The Experts below are selected from a list of 4152 Experts worldwide ranked by ideXlab platform

Minoru Fukuda - One of the best experts on this subject based on the ideXlab platform.

  • Roles of Polysialic Acid in migration and differentiation of neural stem cells.
    Methods in enzymology, 2010
    Co-Authors: Kiyohiko Angata, Minoru Fukuda
    Abstract:

    Polysialic Acid, a homopolymer of α2,8-linked sialic Acid, is one of the carbohydrates expressed on neural precursors in the embryonic and adult brain. Polysialic Acid, synthesized by two polysialyltransferases (ST8SiaII and ST8SiaIV), mainly modulates functions of the neural cell adhesion molecule (NCAM). Polysialic Acid-deficient mice demonstrated that polysialylated NCAM plays crucial roles in various steps of neural development, such as cell survival and cell migration of neural precursors, neuronal guidance, and synapse formation. However, the mechanisms of the diverse phenotypes and molecules affected by Polysialic Acid remain to be defined. To study the roles of Polysialic Acid on neural stem cells, analyses of neural stem cells from Polysialic Acid-deficient and NCAM-deficient mice are useful. Here, we describe how to prepare neural precursor cells from mouse brain and how to analyze migration and differentiation of neurosphere cells in vitro.

  • Polysialic Acid-Directed Migration and Differentiation of Neural Precursors Are Essential for Mouse Brain Development
    Molecular and cellular biology, 2007
    Co-Authors: Kiyohiko Angata, Valerie Huckaby, Barbara Ranscht, Alexey Terskikh, Jamey D. Marth, Minoru Fukuda
    Abstract:

    Polysialic Acid, which is synthesized by two polysialyltransferases, ST8SiaII and ST8SiaIV, plays an essential role in brain development by modifying the neural cell adhesion molecule (NCAM). It is currently unclear how Polysialic Acid functions in different processes of neural development. Here we generated mice doubly mutant in both ST8SiaII and ST8SiaIV to determine the effects of loss of Polysialic Acid on brain development. In contrast to NCAM-deficient, ST8SiaII-deficient, or ST8SiaIV-deficient single mutant mice, ST8SiaII and ST8SiaIV double mutants displayed severe defects in anatomical organization of the forebrain associated with apoptotic cell death. Loss of Polysialic Acid affected both tangential and radial migration of neural precursors during cortical development, resulting in aberrant positioning of neuronal and glial cells. Glial cell differentiation was aberrantly increased in vivo and in vitro in the absence of Polysialic Acid. Consistent with these findings, Polysialic Acid-deficient mice exhibited increased expression of the glial cell marker glial fibrillary Acidic protein and a decrease in expression of Pax6, a transcription factor regulating neural cell migration. These results indicate that Polysialic Acid regulates cell migration and differentiation of neural precursors crucial for brain development.

  • Polysialic Acid and Mucin Type O-Glycans on the Neural Cell Adhesion Molecule Differentially Regulate Myoblast Fusion
    The Journal of biological chemistry, 2003
    Co-Authors: Misa Suzuki, Kiyohiko Angata, Jun Nakayama, Minoru Fukuda
    Abstract:

    Abstract Polysialic Acid attached to the neural cell adhesion molecule (NCAM) is thought to play a critical role in development. NCAM in muscle tissue contains a muscle-specific domain (MSD) to which mucin type O-glycans are attached. In the present study, using the C2C12 myoblast system, we show that NCAM containing MSD is increasingly expressed on the cell surface as myotubes form. Polysialic Acid is primarily attached to N-glycans of NCAM, and polysialylated NCAM is expressed on the outer surface of myotube bundles. By transfecting cDNAs encoding wild type and mutant forms of NCAM, we found that NCAM containing MSD facilitates myoblast fusion, and this effect is diminished by mutating O-glycosylation sites at MSD. By contrast, forced expression of Polysialic Acid in early differentiation stages reduces myotube formation and delays the expression of NCAM containing the MSD domain. Strikingly, inhibition of Polysialic Acid synthesis by antisense DNA approach induced differentiation in both human rhabdomyosarcoma cells, which overexpress Polysialic Acid, and C2C12 cells. These results indicate that Polysialic Acid and mucin type O-glycans on NCAM differentially regulate myoblast fusion, playing critical roles in muscle development.

