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Werner Reutter - One of the best experts on this subject based on the ideXlab platform.

  • Biochemical Engineering of the n acyl side chain of sialic acids alters the kinetics of a glycosylated potassium channel kv3 1
    2011
    Co-Authors: Kristen M Hall, Werner Reutter, Thisbe K Lindhorst, Ruth A Schwalbe
    Abstract:

    The sialic acid of complex N-glycans can be Biochemically engineered by substituting the physiological precursor N-acetylmannosamine with non-natural N-acylmannosamines. The Kv3.1 glycoprotein, a neuronal voltage-gated potassium channel, contains sialic acid. Western blots of the Kv3.1 glycoprotein isolated from transfected B35 neuroblastoma cells incubated with N-acylmannosamines verified sialylated N-glycans attached to the Kv3.1 glycoprotein. Outward ionic currents of Kv3.1 transfected B35 cells treated with N-pentanoylmannosamine or N-propanoylmannosamine had slower activation and inactivation rates than those of untreated cells. Therefore, the N-acyl side chain of sialic acid is intimately connected with the activation and inactivation rates of this glycosylated potassium channel.

  • inhibition of biosynthesis and Biochemical modulation of n acylneuraminic acid Biochemical Engineering of sialoconjugates a review
    2004
    Co-Authors: Werner Reutter, Rudiger Horstkorte
    Abstract:

    The key enzyme of sialic acid biosynthesis is the bifunctional UDP-GlcNAc 2-epimerase/ ManNAc kinase. Novel inhibitors of this enzyme have been synthesized. The N-acyl side chain of sialic acid can be Biochemically engineered by incubating cells with non-natural N-acylmannosamine analogues such as N-propionylmannosamine and related compounds. These modified sialic acids lead to various biological changes, such as stimulation of T-lymphocyte proliferation, inhibition of the uptake of influenza A virus, stimulation of neuritic growth, increased expression of sialyl-Lewis x and altered adhesion. A review with 41 references.

  • Biochemical Engineering of cell surface sialic acids stimulates axonal growth
    2002
    Co-Authors: Bettina Buttner, Werner Reutter, Carolin Schmidt, Christoph Kannicht, Klemens Loster, Hyeyoun Lee, Sabine Nohring, Rudiger Horstkorte
    Abstract:

    Sialylation is essential for development and regeneration in mammals. Using N-propanoylmannosamine, a novel precursor of sialic acid, we were able to incorporate unnatural sialic acids with a prolonged N-acyl side chain (e.g., N-propanoylneuraminic acid) into cell surface glycoconjugates. Here we report that this Biochemical Engineering of sialic acid leads to a stimulation of neuronal cells. Both PC12 cells and cerebellar neurons showed a significant increase in neurite outgrowth after treatment with this novel sialic acid precursor. Furthermore, also the reestablishment of the perforant pathway was stimulated in brain slices. In addition, we surprisingly identified several cytosolic proteins with regulatory functions, which are differentially expressed after treatment with N-propanoylmannosamine. Because sialic acid is the only monosaccharide that is activated in the nucleus, we hypothesize that transcription could be modulated by the unnatural CMP-N-propanoylneuraminic acid and that sialic acid activation might be a general tool to regulate cellular functions, such as neurite outgrowth.

  • Efficient Biochemical Engineering of cellular sialic acids using an unphysiological sialic acid precursor in cells lacking UDP-N-acetylglucosamine 2-epimerase.
    2001
    Co-Authors: Lars R. Mantey, Michael Pawlita, Werner Reutter, Oliver T Keppler, Stephan Hinderlich
    Abstract:

    Sialic acids comprise a family of terminal sugars essential for a variety of biological recognition systems. N-Propanoylmannosamine, an unphysiological sialic acid precursor, is taken up and metabolized by mammalian cells resulting in oligosaccharide-bound N-propanoylneuraminic acid. N-Propanoylmannosamine, applied to endogenously hyposialylated subclones of the myeloid leukemia HL60 and of the B-cell lymphoma BJA-B, both deficient in UDP-N-acetylglucosamine 2-epimerase, is efficiently metabolized to CMP-N-propanoylneuraminic acid resulting in up to 85% of glycoconjugate-associated sialic acids being unphysiological N-propanoylneuraminic acid. Thus, UDP-N-acetylglucosamine 2-epimerase-deficient cell lines provide an important experimental progress in Engineering cells to display an almost homogeneous population of defined, structurally altered sialic acids.

