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Singer D, Camargo SM. Collectrin and ACE2 in renal and intestinal amino acid transport. Channels (Austin) 2014; 5:410-23. [DOI: 10.4161/chan.5.5.16470] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
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Blohm M, Arndt F, Sandig J, Mueller G, Hecher K, Singer D, Weil J. Correlation between maternal and fetal biomarker levels. Thorac Cardiovasc Surg 2014. [DOI: 10.1055/s-0034-1394048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Singer D. [Discussion welcome]. Z Geburtshilfe Neonatol 2014; 218:135. [PMID: 25127344 DOI: 10.1055/s-0034-1385889] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Camargo SMR, Vuille-dit-Bille RN, Mariotta L, Ramadan T, Huggel K, Singer D, Götze O, Verrey F. The Molecular Mechanism of Intestinal Levodopa Absorption and Its Possible Implications for the Treatment of Parkinson’s Disease. J Pharmacol Exp Ther 2014; 351:114-23. [DOI: 10.1124/jpet.114.216317] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
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30
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Singer D. [Three options for case presentation]. Z Geburtshilfe Neonatol 2014; 218:49. [PMID: 24788833 DOI: 10.1055/s-0034-1372652] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Wolf M, Klaassen I, Reinshagen K, Hermann J, Singer D. Neonatale Erstversorgung – „Atypische Intubation“ bei Trachealagenesie. Z Geburtshilfe Neonatol 2014; 218:87-8. [DOI: 10.1055/s-0034-1376232] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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32
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Singer D. [Editorial]. Z Geburtshilfe Neonatol 2013; 217:197. [PMID: 24363247 DOI: 10.1055/s-0033-1363259] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Schwarz J, Singer D, Piedcoq J, Fromentin G, Tomé D, Azzout-Marniche D. P058 Rôle signal des acides aminés et de la leucine dans les cellules hépatiques. NUTR CLIN METAB 2013. [DOI: 10.1016/s0985-0562(13)70390-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Singer D. Back to the Future! Z Geburtshilfe Neonatol 2013; 217:153. [DOI: 10.1055/s-0033-1358470] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Mitra M, Hercík K, Byeon IJL, Ahn J, Hill S, Hinchee-Rodriguez K, Singer D, Byeon CH, Charlton LM, Nam G, Heidecker G, Gronenborn AM, Levin JG. Structural determinants of human APOBEC3A enzymatic and nucleic acid binding properties. Nucleic Acids Res 2013; 42:1095-110. [PMID: 24163103 PMCID: PMC3902935 DOI: 10.1093/nar/gkt945] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Human APOBEC3A (A3A) is a single-domain cytidine deaminase that converts deoxycytidine residues to deoxyuridine in single-stranded DNA (ssDNA). It inhibits a wide range of viruses and endogenous retroelements such as LINE-1, but it can also edit genomic DNA, which may play a role in carcinogenesis. Here, we extend our recent findings on the NMR structure of A3A and report structural, biochemical and cell-based mutagenesis studies to further characterize A3A’s deaminase and nucleic acid binding activities. We find that A3A binds ssRNA, but the RNA and DNA binding interfaces differ and no deamination of ssRNA is detected. Surprisingly, with only one exception (G105A), alanine substitution mutants with changes in residues affected by specific ssDNA binding retain deaminase activity. Furthermore, A3A binds and deaminates ssDNA in a length-dependent manner. Using catalytically active and inactive A3A mutants, we show that the determinants of A3A deaminase activity and anti-LINE-1 activity are not the same. Finally, we demonstrate A3A’s potential to mutate genomic DNA during transient strand separation and show that this process could be counteracted by ssDNA binding proteins. Taken together, our studies provide new insights into the molecular properties of A3A and its role in multiple cellular and antiviral functions.