  • Polysialyltransferases: major players in Polysialic Acid synthesis on the neural cell adhesion molecule
    Biochimie, 2003
    Co-Authors: Kiyohiko Angata, Minoru Fukuda
    Abstract:

    Polysialic Acid is a unique carbohydrate composed of a linear homopolymer of alpha2,8-linked sialic Acid, and is mainly attached to the fifth immunoglobulin-like domain of the neural cell adhesion molecule (NCAM) via a typical N-linked glycan in vertebrate neural system. Polysialic Acid plays critical roles in neural development by modulating adhesive property of NCAM such as neural cell migration, neurite outgrowth, neural pathfinding, and synaptogenesis. The expression of Polysialic Acid is temporally and spatially regulated during neural development. Polysialylation of NCAM is catalyzed by two polysialyltransferases, ST8Sia II (STX) and ST8Sia IV (PST), which belong to the family of six genes encoding alpha 2,8-sialyltransferases. ST8Sia II and IV are expressed differentially in tissue-specific and cell-specific manners, and they apparently have distinct roles in development and organogenesis. The presence of Polysialic Acid is always associated with expression of ST8Sia II and/or IV, suggesting that ST8Sia II and IV are the key enzymes that control the expression of Polysialic Acid. Both ST8Sia II and IV can transfer multiple alpha 2,8-linked sialic Acid residues to an acceptor N-glycan containing a NeuNAc alpha 2-->3 (or 6) Gal beta 1-->4GlcNAc beta 1-->R structure without participation of other enzymes. The two enzymes differently but cooperatively act on NCAM and the amount of Polysialic Acid synthesized by both enzymes together is greater than that synthesized by either enzyme alone. The polysialyltransferases are thus important regulators in Polysialic Acid synthesis and contribute to neural development in the vertebrate.

  • ST8Sia II and ST8Sia IV Polysialyltransferases Exhibit Marked Differences in Utilizing Various Acceptors Containing Oligosialic Acid and Short Polysialic Acid THE BASIS FOR COOPERATIVE POLYSIALYLATION BY TWO ENZYMES
    The Journal of biological chemistry, 2002
    Co-Authors: Kiyohiko Angata, Misa Suzuki, Minoru Fukuda
    Abstract:

    Polysialylation of the neural cell adhesion molecule (NCAM) is thought to play a critical role in neural development. Two polysialyltransferases, ST8Sia II and ST8Sia IV, play dominant roles in Polysialic Acid synthesis on NCAM. However, the individual roles and mechanisms by which these two enzymes form large amounts of Polysialic Acid on NCAM were heretofore unknown. Previous studies indicate that ST8Sia IV forms more highly polysialylated N-glycans on NCAM than ST8Sia II in vitro. In the present study, we first demonstrated that a combination of ST8Sia II and ST8Sia IV cooperatively polysialylated NCAM, resulting in NCAM N-glycans containing more, and thus longer, Polysialic Acid than when the enzymes were used individually. There was also an increase in polysialylated NCAM when we used ST8Sia II and ST8Sia IV sequentially, whereas there appeared to be a subtle increase when the enzymes were used in the reverse order. Furthermore, ST8Sia IV was able to add Polysialic Acid to oligosialylated oligosaccharides and unpolysialylated antennas in N-glycans attached to NCAM, even when Polysialic Acid was attached to at least one of the other antennas. By contrast, ST8Sia II added little Polysialic Acid to the same acceptors. On the other hand, neither ST8Sia II nor ST8Sia IV could add Polysialic Acid to a polysialylated antenna of NCAM N-glycans. These combined results indicate that the synergistic effect of ST8Sia II and ST8Sia IV is caused by: 1) the ability of ST8Sia IV to add Polysialic Acid to oligosialic Acid formed by ST8Sia II, 2) the potential of ST8Sia IV to act on more antennas of N-glycans than ST8Sia II, and 3) the ability of ST8Sia II and ST8Sia IV in combination to act on the fifth and sixth N-glycosylation sites of NCAM.

Kiyohiko Angata - One of the best experts on this subject based on the ideXlab platform.

  • Roles of Polysialic Acid in migration and differentiation of neural stem cells.
    Methods in enzymology, 2010
    Co-Authors: Kiyohiko Angata, Minoru Fukuda
    Abstract:

    Polysialic Acid, a homopolymer of α2,8-linked sialic Acid, is one of the carbohydrates expressed on neural precursors in the embryonic and adult brain. Polysialic Acid, synthesized by two polysialyltransferases (ST8SiaII and ST8SiaIV), mainly modulates functions of the neural cell adhesion molecule (NCAM). Polysialic Acid-deficient mice demonstrated that polysialylated NCAM plays crucial roles in various steps of neural development, such as cell survival and cell migration of neural precursors, neuronal guidance, and synapse formation. However, the mechanisms of the diverse phenotypes and molecules affected by Polysialic Acid remain to be defined. To study the roles of Polysialic Acid on neural stem cells, analyses of neural stem cells from Polysialic Acid-deficient and NCAM-deficient mice are useful. Here, we describe how to prepare neural precursor cells from mouse brain and how to analyze migration and differentiation of neurosphere cells in vitro.

