L9: Extracellular Matrix Flashcards
Functional attributes of ECM
- Structure
- Defense/protection/barrier
- Nutrition (diffusion of metabolic fuels)
- Diffusion of gases, molecules and ions
- Cell growth and survival
- Cell migration
- Lubrication
What is granulation tissue?
- Tissue that is the hallmark of tissue repair
Basic structures of the ECM
- ) Ground substance
- Glycosaminoglycans/mucopolysaccharides
- Proteoglycans
- Multiadhesive Glycoproteins
- Water - ) Fibers/CT
- Collagen
- Reticular (type III collagen)
- Elastic
Characteristics of ground substance. Function
Characteristics:
- Amorphous intercellular material that is transparent, colorless and homogenous, hydrated, fills space b/w cells and fibers, viscous
Function:
- Acts as lubricant, barrier and provides structure, diffusion medium for metabolites
What are the molecules that make up ground substance?
- Glycosaminoglycans/mucopolysaccharides
- Proteoglycans
- Multiadhesive Glycoproteins
- Water
Structure and function of glycosaminoglycans
- Linear polymers of disaccharides that have negatively charged carbosyl groups that attract cations, which attract extracellular fluid. Function here = hydrating effect, which allows for compression resistance
Clinical relevance of glycosaminoglycans
- In Grave’s disease, increased deposition of GAGs (hyaluronic acid and chondroitin sulfate) in retroorbital space that causes exophthalmos.
- Excess deposition of GAGs in Grave’s also involves skin
List of glycosaminoglycans
- ) Dermatan sulfate
- ) Chondroitin sulfate
- ) Heparan sulfate
- ) Keratan sulfate
- ) Hyaluronic acid
- ) Heparin
Structure of proteoglycans
- Linear chains of glycosaminoglycans bound to protein core, majority of weight is attributable to CHOs
Types of proteoglycans
- ) Syndecan
- ) Perlecan
- ) Decorin
- ) Versican
- ) Aggrecan
What is syndecan? Function?
- Syndecan is a type of proteoglycan where core protein of molecule is embedded in cell membrane as transmembrane protein
- In fibroblasts, syndecan serves as co-receptor for fibroblast growth factor
What is perlecan? Function?
- Major proteoglycan type found in basement membranes and CT
- Function = cell adhesion, proliferation, glomerular filtration, development and growth factor binding
Clinical relevance of perlecan
- Enhanced in some types of tumors, promoting proliferation and angiogenesis
Function of versican
- Important in cell-cell and cell-ECM interactions
What are multiadhesive glycoproteins?
- Glycoproteins that molecularly tether cell to EC elements
Structure of multiadhesive glycoproteins?
- Have three primary binding sites:
- 1.) one for integrins (cell adhesion molecules)
- 2.) one for collagen fibers
- 3.) one for proteoglycans
List types of glycoproteins
- ) Fibronectin
- ) Laminin
- ) Nidogen (entactin)
- ) Tenascin
- ) Chrondronectin
- ) Osteonectin
List types of glycoproteins. What are their binding domains and where are they located?
1.) Fibronectin
Binding domains: integrins, collagen, heparin, heparan sulfate and hyaluronic acid
Location: CT, blood plasma, embryonic tissue
2.) Laminin
Binding domains: integrins, heparan sulfate, collagen (IV) and entactin
Location: basal lamina
3.) Nidogen (entactin)
Binding domains: laminin and type IV collagen
Location: basal lamina
4.) Tenascin
Binding domains: syndecans and fibronectin
Location: embryonic tissue
5.) Chrondronectin
Binding domains: collagen II, chondroitin sulfates, hyaluronic acid and integrins of chrondrocytes
Location: cartilage
6.) Osteonectin
Binding domains: collagen I, proteoglycans, integrins of bone cells (cytes and blasts)
Location: bone
List fibers of ECM
- ) Collagen
- ) Reticular
- ) Elastic
What is the most abundant protein in the body?
- Collagen (20-25% of all protein), specifically type I