Curriculum
Module 06 · 55 min
Cell Junctions & the Extracellular Matrix
Tight, adherens, desmosomal, gap — and the matrix that holds tissues together.
CoreClinicalResearch
Topics
What this module covers
- 01Tight junctions (claudins, occludin) and barrier function
- 02Adherens junctions and the cadherin-catenin-actin link
- 03Desmosomes / hemidesmosomes / focal adhesions
- 04Gap junctions and electrical coupling
- 05ECM components: collagens, elastin, proteoglycans, laminins, fibronectin
- 06Matricellular signalling, MMPs, basement membrane
Deep dives
Lesson sub-pages
Learning objectives
By the end of this module you will be able to
- L01Match a junction class to a disease of barrier failure or autoimmunity.
- L02Explain the role of the basement membrane in cancer invasion.
- L03Distinguish E-cadherin loss as cause vs consequence in epithelial-mesenchymal transition.
Expected takeaways
What you should walk away believing
- →Loss of E-cadherin is a hallmark, but not always a driver, of EMT and invasion.
- →Pemphigus = anti-desmoglein autoantibodies; pemphigoid = anti-hemidesmosome — different layers, different blisters.
- →Basement-membrane breach by MMPs is the canonical first step of carcinoma → invasive cancer.
Core summary
At the Core level
Cells in tissues are physically and chemically coupled through specialised junctions and an extracellular matrix that is more than scaffolding — it stores growth factors, transmits force, and signals through integrins. Junction failure breaks barriers (gut, skin, blood-brain). ECM misregulation drives fibrosis, cancer invasion, and connective-tissue disease.
Myth vs reality
Common misconception
Claim
'Leaky gut syndrome' explains a wide range of unexplained symptoms.
Reality
Increased intestinal permeability is real in coeliac, Crohn's, NSAID enteropathy and severe sepsis. The diffuse 'leaky gut' construct sold in supplement marketing has no controlled-trial evidence.
Evidence-graded claims
Claims, scored A–F
B
E-cadherin loss promotes invasive epithelial cancer
Classic in lobular breast cancer and diffuse gastric cancer.
A
Anti-Dsg3 antibodies cause pemphigus vulgaris
Confirmed by passive transfer in mouse.
F
Generic anti-MMP drugs improve cancer outcomes
Failed in trials; broad MMP inhibition has been a notable disappointment.
Quiz
Check your understanding
Q1. Which junction maintains the blood-brain barrier?
Q2. Marfan syndrome is caused by a mutation in:
Flashcards
Lock it in
1 / 3
Front
Cadherin-catenin link to actin?
Click to flip
Suggested reading
Primary literature
- Cell adhesion: the molecular basis of tissue architecture and morphogenesis — Gumbiner, Cell 1996 ↗