Evolution of sialic acid-binding proteins: molecular cloning and expression of fish siglec-4

Lehmann, Friederike; Gäthje, Heiko; Kelm, Sørge; Dietz, Frank

doi:10.1093/glycob/cwh120

Cited by 41 publications

(26 citation statements)

References 37 publications

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“…As demonstrated by Northern blot analysis, expression of these compounds seems to be restricted to the nervous system (Lehmann et al 2004). Localization of these proteins to oligodendrocytes and/or myelin membranes in the fish CNS, however, has not yet been confirmed.…”

Section: The Case Of Magmentioning

confidence: 99%

Features and Functions of Oligodendrocytes and Myelin Proteins of Lower Vertebrate Species

2008

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The myelin-forming cells in the central nervous system (CNS) of lower vertebrate species, in particular those of fish, profoundly differ from their mammalian counterparts in their biochemical phenotype in that they express Po-like glycoproteins as major myelin protein constituents instead of proteolipid protein, while in their overall cellular structure and their cell lineage relationships, they closely resemble mammalian oligodendrocytes. While molecular biology in the past has allowed to appropriately classify the major myelin proteins synthesized by fish oligodendrocytes, heterologous expression studies are expected to give a deeper insight into the particular features and the conserved functions of these proteins required for myelin formation and maintenance in fish. It is hoped that this approach will also help to improve our understanding of the molecular processes underlying the unique capacity of fish oligodendrocytes for remyelination after injury in the CNS. This survey may stimulate neuroscientists to engage into this exciting field.

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Section: The Case Of Magmentioning

confidence: 99%

Features and Functions of Oligodendrocytes and Myelin Proteins of Lower Vertebrate Species

2008

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“…1,2 More than a dozen human Siglecs are reported, of which Siglec-3 and Siglecs-5 through -11 are classified into a subgroup named CD33-related Siglecs (CD33rSiglecs), which are rapidly evolving. [1][2][3][4] Although each CD33rSiglec has unique expression profile, they are predominantly found on leukocytes involved in innate immunity.…”

Section: Introductionmentioning

confidence: 99%

Defining the in vivo function of Siglec-F, a CD33-related Siglec expressed on mouse eosinophils

Zhang

Angata

Cho

et al. 2007

Blood

170

239

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CD33-related Siglecs (CD33rSiglecs) are a family of sialic acid–recognizing lectins on immune cells whose biologic functions are unknown. We studied in vivo functions of Siglec-F, the CD33rSiglec expressed on mouse eosinophils, which are prominent in allergic processes. Induction of allergic lung inflammation in mice caused up-regulation of Siglec-F on blood and bone marrow eosinophils, accompanied by newly induced expression on some CD4+ cells, as well as quantitative up-regulation of endogenous Siglec-F ligands in the lung tissue and airways. Taken together with the tyrosine-based inhibitory motif in the cytosolic tail of Siglec-F, the data suggested a negative feedback loop, controlling allergic responses of eosinophils and helper T cells, via Siglec-F and Siglec-F ligands. To pursue this hypothesis, we created Siglec-F–null mice. Allergen-challenged null mice showed increased lung eosinophil infiltration, enhanced bone marrow and blood eosinophilia, delayed resolution of lung eosinophilia, and reduced peribronchial-cell apoptosis. Anti–Siglec-F antibody cross-linking also enhanced eosinophil apoptosis in vitro. These data support the proposed negative feedback role for Siglec-F, represent the first in vivo demonstration of biologic functions for any CD33rSiglec, and predict a role for human Siglec-8 (the isofunctional paralog of mouse Siglec-F) in regulating the pathogenesis of human eosinophil-mediated disorders.

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“…MAG, also known as Siglec4a, is evolutionarily the oldest member of the Siglec family17. Unlike all other Siglecs, MAG plays no role in the immune system and is exclusively expressed in the nervous system17.…”

mentioning

confidence: 99%

Structural basis of myelin-associated glycoprotein adhesion and signalling

et al. 2016

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Myelin-associated glycoprotein (MAG) is a myelin-expressed cell-adhesion and bi-directional signalling molecule. MAG maintains the myelin–axon spacing by interacting with specific neuronal glycolipids (gangliosides), inhibits axon regeneration and controls myelin formation. The mechanisms underlying MAG adhesion and signalling are unresolved. We present crystal structures of the MAG full ectodomain, which reveal an extended conformation of five Ig domains and a homodimeric arrangement involving membrane-proximal domains Ig4 and Ig5. MAG-oligosaccharide complex structures and biophysical assays show how MAG engages axonal gangliosides at domain Ig1. Two post-translational modifications were identified—N-linked glycosylation at the dimerization interface and tryptophan C-mannosylation proximal to the ganglioside binding site—that appear to have regulatory functions. Structure-guided mutations and neurite outgrowth assays demonstrate MAG dimerization and carbohydrate recognition are essential for its regeneration-inhibiting properties. The combination of trans ganglioside binding and cis homodimerization explains how MAG maintains the myelin–axon spacing and provides a mechanism for MAG-mediated bi-directional signalling.

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Evolution of sialic acid-binding proteins: molecular cloning and expression of fish siglec-4

Cited by 41 publications

References 37 publications

Features and Functions of Oligodendrocytes and Myelin Proteins of Lower Vertebrate Species

Features and Functions of Oligodendrocytes and Myelin Proteins of Lower Vertebrate Species

Defining the in vivo function of Siglec-F, a CD33-related Siglec expressed on mouse eosinophils

Structural basis of myelin-associated glycoprotein adhesion and signalling

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