Extracellular Matrix (ECM)

Cellular Interactions with the ECM

• Integrin proteins connect cells with collagen fibers in the ECM, allowing cells to move through the ECM.

Bone Formation

• Osteoblasts are the cell type responsible for bone formation.

ECM Properties

• The ECM's mechanical property plays an influential role in regulating numerous cell functions.

Cellular Differentiation

• The process by which a cell changes from one cell type to another is called transdifferentiation.
• The mechanical property of the ECM can direct cellular differentiation.

Functions of the ECM

• A common function of the ECM is to provide structural support and regulate cellular behavior.

Components of the ECM

Animal ECM

• The components of the animal ECM include collagen, elastin, proteoglycans, and glycoproteins.

Basement Membranes

• Basement membranes are found in animals surrounding epithelial, endothelial, and smooth muscle cells.

Plant ECM

• The components of the plant ECM include cellulose, hemicellulose, and pectin.

ECM Production and Secretion

• Components of the ECM are produced and secreted by cells through exocytosis.

Proteoglycans

• Heparan sulfate is a type of proteoglycan found in all animal tissues and binds to a variety of protein ligands.
• Decorin is a type of proteoglycan that contributes to the tensile strength of cartilage, tendons, ligaments, and walls of the aorta.
• Keratan sulfate is a type of proteoglycan present in the cornea, cartilage, bones, and the horns of animals.
• Hyaluronic acid is a non-proteoglycan polysaccharide found in abundance in the ECM of load-bearing joints, conferring upon tissues the ability to resist compression.

ECM Proteins

• Collagen is the most abundant protein in the ECM and accounts for 90% of bone matrix protein content.