Lecture 3 Flashcards
1
Q
Connective vs. Epithelial Tissue
A
- Epithelial tissue: Cells directly connected to each other with minimal extracellular matrix
- Connective tissue: Cells dispersed through extracellular matrix
2
Q
Epithelial structure
A
- Tight junction: seals gap between epithelial cells
- Adherens junction: Connects actin filament bundle in one cell with another
- Desmosome: Connects intermediate filaments in one cell to another
- Gap junction: Allows passage of water soluble molecule from cell to cell
- Hemidesmosome: anchors intermediate filaments in cell to extracellular matrix
- Cell-cell junction mediated by cadherins
- Cell-extracellular mediated by integrins
3
Q
Cadherins
A
- Transmembrane proteins expressed by both cells
- Stick to specific cadherin on other cells
- Interactions require Ca++
- Homophilic interactions
- Indirectly link actin cytoskeleton between adjacent cells in epithelial tissue
4
Q
Adhesion Belts
A
- Adhesion belt contraction pulls cells to form a tube
- Express different cadherins to establish new interactions and ensure neural tube closure
5
Q
Tight Junctions
A
- Define domain of the cell
- Apical domain: Surface, cavity, or organ
- Basal domain: Faces inside of the body
- Basal and lateral grouped in basolateral domain
- Maintained by tight junctions
- Occludins and claudins form tight junctions -> homophilic interactions with extracellular domains
- Limit diffusion in extracellular space
- Prevent membrane proteins from moving between apical and basolateral domain
- Active transporters: move glucose into epithelial cell on apical domain
- Passive carriers in basolateral allow glucose to diffuse our of epithelial cell into tissue/blood
6
Q
Integrin
A
- Mediate cell-cell matrix junctions
- Anchor actin filaments to extracellular matrix
7
Q
Polarity cues establish cell cohesion
A
- Adherens junction form first
- Provide polarity cues to define apical from basolateral
- PAR, CRUMB signal apical side -> stimulate by cdc42
- Scribble inhibit PAR, signal to basolateral
