Cell-cell and cell-matrix interactions

Question 1

collagen

-role

Answer 1

• provide structural integrity for bone and cartilage

- major component of basement membrane

Question 2

colagen types: 1, 2, 4,

Answer 2

1: found almost everywher, firbril forming
2: almost exclusively in cartilage, fibril forming
4: plays a big role in basement membranes (basal lamina), network or sheet-forming
- 1 and 2 are connective tissue types, 2 as the cartilage collagen, and 4 as the epithelial basement membrane

Question 3

elastin

Answer 3

• major component of the elastic laminae of the major artery walls
• cross linked by fibrillin

Question 4

proteoglycans and hyaluronan

Answer 4

• ubiquitous
• provide hydration and structural support for cells and cartilage (shock absorbers)
• acts as resevoirs for growth factors and cytokines

Question 5

matricellular proteins

Answer 5

• secreted and bind tightly to the cell surface through their interactions with integrins
• help attach cells to each other and to the ECM via multiple binding sites for cells, proteoglycans, and collagen
• examples: fibronectin and lamin
• help to regulate important cell functions like proliferation, motility, and differentiation via their connections with their interactions with integrins and growth factors

Question 6

integrins

Answer 6

• receptors for fibronectin, lamins, CCN proteins as well as other mols
• often connect to cell signalling and cytoskeletal machinery via tightly complexed protein on cytoplasmic side of membranes

Question 7

cadherins

Answer 7

• calcium-requiring cell adhesion molecules important for maintaining tissue integrity (skin) by connecting the desmosomes of adjacent skin cells.
• defects in cadherin affecting desmosomes can weaken or destroy the integrity of the skin and cause sloughing and blistering
• critical in embryonic development, required for compaction of the embryo

Question 8

cell adhesion molecules

-leukocyte rolling

Answer 8

• leukocyte rolling along the vascular endothelium is due to weak “on-off” interactions betweeen P-selectin on the endothelial cell and a carbohydrate ligand on the leukocyte
• if a tissue is inflammed, the endothelial cells in that area will express platelet activating factor PAF, which binds to the PAF receptor on the leukocyte
• this activates a specific integrin that binds tightly to ICAM-1 on the endothelial cell membrane, causing the leukocyte to stick
• this initiates extravasation of the leukocyte (migration between EC to enter the inflammatory area)

Question 9

matrix metalloproteinases MMPs

Answer 9

• meta-requiring enzymes that degrade matrix molecules, including collagens, proteoglycans, and other proteins
• required for cancer cell metastasis, tissue remodeling, wound healing, and angiogenesis