  • Polysialic Acid-Directed Migration and Differentiation of Neural Precursors Are Essential for Mouse Brain Development
    Molecular and cellular biology, 2007
    Co-Authors: Kiyohiko Angata, Valerie Huckaby, Barbara Ranscht, Alexey Terskikh, Jamey D. Marth, Minoru Fukuda
    Abstract:

    Polysialic Acid, which is synthesized by two polysialyltransferases, ST8SiaII and ST8SiaIV, plays an essential role in brain development by modifying the neural cell adhesion molecule (NCAM). It is currently unclear how Polysialic Acid functions in different processes of neural development. Here we generated mice doubly mutant in both ST8SiaII and ST8SiaIV to determine the effects of loss of Polysialic Acid on brain development. In contrast to NCAM-deficient, ST8SiaII-deficient, or ST8SiaIV-deficient single mutant mice, ST8SiaII and ST8SiaIV double mutants displayed severe defects in anatomical organization of the forebrain associated with apoptotic cell death. Loss of Polysialic Acid affected both tangential and radial migration of neural precursors during cortical development, resulting in aberrant positioning of neuronal and glial cells. Glial cell differentiation was aberrantly increased in vivo and in vitro in the absence of Polysialic Acid. Consistent with these findings, Polysialic Acid-deficient mice exhibited increased expression of the glial cell marker glial fibrillary Acidic protein and a decrease in expression of Pax6, a transcription factor regulating neural cell migration. These results indicate that Polysialic Acid regulates cell migration and differentiation of neural precursors crucial for brain development.

  • Polysialic Acid and Mucin Type O-Glycans on the Neural Cell Adhesion Molecule Differentially Regulate Myoblast Fusion
    The Journal of biological chemistry, 2003
    Co-Authors: Misa Suzuki, Kiyohiko Angata, Jun Nakayama, Minoru Fukuda
    Abstract:

    Abstract Polysialic Acid attached to the neural cell adhesion molecule (NCAM) is thought to play a critical role in development. NCAM in muscle tissue contains a muscle-specific domain (MSD) to which mucin type O-glycans are attached. In the present study, using the C2C12 myoblast system, we show that NCAM containing MSD is increasingly expressed on the cell surface as myotubes form. Polysialic Acid is primarily attached to N-glycans of NCAM, and polysialylated NCAM is expressed on the outer surface of myotube bundles. By transfecting cDNAs encoding wild type and mutant forms of NCAM, we found that NCAM containing MSD facilitates myoblast fusion, and this effect is diminished by mutating O-glycosylation sites at MSD. By contrast, forced expression of Polysialic Acid in early differentiation stages reduces myotube formation and delays the expression of NCAM containing the MSD domain. Strikingly, inhibition of Polysialic Acid synthesis by antisense DNA approach induced differentiation in both human rhabdomyosarcoma cells, which overexpress Polysialic Acid, and C2C12 cells. These results indicate that Polysialic Acid and mucin type O-glycans on NCAM differentially regulate myoblast fusion, playing critical roles in muscle development.

  • Polysialyltransferases: major players in Polysialic Acid synthesis on the neural cell adhesion molecule
    Biochimie, 2003
    Co-Authors: Kiyohiko Angata, Minoru Fukuda
    Abstract:

    Polysialic Acid is a unique carbohydrate composed of a linear homopolymer of alpha2,8-linked sialic Acid, and is mainly attached to the fifth immunoglobulin-like domain of the neural cell adhesion molecule (NCAM) via a typical N-linked glycan in vertebrate neural system. Polysialic Acid plays critical roles in neural development by modulating adhesive property of NCAM such as neural cell migration, neurite outgrowth, neural pathfinding, and synaptogenesis. The expression of Polysialic Acid is temporally and spatially regulated during neural development. Polysialylation of NCAM is catalyzed by two polysialyltransferases, ST8Sia II (STX) and ST8Sia IV (PST), which belong to the family of six genes encoding alpha 2,8-sialyltransferases. ST8Sia II and IV are expressed differentially in tissue-specific and cell-specific manners, and they apparently have distinct roles in development and organogenesis. The presence of Polysialic Acid is always associated with expression of ST8Sia II and/or IV, suggesting that ST8Sia II and IV are the key enzymes that control the expression of Polysialic Acid. Both ST8Sia II and IV can transfer multiple alpha 2,8-linked sialic Acid residues to an acceptor N-glycan containing a NeuNAc alpha 2-->3 (or 6) Gal beta 1-->4GlcNAc beta 1-->R structure without participation of other enzymes. The two enzymes differently but cooperatively act on NCAM and the amount of Polysialic Acid synthesized by both enzymes together is greater than that synthesized by either enzyme alone. The polysialyltransferases are thus important regulators in Polysialic Acid synthesis and contribute to neural development in the vertebrate.

