Basement Membrane Flashcards
How do epithelial cells bind to the basement membrane?
They physically bind via focal adhesions and hemi-desmosomes
How does the basement membrane influence the epithelium?
- it controls the growth and differentiation of epithelium
2. it acts as a barrier to downwards epithelial growth
In what disease is the barrier to downwards epithelial growth compromised?
Cancer
Once the epithelium grows through the basement membrane, it becomes malignant
How does the basement membrane control the flow of nutrients?
It acts as a selective barrier
It controls the flow of nutrients, metabolites and other molecules to and from the epithelium
What are the three layers of the basement membrane?
- lamina lucida
- lamina densa
- lamina reticularis
What is found in the lamina lucida?
- integrins
- laminins 1, 5, 6, 10
- collagens XVII and IV
- dystroglycans
What is found in the lamina densa?
- Collagen IV
- entactin/nidogen
- perlecan
- heparin sulfate proteoglycans
What is found in the lamina reticularis?
- collagens, I, III, V
2. proteoglycans
What is heparin sulphate in the basement membrane?
It is a component of the ECM which is covalently attached to core proteins to form a proteoglycan
Which 2 layers of the basement membrane make up the basal lamina?
Lamina lucida and lamina densa
What is the major component of the basement membrane and what is it involved in?
Type IV collagen
Involved in cell adhesion, migration, differentiation and growth
What does type IV collagen form in the basement membrane?
It anchors fibrils and fibrillin microfibrils when connective tissue attaches to the basal lamina
What does degradation of type IV collagen in the basement membrane lead to?
- angiogenesis
- tissue remodelling
- cancer progression
What is fibronectin?
A glycoprotein found in the extracellular matrix
What will fibronectin bind to?
Membrane-spanning receptor proteins called integrins
What is the role of fibronectin?
It binds extracellular matrix components such as collagen, fibrin and heparin sulphate proteoglycans
What process does fibronectin influence?
It is involved in cell adhesion, growth, migration and differentiation
How is cellular fibronectin assembled?
It is assembled into the ECM
This is an insoluble network that separates and supports the organs and tissues in an organism
What are laminins involved in?
Formation, structure and stability of the basement membrane
What is a laminin?
A type of glycoprotein which is involved in the structural scaffolding of tissues
How do laminins perform their function?
They can separate or connect different tissues
They can also bind to cells and anchor organised tissue cells to the membrane
What is the role of nidogen-1?
It is a glycoprotein that interacts with other components of the basement membrane
It can play a role in cell interactions with the ECM
What will bind to the mesh of type IV collagen in the basement membrane?
Laminin and nidogen
What is the importance of laminin and nidogen binding to IV collagen?
This provides a link to the integrins (laminin receptors) on epithelial cells to produce a hemidesmosome
