Cell Adhesion & the ECM Flashcards
Connective tissue elements x2
- Cells
- Extracellular matrix (ECM)
Cells in connective tissue x4
- Fibroblasts
- Myofibroblasts
- Blood derived cells
- Adipocytes
Elements in ECM x2
- Fibrillar proteins
- GAGs
Function of fibroblasts
Secrete fibrillar proteins & GAGs
2 main fibrous proteins
- Collagen
- Elastin
Fibroblasts & collagen secretion
- how
- uses…
- effect
- Fibroblasts lay down fibrils in direction of others
- Fibripositor –> out of tunnels
- Fibrils are orientated along direction of tendon
Elastin secretion
- main secretory cell
- also secreted by… x2
- structure x2
- Fibroblasts
- Smooth muscle cells
- Chrondroblasts
- Hydrophobic polypeptides
- Like to be in contact –> seek out & crosslink w each other
Myofibroblasts
- function x2
- role in tissue damage
- Secrete fibrillar proteins (e.g. collagen)
- Contract –> as makes actin & myosin
- Make collagen scaffold –> forms fibrous scar –> contracts to reduce size of damaged area
Mast cells
- structure
- Granules = contain histamine, heparin
Plasma cells
- what
- function
- Modified B lymphocytes
- Make & secrete antibodies
Macrophage
- function x2
- Phagocytosis
- Antigen processing & presentation
Adipocytes
- function x3
- Insulation
- Packing
- Energy store
Different cell junctions x4
- Tight junctions
- Adherens junctions
- Desmosomes
- Gap junctions
Tight junctions
- tightness defined by… x3
- function x2
- Claudins, occludins, no. of sealing strands
- Form gates w varying degrees of closedness
- Fence off domains
Adherens junctions
- connects to…
- how works
- Extracellular matrix
- Actin binds via adaptor protein to transmembrane protein (cadherin) = links to actin in another cell
Desmosomes
- links
- how works
- extra feature
- 2 cells
- cadherin proteins = transmembrane proteins –> keratin filaments in both cells join to it
- Plaque –> = against membrane & anchors keratin filaments
Gap junctions
- what
- function x2
- structure
- Hydrophilic channel
- Small molecules can pass through
- Communication
- Connexin proteins
Structure of proteoglycans x3
- GAGs + proteins
- 1 protein & lots of GAGs –> connected by link protein
- Forms a ‘brush-like’ structure
Proteoglycan function x3
- Matrix support (glue-like function)
- Carry lots of water
- Link between proteins of ECM, ECM & cell surface
Proteoglycan location x2
- ECM
- Cartilage
GAG chains
- structure
- properties x2
- Repeating disaccharides
- Highly charged
- Highly hydrated
Linking ECM & cell cytoplasm
- main components & their location x3
- extra components x2
- Collagen fibres OUTside
- Integrin = transmembrane protein
- Actin fibres INside
- Fibronectin to link collagen
- Adaptor protein to link actin
Specialised links - Focal adhesions
- property
- ECM
- intracellular
- function
- Dynamic
- Fibronectin
- Actin
- Signalling platforms
Specialised links - Hemidesmosomes
- property
- ECM
- intracellular
- function
- More stable
- Laminin
- Keratin intermediate filaments
- Strong contacts
ECM interactions & cancer progression –> what happens x5
- Tumour cells accumulate
- Decreased expression of cadherins
- BM breached
- Integrins expressed –> promotes interaction w ECM
- Invasion of tumour cells
Muscular dystrophy
- mutation
- caused by
- effect
- Of dystrophin
- Premature termination of translation
- Muscle fibres degenerate
Approach to treating muscular dystrophy
- drug
- thought to help by…
- PTC 124 (ataluren)
- Overriding premature stop signal mutation –> producing normal dystrophin
