Cell Adhesion Flashcards
What molecules are involved with cell-cell adhesions?
Cadherins
Integrins
What are the functions of cell-cell communication?
WOund healing Inflammation Immune response Tumor metastasis BLood clotting Growth
Is cell adherence reversible?
Yes
Specific and reversible
What are the types of adhesion?
Homotypic adhesion (similar cells) Heterotypic adhesion (Dissimilar cells)
What is an example of a hetertypic adhesion
Neuron and schwann cell
What are N-CAMs?
Neural Adhesion molecule
Where are cadherins found?
Plasma membrane
What moelcule do cadherins need to function?
Calcium allows interaction with neighboring cell via cadherins
What type of side chains do cadherins have?
Carbohydrate side chains
What type of junction do cadherins bind through?
Adherens junctions with Actin cytoskeleton & desmosomes
What are Integrins
Linker proteins
What is a benefit of integrins
Binding is weak with low affinity which allows cells to migrate
What is the organization of cell adhesion?
- Cytoskeletal element (Actin)
- Adaptor proteins
- Transmembrane adhesion proteins (Fibronectin)
- Extracellular ligands (COllagen)
What are the types of cell junctions?
Adhesive (Desmosome, hemidesmosome, adherens junctions)
Tight junctions
Gap junctions
WHat is the purpose of adhesive junctions?
Connect cytoskeleton to cytoskeleton
Allows cells to function as a unit
What types of cells are adhesive junctions most common in?
Cells that experience high stress and pressure (heart, bladder, stomach)
What types of proteins to adhesive junction contain?
Intracellular attachment proteins
Transmembrane linker proteins
What are intracellular attachment proteins?
Located inside plasma membrane
Forms thick plaque on cytoplasmic side
What are transmembrane linker proteins?
Located outside plasma membane
Binds cells to ECM
What tissues are desmosomes often found?
Heart, skin, neck of uterus where structural integrity is important
What is the desmosome made of?
Junctional complex
Cadherins, integrating membranes, transmembrane linker proteins
What is the function of the hemidesmosome?
Connects Epithelial cell to basal membrane using Integrins (laminins)
What are adhesive junctions?
Adhesion Belt encompasses entire cell and connects cytoskeleton to adjacent cell via actin and integrins
Where are adhesive junctions found?
Layers of tissue that line body cavities
What is a gap junction?
A channel formed by six connexins for reciprocal exchange of ions and small molecules
WHat is Zonula occludens protein-1
Major tight junction structural protein
What is the most common junction?
Gap Junction
Where are Gap junctions most commonly found?
In all cells
Specifically cells requiring simultaneous reaction:
Muscle
Nerve
Is there space between tight junctions?
No
What are the tightest junctions of the body?
Epithelial cells of inner ear
Blood-brain barrier
What are the major types of proteins in tight junctions?
Claudins, occuludins
What do tight junctions bind?
Cytoskeleton to adjacent cells
Describe the order to the junctional complex in a cell from basal layer up
Desmosome
Adhesion belt
Tight junction
What is Pemphigus?
Auto-immune disease that attacks Cadherins
Causes skin to fall off
What is the treatment for Pemphigus?
Corticosteroid injections
What desmogelin is the target of pephigus vulgaris? IgA pemphigus? Pemphigus foliaceus?
Dsg3
Dsc1
Dsg1
What is the most common type of Pephigus?
Pemphigus foliaceus
What is the importance of alpha-4 integrins?
The recruitment of lymphocytes and monocytes to inflammation areas
What is Natalizumab?
Humanized monoclonal antibody against alpha4-integrin
What is natalizumab used to treat?
Multiple sclerosis, Crohn’s disease
What type of protein does the focal contact of adherens junctions use?
Integrins
