Ecm L9 Flashcards
How is the basal lamina different in muscle compared to epithelial cells
It surrounds it, whereas with epithelial cells it’s at the bottom of it
What are the 3 major functions of ecm
Strength - Eg cartilage and bone
Communication
Cell migration/ polarity
What 3 things are in ecm which allow communication/signalling
Gf
Hormones
Cytokines
Cell migration occurs when cells pull on the matrix. What is this important for
Embryonic development
Angiogenesis
Tumour development - metastasis
Wound repair
What makes the ecm basal lamina
Cells surrounding it
Is the basal lamina conserved
Yes. Seen in most organisms so similar epithelial tissue
What 2 type 1 collagens are in basal lamina
IV and XVIII (4 and 18)
Other than collagen IV and XViII what is in basal lamina ecm
Fibronectin and laminin
What are the cells called in connective tissues which are always there
Indigenous
What 3 types of cell are in connective tissue (with lots of ecm)
Primitive mesenchymal cells
Fibroblasts
Specialised cells
What are primitive mesenchymal cells
Undifferentiated in the connective tissues. They differentiate into specialised eg chondrocytes,mast cells, adipocytes
What do fibroblast cells do in connective tissue
Produce a lot of ecm in connective tissues
What type of specialised cells make matrix forming Cartilage
Chondrocytes
What type of specialised cells make ecm forming bone
Osteoblasts
Why is matrix needed eg for bone via osteoblast matrix production
For flexibility of bone
What other than indigenous cells are there
Immigrant cells eg lymphocytes finding ag in connective tissue
What 3 types of protein is present in ecm connective tissues
GAGs/ proteoglycans
Fibrous proteins (collagen)
Other glycoproteins (fibronectin,elastin)
What happens to the 3 protein types in structure like bone nd teeth and cornea
They get calcified for strength
What gives gags an anionic charge -ve
Sulphated
What repeating disaccharide makes up gags
N acetyl glucosamine and glucuronic acid
Sulphated
Give examples of gags
Heparin sulphate
Chondroitin sulphate
Keratin sulphate
Hyaluronan / hyaluronic acid
What do gags link to to form proteoglycans
Core proteins (serine links tetrasachride then the gag)
Give example of a simple proteoglycans (1 gag and 1 core)
Decorin
What are complex proteoglycans
Where many gags join into a single core protein
Give example of a complex proteoglycan
Aggrecan
What does aggregation of aggrecans form on 1 linked protein called
Hyaluron (the linker protein)
What does -ve charge allow for function of gags
Binding of many h20 molecules
What does aggrecan becoming an auto antigen for B cells cause disease wise
Rheumatoid arthritis
Which cells make collagen/fibrous proteins in ecm
Fibroblasts
Explain the structure of collagen
3 a polypeptides form a triple helixes inside cell
Then transported out where they aggregate forming fibrils
Then fibrils aggregate to form a collagen fibre
Is collagen the most abundant protein in ecm
Yes
How many diff genes are for collagen
40
Type 1 included XVIII (in connective tissues and basal lamina), what is type 2 and where is it
Type 2 is found in cartilage
Can be collagen II or IX
What substance prevents aggregation of diff helixes to form a fibril inside cells
Procollagen (cleaved by enzymes outside of cell to form fibres)
What do fibronectin glycoproteins do
They allow the ecm Eg collagen to indirectly connect to integrons and the cytoskeleton of a cell
Forms cell ecm connection
What is elastin in ecm for
For stretch eg of arteries
What cell receptors do cells express to allow them to bind to ecm via extracellular domain
Integrins (a and b)
What things do integrins bind to in ecm eg in basal lamina
Collagen IV or XVIII
Which integrin subtype needs fibronectin to bind to ecm
A5b1
How many integrins are there
24
Which adaptor protein is used by integrin for it to make contact with actin/vinculin
Talin (integrin associated protein)
Which cellular pathway is activated via integrin ecm and cell binding via talin and collagen
FAK
Focal adhesion kinase (for migration, gene expression)
Why does integrin need to be activated and then inactivated
For movement of cells along the matrix
When activated it has stronger talin and ecm binding
