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Rolf K. H. Kinne - One of the best experts on this subject based on the ideXlab platform.

  • d glucose recognition and Phlorizin binding sites in human sodium d glucose cotransporter 1 hsglt1 a tryptophan scanning study
    Biochemistry, 2007
    Co-Authors: Navneet K Tyagi, Azad Kumar, Pankaj Goyal, Dharmendra Pandey, Wolfgang Siess, Rolf K. H. Kinne
    Abstract:

    In order to gain a better understanding of the structure-function relation in hSGLT1, single Trp residues were introduced into a functional hSGLT1 mutant devoid of Trps at positions that previously had been postulated to be involved in sugar recognition/translocation and/or Phlorizin binding. The mutant proteins were expressed in Pichia pastoris, purified, and reconstituted into liposomes. In transport experiments the putative sugar binding site mutants W457hSGLT1 and W460hSGLT1 showed a drastic decrease in affinity toward alpha-methyl-d-glucopyranoside with Km values of 13.3 and 5.26 mM compared to 0.4 mM of the Trp-less hSGLT1. In addition, a strong decrease in the inhibitory effect of Phlorizin was observed. In Trp fluorescence studies the position of the emission maxima of the mutants, their sensitivity to N-bromosuccinimide oxidation, and their interaction with water soluble quenchers demonstrate that Trp457 and Trp460 are in contact with the hydrophilic extravesicular environment. In both mutants Trp fluorescence was quenched significantly, but differently, by various glucose analogues. They also show significant protection by d-glucose and Phlorizin against acrylamide, KI, or TCE quenching. W602hSGLT1 and W609hSGLT1, the putative aglucone binding site mutants, exhibit normal sugar and Phlorizin affinity, and show fluorescence properties which indicate that these residues are located in a very hydrophilic environment. Phlorizin and phloretin, but not d-glucose, protect both mutants against collisional quenchers. Depth-calculations using the parallax method suggest a location of Trp457 and Trp460 at an average distance of 10.8 A and 7.4 A from the center of the bilayer, while Trp602 and Trp609 are located outside the membrane. These results suggest that in the native carrier residues Gln at position 457 and Thr at position 460 reside in a hydrophilic access pathway extending 5-7 A into the membrane to which sugars as well as the sugar moiety of inhibitory glucosides bind. Residues Phe602 and Phe609 contribute by their hydrophobic aromatic residues toward binding of the aglucone part of Phlorizin. Thereby in the Phlorizin-carrier complex a close vicinity between these two subdomains of the transporter is established creating a Phlorizin binding pocket with the previously estimated dimensions of 10 x 17 x 7 A.

  • Binding of Phlorizin to the isolated C-terminal extramembranous loop of the Na+/glucose cotransporter assessed by intrinsic tryptophan fluorescence.
    Biochemistry, 2003
    Co-Authors: Xiaobing Xia, Jiann-tso Lin, Rolf K. H. Kinne
    Abstract:

    Phlorizin, a phloretin 2'-glucoside, is a potent inhibitor of the Na(+)/glucose cotransporter (SGLT1). On the basis of transport studies in intact cells, a binding site for Phlorizin was suggested in the region between amino acids 604-610 of the C-terminal loop 13. To further investigate Phlorizin binding titration experiments of the intrinsic Trp fluorescence of isolated wild-type loop 13 and two mutated loops (Y604K and G609K) were carried out. Phlorizin (135 microM) produced approximately 40% quenching of the fluorescence of wild-type loop 13; quenching could also be observed with the two mutated loops. The apparent K(d) was lowest for the wild-type loop 13 (K(d) approximately 23 microM), followed by mutant G609K (57 microM) and mutant Y604K (70 microM). Binding of Phlorizin was further confirmed by a decrease of the accessibility of loop 13 to the collisional quencher acrylamide. The interaction involves the aromatic moiety of the aglucone since phloretin (the aglucone of Phlorizin) showed almost the same effects as Phlorizin, while d-glucose did not. MALDI-TOF experiments revealed that loop 13 contained a disulfide bond between Cys 560 and Cys 608 that is very important for Phlorizin-dependent fluorescence quenching. These studies provide direct evidence that loop 13 is a site (important amino acids including 604-609) for the molecular interaction between SGLT1 and Phlorizin. They confirm that the aglucone part of the glucoside is responsible for this interaction.