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Schmidtke S, Diehl W, Herrmann J, Bergholz R, Singer D. Komplexe gastrointestinale Fehlbildung - Kombinierte Ösophagus- und Duodenalatresie. Z Geburtshilfe Neonatol 2013; 217:147-8. [DOI: 10.1055/s-0033-1356501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Warlitz C, Kobbe R, Helmke K, Höger P, Singer D. [Infantile myofibromatosis]. Z Geburtshilfe Neonatol 2013; 217:112-3. [PMID: 23967509 DOI: 10.1055/s-0033-1349977] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Stangner T, Singer D, Wagner C, Gutsche C, Ueberschär O, Hoffmann R, Kremer F. FACS-sorted particles reduce the data variance in optical tweezers-assisted dynamic force spectroscopy measurements. Phys Biol 2013; 10:046004. [PMID: 23788010 DOI: 10.1088/1478-3975/10/4/046004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
By combining optical tweezers-assisted dynamic force spectroscopy experiments with fluorescence activated cell sorting (FACS), we demonstrate a new approach to reducing the data variance in measuring receptor-ligand interactions on a single molecule level by ensuring similar coating densities. Therefore, the carboxyfluorescein-labelled monophosphorylated peptide tau226-240[pThr231] is anchored on melamine resin beads and these beads are sorted by FACS to achieve a homogeneous surface coverage. To quantify the impact of the fluorescence dye on the bond parameters between the phosphorylated peptide and the corresponding phosphorylation specific anti-human tau monoclonal antibody HPT-104, we perform dynamic force spectroscopy and compare the results to data using unsorted beads covered with the non-fluorescence peptide analogue. Finally, we demonstrate that the data variance of the relative binding frequency is significantly decreased by a factor of 3.4 using pre-sorted colloids with a homogeneous ligand coating compared to using unsorted colloids.
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Hillebrand G, Glosemeyer P, Helmke K, Singer D. Seltene Fehlbildung der Anogenitalregion - Fetale Enterolithiasis als Vorbote einer Penisagenesie. Z Geburtshilfe Neonatol 2013. [DOI: 10.1055/s-0033-1345726] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Singer D. Editorial. Z Geburtshilfe Neonatol 2012. [DOI: 10.1055/s-0032-1331706] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Mariotta L, Ramadan T, Singer D, Guetg A, Herzog B, Stoeger C, Palacín M, Lahoutte T, Camargo SMR, Verrey F. T-type amino acid transporter TAT1 (Slc16a10) is essential for extracellular aromatic amino acid homeostasis control. J Physiol 2012; 590:6413-24. [PMID: 23045339 DOI: 10.1113/jphysiol.2012.239574] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
The uniporter TAT1 (Slc16a10) mediates the facilitated diffusion of aromatic amino acids (AAAs) across basolateral membranes of kidney, small intestine and liver epithelial cells, and across the plasma membrane of non-epithelial cells like skeletal myocytes. Its role for body AA homeostasis has now been investigated using newly generated TAT1 (Slc16a10) defective mice (tat1(-/-)). These mice grow and reproduce normally, show no gross phenotype and no obvious neurological defect. Histological analysis did not reveal abnormalities and there is no compensatory change in any tested AA transporter mRNA. TAT1 null mice, however, display increased plasma, muscle and kidney AAA concentration under both normal and high protein diet, although this concentration remains normal in the liver. A major aromatic aminoaciduria and a smaller urinary loss of all substrates additionally transported by l-type AA antiporter Lat2-4F2hc (Slc7a8) were revealed under a high protein diet. This suggests an epithelial transport defect as also shown by the accumulation of intravenously injected (123)I-2-I-l-Phe in kidney and l-[(3)H]Phe in ex vivo everted gut sac enterocytes. Taken together, these data indicate that the uniporter TAT1 is required to equilibrate the concentration of AAAs across specific membranes. For instance, it enables hepatocytes to function as a sink that controls the extracellular AAAs concentration. Additionally, it facilitates the release of AAAs across the basolateral membrane of small intestine and proximal kidney tubule epithelial cells, thereby allowing the efflux of other neutral AAs presumably via Lat2-4F2hc.
