Polysialic acid regulates sympathetic outflow by facilitating information transfer within the nucleus of the solitary tract

Expression of the large extracellular glycan, polysialic acid (polySia), is restricted in the adult, to brain regions exhibiting high levels of plasticity or remodeling, including the hippocampus, prefrontal cortex, and the nucleus of the solitary tract (NTS). The NTS, located in the dorsal brainstem, receives constant viscerosensory afferent traffic as well as input from central regions controlling sympathetic nerve activity, respiration, gastrointestinal functions, hormonal release, and behavior. Our aims were to determine the ultrastructural location of polySia in the NTS and the functional effects of enzymatic removal of polySia, both in vitro and in vivo polySia immunoreactivity was found throughout the adult rat NTS. Electron microscopy demonstrated polySia at sites that influence neurotransmission: the extracellular space, fine astrocytic processes, and neuronal terminals. Removing polySia from the NTS had functional consequences. Whole-cell electrophysiological recordings revealed altered intrinsic membrane properties, enhancing voltage-gated K+ currents and increasing intracellular Ca2+ Viscerosensory afferent processing was also disrupted, dampening low-frequency excitatory input and potentiating high-frequency sustained currents at second-order neurons. Removal of polySia in the NTS of anesthetized rats increased sympathetic nerve activity, whereas functionally related enzymes that do not alter polySia expression had little effect. These data indicate that polySia is required for the normal transmission of information through the NTS and that changes in its expression alter sympathetic outflow. polySia is abundant in multiple but discrete brain regions, including sensory nuclei, in both the adult rat and human, where it may regulate neuronal function by mechanisms identified here.SIGNIFICANCE STATEMENT All cells are coated in glycans (sugars) existing predominantly as glycolipids, proteoglycans, or glycoproteins formed by the most complex form of posttranslational modification, glycosylation. How these glycans influence brain function is only now beginning to be elucidated. The adult nucleus of the solitary tract has abundant polysialic acid (polySia) and is a major site of integration, receiving viscerosensory information which controls critical homeostatic functions. Our data reveal that polySia is a determinant of neuronal behavior and excitatory transmission in the nucleus of the solitary tract, regulating sympathetic nerve activity. polySia is abundantly expressed at distinct brain sites in adult, including major sensory nuclei, suggesting that sensory transmission may also be influenced via mechanisms described here. These findings hint at the importance of elucidating how other glycans influence neural function.Phillip Bokiniec, Shila Shahbazian, Stuart J. McDougall, Britt A. Berning, Delfine Cheng, Ida J. Llewellyn-Smith ... et al

Long-term intrathecal administration of morphine vs. baclofen: differences in CSF glycoconjugate profiles using multiglycomics

Published: 09 September 2021Opioid use for treatment of persistent pain has increased dramatically over the past two decades, but it has not resulted in improved pain management outcomes. To understand the molecular mechanisms of opioids, molecular signatures that arise from opioid exposure are often sought after, using various analytical methods. In this study, we performed proteomics, and multiglycomics via sequential analysis of polysialic acids, glycosaminoglycans, N-glycans and O-glycans, using the same cerebral spinal fluid (CSF) sample from patients that had long-term (>2 years), intrathecal morphine or baclofen administered via an indwelling pump. Proteomics and N-glycomics signatures between the two treatment groups were highly conserved, while significant differences were observed in polysialic acid, heparan sulfate glycosaminoglycan and O-glycan profiles between the two treatment groups. This represents the first study to investigate the potential relationships between diverse CSF conjugated glycans and long-term intrathecal drug exposure. The unique changes, observed by a sequential analytical workflow, reflect previously undescribed molecular effects of opioid administration and pain management.Edward S.X. Moh, Krishnatej Nishtala, Sameera Iqbal, Vasiliki Staikopoulos, Dilip Kapur, Mark R. Hutchinson, and Nicolle H. Packe

The effect of streptozotocin-induced hyperglycemia on N-and O-linked protein glycosylation in mouse ovary