  • ST8Sia II and ST8Sia IV Polysialyltransferases Exhibit Marked Differences in Utilizing Various Acceptors Containing Oligosialic Acid and Short Polysialic Acid THE BASIS FOR COOPERATIVE POLYSIALYLATION BY TWO ENZYMES
    The Journal of biological chemistry, 2002
    Co-Authors: Kiyohiko Angata, Misa Suzuki, Minoru Fukuda
    Abstract:

    Polysialylation of the neural cell adhesion molecule (NCAM) is thought to play a critical role in neural development. Two polysialyltransferases, ST8Sia II and ST8Sia IV, play dominant roles in Polysialic Acid synthesis on NCAM. However, the individual roles and mechanisms by which these two enzymes form large amounts of Polysialic Acid on NCAM were heretofore unknown. Previous studies indicate that ST8Sia IV forms more highly polysialylated N-glycans on NCAM than ST8Sia II in vitro. In the present study, we first demonstrated that a combination of ST8Sia II and ST8Sia IV cooperatively polysialylated NCAM, resulting in NCAM N-glycans containing more, and thus longer, Polysialic Acid than when the enzymes were used individually. There was also an increase in polysialylated NCAM when we used ST8Sia II and ST8Sia IV sequentially, whereas there appeared to be a subtle increase when the enzymes were used in the reverse order. Furthermore, ST8Sia IV was able to add Polysialic Acid to oligosialylated oligosaccharides and unpolysialylated antennas in N-glycans attached to NCAM, even when Polysialic Acid was attached to at least one of the other antennas. By contrast, ST8Sia II added little Polysialic Acid to the same acceptors. On the other hand, neither ST8Sia II nor ST8Sia IV could add Polysialic Acid to a polysialylated antenna of NCAM N-glycans. These combined results indicate that the synergistic effect of ST8Sia II and ST8Sia IV is caused by: 1) the ability of ST8Sia IV to add Polysialic Acid to oligosialic Acid formed by ST8Sia II, 2) the potential of ST8Sia IV to act on more antennas of N-glycans than ST8Sia II, and 3) the ability of ST8Sia II and ST8Sia IV in combination to act on the fifth and sixth N-glycosylation sites of NCAM.

Harold J. Jennings - One of the best experts on this subject based on the ideXlab platform.

  • Immunization with N-propionyl Polysialic Acid–KLH conjugate in patients with small cell lung cancer is safe and induces IgM antibodies reactive with SCLC cells and bactericidal against group B meningococci
    Cancer Immunology Immunotherapy, 2012
    Co-Authors: Lee M. Krug, Govind Ragupathi, Chandra Hood, Constantine George, Ronglai Shen, Lauren Abrey, Harold J. Jennings, Mark G. Kris, Feng Hong, Philip O. Livingston
    Abstract:

    Purpose Polysialic Acid (polySA) is a polymer side chain bound to the neural cell adhesion molecule that is extensively expressed on the surface of small cell lung cancer (SCLC) cells. In our previous study, a robust antibody response was noted in patients with SCLC after vaccination with 30 μg of keyhole limpet hemocyanin (KLH)-conjugated N-propionylated (NP-) polySA, but peripheral neuropathy and ataxia were detected in several vaccinated patients. The objectives of the current trial were to establish the lowest optimal dose and to confirm the safety of the induction of antibodies against polySA with the NP-polySA vaccine. Experimental design Patients with SCLC who completed initial treatment and had no evidence of disease progression were injected with either 10 or 3 μg of NP-polySA conjugated to KLH and mixed with 100 μg of immunologic adjuvant (QS-21) at weeks 1, 2, 3, 4, 8, and 16. Results Nine patients were enrolled at each of the two dose levels. Prior to vaccination, one patient in each group had low-titer antibodies against Polysialic Acid. All patients at the 10 μg vaccine dose level responded to vaccination with IgM antibody titers against Polysialic Acid (median titer 1/1,280 by ELISA), and all but one patient made IgM and IgG antibodies against the artificial vaccine immunogen, NP-Polysialic Acid (median titer 1/10,240). The antibody responses at the 3 μg vaccine dose level were lower; six of nine patients developed antibodies against Polysialic Acid (median titer 1/160). Post-vaccination sera from 6/9 and 3/9 patients in the 10 and 3 μg groups reacted strongly with human SCLC cells by fluorescent-activated cell sorting (FACS). Sera from all patients in the 10 μg dose group also had bactericidal activity against group B meningococci with rabbit complement. Self-limited grade 3 ataxia of unclear etiology was seen in 1 of 18 patients. Conclusions Vaccination with NP-polySA–KLH resulted in consistent high-titer antibody responses, with the 10 μg dose significantly more immunogenic than the 3 μg dose. This study establishes the lowest optimally immunogenic dose of NP-Polysialic Acid in this NP-Polysialic Acid–KLH conjugate vaccine to be at least 10 μg, and it establishes the vaccine’s safety. We plan to incorporate NP-polySA into a polyvalent vaccine against SCLC with four glycolipid antigens also widely expressed in SCLC–GD2, GD3, fucosylated GM1, and globo H.

