cell mobility and cytoskeleton

What is the cytoskeleton?

A dynamic netowkr of proteins within the cells

What are its key functions?

• Gives shape to the cells

• Directs cell shape changes

• Anchors organelles

• Attaches cell to surfaces

• Contractile machinery to transport vesicles and organelles

What are the three components?

• Microfilaments (actin) – 7 nm

• Intermediate filaments – 10 nm

• Microtubules – 25 nm

Structure of microtubules?

Made of α-tubulin and β-tubulin dimers forming 13 protofilaments

Function of microtubules?

• Provide support

• Act as tracks for intracellular transport

• Form mitotic spindle

Key features of intermediete filaments?

• Most stable/permanent component

• Maintain structural integrity

Function of intermediete filaments?

• Anchor organelles

• Anchor cell to cell and matrix

Structure of actin filaments?

Actin monomers forming a double helix

Where are they located

Just below the cell membrane forming a net like a spiderweb

What drives actin movement?

Polymerisation and depolymerisation

What does this cause?

• Cell shape change

• Membrane protrusion

How do cells move?

• Actin filaments grow fast to push the membrane

• Form pseudopodia/podosomes

What is needed for movement?

• Cell adhesion molecules (CAMs)

• Integrins

What allows cells to invade tissues?

MMPs degrade the ECM

What starts metastasis?

• Loss of E-cadherin

• Epithelial-Mesenchymal Transition (EMT)

What happens next?

• Cells migrate

• Enter bloodstream

• Form secondary tumours