Xueqi Wang - One of the best experts on this subject based on the ideXlab platform.

  • targeting of sodium glucose cotransporters with Phlorizin inhibits polycystic kidney disease progression in han sprd rats
    Kidney International, 2013
    Co-Authors: Xueqi Wang, Suhua Zhang, Yang Liu, Daniela Spichtig, Sarika Kapoor, Hermann Koepsell, Nilufar Mohebbi, Stephan Segerer
    Abstract:

    Renal tubular epithelial cell proliferation and transepithelial cyst fluid secretion are key features in the progression of polycystic kidney disease (PKD). As the role of the apical renal sodium–glucose cotransporters in these processes is not known, we tested whether Phlorizin inhibits cyst growth and delays renal disease progression in a rat model of PKD. Glycosuria was induced by subcutaneous injection of Phlorizin in male heterozygous (Cy/+) and wild-type Han:SPRD rats. Phlorizin induced immediate and sustained glycosuria and osmotic diuresis in these rats. Cy/+ rats treated with Phlorizin for 5 weeks showed a significant increase in creatinine clearance, a lower 2-kidneys/body weight ratio, a lower renal cyst index, and reduced urinary albumin excretion as compared with vehicle-treated Cy/+ rats. Measurement of Ki67 staining found significantly lower cell proliferation in dilated tubules and cysts of Cy/+ rats treated with Phlorizin, as well as a marked inhibition of the activated MAP kinase pathway. In contrast, the mTOR pathway remained unaltered. Phlorizin dose dependently inhibited MAP kinase in cultured tubular epithelial cells from Cy/+ rats. Thus, long-term treatment with Phlorizin significantly inhibits cystic disease progression in a rat model of PKD. Hence, induction of glycosuria and osmotic diuresis (glycuresis) by renal sodium–glucose cotransporters inhibition could have a therapeutic effect in polycystic kidney disease.

  • Targeting of sodium–glucose cotransporters with Phlorizin inhibits polycystic kidney disease progression in Han:SPRD rats
    Kidney International, 2013
    Co-Authors: Xueqi Wang, Suhua Zhang, Yang Liu, Daniela Spichtig, Sarika Kapoor, Hermann Koepsell, Nilufar Mohebbi, Stephan Segerer, Andreas L. Serra, Daniel Rodriguez
    Abstract:

    Renal tubular epithelial cell proliferation and transepithelial cyst fluid secretion are key features in the progression of polycystic kidney disease (PKD). As the role of the apical renal sodium–glucose cotransporters in these processes is not known, we tested whether Phlorizin inhibits cyst growth and delays renal disease progression in a rat model of PKD. Glycosuria was induced by subcutaneous injection of Phlorizin in male heterozygous (Cy/+) and wild-type Han:SPRD rats. Phlorizin induced immediate and sustained glycosuria and osmotic diuresis in these rats. Cy/+ rats treated with Phlorizin for 5 weeks showed a significant increase in creatinine clearance, a lower 2-kidneys/body weight ratio, a lower renal cyst index, and reduced urinary albumin excretion as compared with vehicle-treated Cy/+ rats. Measurement of Ki67 staining found significantly lower cell proliferation in dilated tubules and cysts of Cy/+ rats treated with Phlorizin, as well as a marked inhibition of the activated MAP kinase pathway. In contrast, the mTOR pathway remained unaltered. Phlorizin dose dependently inhibited MAP kinase in cultured tubular epithelial cells from Cy/+ rats. Thus, long-term treatment with Phlorizin significantly inhibits cystic disease progression in a rat model of PKD. Hence, induction of glycosuria and osmotic diuresis (glycuresis) by renal sodium–glucose cotransporters inhibition could have a therapeutic effect in polycystic kidney disease.

Kurt Kalcher - One of the best experts on this subject based on the ideXlab platform.

