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Mariotta L, Ramadan T, Singer D, Camargo SMR, Verrey F. Dietary homeostasis challenge in mice lacking aromatic amino acid transporter TAT1/Slc16a10. FASEB J 2011. [DOI: 10.1096/fasebj.25.1_supplement.1038.19] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Wagner G, Singer D. Zur Darstellung von 2-Hydroxy-thiobenzaniliden und 3-Aryl-mono- und -dithionbenzoxazinen-(1,3). ACTA ACUST UNITED AC 2010. [DOI: 10.1002/zfch.19630030408] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Weiser J, Christner M, Rohde H, Singer D. Detektion und Identifikation von Bakterien anhand ihrer Wärmeabgabe: eine mikrokalorimetrische Untersuchung. KLINISCHE PADIATRIE 2010. [DOI: 10.1055/s-0030-1261529] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Schwalm A, Hillebrand G, Singer D. Früherkennung der Late Onset – Sepsis mittels integrativer Software? KLINISCHE PADIATRIE 2010. [DOI: 10.1055/s-0030-1261287] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Blohm M, Lehmberg K, Hillebrand G, Neu A, Ridderbusch I, Schneppenheim R, Singer D. Unterarmgangrän und Hirninfarkt bei „normaler“ Gerinnung: Homozygoter Antithrombin III – Mangel Typ II (Budapest). KLINISCHE PADIATRIE 2010. [DOI: 10.1055/s-0030-1261589] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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56
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Lehmberg K, Klaassen I, Hillebrand G, Zylla S, Kutscha C, Hassenpflug W, Schneppenheim R, Singer D. Kongenitale thrombotisch-thrombozytopenische Purpura (Upshaw-Schulman-Syndrom): Differenzialdiagnose der neonatalen Sepsis mit disseminierter intravasaler Gerinnung. KLINISCHE PADIATRIE 2010. [DOI: 10.1055/s-0030-1261530] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Weiser J, Christner M, Rohde H, Singer D. Beschleunigte Detektion von Katheterinfektionen mittels Mikrokalorimetrie: eine methodische Untersuchung. KLINISCHE PADIATRIE 2010. [DOI: 10.1055/s-0030-1261358] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Blohm M, Schmitt C, Riedel F, Helmke K, Singer D. Unerwartete Beatmungskomplikation: Absaugkatheterspitze als endobronchialer Fremdkörper. KLINISCHE PADIATRIE 2010. [DOI: 10.1055/s-0030-1261633] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Praefcke K, Singer D, Gündogan B, Gutbier K, Langner M. Columnare und nematische Phasen neuer makrodiscotischer Materialien [1]. ACTA ACUST UNITED AC 2010. [DOI: 10.1002/bbpc.19930971029] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Praefcke K, Singer D, Gündogan B, Gutbier K, Langner M. Columnare und nematische Phasen neuer makrodiscotischer Materialien [1]. ACTA ACUST UNITED AC 2010. [DOI: 10.1002/bbpc.19940980117] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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61
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Singer D. Pulmonale Hypertension bei Zwerchfellhernie: Von der Struktur zur Funktion und zurück. Z Geburtshilfe Neonatol 2010. [DOI: 10.1055/s-0030-1248817] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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62
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Tarini B, Goldenberg A, Singer D, Clark S, Butchart A, Davis M. Not without my Permission: Parents’ Willingness to Permit Use of Newborn Screening Samples for Research. Public Health Genomics 2010; 13:125-30. [DOI: 10.1159/000228724] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2009] [Accepted: 04/16/2009] [Indexed: 11/19/2022] Open
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Singer D, Camargo SMR, Huggel K, Romeo E, Danilczyk U, Kuba K, Chesnov S, Caron MG, Penninger JM, Verrey F. Orphan transporter SLC6A18 is renal neutral amino acid transporter B0AT3. J Biol Chem 2009; 284:19953-60. [PMID: 19478081 DOI: 10.1074/jbc.m109.011171] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The orphan transporter Slc6a18 (XT2) is highly expressed at the luminal membrane of kidney proximal tubules and displays approximately 50% identity with Slc6a19 (B(0)AT1), which is the main neutral amino acid transporter in both kidney and small intestine. As yet, the amino acid transport function of XT2 has only been experimentally supported by the urinary glycine loss observed in xt2 null mice. We report here that in Xenopus laevis oocytes, co-expressed ACE2 (angiotensin-converting enzyme 2) associates with XT2 and reveals its function as a Na(+)- and Cl(-)-de pend ent neutral amino acid transporter. In contrast to its association with ACE2 observed in Xenopus laevis oocytes, our experiments with ace2 and collectrin null mice demonstrate that in vivo it is Collectrin, a smaller homologue of ACE2, that is required for functional expression of XT2 in kidney. To assess the function of XT2 in vivo, we reanalyzed its knock-out mouse model after more than 10 generations of backcrossing into C57BL/6 background. In addition to the previously published glycinuria, we observed a urinary loss of several other amino acids, in particular beta-branched and small neutral ones. Using telemetry, we confirmed the previously described link of XT2 absence with hypertension but only in physically restrained animals. Taken together, our data indicate that the formerly orphan transporter XT2 functions as a sodium and chloride-de pend ent neutral amino acid transporter that we propose to rename B(0)AT3.
