vbl) depolarized upon change of bath [K+] from 3 to 20 mmol l-1 demonstrating a large K+ conDuctance in this membrane. In Collecting tubules and Collecting Ducts a Vbl of -66±2 mV and -74±4 mV depolarized by 30±2 mV and 36±3 mV, respectively (N=23; 15). The K+ channel inhibitor Ba2+ (1 mmol l-1) inhibited the basolateral K+ conDuctance and depolarized a Vbl of -64±4 mV by 30±6 mV (N=8). Luminal K+ steps (3 to 20 mmol l-1) demonstrated a K+ conDuctance in the apical cell membrane. In Collecting tubules and Collecting Ducts a Vbl of -70±3 mV and -73±3 mV depolarized by 11±3 mV and 16±3 mV, respectively (N=11; 11). This conDuctance could also be inhibited by Ba2+, which depolarized a Vbl of -71±5 mV by 9±3 mV (N=5). The pump inhibitor ouabain (1 mmol l-1) depolarized Vbl, but addition of furosemide to bath solution did not affect Vbl. The [K+] in urine varied from 1.3 to 22.8 mmol l-1. In conclusion, we propose that the Collecting Duct System of B. bufo secretes K+ into the urine via luminal K+ channels.
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k transport in the mesonephric Collecting Duct System of the toad bufo bufo microelectrode recordings from isolated and perfused tubules
The Journal of Experimental Biology, 2002Co-Authors: Nadja Møbjerg, Erik Larsen, Ivana NovakAbstract:SUMMARY We studied the mechanisms of K+ transport in cells from isolated and perfused Collecting tubules and Ducts from the mesonephric kidney of the toad Bufo bufo. Cells were impaled with microelectrodes across the basal cell membrane. The basolateral membrane potential (Vbl) depolarized upon change of bath [K+] from 3 to 20 mmol l-1 demonstrating a large K+ conDuctance in this membrane. In Collecting tubules and Collecting Ducts a Vbl of -66±2 mV and -74±4 mV depolarized by 30±2 mV and 36±3 mV, respectively (N=23; 15). The K+ channel inhibitor Ba2+ (1 mmol l-1) inhibited the basolateral K+ conDuctance and depolarized a Vbl of -64±4 mV by 30±6 mV (N=8). Luminal K+ steps (3 to 20 mmol l-1) demonstrated a K+ conDuctance in the apical cell membrane. In Collecting tubules and Collecting Ducts a Vbl of -70±3 mV and -73±3 mV depolarized by 11±3 mV and 16±3 mV, respectively (N=11; 11). This conDuctance could also be inhibited by Ba2+, which depolarized a Vbl of -71±5 mV by 9±3 mV (N=5). The pump inhibitor ouabain (1 mmol l-1) depolarized Vbl, but addition of furosemide to bath solution did not affect Vbl. The [K+] in urine varied from 1.3 to 22.8 mmol l-1. In conclusion, we propose that the Collecting Duct System of B. bufo secretes K+ into the urine via luminal K+ channels.
Y. Weiss - One of the best experts on this subject based on the ideXlab platform.
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Reporter gene recombination in juxtaglomerular granular and Collecting Duct cells by human renin promoter-Cre recombinase transgene
Physiological genomics, 2006Co-Authors: S. Germain, H. Castrop, F. Theilig, S. Bachmann, J. Briggs, A. Kurtz, F Schweda, J Schnermann, M Oppermann, Y. WeissAbstract:To assess the feasibility of using the renin promoter for expressing Cre recombinase in juxtaglomerular (JG) cells only, we generated five independent transgenic mouse lines (designated hRen-Cre) expressing Cre recombinase under control of a 12.2-kb human renin promoter. In the kidneys of adult mice Cre mRNA (RT-PCR) was found in the renal cortex, with Cre protein (immunohistochemistry) being localized in afferent arterioles and to a lower degree in interlobular arteries. Cre mRNA levels were regulated in a renin-typical fashion by changes in oral salt intake, water restriction, or isoproterenol infusion, indicating the presence of key regulatory elements within 12.2 kb of the 5'-flanking region of the human renin gene. hRen-Cre mice were interbred with both the ROSA26-EGFP and ROSA26-lacZ reporter strains to assess renin promoter activity from Cre-mediated excision of a floxed stop cassette and subsequent enhanced green fluorescent protein (EGFP) and beta-galactosidase (beta-gal) detection. In adult mice, beta-gal staining and EGFP were observed in afferent arterioles and interlobular arteries, overlapping with Cre protein expression. In addition, intense beta-gal staining was found in cortical and medullary Collecting Ducts where Cre expression was minimal. In embryonic kidneys, beta-gal staining was detected in the developing Collecting Duct System beginning at embryonic day 12, showing substantial activity of the human renin promoter in the branching ureteric bud. Our data indicate that besides its well-known activity in JG cells and renal vessels the human renin promoter is transiently active in the Collecting Duct System during kidney development, complicating the use of this approach for JG cell-specific excision of floxed targets.