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Singer D, Camargo SMR, Ramadan T, Schäfer M, Mariotta L, Herzog B, Huggel K, Wolfer D, Werner S, Penninger JM, Verrey F. Defective intestinal amino acid absorption in Ace2 null mice. Am J Physiol Gastrointest Liver Physiol 2012; 303:G686-95. [PMID: 22790597 DOI: 10.1152/ajpgi.00140.2012] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Mutations in the main intestinal and kidney luminal neutral amino acid transporter B(0)AT1 (Slc6a19) lead to Hartnup disorder, a condition that is characterized by neutral aminoaciduria and in some cases pellagra-like symptoms. These latter symptoms caused by low-niacin are thought to result from defective intestinal absorption of its precursor L-tryptophan. Since Ace2 is necessary for intestinal B(0)AT1 expression, we tested the impact of intestinal B(0)AT1 absence in ace2 null mice. Their weight gain following weaning was decreased, and Na(+)-dependent uptake of B(0)AT1 substrates measured in everted intestinal rings was defective. Additionally, high-affinity Na(+)-dependent transport of L-proline, presumably via SIT1 (Slc6a20), was absent, whereas glucose uptake via SGLT1 (Slc5a1) was not affected. Measurements of small intestine luminal amino acid content following gavage showed that more L-tryptophan than other B(0)AT1 substrates reach the ileum in wild-type mice, which is in line with its known lower apparent affinity. In ace2 null mice, the absorption defect was confirmed by a severalfold increase of L-tryptophan and of other neutral amino acids reaching the ileum lumen. Furthermore, plasma and muscle levels of glycine and L-tryptophan were significantly decreased in ace2 null mice, with other neutral amino acids displaying a similar trend. A low-protein/low-niacin diet challenge led to differential changes in plasma amino acid levels in both wild-type and ace2 null mice, but only in ace2 null mice to a stop in weight gain. Despite the combination of low-niacin with a low-protein diet, plasma niacin concentrations remained normal in ace2 null mice and no pellagra symptoms, such as photosensitive skin rash or ataxia, were observed. In summary, mice lacking Ace2-dependent intestinal amino acid transport display no total niacin deficiency nor clear pellagra symptoms, even under a low-protein and low-niacin diet, despite gross amino acid homeostasis alterations.
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Singer D. Editorial. Z Geburtshilfe Neonatol 2012. [DOI: 10.1055/s-0032-1323658] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Singer D. [Long-term survival of preterm neonates]. Bundesgesundheitsblatt Gesundheitsforschung Gesundheitsschutz 2012; 55:568-75. [PMID: 22441527 DOI: 10.1007/s00103-012-1453-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
In view of the increased survival rate of very preterm neonates, several longitudinal studies were done to assess the quality of life of the survivors. They revealed a fairly constant rate of 25-30% of sensorineural and/or motor impairment. Beyond those "major handicaps," further problems may arise in every single period of life, which, albeit less severe, add to the burden of prematurity. These include growth retardation and cognitive delay in the school age, affected psychosocial behavior during adolescence, and the "metabolic syndrome" of formerly malnourished fetuses in adulthood. Thus, the epidemiologic studies not only confirmed the role of regionalization in the quality of perinatology, but also supported a more farsighted approach to the sequelae of prematurity. Like in young adults who grew up with congenital heart defects, also in former preterm neonates, appropriate medical care has to be provided for an increasing number of long-term survivors. Moreover, the life-long effects of metabolic imprinting in growth-retarded fetuses underline the primary-preventive role of perinatal medicine, extending far beyond the "baby" stage of human development.
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Mann E, Singer D, Pitkin J, Panay N, Hunter M. 139 PSYCHOSOCIAL ADJUSTMENT IN WOMENWITH PREMATURE MENOPAUSE: A CROSS-SECTIONAL SURVEY. Maturitas 2012. [DOI: 10.1016/s0378-5122(12)70250-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Mann E, Singer D, Pitkin J, Panay N, Hunter MS. Psychosocial adjustment in women with premature menopause: a cross-sectional survey. Climacteric 2012; 15:481-9. [DOI: 10.3109/13697137.2011.647841] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Blohm ME, Hartwich J, Obrecht D, Müller G, Weil J, Singer D. Left ventricular stroke volume measurement by impedance cardiography correlates with echocardiography in neonates. Crit Care 2012. [PMCID: PMC3363643 DOI: 10.1186/cc10832] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022] Open
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Höing SJ, Singer D, Speer CP, Wermke K. Beeinflusst der Geburtsmodus die Schreimelodie bei Neugeborenen? Z Geburtshilfe Neonatol 2011. [DOI: 10.1055/s-0031-1293461] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/15/2022]
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Singer D, Mann E, Hunter MS, Pitkin J, Panay N. The silent grief: psychosocial aspects of premature ovarian failure. Climacteric 2011; 14:428-37. [DOI: 10.3109/13697137.2011.571320] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Singer D, Chotechuang N, Chaumontet C, Gaudichon C, Fromentin G, Tomé D, Azzout‐Marniche D. Leucine and Branched‐Chain Amino Acids Modulate Translation in Rat Primary Hepatocytes. FASEB J 2011. [DOI: 10.1096/fasebj.25.1_supplement.983.15] [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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