Targeting lung fibrosis: Dissecting molecular crosstalk mechanisms that drive disease pathogenesis and therapeutic response

Idiopathic pulmonary fibrosis (IPF) is chronic, progressive, lung disease with very high morbidity. Transforming growth factor-B (TGF-B) and aVB6 integrin are key drivers of IPF; aVB6 applies mechanical force on latent TGF-B to potently release active TGF-B.

We have found: 1) aVB6 signalling complexes recruit a mucin-galectin-3 regulatory module; 2) MUC1-galectin-3 interaction regulates growth factor receptor (GFR) clustering and trafficking. In vivo, MUC1 and galectin-3 promote lung fibrosis and galectin-3-targeting drugs inhibit TGF-B activity to suppress late-stage progression.

MUC1 spatially-constrains integrin activation; the bulky glycoprotein funnels receptors into adhesions and applies compressive tension to promote integrin activation.

This new paradigm of integrin activation leads to our hypothesis: Galectin-3 and MUC1 co-ordinate aVB6 clustering to drive TGF-B activation during IPF pathogenesis.

Objectives & Experimental Approach

1) Determine impact of MUC1-galectin-3 interaction on aVB6 trafficking and ligand engagement:
aVB6 trafficking will be analysed using biochemical endocytosis/recycling assays. aVB6 clustering and ligand-binding will be analysed by immunofluorescence using activation-specific anti-aVB6 antibodies.

In all objectives, contributions of MUC1 compressive tension or signalling will be analysed using mechanically-tuned glycoprotein-mimetics and MUC1 ectodomain/cytodomain mutants in lung epithelial cells. Involvement of MUC1-galectin-3 interaction, will be assessed in presence/absence of galectin-3 or galectin-3-targeting drugs.

2) Analyse whether MUC1-galectin-3 interaction regulates aVB6-medicated force application and TGF-B activation:
Quantitative traction force microscopy and TGF-B1 activity luciferse reporter assays will demonstrate whether biophysical and signalling properties of MUC1-galectin-3 regulate aVB6-mediated mechanical forces and activate TGF-B.

3) Test whether MUC1-galectin-3 interaction co-ordinates aVB6 funnelling to drive TGF-B activation:
Student will visit Paszek Lab to perform Topographical-Scanning Angle Interference Microscopy to analyse membrane deformation using FRET reporters of MUC1 compression and aVB6 activation-specific antibodies.

4) Determine whether MUC1-galectin-3-mediated regulation of aVB6/TGF-B modulates response to galectin-3- and aVB6-targeting drugs:
Organotypic IPF models will be used to test involvement of MUC1-galectin-3 interaction on aVB6-dependent disease initiation/progression. Preclinical IPF models will be utilised following administration of galectin-3- and aVB6-targeting drugs.

Novelty & Timeliness

IPF incidence is rising and in critical need of novel avenues for therapeutic management. This multidisciplinary project will reveal how aVB6, MUC1 and galectin-3 co-operate to activate TGF-B; illuminating the mechanisms driving IPF pathogenesis and drug responses.