• Cell Junctions, Cell Adhesion, and the Extracellular Matrix

The role of tight junction

Anchoring junction

Adherens junction

Desmosomes

Focal adhesions

Desmosomes and Hemidesmosomes

Gap junction channel

Gap junctions

Gap junction coupling in the ovarian follicle

The regulation of gap-junction coupling by a neurotransmitter

Cell-Cell Adhesion

Three mechanisms of cell-cell adhesion

The structure and function of cadherins

Cadherin-dependent cell sorting

Cadherin diversity in the CNS

The linkage of classical cadherins to actin filaments

The structure and function of selectins

The cell adhesion protein N-CAM

The connective tissue underlying an epithelium

The repeating disaccharide sequence of a dermatan sulfate glycosaminoglycan (GAG) chain

The relative dimensions and volumes occupied by various macromolicules

The repeating disaccharide sequence in hyaluronan

The linkage between a GAG chain and its core protein in proteoglycan molecule

Examples of proteoglycan

An aggrecan

Structure of a typical collagen molecule

Type IX collagen

Stretching a network of elastin molecules

The structure of fibronectin dimer

The structure of laminin

Three ways in which basal laminae are organized

The molecular structure of a basal lamina

The comparative shapes and sizes of some of the major ECM macromolecules

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Anchorage dependence and the importance of cell spreading

The degradation of matrix components

Slow and continuous turnover of ECM

Matrix metalloproteasesSerine protease

Controlled, specific degradation -> important to cell migration *Clear a path through matrix *Expose cryptic sites that promote cell binding, cell migration *Promote cell detachment *Release signal proteins that stimulate cell migration

Tightly controlledLocal activation; plasminogen activator activates inactive plasminogen to plasminConfinement by cell-surface receptor; urokinase-type plasminogen activatorSecretion of inhibitor; tissue inhibitors of metalloproteases, serpins

The importance of proteases bound to cell-surface receptors

The structure of an integrin receptor

The regulation of the extracellular binding activity of a cell’s integrins from within

Excessive numbers of focal adhesions in FAK-deficient fibroblasts

Matrix-dependent cell survival in the formation of the proamniotic cavity