Flashcards in Regulation of Cell Motility Deck (35)
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
What are the different types of tumour cell migration?
Single cell migration (ameboid)
Mesenchymal single cells
What physiological phenomena does tumour migration mimic?
Morphogenesis e.g. angiogenesis
What did a comparison of the expression profile of invasive cells vs primary tumours show to be upregulated in invasive cells?
What makes normal migrating cells stop moving?
Contact inhibition of locomotion
How are tumour cells different in this aspect?
They lose contact inhibition of locomotion so they can multilayer
What is another term for ECM proteins?
What are filopodia?
Finger-like protrusions that are rich in actin filaments
They sense the local environment
What are lamellipodia?
Sheet-like protrusions that are rich in actin filaments
What are the four main stages of cell movement?
What are the attachments between the cell and the surface that it is moving along called?
What are the monomers of actin filaments?
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
What protein complex is important in initiating polymerisation?
This forms a trimer with actin and is good at initiating polymerisation
What is the limiting step in actin dynamics?
Formation of Arp2/3-actin trimers to initiate polymerisation
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
Name some + end capping proteins.
Name some – end capping proteins.
Name some severing proteins.
What are the features of the actin filaments in severed populations?
Actin filaments can grow and shrink more rapidly
What can happen to single filaments of actin to improve their structural integrity?
They can be bundled or cross-linked
Name some proteins involved in these processes.
Which protein allows branching of the actin filaments?
At what angle do they branch?
Summarise the actions of Arp2/3.
They initiate nucleation
They cap filaments
They cause branching
Describe what causes the gel-sol transition.
The actin filaments can be severed to make the cell more fluid
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
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
State four signalling mechanisms that regulate the actin cytoskeleton.
Ion flux changes