  • Biochemical Engineering of the side chain of sialic acids increases the biological stability of the highly sialylated cell adhesion molecule ceacam1
    2001
    Co-Authors: Rudiger Horstkorte, Lars R. Mantey, Lothar Lucka, Kerstin Danker, Werner Reutter
    Abstract:

    Abstract The biological half-life time of many glycoproteins is regulated via terminal sialic acids. In this study we determined the half-lives of two different cell adhesion molecules, CEACAM1 and the α1-integrin subunit, in PC12-cells before and after Biochemical Engineering the side chain of sialic acids by the use of N -propanoylmannosamine. Both are transmembrane glycoproteins. While the immunoglobulin superfamily member CEACAM1 mediates homophilic cell–cell adhesion the α1-integrin subunit is involved in cell–matrix interactions. We found that the half-life of the highly sialylated CEACAM1 is increased from 26 to 40 h by replacement of the N -acetylneuraminic acid by the novel, engineered N -propanoylneuraminic acids, whereas the half-life of the α1-integrin subunit remains unaffected under the same conditions. This demonstrates that Biochemical Engineering not only modulates the structure of cell surface sialic acids, but that Biochemical Engineering also influences biological stability of defined glycoproteins.

Rudiger Horstkorte - One of the best experts on this subject based on the ideXlab platform.

  • inhibition of biosynthesis and Biochemical modulation of n acylneuraminic acid Biochemical Engineering of sialoconjugates a review
    2004
    Co-Authors: Werner Reutter, Rudiger Horstkorte
    Abstract:

    The key enzyme of sialic acid biosynthesis is the bifunctional UDP-GlcNAc 2-epimerase/ ManNAc kinase. Novel inhibitors of this enzyme have been synthesized. The N-acyl side chain of sialic acid can be Biochemically engineered by incubating cells with non-natural N-acylmannosamine analogues such as N-propionylmannosamine and related compounds. These modified sialic acids lead to various biological changes, such as stimulation of T-lymphocyte proliferation, inhibition of the uptake of influenza A virus, stimulation of neuritic growth, increased expression of sialyl-Lewis x and altered adhesion. A review with 41 references.

  • Biochemical Engineering of cell surface sialic acids stimulates axonal growth
    2002
    Co-Authors: Bettina Buttner, Werner Reutter, Carolin Schmidt, Christoph Kannicht, Klemens Loster, Hyeyoun Lee, Sabine Nohring, Rudiger Horstkorte
    Abstract:

    Sialylation is essential for development and regeneration in mammals. Using N-propanoylmannosamine, a novel precursor of sialic acid, we were able to incorporate unnatural sialic acids with a prolonged N-acyl side chain (e.g., N-propanoylneuraminic acid) into cell surface glycoconjugates. Here we report that this Biochemical Engineering of sialic acid leads to a stimulation of neuronal cells. Both PC12 cells and cerebellar neurons showed a significant increase in neurite outgrowth after treatment with this novel sialic acid precursor. Furthermore, also the reestablishment of the perforant pathway was stimulated in brain slices. In addition, we surprisingly identified several cytosolic proteins with regulatory functions, which are differentially expressed after treatment with N-propanoylmannosamine. Because sialic acid is the only monosaccharide that is activated in the nucleus, we hypothesize that transcription could be modulated by the unnatural CMP-N-propanoylneuraminic acid and that sialic acid activation might be a general tool to regulate cellular functions, such as neurite outgrowth.