  • highly selective electrochemical determination of Phlorizin using square wave voltammetry at a boron doped diamond electrode
    Food Analytical Methods, 2017
    Co-Authors: Eda Mehmeti, Dalibor M Stankovic, Astrid Ortner, Janez Zavasnik, Kurt Kalcher
    Abstract:

    A boron-doped diamond electrode was used as an electrochemical sensor for the determination of Phlorizin (aka phloridzin, phlorrhizin) using square wave voltammetry (SWV). Phlorizin (Phl) exhibited a well-defined oxidation peak at +0.9 V (versus Ag/AgCl electrode 3 M KCl) in solutions with a pH value of 6.0. Parameters such as pH value and scan rate were optimized for cyclic voltammetry as well as amplitude and frequency for SWV. The sensor gave excellent response with a wide linear dynamic range for concentrations of Phlorizin from 3 to 100 μM with a detection limit of 0.23 μM and a good repeatability (± 0.9%, n = 7 measurements, c = 10 μM). The effect of interferences by most common compounds was tested, and the method was successfully applied to the determination of the title compound in apple root extracts and urine samples with satisfactory recovery.

Stephan Segerer - One of the best experts on this subject based on the ideXlab platform.

  • targeting of sodium glucose cotransporters with Phlorizin inhibits polycystic kidney disease progression in han sprd rats
    Kidney International, 2013
    Co-Authors: Xueqi Wang, Suhua Zhang, Yang Liu, Daniela Spichtig, Sarika Kapoor, Hermann Koepsell, Nilufar Mohebbi, Stephan Segerer
    Abstract:

    Renal tubular epithelial cell proliferation and transepithelial cyst fluid secretion are key features in the progression of polycystic kidney disease (PKD). As the role of the apical renal sodium–glucose cotransporters in these processes is not known, we tested whether Phlorizin inhibits cyst growth and delays renal disease progression in a rat model of PKD. Glycosuria was induced by subcutaneous injection of Phlorizin in male heterozygous (Cy/+) and wild-type Han:SPRD rats. Phlorizin induced immediate and sustained glycosuria and osmotic diuresis in these rats. Cy/+ rats treated with Phlorizin for 5 weeks showed a significant increase in creatinine clearance, a lower 2-kidneys/body weight ratio, a lower renal cyst index, and reduced urinary albumin excretion as compared with vehicle-treated Cy/+ rats. Measurement of Ki67 staining found significantly lower cell proliferation in dilated tubules and cysts of Cy/+ rats treated with Phlorizin, as well as a marked inhibition of the activated MAP kinase pathway. In contrast, the mTOR pathway remained unaltered. Phlorizin dose dependently inhibited MAP kinase in cultured tubular epithelial cells from Cy/+ rats. Thus, long-term treatment with Phlorizin significantly inhibits cystic disease progression in a rat model of PKD. Hence, induction of glycosuria and osmotic diuresis (glycuresis) by renal sodium–glucose cotransporters inhibition could have a therapeutic effect in polycystic kidney disease.

  • Targeting of sodium–glucose cotransporters with Phlorizin inhibits polycystic kidney disease progression in Han:SPRD rats
    Kidney International, 2013
    Co-Authors: Xueqi Wang, Suhua Zhang, Yang Liu, Daniela Spichtig, Sarika Kapoor, Hermann Koepsell, Nilufar Mohebbi, Stephan Segerer, Andreas L. Serra, Daniel Rodriguez
    Abstract:

    Renal tubular epithelial cell proliferation and transepithelial cyst fluid secretion are key features in the progression of polycystic kidney disease (PKD). As the role of the apical renal sodium–glucose cotransporters in these processes is not known, we tested whether Phlorizin inhibits cyst growth and delays renal disease progression in a rat model of PKD. Glycosuria was induced by subcutaneous injection of Phlorizin in male heterozygous (Cy/+) and wild-type Han:SPRD rats. Phlorizin induced immediate and sustained glycosuria and osmotic diuresis in these rats. Cy/+ rats treated with Phlorizin for 5 weeks showed a significant increase in creatinine clearance, a lower 2-kidneys/body weight ratio, a lower renal cyst index, and reduced urinary albumin excretion as compared with vehicle-treated Cy/+ rats. Measurement of Ki67 staining found significantly lower cell proliferation in dilated tubules and cysts of Cy/+ rats treated with Phlorizin, as well as a marked inhibition of the activated MAP kinase pathway. In contrast, the mTOR pathway remained unaltered. Phlorizin dose dependently inhibited MAP kinase in cultured tubular epithelial cells from Cy/+ rats. Thus, long-term treatment with Phlorizin significantly inhibits cystic disease progression in a rat model of PKD. Hence, induction of glycosuria and osmotic diuresis (glycuresis) by renal sodium–glucose cotransporters inhibition could have a therapeutic effect in polycystic kidney disease.

