Signalling 4 - Cell:Cell Contact - Juxtacrine Flashcards
1
Q
What is lateral inhibition?
A
- the fate of one cell is determined by neighbouring cells
- structures are organised by inhibitory signalling at a close range
2
Q
Describe trichome formation
A
- epidermal precursor cells are indistinguishable
- one cell is selected as trichome precursor
- cell then differentiates into mature trichome
3
Q
What 2 key properties are needed for a trichome to function properly?
A
- trichome spacing - patterning on the plant surface
- trichome anatomy - differentiation of individual trichomes
4
Q
How is trichome spacing regulated?
A
- once a neighbour decides to be a trichome, it prevents neighbouring cells from becoming trichomes
- triptychon is essential for lateral inhibition
5
Q
explain the spacing of insect hairs
A
- bristles never form next to each other due to lateral inhibition
6
Q
how is cell:cell contact signalling used in the formation of the crypt structure in villi?
A
- repulsive force between EphB and EphrinB proteins
- these are transmembrane proteins
- EphB+ and EphrinB+ cells segregate
- prolifterating stem cells in the crypto make EphB
- cells surrounding express EphrinB
- as stem cells proliferate they cannot leave crypt as would involve mixing
- pressure is revolved by EphB+ cell buckling to produce crypt
7
Q
What is another example of Eph/Ephrin contact dependent repulsion?
A
axon growth cone navigation
8
Q
What is autocrine signalling?
A
- the cell responds to its own signal
