Lecture 10: Cell migration Flashcards
What are lamellipodia
thin, sheet-like membrane protrusions found at the leading edge (front) of motile cells (BRANCHED)
Made up of actin filaments in a mesh like structure
Name of protein that gives lamellopodia mesh like structure
Arp2/3 complex
2 key functions of arp 2/3
nucleates assembly of new actin filaments
And
prevents disassembly at the minus end
Where do actin filaments disassemble in lamellipodia
at the rear end
Arp starts to come off so it means they don’t just grow forever
What are filopodia
parallel extensions of actin filaments
They extend beyond lamellopodia
Name of proteins that allow filopodia to extend
formins
They simply add actin monomers to the plus end to extend it out
What keeps the filopodia anchored
Interactions with other actin filaments
Via cross linked proteins
Key function of filopodia
guiding migrating cell
Like antennae
Probes the environment to make new contact with environemnt
What are the two ways protrusions adhere to the surface
focal contacts with membrane proteins called integrins
And
Contractile actin bundles which attach to the focal contacts
How is the rear end of the cell pulled forward
myosin II
What type of protein is important to establish cell polarity
microtubule capping proteins
Stabilises growing microtubules
How is cell migration important in the immune system
allows movement of cells such as neutrophils to respond to chemoattractants and move towards bacteria, open wound etc.
what are the 2 types on intermediate filaments
cytoplasmic
nuclear
what are the 3 types of cytoplasmic intermediate filament
keratin filaments
vimentin (e.g. desmin)
neurofilaments
what are the intermediate filaments in nucleus
nuclear lamins
fucntion of nuclear lamin
sternghtens nucleus
importantn in cells that have to squeeze through small spaces
what can mutations in nuclear lamins lead to
progeria
what nulcleotides do intermediate filaments bind to
trick question
they dont bind to any
ha
IFs are generally stable, but at what point in cell cycle do they disassemble
during cell division
triggered by phosphorylation
how are keratin filaments linked between cells
via desmosomes
which is why desmosomes being mutated is bad
what can keratin mutations cause
blistering of the skin
where is desmin found
remember, desmin is a type of cytoplasmic IF
found in cardiac muscle
skeletal muscle
smooth muscle
what can desmin mutations cause
muscular dystrophy
cariac myopathy
hwo is desmin in adjacent cells
via desmosomes
what are the level of intermediate filament assembly
the monomer is an alpha helix
this turns into a coiled coil dimer
which then stacks to form a tetramer (2 dimers on top of each other)
8 of these tetramers come together to form the filament
wha protein links IFs, actin filaments, microtubules together
plectin
what can plectin mutations cause
skin disruption
muscular dystrophy
neurdegeneration