Suhua Zhang - One of the best experts on this subject based on the ideXlab platform.

  • targeting of sodium glucose cotransporters with Phlorizin inhibits polycystic kidney disease progression in han sprd rats
    Kidney International, 2013
    Co-Authors: Xueqi Wang, Suhua Zhang, Yang Liu, Daniela Spichtig, Sarika Kapoor, Hermann Koepsell, Nilufar Mohebbi, Stephan Segerer
    Abstract:

    Renal tubular epithelial cell proliferation and transepithelial cyst fluid secretion are key features in the progression of polycystic kidney disease (PKD). As the role of the apical renal sodium–glucose cotransporters in these processes is not known, we tested whether Phlorizin inhibits cyst growth and delays renal disease progression in a rat model of PKD. Glycosuria was induced by subcutaneous injection of Phlorizin in male heterozygous (Cy/+) and wild-type Han:SPRD rats. Phlorizin induced immediate and sustained glycosuria and osmotic diuresis in these rats. Cy/+ rats treated with Phlorizin for 5 weeks showed a significant increase in creatinine clearance, a lower 2-kidneys/body weight ratio, a lower renal cyst index, and reduced urinary albumin excretion as compared with vehicle-treated Cy/+ rats. Measurement of Ki67 staining found significantly lower cell proliferation in dilated tubules and cysts of Cy/+ rats treated with Phlorizin, as well as a marked inhibition of the activated MAP kinase pathway. In contrast, the mTOR pathway remained unaltered. Phlorizin dose dependently inhibited MAP kinase in cultured tubular epithelial cells from Cy/+ rats. Thus, long-term treatment with Phlorizin significantly inhibits cystic disease progression in a rat model of PKD. Hence, induction of glycosuria and osmotic diuresis (glycuresis) by renal sodium–glucose cotransporters inhibition could have a therapeutic effect in polycystic kidney disease.

  • Targeting of sodium–glucose cotransporters with Phlorizin inhibits polycystic kidney disease progression in Han:SPRD rats
    Kidney International, 2013
    Co-Authors: Xueqi Wang, Suhua Zhang, Yang Liu, Daniela Spichtig, Sarika Kapoor, Hermann Koepsell, Nilufar Mohebbi, Stephan Segerer, Andreas L. Serra, Daniel Rodriguez
    Abstract:

    Renal tubular epithelial cell proliferation and transepithelial cyst fluid secretion are key features in the progression of polycystic kidney disease (PKD). As the role of the apical renal sodium–glucose cotransporters in these processes is not known, we tested whether Phlorizin inhibits cyst growth and delays renal disease progression in a rat model of PKD. Glycosuria was induced by subcutaneous injection of Phlorizin in male heterozygous (Cy/+) and wild-type Han:SPRD rats. Phlorizin induced immediate and sustained glycosuria and osmotic diuresis in these rats. Cy/+ rats treated with Phlorizin for 5 weeks showed a significant increase in creatinine clearance, a lower 2-kidneys/body weight ratio, a lower renal cyst index, and reduced urinary albumin excretion as compared with vehicle-treated Cy/+ rats. Measurement of Ki67 staining found significantly lower cell proliferation in dilated tubules and cysts of Cy/+ rats treated with Phlorizin, as well as a marked inhibition of the activated MAP kinase pathway. In contrast, the mTOR pathway remained unaltered. Phlorizin dose dependently inhibited MAP kinase in cultured tubular epithelial cells from Cy/+ rats. Thus, long-term treatment with Phlorizin significantly inhibits cystic disease progression in a rat model of PKD. Hence, induction of glycosuria and osmotic diuresis (glycuresis) by renal sodium–glucose cotransporters inhibition could have a therapeutic effect in polycystic kidney disease.