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Hering J, Singer D. Der postnatale Energieumsatzanstieg bei Frühgeborenen: – Biologische Konstante oder alimentäre Variable? Z Geburtshilfe Neonatol 2009. [DOI: 10.1055/s-0029-1223018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Camargo SM, Singer D, Makrides V, Huggel K, Pos KM, Wagner CA, Kuba K, Danilczyk U, Skovby F, Kleta R, Penninger JM, Verrey F. Tissue-specific amino acid transporter partners ACE2 and collectrin differentially interact with hartnup mutations. Gastroenterology 2009; 136:872-82. [PMID: 19185582 PMCID: PMC7094282 DOI: 10.1053/j.gastro.2008.10.055] [Citation(s) in RCA: 208] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/23/2008] [Revised: 09/17/2008] [Accepted: 10/23/2008] [Indexed: 02/08/2023]
Abstract
BACKGROUND & AIMS Hartnup amino acid transporter B(0)AT1 (SLC6A19) is the major luminal sodium-dependent neutral amino acid transporter of small intestine and kidney proximal tubule. The expression of B(0)AT1 in kidney was recently shown to depend on its association with collectrin (Tmem27), a protein homologous to the membrane-anchoring domain of angiotensin-converting enzyme (ACE) 2. METHODS Because collectrin is almost absent from small intestine, we tested the hypothesis that it is ACE2 that interacts with B(0)AT1 in enterocytes. Furthermore, because B(0)AT1 expression depends on an associated protein, we tested the hypothesis that Hartnup-causing B(0)AT1 mutations differentially impact on B(0)AT1 interaction with intestinal and kidney accessory proteins. RESULTS Immunofluorescence, coimmunoprecipitation, and functional experiments using wild-type and ace2-null mice showed that expression of B(0)AT1 in small intestine critically depends on ACE2. Coexpressing new and previously identified Hartnup disorder-causing missense mutations of B(0)AT1 with either collectrin or ACE2 in Xenopus laevis oocytes showed that the high-frequency D173N and the newly identified P265L mutant B(0)AT1 transporters can still be activated by ACE2 but not collectrin coexpression. In contrast, the human A69T and R240Q B(0)AT1 mutants cannot be activated by either of the associated proteins, although they function as wild-type B(0)AT1 when expressed alone. CONCLUSIONS We thus show that ACE2 is necessary for the expression of the Hartnup transporter in intestine and suggest that the differential functional association of mutant B(0)AT1 transporters with ACE2 and collectrin in intestine and kidney, respectively, participates in the phenotypic heterogeneity of human Hartnup disorder.
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Singer D, Herth N, Kuhlmann J, Holland-Nell K, Beck-Sickinger A, Hoffmann R. Mapping of phosphorylation-dependent anti-tau monoclonal antibodies in immunoblots using human tau-constructs synthesized by native chemical ligation. Biochem Biophys Res Commun 2008; 367:318-22. [DOI: 10.1016/j.bbrc.2007.12.109] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2007] [Accepted: 12/14/2007] [Indexed: 11/28/2022]
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Abstract
Homeothermy is the result of an evolutionary process during which every increase in oxygen supply led to a consecutive increase in metabolic rate and, thus, to a new dependence on favorable ambient conditions. In response to the food scarcity of winter months, some inhabitants of temperate zones developed an ability to hibernate which is characterized by a fully thermocontrolled reduction in body temperature down to near zero values. Hibernation thus illustrates that in homeotherms, not only the body shell is poikilothermic, but also the core temperature is more variable than often assumed. However, in contrast to clinical hypothermia, natural torpidity does not consist of a cold-induced reduction in metabolic rate, but of an endogenous metabolic reduction with subsequent lowering of body temperature. As a factor of metabolic suppression, the pH has been suspected which, in hibernators, is kept constant at 7.4 by relative hypoventilation (pH-stat) which differs from its passive shift in the poikilothermic body shell (alpha-stat). In clinical hypothermia, temperature governs the metabolic rate in that, depending on the state of thermoregulation, either a cold defense reaction with an increased metabolic rate (accidental hypothermia) or a cold-induced reduction in metabolic rate (induced hypothermia) occurs. However, as can be learned from hibernators, the lower limit of hypothermia tolerance seems to be due to a uniform minimal metabolic rate rather than to the species-specific body temperature at which this metabolic limit is reached, depending on body size and basal metabolic rate. Accordingly, in judging the sequelae of hypothermia, the degree of cooling should be given less emphasis than the resulting effects on metabolic rate.
