Molecular characterization of a new urea transporter in the human kidney

Olivès, Bernadette; Martial, Sonia; Matteï, Marie‐Geneviève; Matassi, Giorgio; Rousselet, Germain; Ripoche, Pierre; Cartron, Jean‐Pierre; Bailly, Pascal

doi:10.1016/0014-5793(96)00425-5

Cited by 107 publications

(70 citation statements)

References 22 publications

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“…It is transcribed in the same direction as the other five genes, but there is no homologous gene in H. influenzae, and it is not clear whether it is separate from the preceding gene cluster. It is interesting to note that the predicted Utp polypeptide has considerable sequence identity with mammalian urea transport proteins, which are believed to transport urea via facilitated diffusion, although there is also evidence for sodium-dependent active transport (28,29,37,43). There is evidence for carrier-mediated energy-dependent urea uptake systems in various bacteria (14)(15)(16)38), and genes (fmdABCDE) encoding an outer membrane porin and a binding protein-dependent permease system for the uptake of short-chain amides and urea in Methylophilus methylotrophus have been identified (21,22).…”

Section: Discussionmentioning

confidence: 99%

Novel Genes Affecting Urease Activity inActinobacillus pleuropneumoniae

2001

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Characterization of a series of urease-negative transposon mutations of Actinobacillus pleuropneumoniae revealed that many of the mutants had insertions 2 to 4 kbp upstream of the urease gene cluster. A 5-kbp upstream region of DNA was sequenced and found to contain six open reading frames (ORFs) transcribed in the same orientation as the urease genes. As well, a partial ORF, apuR, 202 bp upstream of these six ORFs, is transcribed in the opposite orientation. The predicted product of this partial ORF shows homology with many members of the LysR family of transcriptional regulators. Five of the ORFs (cbiKLMQO) appear to form an operon encoding a putative nickel and cobalt periplasmic permease system. The cbiM and cbiQ genes encode proteins that have sequence similarity with known cobalt transport membrane proteins, and the cbiO gene encodes a cobalt transport ATP-binding protein homologue. The product of the cbiK gene is predicted to be the periplasmic-binding-protein component of the system, though it does not show any sequence similarity with CbiN, the cobalt-binding periplasmic protein. Escherichia coli clones containing this putative transport operon together with the urease genes of A. pleuropneumoniae were urease positive when grown in unsupplemented Luria-Bertani broth, whereas a clone containing only the minimal urease gene cluster required the addition of high concentrations of NiCl 2 for full urease activity. This result supports the hypothesis that nickel is a substrate for this permease system. The sixth ORF, utp, appears to encode an integral membrane protein which has significant sequence identity with mammalian urea transport proteins, though its function in A. pleuropneumoniae remains to be determined.The genes required for urease activity in various bacterial species typically include those encoding the structural subunits and those encoding the accessory proteins involved in insertion of two nickel ions within the catalytic site (24). In bacteria with urea-inducible gene clusters, the regulatory gene, ureR, is also present (24). Because of the requirement for nickel as a cofactor, genes such as Helicobacter pylori nixA and Alcaligenes eutrophus hoxN that encode nickel uptake systems have also been shown to affect urease activity (23,41).We recently identified the urease gene cluster of the gramnegative swine pathogen Actinobacillus pleuropneumoniae (4). The organization of the A. pleuropneumoniae gene cluster was found to be similar to that of other bacterial ureases, with the first three genes encoding the structural subunits (UreABC), and the accessory proteins (UreEFGD) encoded by four contiguous genes downstream. There was no evidence of a regulatory gene (ureR) upstream of the cluster.In order to further characterize the urease activity of A. pleuropneumoniae, a bank of transposon mutants of strain CM5 Nal r was generated and screened for urease-negative isolates. A large number of insertions in the urease-negative mutants mapped upstream of the urease gene cluster. Therefore, the 5-kbp reg...

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Section: Discussionmentioning

confidence: 99%

Novel Genes Affecting Urease Activity inActinobacillus pleuropneumoniae

2001

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“…3 In the explants, Pecam1 + endothelial cells, Pax2 + epithelial tubules resembling proximal and distal tubules, and renal corpuscle structures were formed (Supplemental Figure 1, A and B). The explants expressed also the type II Na/Pi cotransporter NaPi-IIa Slc34a1 for the brush border membrane in the proximal tubule, 28 the Slc14a2 for the descending thin limb of Henle's loop, 29 the Na-K-Cl transporter Slc12a1 (nkcc2) for the thick ascending limb of Henle's loop, 30 the voltage-gated chloride channel ClcnKb for the thick ascending limb of Henle's loop and the distal convoluted tubules, 31 the thiazide-sensitive sodium chloride cotransporter Slc12a3 (NCC) for the distal convoluted tubules, 32,33 and finally Podxl for the glomerular podocytes in the renal corpuscle 34 (Figure 2, iMM). Thus, the induced MM also assembles well segmented nephric tubules ex vivo.…”

