Cell Bio - Cell death, ECM and migration
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What are Tight junctions
Specialised cell to cell connections that seal the gap between epithelial cells
What are Adherens junctions
Cell to cell structures that connect actin filament bundles in one cell to the adjacent one.
What are Desmosomes
Intracellular junctions
What do Desmosomes do?
They connect intermediate filaments in one cell to those in the next cell
What are Gap junctions
Specialised channels that connects the cytoplasm of next dor cells
What are Hemidesomsomes
Small stud-like structures found in keratinocytes of the epidermis of the skin
What do Hemidesmosomes do?
They anchor intermediate filaments in cells to the ECM
What are Actin-linked cell-matrix junctions?
Structures that anchor actin filaments in the cell to the ECM.
What are Cadherins
Transmembrane molecules with large extracellular parts folded into 5 domains
How many domains in Cadherins contain Calcium ion binding sites?
3
Where do you find E-cadherin
In epithelial cells
Where can you find N-cadherin
In the nervous system
What do Epithelial cells line?
The outer and inner surfaces of the body
What do Endothelial cells line?
Capillaries and other blood vessels
What is the Epidermis comprised of?
Keratinocytes
What are Keratinocytes?
Skin epithelial cells
How do Cadherins mediate cell-cell adhesions?
Through Homophilic mechanisms
Homophilic Mechanisms
Adhesion molecules on one cell, binding to identical molecules on another cell
Integrins
Family of transmembrane cell surface receptors
Where is ICAM-1 expressed?
On the surface of endothelial cells
What is ICAM-1?
A glycoprotein that regulates leukocyte recruitment.
What does icam-1 primarily bind to?
LFA-1 and Mac-1
In atherosclerosis, what is the expression of ICAM-1 up-regulated on?
Endothelial cells
How do Adherens junction connect actin filament bundles?
Using transmembrane proteins
Name a transmembrane protein
Cadherins
What is Blebbing?
The formation of spherical, bulge-like protrusions on the plasma membrane
What is CED-3
The apoptotic caspase in C.elegans
What are Caspases?
Protease enzymes that play essential roles in programmed cell death
When apoptotic caspases are activated, is it reversible or irreversible?
Irreversible
What does CED-4 do?
Activates CED-3
Promotes cell death
Which splice variant of CED-4 promotes apoptosis?
CED-4S
Which splice variant of CED-4 inhibits apoptosis?
CED-4L
What does CED-4L inhibit apoptosis as?
As a dominant negative inhibitor
What does CED-9 do?
It inhibits apoptosis
How does ced-9 inhibit apoptosis?
It binds to ced-4s preventing cell death from happening
What is egl-1?
A proteins that acts as an activator for apoptosis
Pro-apoptotic
Proteins that trigger apoptosis
Anti-apoptotic
Proteins that prevent apoptosis
What do death receptors activate?
Caspase cascades
Which inhibitor caspase does death receptors activate?
Caspase 8
Which effector caspases do Death receptors activate?
Caspases 3-7
What do death receptors do?
They detect the presence of extracellular death signals
What sort of proteins are Caspase 3 and Caspase 7?
Executioner proteins
Which caspase cleaves the BH3-only protein?
Caspase 8
What is the activated form of BID?
Truncated BID
What does truncated BID do?
It stimulates intrinsic apoptotic pathway by binding directly to Bax
Where is Type I collagen mainly found
Skin and Bones
Where is Type II collagen mainly found?
In cartilage
Where is Type III collagen mainly found?
Mainly in connective tissue
Where is Type IV collagen mainly found?
In the Basal Lamina
What is the repeating sequence of Collagen
Gly-X-Y
What is the X in Gly-X-Y usually
Proline
What is the Y in Gly-X-Y usually?
Hydroxyproline
What is the basal lamina susceptible to?
Proteolysis
Why is the basal lamina susceptible to proteolysis
Because of the triple helix being interrupted several times
What are Laminins
Multi domain glycoproteins
Function of Laminins
Forming and stabilising the basal lamina
What are Integrins
A large family of heterodimeric proteins
What do heterodimeric proteins exist as?
Alpha and Beta
How are cell adhesion assays used?
They are used today to study how cells interact with the ECM.