Extracellular Matrix Flashcards
ECM provides ?
Support, strength, framework and protection
What is the difference in ECM between animals and plants ?
In animals:
- Strong
- Agile
- Motile
- Flexible
In plants:
- Weak
- Fragile
- Rigid
- Thin
Plant cell strength comes from ?
Cell wall
Cell walls composed of ?
Polysaccharides
Mainly composed of ?
Cellulose (inner layers) and pectin (outer layers)
Help to maintain and control?
Internal osmotic swelling
What is the most abundant organic macromolecule on earth ?
Cellulose
Cellulose microfibrils arranged in ?
Crisscross lattice interwoven with other polysaccharides and structural proteins
What does this arrangement provide ?
Tensile strength and resists compression
Orientation of cellulose microfibrils dictates direction of ?
Cell growth and elongation
Membrane attached microtubules guide ?
Location of enzyme complexes for cellulose formation
Cytoskeleton controls ?
Plant shape and tissue modelling
Connective tissue contains ?
Most ECM
Highly varied tissues, varying from ?
Hard (bone), flexible (tendons), rubber (cartilage) or soft (jelly-like substance in eyes)
Explain ECM - Fibroblasts ?
- ECM laid down by fibroblasts
- Elongated, spindle-shaped cells
- Attach to and secrete collagen
- Cancer-associated fibroblasts (CAFs) contribute to malignancy
Fibroblasts scattered amongst ?
ECM
Explain ECM - Collagen ?
- 20 collagen genes in mammals
- Encode different collagen types
- Constitute ~25% protein mass in mammals
- Long, stiff triple helical structure
- Collagen molecules can assemble into polymers = collagen fibrils
- Collagen fibrils can pack together further = collagen fibers
Explain Collagen synthesis (ECM) ?
- Collagen synthesis completed outside of cell
- Precursor procollagen made inside cells and secreted by exocytosis
- Procollagen contains peptide extensions that prevent collagen microfibril formation
- Enzymes called procollagen proteinases cut terminal extensions
- Collagen formed and assembled only in the extracellular space
Explain Collagen organisation ?
- Collagen deposition must be coordinated for proper connective tissue function
- Collagen deposited then rearranged by fibroblasts
- Fibroblasts crawl over collagen fibers compacting and aligning
Ehlers-Danlos Syndrome (EDS) collection of ?
Rare inherited conditions affecting connective tissue
What does EDS lead to ?
Stretchy skin, hypermobility in joints
What do serious cases cause?
Vasculature weakness
Is there a treatment available for EDS ?
No treatment available, lifestyle management, physiotherapy
Cells do not attach well to ECM – instead use ?
A collagen-fibronectin-integrin axis
Fibronectin secreted by ?
Fibroblasts – one part binds collagen, other part binds cell
Cell attaches to fibronectin through ?
Receptor proteins called integrins