  • Vaccination of Small Cell Lung Cancer Patients with Polysialic Acid or N-Propionylated Polysialic Acid Conjugated to Keyhole Limpet Hemocyanin
    Clinical cancer research : an official journal of the American Association for Cancer Research, 2004
    Co-Authors: Lee M. Krug, Govind Ragupathi, Chandra Hood, Harold J. Jennings, Mark G. Kris, Zhongwu Guo, Vincent A. Miller, Barbara Pizzo, Leslie B. Tyson
    Abstract:

    Purpose: Long chain Polysialic Acid (polySA) is a side chain on embryonal neural cell adhesion molecules that, in the adult, is largely restricted to small cell lung cancer (SCLC). Long chains of polySA are also expressed on group B meningococcus. In this clinical trial, we aimed to elicit an immune response against Polysialic Acid to target clinically inapparent residual disease in patients with SCLC who had successfully completed initial therapy. Experimental Design: Patients were vaccinated with either 30 μg unmodified polySA or N -propionylated-polySA (NP-polySA), conjugated to keyhole limpet hemocyanin (KLH) and mixed with 100 μg of immunological adjuvant QS-21 at weeks 1, 2, 3, 4, 8, and 16. Results: Of the 5 evaluable patients vaccinated with unmodified polySA, only 1 mounted an IgM antibody response to polySA. On the other hand, all 6 of the patients vaccinated with NP-polySA produced IgM antibodies to NP-polySA and these cross-reacted with unmodified polySA in all but 1 case. IgG antibodies to NP-polySA were observed in 5 of the patients, but these did not cross-react with polySA. The presence of IgM antibodies reactive with SCLC cell lines was confirmed in this group by flow cytometry. Complement-dependent lysis of tumor cells could not be demonstrated. However, postimmunization sera induced significant bactericidal activity against group B meningococcus when combined with rabbit complement. Conclusions: Vaccination with NP-polySA-KLH, but not polySA-KLH, resulted in a consistent high titer antibody response. We are now conducting a de-escalation dosing study with NP-polySA-KLH to better assess the immunogenicity, toxicities, and optimal dose of this vaccine. We plan to incorporate this vaccine as a component of a polyvalent vaccine with GM2, fucosylated GM1, and Globo H to target SCLC.

  • Biochemical Engineering of Surface α2–8 Polysialic Acid for Immunotargeting Tumor Cells
    The Journal of biological chemistry, 2000
    Co-Authors: Tianmin Liu, Zhongwu Guo, Qingling Yang, Subash Sad, Harold J. Jennings
    Abstract:

    To target tumor cells for immunotherapy, we evaluated the feasibility of altering the epitopes on the surface Polysialic Acid of tumor cells. A precursor (N-propionylmannosamine), when incubated with leukemic cells, RBL-2H3 and RMA, resulted in substitution of the N-acetyl groups of surface alpha2-8 Polysialic Acid with N-propionyl groups. Expression of the altered alpha2-8 N-propionylPolysialic Acid on the surface of tumor cells induced their susceptibility to cell death mediated by monoclonal antibody 13D9 (mAb 13D9), which specifically recognizes alpha2-8 N-propionylated Polysialic Acid. The expression of alpha2-8 N-propionylated Polysialic Acid and the lysis of tumor cells by antibody-dependent cytotoxicity depended on the time and dose of incorporation of N-propionylated mannosamine. In vivo, mAb 13D9 effectively controlled metastasis of leukemic cells RMA when mice were administered the precursor N-propionylated mannosamine.

  • Antibodies to Polysialic Acid and its N-Propyl Derivative: Binding Properties and Interaction with Human Embryonal Brain Glycopeptides
    The Journal of infectious diseases, 1995
    Co-Authors: Jukka Häyrinen, Harold J. Jennings, Rita Gerardy-schahn, Geneviève Rougon, Howard V. Raff, Nobuo Hanai, Jukka Finne
    Abstract:

    There is no efficient vaccine against group B meningococcal meningitis because of tolerance induced by host tissue Polysialic Acid cross-reacting with the capsular polysaccharide. The specificities of Polysialic Acid-antibody interactions were studied using a ligand binding assay. Antibodies 735, 20-1, 2-1B, 2-2B, 5E1, and t5E1 and antibodies against N-propionylated group B meningococcal polysaccharide-tetanus toxoid conjugate (NP-4, 106-6) bound polysialylated human embryonal brain glycopeptides but not control glycopeptides or disialosyllactose, whereas antibodies 109-3 and I-627 were more specific for the N-propionylated polysaccharide. Antiganglioside antibodies (KM538, KM641) did not cross-react with Polysialic Acid. Human class-switched antibodies 5E1 (IgM) and t5E1 (IgG) reacted identically with all compounds tested and no temperature-dependent differences were observed. All anti-polysialosyl antibodies required a polysaccharide chain of 8-10 residues for binding independent of the immunizing antigen, animal species, or immunoglobulin class. The results suggest careful evaluation of Polysialic Acid cross-reactivity in vaccine development.

