cell adhesion and extracellular matrix Flashcards
(22 cards)
what do we find in extracellular matrix?
fibrillar proteins and polysaccharide glyogosaminoglycans (GAGs)-organised into proteoglycans
cells in connective tissue
chondrocytes osteoblasts fibroblasts myofibroblasts blood cells adipocytes
Fibrillar proteins
collagen
elastin
fibronectin
laminin
What is special about collagen?
packed into large vescicles in RER
Secreted by exocytosis in a membrane tube called fibriposter to make a fibril
fibril organised into fibres by other cells
what synthesises elastin?
fibroblasts
smooth muscle cells
chondroblasts
what do proteoglycans do?
what is their charge?
matrix support/cushioning and hydration
glue like function
links between proteins of ECM and ECM and cell surface
What are GAGs and what is their charge?
Chains of repeating disaccharide units
Highly negatively charged
How does the ECM bind to cytoskeleton?
Colleagen and proteoglycan bind to fibronectin which binds o integrin which binds to adaptor protein then actin cytoskeleton
What are the two functions of myofibroblasts?
Secrete collagen and asct as smooth muscle cells (synthesise actin, myosin, desmin)
4 functions of myofibroblasts in tissue damage
proliferate
secrete collagen
consolidate damaged area
contract
Functions of adipocytes
energy storage
packing (eye)
insulation
Obob genes mean that
You become resistant to leptin
function of cell junctions and adhesion proteins
link cells and their cytoskeletons to:
other cells
ECM
List 4 cell junctions
tight junctions
adherens
desmosome(filaments, plaque, cadherins)
gap junction
cell to cell adhesion done by
integrin, selectin, CAM
Cell to ECM
focal adhesion(integrins, signalling platforms) hemi-desmosome(more stable, intermediate filaments, laminin in BM) integrin membrane proteoglycan
What do tight junctions do
Define polarity
Allow passage of substances between cells
Determine permeability (different claudins)
can link actin to cytoskeleton
Gap junctions
look like flowers
communication
hydrophobic channels, small molecules
coordination of function
CAUSE Duchenne’s muscular dystrophy
Absence of adaptor for integrin to intracellular compartment due to gene mutation(premature termination of translation)
CONSEQUENCE dmd
Damage to muscle fibre due to muscle tearing
muscle wasting and weakness - unable to walk by 12
What drug is used to combat DMD and how does it work?
PTC 124, ataluren
Overrides premature stop signal mutation to produce normal dystrophin
Role of cell adhesions and interactions with ECM during cancer stages
tumour cells accumulate, cadherins reduced and invasion of BM. Integrins promote interaction with ECM and non epithelial cells
