Question

Explain how extracellular matrix components affect the mechanical properties of tissues

Answer 1

Extracellular Matrix

Complex network of polysaccharides (such as glycosaminoglycan or cellulose) and proteins (such as collagen) secreted by cells. A structural component of tissues that also influences their development and physiology

ECM regulates

1. proliferation

2. survival

3. differentiation

4. migration, adhesion

5. shape, polarity

Major components of animal ECM

cells: (Epithelial cells, fibroblasts, osteocytes, chondrocytes)

molecules: glycosaminoglycans, collagen, fibronectin, elastin, laminin

Glycosaminoglycans:-

polysaccharide chain that can form a gel that acts as a "space filler" in the extracellular matrix of connective tissues

composed of long, unbranching chains of repeating disaccharide subunits

Rich in sulfate and COO-, so highly negatively charged and high attraction to cations

Collagen

triple-stranded, fibrous protein that is a major component of the extracellular matrix and connective tissues; it is the main protein in animal tissues, and different forms can be found in skin, tendon, bone, cartilage, and blood vessels

collagen provides

tensile strength

attachment for protein for cells

Elastin

rubbery, arranged as fibers or discontinuous sheets

like collagen, synthesizes as precursor (tropoelastin) and polymerizes in ECM

critical in tissues that require recoil, like lungs and larger arteries

laminin

present in epithelial basal lamina

like FN, large, disulfide bonded, self assembling, multi domain protein

Fibronectin

extracellular matrix protein that helps attach to the matrix by acting as a linker that binds to a cell-surface integrin molecule on one end and to a matrix component, such as collagen, on the other

Integrin

family of transmembrane proteins present on all cell surfaces that enable cells to make and break attachments to the extracellular matrix, allowing them to crawl through tissue

transmembrane heterodimers (a and b)

24 alpha and 9 beta dimers