  • Comparison of the conformation of the epitope of .alpha.(2 .fwdarw. 8) Polysialic Acid with its reduced and N-acyl derivatives
    Biochemistry, 1993
    Co-Authors: Herbert Baumann, Jean Robert Brisson, Francis Michon, Robert Pon, Harold J. Jennings
    Abstract:

    The immunological properties of alpha(2-->8) Polysialic Acid have been rationalized in terms of the presence of an epitope situated on a unique extended helical segment (n approximately 9) of the polymer. The critical importance of the carboxylate group to the stability of the extended helical epitope can be ascertained from NMR spectrocopic studies and potential energy calculations on the carboxyl reduced alpha(2-->8) Polysialic Acid. These studies indicate that the extended helix (n approximately 9) is not stabilized in the reduced polymer and that the majority of conformers can only have helical parameters with n = 2 and 3. This result is also consistent with the fact that the reduced alpha(2-->8) Polysialic Acid, contrary to its Acidic counterpart, exhibits conventional immunological properties. Only five to six reduced oligomers are required to inhibit the binding of the reduced Polysialic Acid to its homologous antiserum. NMR spectroscopic analysis and potential energy calculations on the N-propionyl, N-butanoyl, N-isobutanoyl, N-pentanoyl, N-hexanoyl, and N-glycolyl derivatives of alpha(2-->8) Polysialic Acid indicate that, despite the bulk of some of these substituents, they did not disrupt the extended helical conformer. The presence of the extended helical epitope in some of these N-acyl derivatives has also been confirmed from immunological data.

Jürgen Roth - One of the best experts on this subject based on the ideXlab platform.

  • Cellular site of synthesis and dynamics of cell surface re-expression of Polysialic Acid of the neural cell adhesion molecule.
    FEBS Journal, 1994
    Co-Authors: Paul Scheidegger, Peter M. Lackie, Judit Papay, Christian Zuber, Jürgen Roth
    Abstract:

    Homopolymers of α-2,8-ketosidically linked sialic Acid (Polysialic Acid) represent a posttranslational modification which, in mammals, appears to be unique for the neural cell adhesion molecule and the a subunit of sodium channels in brain. Under steady-state conditions, Polysialic Acid is detectable in the plasma membrane of different cell types but not in the cytoplasm. We have studied the site of synthesis and the cell surface re-expression of Polysialic Acid in a clonal subline of small cell lung carcinoma using the monoclonal antibody 735 and bacteriophage endosialidase, both specific reagents for Polysialic Acid. After enzymic removal, cell surface Polysialic Acid re-expression reached control levels only after 5 days. When Golgi to plasma membrane transport of endosialidase-treated cells was blocked by culture at 20°C or in the presence of monensin at 37°C, de-novo -synthesized Polysialic Acid became detectable in the Golgi apparatus. Our data show that synthesis of Polysialic Acid of the neural cell adhesion molecule with a degree of polymerization of at least nine occurs intracellular in the Golgi apparatus of a human small cell lung carcinoma cell line.

  • Polysialic Acid is associated with sodium channels and the neural cell adhesion molecule N-CAM in adult rat brain.
    The Journal of biological chemistry, 1992
    Co-Authors: Christian Zuber, Peter M. Lackie, William A. Catterall, Jürgen Roth
    Abstract:

    Abstract We have studied alpha 2,8-linked Polysialic Acid (polySia) and the neural cell adhesion molecule (N-CAM) in the adult rat brain by immunohistochemistry and Western blot analysis. Both molecules were widely distributed but not ubiquitous. Various brain regions showed colocalization of polySia and N-CAM. Strong immunoreactivity for polySia was seen in regions which were negative for N-CAM, such as the main and accessory olfactory bulbs. Immunohistochemical evidence for the heterogeneity of polySia expression in different brain regions was confirmed by immunoblotting. We present evidence that N-CAM is not the only polySia bearing protein in adult rat brain. Specifically, immunoprecipitation using the polySia-specific monoclonal antibody mAb 735 precipitated not only N-CAM isoforms carrying polySia, but also the sodium channel alpha subunit. Immunoblotting using sodium channel alpha subunit antibody (SP20) revealed a smear from 250 kDa upwards. PolySia removal using an endoneuraminidase specific for alpha 2,8-linked Polysialic Acid of 8 or more residues long, reduced this smear to a single band at 250 kDa. Thus both N-CAM and sodium channels carry homopolymers of alpha 2,8-linked Polysialic Acid in adult rat brain.