  • Biochemical Engineering of the side chain of sialic acids increases the biological stability of the highly sialylated cell adhesion molecule ceacam1
    2001
    Co-Authors: Rudiger Horstkorte, Lars R. Mantey, Lothar Lucka, Kerstin Danker, Werner Reutter
    Abstract:

    Abstract The biological half-life time of many glycoproteins is regulated via terminal sialic acids. In this study we determined the half-lives of two different cell adhesion molecules, CEACAM1 and the α1-integrin subunit, in PC12-cells before and after Biochemical Engineering the side chain of sialic acids by the use of N -propanoylmannosamine. Both are transmembrane glycoproteins. While the immunoglobulin superfamily member CEACAM1 mediates homophilic cell–cell adhesion the α1-integrin subunit is involved in cell–matrix interactions. We found that the half-life of the highly sialylated CEACAM1 is increased from 26 to 40 h by replacement of the N -acetylneuraminic acid by the novel, engineered N -propanoylneuraminic acids, whereas the half-life of the α1-integrin subunit remains unaffected under the same conditions. This demonstrates that Biochemical Engineering not only modulates the structure of cell surface sialic acids, but that Biochemical Engineering also influences biological stability of defined glycoproteins.

  • Biochemical Engineering of the n acyl side chain of sialic acid biological implications
    2001
    Co-Authors: Oliver T Keppler, Michael Pawlita, Rudiger Horstkorte, Carolin Schmidt, Werner Reutter
    Abstract:

    : N-Acetylneuraminic acid is the most prominent sialic acid in eukaryotes. The structural diversity of sialic acid is exploited by viruses, bacteria, and toxins and by the sialoglycoproteins and sialoglycolipids involved in cell-cell recognition in their highly specific recognition and binding to cellular receptors. The physiological precursor of all sialic acids is N-acetyl D-mannosamine (ManNAc). By recent findings it could be shown that synthetic N-acyl-modified D-mannosamines can be taken up by cells and efficiently metabolized to the respective N-acyl-modified neuraminic acids in vitro and in vivo. Successfully employed D-mannosamines with modified N-acyl side chains include N-propanoyl- (ManNProp), N-butanoyl- (ManNBut)-, N-pentanoyl- (ManNPent), N-hexanoyl- (ManNHex), N-crotonoyl- (ManNCrot), N-levulinoyl- (ManNLev), N-glycolyl- (ManNGc), and N-azidoacetyl D-mannosamine (ManNAc-azido). All of these compounds are metabolized by the promiscuous sialic acid biosynthetic pathway and are incorporated into cell surface sialoglycoconjugates replacing in a cell type-specific manner 10-85% of normal sialic acids. Application of these compounds to different biological systems has revealed important and unexpected functions of the N-acyl side chain of sialic acids, including its crucial role for the interaction of different viruses with their sialylated host cell receptors. Also, treatment with ManNProp, which contains only one additional methylene group compared to the physiological precursor ManNAc, induced proliferation of astrocytes, microglia, and peripheral T-lymphocytes. Unique, chemically reactive ketone and azido groups can be introduced biosynthetically into cell surface sialoglycans using N-acyl-modified sialic acid precursors, a process offering a variety of applications including the generation of artificial cellular receptors for viral gene delivery. This group of novel sialic acid precursors enabled studies on sialic acid modifications on the surface of living cells and has improved our understanding of carbohydrate receptors in their native environment. The Biochemical Engineering of the side chain of sialic acid offers new tools to study its biological relevance and to exploit it as a tag for therapeutic and diagnostic applications.

  • Biochemical Engineering of neural cell surfaces by the synthetic N-propanoyl-substituted neuraminic acid precursor.
    1998
    Co-Authors: Carolin Schmidt, Werner Reutter, Peer Stehling, Jutta Schnitzer, Rudiger Horstkorte
    Abstract:

    Sialylation of glycoproteins and glycolipids plays an important role during development, regeneration, and pathogenesis of diseases. During times of intense plasticity within the nervous system, such as development and regeneration, sialylation of neural cells is distinct from the time of its maintenance. In this study, a synthetic precursor of neuraminic acid, N-propanoylmannosamine (N-propanoyl neuraminic acid precursor (P-NAP)), is applied to the culture medium of oligodendrocyte progenitor cells, microglia, astrocytes, and neurons from neonatal rat brains to alter sialylation of glycoconjugates within these cells. P-NAP is metabolized and incorporated as N-propanoyl neuraminic acid into glycoproteins of the cell membrane. P-NAP stimulates the proliferation of astrocytes and microglia but not of oligodendrocyte progenitor in vitro. However, P-NAP increases the number of oligodendrocyte progenitor cells expressing the early oligodendroglial surface marker A2B5 epitope. In the presence of P-NAP, cerebellar neurons (but not astrocytes) in microexplant cultures start to express the oligodendroglial progenitor marker A2B5 epitope, which is normally undetectable on these cells. The controls, which were performed in the absence of any additive or in the presence of the physiological precursor of neuraminic acid, N-acetylmannosamine, did not show any increase in A2B5 expression.

