[5] Varki A, Gagneux P. Multifarious roles
of sialic acids in immunity.
«We discovered that Neu1, a protein nicknamed after «neuraminidase 1,» turns the absorption of sugar «on» or «off» in body cells, by regulating the amount
of sialic acid on the surface of cells,» Dr. Pshezhetsky explains.
The positive effect
of sialic acid Neu5Gc on the respiratory system was confirmed using a mouse - model: The Neu5Gc molecules consumed with food improved the pulmonary function of the mice, therefore reducing asthma symptoms.
Since the attachment
of sialic acid to an Fc group requires the presence of another glycan called galactose, the team created two enzymes termed B4Fc and ST6Fc, which induce the attachment of galactose and sialic acid respectively.
Her research focuses on disorders
of sialic acid metabolism and of lysosome - related organelles.
Oral administration
of the sialic acid precursor N - acetyl - mannosamine (ManNAc) partially rescues the kidney defect, allowing the mutant mice to survive.
Without adequate supplies
of sialic acid, progressive muscle degeneration (or myopathy) sets in.
The cellular localization of the polymers was confirmed by subcellular fractionation of the cells, followed by digestion with endoglycosidase H (Figure 2C and Supplemental Figure 3C), an enzyme that removes N - linked glycans still in the high mannose ER form but does not affect oligosaccharide chains after the addition
of sialic acid in the Golgi apparatus.
One
of the sialic acid - containing molecules gliadin binds to is called GM1 ganglioside.
Not exact matches
These modules recognise a specific sugar molecule,
sialic acid, which caps the end
of mucin glycan chains.
They can absorb
sialic acid through contact with animals or by eating food
of animal origin and integrate it into their glycoproteins.
If we can remove
sialic acid residues from the cell surface, this will force the insulin receptor do its job
of absorbing blood sugar properly.
Some
of these sugars, called
sialic acids, help tumors hide from the immune system.
Wilson's laboratory used X-ray crystallography to determine the atomic structures
of the H7N9 hemagglutinin protein bound to these
sialic acid receptor molecules.
In previous work, Anthony's group and others have found that the anti-inflammatory effect
of high - dose IVIG can be attributed to a minor fraction
of antibodies to which a glycan called
sialic acid has been attached to their Fc region.
The treatment consists
of providing N - acetylmannosamine, which forms
sialic acid in the body.
[MR: This is because lack
of Neu1 means that it's not available to strip
sialic acids from LAMP - 1, and oversialylated LAMP - 1 leads to loss
of its inhibitory function over lyso exocytosis, apparently leading to a nonspecific puking out
of its contents into the ECF].
Sialic acid synthesis is tightly regulated; defects in this pathway cause a variety of disorders, including hereditary inclusion body myopathy (HIBM), sialuria, infantile sialic acid storage disease (ISSD), and Salla di
Sialic acid synthesis is tightly regulated; defects in this pathway cause a variety
of disorders, including hereditary inclusion body myopathy (HIBM), sialuria, infantile
sialic acid storage disease (ISSD), and Salla di
sialic acid storage disease (ISSD), and Salla disease.
Neu5Gc is the glycolyl capped
sialic acid that is found on the cell surfaces
of all mammals except humans, who lost the gene for the enzyme to oxidize the acetyl version.
Human milk oligosaccharides (HMO) are a mixture
of indigestible oligosaccharides composed
of glucose, galactose, fucose,
sialic acid and N - acetyl - glucosamine [1].
Presumably free
sialic acid is made available to such pathogens by other, sialidase - expressing bacteria living in the same niche, or... by host sialidases that are activated in the course
of inflammation.
To date, the published research on this topic has focused on the possibility
of pathogens incorporating Neu5Ac, the primary human
sialic acid, from human cells into their cell walls, and subsequently triggering autoimmunity against Neu5Ac.