  • Polysialic Acid of the neural cell adhesion molecule distinguishes small cell lung carcinoma from carcinoids
    The American journal of pathology, 1991
    Co-Authors: Paul Komminoth, Jürgen Roth, Dieter Bitter-suermann, Peter M. Lackie, Ph. U. Heitz
    Abstract:

    The neural cell adhesion molecule (NCAM) exists in various types of neuroendocrine cells and their tumors. A typical feature of NCAM is Polysialic Acid, of which the chain length is developmentally regulated. The authors have performed a comparative immunohistochemical study on small cell lung carcinomas and bronchial as well as gastrointestinal carcinoids with the monoclonal antibody (MAb) 735 reactive with the long-chain form of Polysialic Acid. The small cell lung carcinomas, irrespective of their histological type, were positive for Polysialic Acid. Metastatic tumor cell complexes also exhibited immunostaining. The tumor cell-surface-associated immunostaining for Polysialic Acid was sensitive to endoneuraminidase. The mature and atypical bronchial and gastrointestinal carcinoids were not immunoreactive for Polysialic Acid. Cytoplasmic staining in groups of cells of carcinoids (2 of 28 cases) was due to nonspecific antibody binding, which could be prevented by increased ion strength. These data indicate that neuroendocrine tumors of the lung can be distinguished by their content of highly sialylated NCAM.

  • Polysialic Acid as a marker of both immature and mature neural tissue in human teratomas.
    Modern pathology : an official journal of the United States and Canadian Academy of Pathology Inc, 1991
    Co-Authors: R A Metzman, Michael J. Warhol, B Gee, Jürgen Roth
    Abstract:

    The neural cell adhesion molecule (NCAM) is involved in cell-cell interaction during neural development. We employed a monoclonal antibody directed against the long chain Polysialic Acid moiety of NCAM to evaluate its usefulness as a marker of primitive neural elements in teratomas. This marker was compared with other neural markers, S-100, glial fibrillary Acidic protein (GFAP), neurofilament protein (NFL), nerve growth factor receptor (NGFR), as to its effectiveness in labeled neural tissue in human teratomas. The anti-Polysialic Acid antibody was the only reagent that consistently marked all types of neural tissue, both mature and immature in these lesions. Immature neural elements alone have prognostic significance in teratomas. Our results indicate that anti-Polysialic Acid antibodies are the most sensitive and useful markers of immature neural elements in these lesions.

Herbert Hildebrandt - One of the best experts on this subject based on the ideXlab platform.

  • sialic Acids in the brain gangliosides and Polysialic Acid in nervous system development stability disease and regeneration
    Physical Review, 2014
    Co-Authors: Ronald L Schnaar, Herbert Hildebrandt, Rita Gerardyschahn
    Abstract:

    Every cell in nature carries a rich surface coat of glycans, its glycocalyx, which constitutes the cell's interface with its environment. In eukaryotes, the glycocalyx is composed of glycolipids, glycoproteins, and proteoglycans, the compositions of which vary among different tissues and cell types. Many of the linear and branched glycans on cell surface glycoproteins and glycolipids of vertebrates are terminated with sialic Acids, nine-carbon sugars with a carboxylic Acid, a glycerol side-chain, and an N-acyl group that, along with their display at the outmost end of cell surface glycans, provide for varied molecular interactions. Among their functions, sialic Acids regulate cell-cell interactions, modulate the activities of their glycoprotein and glycolipid scaffolds as well as other cell surface molecules, and are receptors for pathogens and toxins. In the brain, two families of sialoglycans are of particular interest: gangliosides and Polysialic Acid. Gangliosides, sialylated glycosphingolipids, are the most abundant sialoglycans of nerve cells. Mouse genetic studies and human disorders of ganglioside metabolism implicate gangliosides in axon-myelin interactions, axon stability, axon regeneration, and the modulation of nerve cell excitability. Polysialic Acid is a unique homopolymer that reaches >90 sialic Acid residues attached to select glycoproteins, especially the neural cell adhesion molecule in the brain. Molecular, cellular, and genetic studies implicate Polysialic Acid in the control of cell-cell and cell-matrix interactions, intermolecular interactions at cell surfaces, and interactions with other molecules in the cellular environment. Polysialic Acid is essential for appropriate brain development, and polymorphisms in the human genes responsible for Polysialic Acid biosynthesis are associated with psychiatric disorders including schizophrenia, autism, and bipolar disorder. Polysialic Acid also appears to play a role in adult brain plasticity, including regeneration. Together, vertebrate brain sialoglycans are key regulatory components that contribute to proper development, maintenance, and health of the nervous system.