Carolin Schmidt - One of the best experts on this subject based on the ideXlab platform.

  • Biochemical Engineering of cell surface sialic acids stimulates axonal growth
    2002
    Co-Authors: Bettina Buttner, Werner Reutter, Carolin Schmidt, Christoph Kannicht, Klemens Loster, Hyeyoun Lee, Sabine Nohring, Rudiger Horstkorte
    Abstract:

    Sialylation is essential for development and regeneration in mammals. Using N-propanoylmannosamine, a novel precursor of sialic acid, we were able to incorporate unnatural sialic acids with a prolonged N-acyl side chain (e.g., N-propanoylneuraminic acid) into cell surface glycoconjugates. Here we report that this Biochemical Engineering of sialic acid leads to a stimulation of neuronal cells. Both PC12 cells and cerebellar neurons showed a significant increase in neurite outgrowth after treatment with this novel sialic acid precursor. Furthermore, also the reestablishment of the perforant pathway was stimulated in brain slices. In addition, we surprisingly identified several cytosolic proteins with regulatory functions, which are differentially expressed after treatment with N-propanoylmannosamine. Because sialic acid is the only monosaccharide that is activated in the nucleus, we hypothesize that transcription could be modulated by the unnatural CMP-N-propanoylneuraminic acid and that sialic acid activation might be a general tool to regulate cellular functions, such as neurite outgrowth.

  • Biochemical Engineering of the n acyl side chain of sialic acid biological implications
    2001
    Co-Authors: Oliver T Keppler, Michael Pawlita, Rudiger Horstkorte, Carolin Schmidt, Werner Reutter
    Abstract:

    : N-Acetylneuraminic acid is the most prominent sialic acid in eukaryotes. The structural diversity of sialic acid is exploited by viruses, bacteria, and toxins and by the sialoglycoproteins and sialoglycolipids involved in cell-cell recognition in their highly specific recognition and binding to cellular receptors. The physiological precursor of all sialic acids is N-acetyl D-mannosamine (ManNAc). By recent findings it could be shown that synthetic N-acyl-modified D-mannosamines can be taken up by cells and efficiently metabolized to the respective N-acyl-modified neuraminic acids in vitro and in vivo. Successfully employed D-mannosamines with modified N-acyl side chains include N-propanoyl- (ManNProp), N-butanoyl- (ManNBut)-, N-pentanoyl- (ManNPent), N-hexanoyl- (ManNHex), N-crotonoyl- (ManNCrot), N-levulinoyl- (ManNLev), N-glycolyl- (ManNGc), and N-azidoacetyl D-mannosamine (ManNAc-azido). All of these compounds are metabolized by the promiscuous sialic acid biosynthetic pathway and are incorporated into cell surface sialoglycoconjugates replacing in a cell type-specific manner 10-85% of normal sialic acids. Application of these compounds to different biological systems has revealed important and unexpected functions of the N-acyl side chain of sialic acids, including its crucial role for the interaction of different viruses with their sialylated host cell receptors. Also, treatment with ManNProp, which contains only one additional methylene group compared to the physiological precursor ManNAc, induced proliferation of astrocytes, microglia, and peripheral T-lymphocytes. Unique, chemically reactive ketone and azido groups can be introduced biosynthetically into cell surface sialoglycans using N-acyl-modified sialic acid precursors, a process offering a variety of applications including the generation of artificial cellular receptors for viral gene delivery. This group of novel sialic acid precursors enabled studies on sialic acid modifications on the surface of living cells and has improved our understanding of carbohydrate receptors in their native environment. The Biochemical Engineering of the side chain of sialic acid offers new tools to study its biological relevance and to exploit it as a tag for therapeutic and diagnostic applications.