Section: Tubule Induction Of the Kidney Mesenchyme Progenitor Cells Lmentioning

confidence: 99%

Functional Genetic Targeting of Embryonic Kidney Progenitor Cells Ex Vivo

Junttila

Saarela

Halt

et al. 2015

Journal of the American Society of Nephrology

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The embryonic mammalian metanephric mesenchyme (MM) is a unique tissue because it is competent to generate the nephrons in response to Wnt signaling. An ex vivo culture in which the MM is separated from the ureteric bud (UB), the natural inducer, can be used as a classic tubule induction model for studying nephrogenesis. However, technological restrictions currently prevent using this model to study the molecular genetic details before or during tubule induction. Using nephron segment-specific markers, we now show that tubule induction in the MM ex vivo also leads to the assembly of highly segmented nephrons. This induction capacity was reconstituted when MM tissue was dissociated into a cell suspension and then reaggregated (drMM) in the presence of human recombinant bone morphogenetic protein 7/human recombinant fibroblast growth factor 2 for 24 hours before induction. Growth factor-treated drMM also recovered the capacity for organogenesis when recombined with the UB. Cell tracking and time-lapse imaging of chimeric drMM cultures indicated that the nephron is not derived from a single progenitor cell. Furthermore, viral vector-mediated transduction of green fluorescent protein was much more efficient in dissociated MM cells than in intact mesenchyme, and the nephrogenic competence of transduced drMM progenitor cells was preserved. Moreover, drMM cells transduced with viral vectors mediating Lhx1 knockdown were excluded from the nephric tubules, whereas cells transduced with control vectors were incorporated. In summary, these techniques allow reproducible cellular and molecular examinations of the mechanisms behind nephrogenesis and kidney organogenesis in an ex vivo organ culture/organoid setting.

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“…Further, after heterologous expression in Xenopus oocytes, strUT-1 and strUT-2 had almost identical functional responses to urea analogs, indicating comparable substrate specificities. In contrast, the mammalian urea transporter splice variants exhibit differences in specificity to urea transport inhibition by urea analogs (26,35,44).…”

Section: Discussionmentioning

confidence: 98%

Cloning and functional characterization of a second urea transporter from the kidney of the Atlantic stingray,Dasyatis sabina

Janech¹,

Fitzgibbon²,

Nowak³

et al. 2006

American Journal of Physiology-Regulatory, Integrative and Comp

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. Cloning and functional characterization of a second urea transporter from the kidney of the Atlantic stingray, Dasyatis sabina. Am J Physiol Regul Integr Comp Physiol 291: R844 -R853, 2006. First published April 13, 2006; doi:10.1152/ajpregu.00739.2005.-The cloning of cDNAs encoding facilitated urea transporters (UTs) from the kidneys of the elasmobranchs indicates that in these fish renal urea reabsorption occurs, at least in part, by passive processes. The previously described elasmobranch urea transporter clones from shark (shUT) and stingray (strUT-1) differ from each other primarily because of the COOHterminus of the predicted strUT-1 translation product being extended by 51-amino acid residues compared with shUT. Previously, we noted multiple UT transcripts were present in stingray kidney. We hypothesized that a COOH terminally abbreviated UT isoform, homologous to shUT, would also be present in stingray kidney. Therefore, we used 5Ј/3Ј rapid amplification of cDNA ends to identify a 3ЈUTR-variant (strUT-1a) of the cDNA that encodes (strUT-1), as well as three, 3ЈUTR-variant cDNAs (strUT-2a,b,c) that encode a second phloretinsensitive, urea transporter (strUT-2). The 5ЈUTR and the first 1,132 nucleotides of the predicted coding region of the strUT-2 cDNAs are identical to the strUT-1 cDNAs. The remainder of the coding region contains only five novel nucleotides. The strUT-2 cDNAs putatively encode a 379-amino acid protein, the first 377 amino acids identical to strUT-1 plus 2 additional amino acids. We conclude that 1) a second UT isoform is expressed in the Atlantic stingray and that this isoform is similar in size to the UT previously cloned from the kidney of the dogfish shark, and 2) at least five transcripts encoding the 2 stingray UTs are derived from a single gene product through alternative splicing and polyadenylation. elasmobranch; euryhaline; alternative splicing; osmoregulation MARINE ELASMOBRANCHS (sharks, skates, and rays) use a unique volume-and osmoregulatory strategy; in general, they maintain their body fluids hyperosmotic to the ambient environment (for a review, see Ref. 15; see also 29,42). The high body fluid osmolality is achieved, in large part, by the retention of urea. At ocean salinities, plasma urea concentrations average 350 mmol/l, and urea contributes 30 -50% of the plasma osmolality (for a review, see Ref. 15). The use of this strategy for body fluid volume regulation necessitates the efficient reabsorption of most of the filtered load of urea by the kidneys. For marine elasmobranchs maintained at ocean salinities, fractional urea reabsorption is 90 -98% (9, 14, 34).

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Molecular characterization of a new urea transporter in the human kidney

Cited by 107 publications

References 22 publications

Novel Genes Affecting Urease Activity inActinobacillus pleuropneumoniae

Novel Genes Affecting Urease Activity inActinobacillus pleuropneumoniae

Functional Genetic Targeting of Embryonic Kidney Progenitor Cells Ex Vivo

Cloning and functional characterization of a second urea transporter from the kidney of the Atlantic stingray,Dasyatis sabina

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