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Löwe V, Singer D. Quantitative Thermographie bei Neugeborenen unter verschiedenen Arten von Wärmestrahlung. Z Geburtshilfe Neonatol 2008. [DOI: 10.1055/s-2008-1079051] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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69
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Diehl T, Hillebrand G, Richter B, Singer D. Mehrstufiger operativer Verschluss einer großen Omphalozele bei einem Frühgeborenen 26+0 SSW. Z Geburtshilfe Neonatol 2008. [DOI: 10.1055/s-2008-1078949] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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70
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Buss A, Singer D. Variationen im Energiegehalt der Muttermilch: Eine verbrennungskalorimetrische Untersuchung. Z Geburtshilfe Neonatol 2008. [DOI: 10.1055/s-2008-1078993] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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71
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Hillebrand G, Glosemeyer P, Helmke K, Akkurt I, Singer D. Akute perinatologische Probleme und langfristige Behandlungsoptionen bei einem männlichen Neugeborenen mit Aphallie und Analatresie. Z Geburtshilfe Neonatol 2008. [DOI: 10.1055/s-2008-1079001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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72
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Wirbelauer J, Thomas W, Darge K, Singer D. Zentrale Zyanose und Verdichtungen im Thoraxröntgenbild bei einem Säugling. Monatsschr Kinderheilkd 2007. [DOI: 10.1007/s00112-007-1578-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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73
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Traa Y, Singer D. Tetraethylorthosilicat–modifizierte Zeolithe als Katalysatoren für die Dehydroalkylierung von Toluol mit Ethan. CHEM-ING-TECH 2007. [DOI: 10.1002/cite.200700031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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74
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Zuber AM, Singer D, Penninger JM, Rossier BC, Firsov D. Increased renal responsiveness to vasopressin and enhanced V2 receptor signaling in RGS2-/- mice. J Am Soc Nephrol 2007; 18:1672-8. [PMID: 17475820 DOI: 10.1681/asn.2007010032] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
The antidiuretic effect of vasopressin is mediated by V2 receptors (V2R) that are located in kidney connecting tubules and collecting ducts. This study provides evidence that V2R signaling is negatively regulated by regulator of G protein signaling 2 (RGS2), a member of the family of RGS proteins. This study demonstrates that (1) RGS2 expression in the kidney is restricted to the vasopressin-sensitive part of the nephron (thick ascending limb, connecting tubule, and collecting duct); (2) expression of RGS2 is rapidly upregulated by vasopressin; (3) the vasopressin-dependent accumulation of cAMP, the principal messenger of V2R signaling, is significantly higher in collecting ducts that are microdissected from the RGS2(-/-) mice compared with their wild-type littermates; and (4) analysis of urine output of mice that were exposed to water restriction followed by acute water loading revealed that RGS2(-/-) mice exhibit an increased renal responsiveness to vasopressin. It is proposed that RGS2 is involved in negative feedback regulation of V2R signaling.
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Danilczyk U, Sarao R, Remy C, Benabbas C, Stange G, Richter A, Arya S, Pospisilik JA, Singer D, Camargo SMR, Makrides V, Ramadan T, Verrey F, Wagner CA, Penninger JM. Essential role for collectrin in renal amino acid transport. Nature 2006; 444:1088-91. [PMID: 17167413 DOI: 10.1038/nature05475] [Citation(s) in RCA: 170] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2006] [Accepted: 11/23/2006] [Indexed: 11/09/2022]
Abstract
Angiotensin -converting enzyme 2 (ACE2) is a regulator of the renin angiotensin system involved in acute lung failure, cardiovascular functions and severe acute respiratory syndrome (SARS) infections in mammals. A gene encoding a homologue to ACE2, termed collectrin (Tmem27), has been identified in immediate proximity to the ace2 locus. The in vivo function of collectrin was unclear. Here we report that targeted disruption of collectrin in mice results in a severe defect in renal amino acid uptake owing to downregulation of apical amino acid transporters in the kidney. Collectrin associates with multiple apical transporters and defines a novel group of renal amino acid transporters. Expression of collectrin in Xenopus oocytes and Madin-Darby canine kidney (MDCK) cells enhances amino acid transport by the transporter B(0)AT1. These data identify collectrin as a key regulator of renal amino acid uptake.
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