Flashcards in Invasion Deck (35):
1. What are the changes that occur in the cells that occur during tumour progression?
Genetic alterations lead to hyperproliferation, disassembly of cell-cell contacts, loss of polarity, increased motility and cleavage of ECM proteins
2. What are the different types of tumour cell migration?
Single cell migration (ameboid)
Mesenchymal single cells
3. What physiological phenomena does tumour migration mimic?
Morphogenesis e.g. angiogenesis
4. What did a comparison of the expression profile of invasive cells vs primary tumours show to be upregulated in invasive cells?
5. What makes normal migrating cells stop moving?
Contact inhibition of locomotion
6. How are tumour cells different in this aspect?
They lose contact inhibition of locomotion so they can multilayer
7. What is another term for ECM proteins?
8. What are filopodia?
Finger-like protrusions that are rich in actin filaments
They sense the local environment
9. What are lamellipodia?
Sheet-like protrusions that are rich in actin filaments
10. What are the four main stages of cell movement?
11. What are the attachments between the cell and the surface that it is moving along called?
12. What are the monomers of actin filaments?
13. Describe the polarity of acting filaments.
They have a plus end and a minus end
The monomers preferentially get added on at the plus end
14. What protein complex is important in initiating polymerisation?
This forms a trimer with actin and is good at initiating polymerisation
15. What is the limiting step in actin dynamics?
Nucleation- Formation of Arp2/3-actin trimers to initiate polymerisation
16. State two proteins that bind to free G-actin and describe how they affect elongation.
Promote elongation – profilin (these deliver the G-actin to the growing filament)
Sequesters G-actin – Beta4 thymosin ADF, cofilin
17. Name some + end capping proteins.
18. Name some – end capping proteins.
19. Name some severing proteins.
20. What are the features of the actin filaments in severed populations?
Actin filaments can grow and shrink more rapidly
21. What can happen to single filaments of actin to improve their structural integrity?
They can be bundled or cross-linked
22. Name some proteins involved in these processes (bundling and cross linking)
23. Which protein allows branching of the actin filaments?
24. At what angle do they branch?
25. Summarise the actions of Arp2/3.
They initiate nucleation
They cap filaments
They cause branching
26. Describe what causes the gel-sol transition
The actin filaments can be severed to make the cell more fluid
27. Describe the actin processes that take place during the protusion of lamellipodia.
There is polymerisation, disassembly, branching and capping
There is net filament assembly at the leading edge
28. Describe the actin processes that take place during the formation of filopodia.
Bundling and cross-linking
As soon as the finger wants to retract it will collapse at the base
29. State four signalling mechanisms that regulate the actin cytoskeleton.
Ion flux changes
30. What are the three most important small GTPases in terms of the actin cytoskeleton and what does activation of each cause?
Cdc42 – filopodia
Rac – lamellipodia
Rho – stress fibres
NOTE: these are all part of the Rho family
31. Explain how Rac causes actin polymerisation/organisation.
Rac binds to and activates WAVE
WAVE then activates Arp2/3, which is important in actin organisation
32. Explain how Cdc42 causes actin polymerisation/organisation.
Cdc42 binds to WASP
WASP also activates Arp2/3
33. Which small GTPases are involved in lamellipodia protrusion?
34. Which small GTPases are involved in focal adhesion assembly?
Rac and Rho