  • Biochemical Engineering of neural cell surfaces by the synthetic N-propanoyl-substituted neuraminic acid precursor.
    1998
    Co-Authors: Carolin Schmidt, Werner Reutter, Peer Stehling, Jutta Schnitzer, Rudiger Horstkorte
    Abstract:

    Sialylation of glycoproteins and glycolipids plays an important role during development, regeneration, and pathogenesis of diseases. During times of intense plasticity within the nervous system, such as development and regeneration, sialylation of neural cells is distinct from the time of its maintenance. In this study, a synthetic precursor of neuraminic acid, N-propanoylmannosamine (N-propanoyl neuraminic acid precursor (P-NAP)), is applied to the culture medium of oligodendrocyte progenitor cells, microglia, astrocytes, and neurons from neonatal rat brains to alter sialylation of glycoconjugates within these cells. P-NAP is metabolized and incorporated as N-propanoyl neuraminic acid into glycoproteins of the cell membrane. P-NAP stimulates the proliferation of astrocytes and microglia but not of oligodendrocyte progenitor in vitro. However, P-NAP increases the number of oligodendrocyte progenitor cells expressing the early oligodendroglial surface marker A2B5 epitope. In the presence of P-NAP, cerebellar neurons (but not astrocytes) in microexplant cultures start to express the oligodendroglial progenitor marker A2B5 epitope, which is normally undetectable on these cells. The controls, which were performed in the absence of any additive or in the presence of the physiological precursor of neuraminic acid, N-acetylmannosamine, did not show any increase in A2B5 expression.

Oliver T Keppler - One of the best experts on this subject based on the ideXlab platform.

  • Efficient Biochemical Engineering of cellular sialic acids using an unphysiological sialic acid precursor in cells lacking UDP-N-acetylglucosamine 2-epimerase.
    2001
    Co-Authors: Lars R. Mantey, Michael Pawlita, Werner Reutter, Oliver T Keppler, Stephan Hinderlich
    Abstract:

    Sialic acids comprise a family of terminal sugars essential for a variety of biological recognition systems. N-Propanoylmannosamine, an unphysiological sialic acid precursor, is taken up and metabolized by mammalian cells resulting in oligosaccharide-bound N-propanoylneuraminic acid. N-Propanoylmannosamine, applied to endogenously hyposialylated subclones of the myeloid leukemia HL60 and of the B-cell lymphoma BJA-B, both deficient in UDP-N-acetylglucosamine 2-epimerase, is efficiently metabolized to CMP-N-propanoylneuraminic acid resulting in up to 85% of glycoconjugate-associated sialic acids being unphysiological N-propanoylneuraminic acid. Thus, UDP-N-acetylglucosamine 2-epimerase-deficient cell lines provide an important experimental progress in Engineering cells to display an almost homogeneous population of defined, structurally altered sialic acids.

  • Biochemical Engineering of the n acyl side chain of sialic acid biological implications
    2001
    Co-Authors: Oliver T Keppler, Michael Pawlita, Rudiger Horstkorte, Carolin Schmidt, Werner Reutter
    Abstract:

    : N-Acetylneuraminic acid is the most prominent sialic acid in eukaryotes. The structural diversity of sialic acid is exploited by viruses, bacteria, and toxins and by the sialoglycoproteins and sialoglycolipids involved in cell-cell recognition in their highly specific recognition and binding to cellular receptors. The physiological precursor of all sialic acids is N-acetyl D-mannosamine (ManNAc). By recent findings it could be shown that synthetic N-acyl-modified D-mannosamines can be taken up by cells and efficiently metabolized to the respective N-acyl-modified neuraminic acids in vitro and in vivo. Successfully employed D-mannosamines with modified N-acyl side chains include N-propanoyl- (ManNProp), N-butanoyl- (ManNBut)-, N-pentanoyl- (ManNPent), N-hexanoyl- (ManNHex), N-crotonoyl- (ManNCrot), N-levulinoyl- (ManNLev), N-glycolyl- (ManNGc), and N-azidoacetyl D-mannosamine (ManNAc-azido). All of these compounds are metabolized by the promiscuous sialic acid biosynthetic pathway and are incorporated into cell surface sialoglycoconjugates replacing in a cell type-specific manner 10-85% of normal sialic acids. Application of these compounds to different biological systems has revealed important and unexpected functions of the N-acyl side chain of sialic acids, including its crucial role for the interaction of different viruses with their sialylated host cell receptors. Also, treatment with ManNProp, which contains only one additional methylene group compared to the physiological precursor ManNAc, induced proliferation of astrocytes, microglia, and peripheral T-lymphocytes. Unique, chemically reactive ketone and azido groups can be introduced biosynthetically into cell surface sialoglycans using N-acyl-modified sialic acid precursors, a process offering a variety of applications including the generation of artificial cellular receptors for viral gene delivery. This group of novel sialic acid precursors enabled studies on sialic acid modifications on the surface of living cells and has improved our understanding of carbohydrate receptors in their native environment. The Biochemical Engineering of the side chain of sialic acid offers new tools to study its biological relevance and to exploit it as a tag for therapeutic and diagnostic applications.

