https://padlet.com/lulucullen22/fij57jobhtbnjo07 en-us 2022-11-16 20:03:50 UTC 2022-12-04 14:39:14 UTC hello@padlet.com lulucullen22 https://padlet.com/lulucullen22/fij57jobhtbnjo07/wish/2387243686 2022-11-16 20:03:50 UTC https://padlet.com/lulucullen22/fij57jobhtbnjo07/wish/2387243686 lulucullen22 https://padlet.com/lulucullen22/fij57jobhtbnjo07/wish/2387243688 Cancer cells can reactivate the cytoskeletal mechanisms of motility to metastasize to other tissues]]> 2022-11-16 20:03:50 UTC https://padlet.com/lulucullen22/fij57jobhtbnjo07/wish/2387243688 lulucullen22 https://padlet.com/lulucullen22/fij57jobhtbnjo07/wish/2387243689 2022-11-16 20:03:50 UTC https://padlet.com/lulucullen22/fij57jobhtbnjo07/wish/2387243689 lulucullen22 https://padlet.com/lulucullen22/fij57jobhtbnjo07/wish/2387243690 2022-11-16 20:03:50 UTC https://padlet.com/lulucullen22/fij57jobhtbnjo07/wish/2387243690 lulucullen22 https://padlet.com/lulucullen22/fij57jobhtbnjo07/wish/2387243692 2022-11-16 20:03:50 UTC https://padlet.com/lulucullen22/fij57jobhtbnjo07/wish/2387243692 lulucullen22 https://padlet.com/lulucullen22/fij57jobhtbnjo07/wish/2387243693 2022-11-16 20:03:50 UTC https://padlet.com/lulucullen22/fij57jobhtbnjo07/wish/2387243693 lulucullen22 https://padlet.com/lulucullen22/fij57jobhtbnjo07/wish/2387243695

Wound created 😢 

Platelets recruited to site to form fibrin site that seals the wound

Macrophages and neutrophils crawl to the site to clear debris and kill invasive species, mitigating infection

Epithelial cells in surrounding tissue undergo a Epithelial-mesenchymal transition (EMT) and become motile to cover the wound in a process called re-epithelialization

]]> 2022-11-16 20:03:50 UTC https://padlet.com/lulucullen22/fij57jobhtbnjo07/wish/2387243695 lulucullen22 https://padlet.com/lulucullen22/fij57jobhtbnjo07/wish/2387243696 Cell motility is important for wiring the complex patterns of neuronal connectivity in the brain. A developing axon navigates towards its synaptic target with the help of the "growth cone" at its tip. The dynamics of the growth cones' actin (red) and microtubule (green) cytoskeleton steers the axon and is essential for directional migration. 


]]> 2022-11-16 20:03:50 UTC https://padlet.com/lulucullen22/fij57jobhtbnjo07/wish/2387243696 lulucullen22 https://padlet.com/lulucullen22/fij57jobhtbnjo07/wish/2387243697 Monomeric GTPases (activated by extracellular factors binding to receptor --> intracellular signalling cascade)

• Cdc42: involved in filopodia formation
• Rac1: regulates lamellipodia formation
• RhoA: interacts with myosin ands aids the formation of stress fibres and focal adhesion

]]> 2022-11-16 20:03:50 UTC https://padlet.com/lulucullen22/fij57jobhtbnjo07/wish/2387243697 lulucullen22 https://padlet.com/lulucullen22/fij57jobhtbnjo07/wish/2387243698 Certain structures (ie. lamellipodium) only form at the front other the cells, whereas others only form at the rear]]> 2022-11-16 20:03:50 UTC https://padlet.com/lulucullen22/fij57jobhtbnjo07/wish/2387243698 lulucullen22 https://padlet.com/lulucullen22/fij57jobhtbnjo07/wish/2387243699 2022-11-16 20:03:50 UTC https://padlet.com/lulucullen22/fij57jobhtbnjo07/wish/2387243699 lulucullen22 https://padlet.com/lulucullen22/fij57jobhtbnjo07/wish/2387243700 Specialised macrophages that patrol tiny vessels in the liver called sinusoids, recycling old red blood cells and ingesting pathogens.]]> 2022-11-16 20:03:50 UTC https://padlet.com/lulucullen22/fij57jobhtbnjo07/wish/2387243700 lulucullen22 https://padlet.com/lulucullen22/fij57jobhtbnjo07/wish/2387243701

After determining its direction of motion, the cell extends a protrusion in this direction via actin polymerisation at the leading edge

The cell adheres its leading edge to the surface on which it is moving and de-adheres at the trailing edge

The whole cell body is pulled forward by contractile forces generated at the rear of the cell

