L15- Notch signalling Flashcards
1
Q
What is the notch pathway?
A
- Cell-cell communication pathway that allows direct regulation of gene expression
- Controls cell fate in many developmental systems
- Has been implicated in cancer and in maintenance of stem cell populations
2
Q
What is the mechanism of the notch pathway?
A
- Delta ligand on one cell binds to notch receptor on another cell
- Binding stretches notch, allowing it to become accessible by delta-secretase for cutting
- NCID is cut and able to enter the signal receiving cells nucleus
- NCID binds to Su(H) in the nucleus causing conformational change, allowing transcription of DNA to take place
3
Q
How is the arrangement of hair and supporting cells formed?
A
- Precursors know whether to differentiate into hair cells or supporting cells by lateral inhibition
- Differences in delta expression are amplified by notch negative feedback loop
- All cells are equal at first and communication via notch allows them to decide differentiation- different cell types
4
Q
What happens to cells containing more notch?
A
- They contain more NICD which activates Su(H)
- This transcribes inhibitory genes that prevent delta production
- This causes centre cell to express high levels of delta and its neighbours do not
5
Q
What do hair cells and supporting cells express?
A
Hair cells= delta
Supporting cells= notch
6
Q
What are examples of notch and Wnt pathways?
A
- Inner ear
* Interstitial epithelium
7
Q
What does notch do in the gut epithelia?
A
No notch= secretory cells
High notch= absorptive cells