Michael Pawlita - One of the best experts on this subject based on the ideXlab platform.

  • Efficient Biochemical Engineering of cellular sialic acids using an unphysiological sialic acid precursor in cells lacking UDP-N-acetylglucosamine 2-epimerase.
    2001
    Co-Authors: Lars R. Mantey, Michael Pawlita, Werner Reutter, Oliver T Keppler, Stephan Hinderlich
    Abstract:

    Sialic acids comprise a family of terminal sugars essential for a variety of biological recognition systems. N-Propanoylmannosamine, an unphysiological sialic acid precursor, is taken up and metabolized by mammalian cells resulting in oligosaccharide-bound N-propanoylneuraminic acid. N-Propanoylmannosamine, applied to endogenously hyposialylated subclones of the myeloid leukemia HL60 and of the B-cell lymphoma BJA-B, both deficient in UDP-N-acetylglucosamine 2-epimerase, is efficiently metabolized to CMP-N-propanoylneuraminic acid resulting in up to 85% of glycoconjugate-associated sialic acids being unphysiological N-propanoylneuraminic acid. Thus, UDP-N-acetylglucosamine 2-epimerase-deficient cell lines provide an important experimental progress in Engineering cells to display an almost homogeneous population of defined, structurally altered sialic acids.

  • Biochemical Engineering of the n acyl side chain of sialic acid biological implications
    2001
    Co-Authors: Oliver T Keppler, Michael Pawlita, Rudiger Horstkorte, Carolin Schmidt, Werner Reutter
    Abstract:

    : N-Acetylneuraminic acid is the most prominent sialic acid in eukaryotes. The structural diversity of sialic acid is exploited by viruses, bacteria, and toxins and by the sialoglycoproteins and sialoglycolipids involved in cell-cell recognition in their highly specific recognition and binding to cellular receptors. The physiological precursor of all sialic acids is N-acetyl D-mannosamine (ManNAc). By recent findings it could be shown that synthetic N-acyl-modified D-mannosamines can be taken up by cells and efficiently metabolized to the respective N-acyl-modified neuraminic acids in vitro and in vivo. Successfully employed D-mannosamines with modified N-acyl side chains include N-propanoyl- (ManNProp), N-butanoyl- (ManNBut)-, N-pentanoyl- (ManNPent), N-hexanoyl- (ManNHex), N-crotonoyl- (ManNCrot), N-levulinoyl- (ManNLev), N-glycolyl- (ManNGc), and N-azidoacetyl D-mannosamine (ManNAc-azido). All of these compounds are metabolized by the promiscuous sialic acid biosynthetic pathway and are incorporated into cell surface sialoglycoconjugates replacing in a cell type-specific manner 10-85% of normal sialic acids. Application of these compounds to different biological systems has revealed important and unexpected functions of the N-acyl side chain of sialic acids, including its crucial role for the interaction of different viruses with their sialylated host cell receptors. Also, treatment with ManNProp, which contains only one additional methylene group compared to the physiological precursor ManNAc, induced proliferation of astrocytes, microglia, and peripheral T-lymphocytes. Unique, chemically reactive ketone and azido groups can be introduced biosynthetically into cell surface sialoglycans using N-acyl-modified sialic acid precursors, a process offering a variety of applications including the generation of artificial cellular receptors for viral gene delivery. This group of novel sialic acid precursors enabled studies on sialic acid modifications on the surface of living cells and has improved our understanding of carbohydrate receptors in their native environment. The Biochemical Engineering of the side chain of sialic acid offers new tools to study its biological relevance and to exploit it as a tag for therapeutic and diagnostic applications.