]]> 2022-11-16 20:03:50 UTC https://padlet.com/lulucullen22/fij57jobhtbnjo07/wish/2387243701 lulucullen22 https://padlet.com/lulucullen22/fij57jobhtbnjo07/wish/2387243702 2022-11-16 20:03:50 UTC https://padlet.com/lulucullen22/fij57jobhtbnjo07/wish/2387243702 lulucullen22 https://padlet.com/lulucullen22/fij57jobhtbnjo07/wish/2387243703

Polarity: the actin filaments in the meshwork are mostly orientated with the + end facing forward

Dynamic instability: allows lamellipodia to be rapidly assembled and disassembled

Treadmilling: the lamellipodia meshwork as a whole undergoes treadmilling, assembling at the front and disassembling at the back

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Arp2/3: facilitates nucleation of branched actin networks, driving the leading edge forward in a protrusion

• Binds to - end of actin filaments
• Highly concentrated near the front of the lamellipodia, where nucleation is most active

Filamin: cross-links actin filaments into a three dimensional network in lamellipodia

Formins: facilitate the nucleation of long, straight actin filaments in fillopodia

Fimbrin/fascin: link and reinforce tight parallel bundles in fillopodia

α-actinin: link and reinforce (less tight) antiparallel bundles in stress fibres

Profilin: promotes polymerisation at the + end

Cofilin: binds older (ADP-bound) coils and twists them tighter, applying mechanical stress that stimulates filament disassembly --> accelerates turnover of the leading edge 

• --> abundant supply of actin monomers
• Dense branched actin network excludes organelles so must be dismantled for the cell to move forward

Adaptor proteins: create adhesions, bind to intergrins and link the actin cytoskeleton to the substratum

Myosin: mediate contractile forces on stress fibers to generate traction

]]> 2022-11-16 20:03:50 UTC https://padlet.com/lulucullen22/fij57jobhtbnjo07/wish/2387243704 lulucullen22 https://padlet.com/lulucullen22/fij57jobhtbnjo07/wish/2387243705 Lamellipodia 

• Thin sheet of cross-linked actin filaments that stretches out to the cell's periphery (leading edge)
• Generate pushing forces that drive the cell forward
  • Continuous branching - off and cross-linking of actin generates the protrusive force needed to overcome the compressive force of the plasma membrane

Fillopodia

• Core of actin filaments in a tight, parallel bundle
• Function as antennae for cells to probe their environment

Stress fibres

• Bundles of antiparallel actin filaments associated with non-muscle myosin II
• Interact with myosin to generate contractile forces that drive the cell forward

]]> 2022-11-16 20:03:50 UTC https://padlet.com/lulucullen22/fij57jobhtbnjo07/wish/2387243705 lulucullen22 https://padlet.com/lulucullen22/fij57jobhtbnjo07/wish/2387243706

Macrophages and neutrophils - crawl to sites of infection and engulf foreign invades as part of the innate immune response.

Osteoclasts

Fibroblasts

Predatory amoebae

Neural crest cells - during development, NCCs migrate from their site of origin in the neural tube to a variety of sites throughout the embryo.

Cancer cells - metastasis 

]]> 2022-11-16 20:03:50 UTC https://padlet.com/lulucullen22/fij57jobhtbnjo07/wish/2387243706 lulucullen22 https://padlet.com/lulucullen22/fij57jobhtbnjo07/wish/2387243707

Arp2/3: p906-908

Filamin: p912-913

Cell migration: p951-956

]]> 2022-11-16 20:03:50 UTC https://padlet.com/lulucullen22/fij57jobhtbnjo07/wish/2387243707 lulucullen22 https://padlet.com/lulucullen22/fij57jobhtbnjo07/wish/2387243710 Exception: sperm]]> 2022-11-16 20:03:50 UTC https://padlet.com/lulucullen22/fij57jobhtbnjo07/wish/2387243710 lulucullen22 https://padlet.com/lulucullen22/fij57jobhtbnjo07/wish/2408035121 1. Initial cell polarisation (selection of direction)

• Cdc42-GTP --> recruits formins --> nucleation of long, straight actin filaments --> extension of fillopodia --> sense and respond to extracellular cues 

2. Active Rac GTPase --> formation of lamellipodia

• Activated exclusively at leading edge
• Promotes actin polymerisation at cell periphery
• Recruits/activates Arp2/2 (via WAVE) --> stimulates nucleation of branched actin networks

3. Active Rho GTPase --> promotes formation of actin-myosin contractile bundles/stress fibres

• Activated predominately at rear
• Recruits/activates formins --> stimulates nucleation/elongation of long, straight actin filaments
• Effectors inhibit cofilin --> actin filament stabilisation
• Effectors activate myosin-II --> contractile activity --> tension
• Promotes clustering of integrins and associated proteins --> formation of focal adhesions

Rac and Rho pathways are mutually antagonistic

• Rac effectors inhibit Rho activity
• --> cell polarisation --> directionality of movement

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