6 workshop

What experimental observation suggested mutant mice were more susceptible to H. pylori infection

The mucus in mutant mice failed to trap H. pylori effectively

Why is fucose important for trapping H. pylori in mucus

Fucose forms part of terminal glycan structures such as Lewis antigens that H. pylori binds to

What happens to H. pylori trapping when mucins lack fucose

Bacterial binding to mucus is reduced allowing bacteria to penetrate the mucus layer

Why was reduced fucosylation not due to loss of fucosyltransferase activity

The enzymatic activity of fucosyltransferase was normal in vitro

What is one possible explanation for normal enzyme activity but reduced fucosylation in vivo

The fucosyltransferase may be mislocalized within the cell

How could mislocalisation of fucosyltransferase be experimentally tested

Using immunocytochemistry to visualise enzyme localisation in cells

Why might GDP-fucose availability limit mucin fucosylation

GDP-fucose is the activated sugar donor required for fucosylation

Where is GDP-fucose synthesised in the cell

In the cytosol

Why must GDP-fucose be transported into the Golgi

Fucosyltransferases act within the Golgi lumen

What cellular defect can prevent GDP-fucose reaching the Golgi

Loss or mutation of the GDP-fucose transporter

What is the name of the GDP-fucose transporter

SLC35C1

How could a GDP-fucose transport defect be experimentally confirmed

By genetic correction or supplying GDP-fucose and restoring fucosylation

What distinguishes CF mucus from non-CF mucus

CF mucus is hyperconcentrated, viscous and poorly hydrated

Why is mucus transport reduced in cystic fibrosis

Thick viscoelastic mucus is difficult for cilia to move

What effect does sialidase treatment have on mucus

Sialic acid removal reduces negative charge causing mucin collapse

Why does removing sialic acid worsen mucus clearance

Sialic acids promote electrostatic repulsion that maintains mucus expansion

How does sialic acid removal affect membrane-tethered mucins

Loss of repulsion collapses the polymer brush on cilia

What consequence does brush collapse have for ciliary function

Reduced space for ciliary beating impairs mucus transport

What do reducing agents do to mucins

They break disulfide bonds linking mucin polymers

How does breaking disulfide bonds affect mucus viscosity

It reduces polymer size and lowers viscoelasticity

Why might excessive mucin breakdown still be problematic

Overly small polymers may not be efficiently cleared

What is the rationale behind hypertonic saline therapy in CF

It draws water onto the epithelial surface to hydrate mucus

How does mannitol improve mucus clearance

It acts osmotically to increase water content of mucus

What is the primary intestinal gel-forming mucin

MUC2

What happens to parasite infection in MUC2 knockout mice

Infection becomes acute but not chronic

What does this indicate about MUC2 in parasite defence

MUC2 contributes but is not essential for parasite expulsion

Which mucin is upregulated during intestinal parasite infection

MUC5AC

What immune response drives MUC5AC induction

Type 2 immunity mediated by IL-13

What happens when MUC5AC is knocked out during infection

Mice become susceptible to chronic infection

What does this reveal about MUC5AC

MUC5AC is critical for parasite expulsion

What is the weep and sweep hypothesis

Increased mucus secretion and peristalsis flush parasites from the gut

How does glycosylation change during parasite infection

Increased sulfation of mucins is observed

What happens when sulfate transport is disrupted

Mice shift from resistant to susceptible to infection

What new role of mucins has recent research revealed

Mucin glycans directly regulate microbial gene expression

How do mucin glycans affect bacterial virulence

They suppress biofilm formation and toxin production

What virulence system is suppressed by MUC2 in Salmonella

SPI-1 type III secretion system

Why are monosaccharides insufficient to replicate mucin effects

Full glycan presentation on a protein scaffold is required

What experimental tools are now used to study mucin glycan effects

Synthetic glycopeptides with defined glycan structures

Why is this research area important therapeutically

It offers new strategies to control dysbiosis and infection