  • Polysialic Acid in Brain Development and Synaptic Plasticity
    Topics in current chemistry, 2013
    Co-Authors: Herbert Hildebrandt, Alexander Dityatev
    Abstract:

    Polymers of sialic Acid can be produced by pro- and eukaryotic cells. In vertebrates Polysialic Acid consists of α2,8-linked N-acetylneuraminic Acid and is most prominent during nervous system development. Polysialic Acid is produced by two complementary sialyltransferases, ST8SiaII and ST8SiaIV. The major, but not the only, carrier of Polysialic Acid is the neural cell adhesion molecule (NCAM). In this review we highlight how polySia dictates the interactions of various cell types during development and plasticity of the vertebrate central nervous system on different molecular levels. Recent progress in generating mouse models with differential ablation of the polysialyltransferases or NCAM revealed the dramatic impact of Polysialic Acid-negative NCAM on brain development and elaborate electrophysiological studies allowed for new insights into the role of Polysialic Acid in regulating synaptic plasticity and learning. The implications of dysregulated polysialylation for brain disease and neuropsychiatric disorders are discussed.

  • Polysialic Acid: Versatile Modification of NCAM, SynCAM 1 and Neuropilin-2
    Neurochemical research, 2013
    Co-Authors: Martina Mühlenhoff, Rita Gerardy-schahn, Manuela Rollenhagen, Sebastian Werneburg, Herbert Hildebrandt
    Abstract:

    The glycan Polysialic Acid is well-known as a unique posttranslational modification of the neural cell adhesion molecule NCAM. Despite remarkable acceptor specificity, however, a few other proteins can be targets of polysialylation. Here, we recapitulate the biosynthesis of Polysialic Acid by the two polysialyltransferases ST8SIA2 and ST8SIA4 and highlight the increasing evidence that variation in the human ST8SIA2 gene is linked to schizophrenia and possibly other neuropsychiatric disorders. Moreover, we summarize the knowledge on the role of NCAM polysialylation in brain development gained by the analysis of NCAM- and polysialyltransferase-deficient mouse models. The last part of this review is focused on recent advances in identifying SynCAM 1 and neuropilin-2 as novel acceptors of Polysialic Acid in NG2 cells of the perinatal brain and in dendritic cells of the immune system, respectively.

  • NCAM and polysialyltransferase profiles match dopaminergic marker gene expression but Polysialic Acid is dispensable for development of the midbrain dopamine system.
    Journal of neurochemistry, 2009
    Co-Authors: Miriam Schiff, Birgit Weinhold, Claudia Grothe, Herbert Hildebrandt
    Abstract:

    The modification of the neural cell adhesion molecule (NCAM) with Polysialic Acid plays a pivotal role in the developing nervous system. Here we studied the expression and function of Polysialic Acid during development of the mesencephalic dopaminergic system of mice. Using immunohistochemistry, Polysialic Acid was detected on nestin-positive radial glia processes and on cell somata in the pial zone of the midbrain at embryonic day E11.5 and E14.5. As studied by quantitative real-time RT-PCR, mRNA profiles of NCAM and the polysialyltransferases, ST8SiaII and ST8SiaIV, matched the course of tyrosine hydroxylase, dopamine transporter, nur-related factor 1, and paired-like homeodomain transcription factor 3 expression, which were used as marker genes of dopaminergic development. Asking for a possible role of polysialylation during formation of the dopaminergic system, mice lacking Polysialic Acid because of ablation of both St8siaII and St8siaIV were analyzed at selected time points by tyrosine hydroxylase immunohistochemistry and by real-time RT-PCR of dopaminergic markers. Surprisingly, no differences between wild-type and mutant mice could be detected. Likewise, enzymatic removal of Polysialic Acid from cultured neurons of the ventral embryonic midbrain had no effect on the expression of dopaminergic marker genes. We conclude that despite its abundance Polysialic Acid is dispensable for the formation of the mesencephalic dopaminergic system.

  • dissecting Polysialic Acid and ncam functions in brain development
    Journal of Neurochemistry, 2007
    Co-Authors: Herbert Hildebrandt, Martina Mühlenhoff, Birgit Weinhold, Rita Gerardyschahn
    Abstract:

    The unique modification of the neural cell adhesion molecule (NCAM) by Polysialic Acid (polySia) is tightly associated with nervous system development and plasticity. The prevailing view that this large carbohydrate polymer acts as an anti-adhesive factor seems straightforward at first sight. However, during almost 25 years of polySia research it became increasingly clear that the impact of polySia on cell surface interactions can not be explained by one unifying mechanism. Recent progress in the generation of mouse models, which partially or completely lack polySia due to ablation of one or both of the two polySia synthesizing enzymes, provides novel insights into the function of this unique post-translational modification. The present review is focused on a phenotype comparison between the newly established mouse strains which combine polySia-deficiency with normal NCAM expression and the well-characterized NCAM negative mouse model. Analysis of shared and individual phenotypes allows a clear distinction between NCAM and polySia functions and revealed that polySia plays a vital role as a specific control element of NCAM-mediated interactions.