Cell Interactions with Connective Tissue Flashcards
What stabilizes elastin networks?
- what makes up these structures?
- Crosslinks Stabilize
- Derived from Aldehydes of Lysine
What protein performs an analogous function to fibronectin in the basal lamina?
- Laminin
What 3 roles does ECM play in the life of a cell?
- Cell Behavior
- Development
- Vitality
What weak molecular effects are responsible for elastin’s elasticity?
- Relaxed State
- Stretched State
- Hydrophobic Effects
Relaxed State:
- Hydrophobic elastin residues fold up against each other and exclude water
Stretched state:
- H20 gets into hyrophobic spaces but hydrophobic residues do not like this and are pressed back out by when tissue is relaxed
What protein functions in exactly the opposite fashion of elastin?
- Aggrecan
What molecule is creates the crosslinks between elastin molecules?
- Desomsines
Desmosines
- what makes them up
- what do they do
- Enzyme Dependence
- 4 allysine are forms from the lysines of up to 4 different proteins
- These 4 come together to make Desmosine
- 4 joined proteins = crosslink
*****Needs LYSYL OXIDASE to form
What type of amino acids are needed in elastin proteins?
- Hydrophobic Residues
2. Lysine to make Desmosines for crosslinking
How does intracellular actin interact with extracellular collagen?
Integrin Proteins
What are the 4 general binding domains of fibronectin?
- Self-Association domain
- Collagen Binding Domain
- Cell Binding Domain
- Heparin Binding
What sequence allows the cell binding domain to interact with integrins?
- RGD sequence
**AKA: Arg-Gly-Asp
What lies between:
- Integrin and Collagen
- Integrin and Actin
Btwn Integrin and Collagen:
- Fibronectin
Btwn Integrin and Actin:
- Adaptor Protein (Talin)
What else may be in the cell membrane that allows the cell to bind more tightly to fibronectin?
- Membrane Heparan Sulfate Proteoglycans
Integrin:
- subunits
Alpha and Beta subunits that are both TRANSMEMBRANE POLYPEPTIDES
What is bound by the Extracellular portion of integrins?
- Intracellular?
Extracellular:
- Matrix Proteins
Intracellular:
- Intracellular Cytoskeletal Signalling Machinery
What activates cell adhesion by integrins?
- Cytokines etc. bind EXTAcellular molecule and send INTRAcellular signal to integrin activating it to bind
How can integrin binding in itself signal for survival, growth, and differentiation of cells?
- Integrin binding by cells can activate intracellular signalling molecules
What determines the type of integrin expressed on each cell?
- Developmental/Transcriptional Controls
What is Glanzman’s Thrombasthenia?
- Cause
- Symptom
- Platelets Lack integrin resulting in bleeding problems
**Prevents cell-cell adhesion allowing for blood clots
What is Leukocyte adhesion deficiency?
- Cause
- Symptom
- No selectins on endothelial cells of blood vessels
- Leukocytes aren’t slowed down enough to be grabbed and extravasularized by endothelial cells, which allows for the immune response
3 areas of the body where the basal lamina is essential.
- Muscle
- Epithelium
- Kidney Glomerulus
**Overall purpose of basal lamina is to separate types of ECM and cells
What is separted by the basal lamina in:
- Muscle
- Epithelium
- Kidney Glomerulus
Kidney Glomerulus:
Epithelial Cell from Endothelial Cell
Muscle:
Cell from CT
Epithelium:
Cell from CT
What type of collagen is important in the basal lamina?
- associated proteins
- TYPE IV
- Laminin binds type IV collagen linking it to cell surrounding the basement membrane
Laminin
- Shape
- What it binds
- Cross shaped
Can bind:
- Perlecan
- Type IV collagen
- Nidogen
What proteins allow for retinal cells and liver cells to find each other among other cell types?
Cadherins (Ca2+ dependent)
What role does the basal lamina play in the kidney?
Filtration - larger macromolecules are retained in the blood vessels, smaller wastes go into urinary space
In most cases what restricts cells to their environment?
Integrins
What problems do integrins pose to cancers that want to metastasize?
- Keeps them from moving around through different basal laminae/ compartment
**To metastasize they must overcome this barrier
STEPS CANCER CELLS MUST TAKE TO METASTASIZE
- Invasive cell must break through basal lamina using MMPs
- Must be able to move through tissue to get to BVs (requires NEW integrins)
- Penetrate 2nd basal lamina to enter and survive in blood/lymph
- Must move and survive in a SECOND NEW ECM.
T or F: laminin is a glycoprotein
True