Post-translational modification of proteins namely glycosylation influences cellular behavior, structural properties and interactions including during ovarian follicle development and atresia. However, little is known about protein glycosylation changes occurring in diabetes mellitus in ovarian tissues despite the well-known influence of diabetes on the outcome of successful embryo implantation. In our study, the use of PGC chromatography-ESI mass spectrometry in negative ion mode enabled the identification of 138 N-glycans and 6 O-glycans on the proteins of Streptozotocin-induced (STZ) diabetic mouse ovarian tissues (n = 3). Diabetic mouse ovaries exhibited a relative decrease in sialylation, fucosylation and, to a lesser extent, branched N-linked glycan structures, as well as an increase in oligomannose structures on their proteins, compared with nondiabetic mouse ovaries. Changes in N-glycans occurred in the diabetic liver tissue but were more evident in diabetic ovarian tissue of the same mouse, suggesting an organ-specific effect of diabetes mellitus on protein glycosylation. Although at a very low amount, O-GalNAc glycans of mice ovaries were present as core type 1 and core type 2 glycans; with a relative increase in the NeuGc:NeuAc ratio as the most significant difference between control and diabetic ovarian tissues. STZ-treated mice also showed a trend towards an increase in TNF-α and IL1-B inflammatory cytokines, which have previously been shown to influence protein glycosylation.Abdulrahman M Shathili, Hannah M Brown, Arun V Everest-Dass, Tiffany C Y Tan, Lindsay M Parker, Jeremy G Thompson, Nicolle H Packe

Fabrieksschema T.N.T.-bereiding

Document(en) uit de collectie Chemische ProcestechnologieDelftChemTechApplied Science

Raw N-glycan mass spectrometry imaging data on formalin-fixed mouse kidney

Provided is the annotated raw data for N-glycan mass spectrometry imaging (MSI) annotations in thin cross-sections of formalin-fixed and paraffin-embedded murine kidney. Relevant meta-data have been provided in this brief and the raw MSI data can be accessed using ProteomeXchange with the PRoteomics IDEntifications (PRIDE) identifier PXD009808. This brief is the first in a set of submissions from our group which will make raw data publicly accessible for existing and future MSI studies.Ove J.R.Gustafsson, Matthew T.Briggs, Mark R.Condina, Lyron J. Winderbaum, Matthias Pelzing, Shaun R.McColl ... et al

MALDI mass spectrometry imaging of early- and late-stage serous ovarian cancer tissue reveals stage-specific N-glycans

Epithelial ovarian cancer is one of the most fatal gynecological malignancies in adult women. As studies on protein N-glycosylation have extensively reported aberrant patterns in the ovarian cancer tumor microenvironment, obtaining spatial information will uncover tumor-specific N-glycan alterations in ovarian cancer development and progression. matrix-assisted laser desorption/ionization (MALDI) mass spectrometry imaging (MSI) is employed to investigate N-glycan distribution on formalin-fixed paraffin-embedded ovarian cancer tissue sections from early- and late-stage patients. Tumor-specific N-glycans are identified and structurally characterized by porous graphitized carbon-liquid chromatography-electrospray ionization-tandem mass spectrometry (PGC-LC-ESI-MS/MS), and then assigned to high-resolution images obtained from MALDI-MSI. Spatial distribution of 14 N-glycans is obtained by MALDI-MSI and 42 N-glycans (including structural and compositional isomers) identified and structurally characterized by LC-MS. The spatial distribution of oligomannose, complex neutral, bisecting, and sialylated N-glycan families are localized to the tumor regions of late-stage ovarian cancer patients relative to early-stage patients. Potential N-glycan diagnostic markers that emerge include the oligomannose structure, (Hex)₆ + (Man)₃ (GlcNAc)₂ , and the complex neutral structure, (Hex)₂ (HexNAc)₂ (Deoxyhexose)₁ + (Man)₃ (GlcNAc)₂. The distribution of these markers is evaluated using a tissue microarray of early- and late-stage patients.Matthew T. Briggs, Mark R. Condina, Yin Ying Ho, Arun V. Everest-Dass, Parul Mittal, Gurjeet Kaur, Martin K. Oehler, Nicolle H. Packer, and Peter Hoffman

Congenital Disorders of Glycosylation

This chapter discusses inherited human diseases that are caused by defects in glycan biosynthesis and metabolism (congenital disorders of glycosylation, CDGs). Representative examples are described of genetic defects in the major glycan families and what lessons we can learn from them about glycobiology. Among genetic disorders of glycosylation, those caused by somatic mutations are described in Chapter 46. Disorders affecting the lysosomal degradation of glycans are described in Chapter 44. Although the term “congenital disorders” by definition include those caused by nongenetic, unfavorable in utero conditions, the term “congenital disorders of glycosylation (CDG)” is now widely used as an equivalent of inherited disorders of glycosylation