Pre-Medicine Program - Cell Filament Systems
Introduction to the Cytoskeleton
|MT and MF movements|
J Cell Biol, 158:31-37, 2002
Red - actin (microfilaments).
This lecture will provide an introduction to the 3 filament systems microfilaments, intermediate filaments, microtubules that together form the cell cytoskeleton. We have introduced the concept of dynamic processes with the eukaryotic cell, but how are these processes of change driven? The cell skeleton, unlike our own rigid skeleton, is the tool by which nearly all dynamic processes take place within the cell and by the whole cell. Key dynamic events of cell shape, surface specializations, cell division, development, adhesion, migration and intracellular transport can all be related to the cell cytoskeleton. All these processes require energy!
"Its not an artefact!"
- Image - EM - Gut Epithelia cell (villi and junctions)
- cytoplasmic - cortical meshwork under plasma membrane and three dimensional meshwork through cytoplasm
- nuclear - cortical meshwork under nuclear envelope
- assembly - some spontaneous, specific assembly sites
- dynamic - variable stability, high to low stability, stability can be altered by associated proteins, signals and drugs
Cytoskeleton Movies: Play Movie - Exocytic transport | Play Movie - Vesicles Bidirectional Microtubule Movement | Play Movie - Respiratory Cilia | Play Movie - Axon Microtubules | Spermatozoa Motility | Kinesin motor
- non-muscle - cell cytoskeletons
- muscle cells - have additional contractile filament system
Smallest to largest size:
- Microfilaments MF (7 nm)
- Intermediate Filaments IF (10 nm)
- Microtubules MT (25 nm)
- 1 nanometre (nm) = 1 x 10 -9 m (light microscope resolution is about 200 nm)
|Actin Filament Assembly|
Intermediate filament organization
Hutchinson-Gilford Progeria Syndrome
|Intermediate Filament Family|
|Intermediate Filament - Primer|
Note this video does not include a description of the IF found in the nucleus.
- 25 nm diameter, 14 nm internal channel
- tubulin - cytoplasmic
- All cells contain - Same core structure, Same motors Dynein (-) inwards (retrograde transport) and Kinesin (+) outwards (anterograde transport), Different associated proteins
- Dynamic - Continuous remodelling
- Movement - Intracellular > cellular, Cell division forms the mitotic spindle
- Specialized structures - centrosome, basal bodies, spindle apparatus (mitosis, meiosis), Cell processes - cilia, spermatozoa tail (9+2)
|Cell division phases|
J Cell Biol 168:21-28.
|Microtubule Kinesin Motor|
- Links: Vesicles Display Bidirectional Motility along Microtubules | dyenin-stepping | Kinesin Walking | Dynein | Current Biology
- many mutations associated with human diseases
- toxins can affect organization
- infective bacteria and viruses can be appropriate (use)
Many cancer therapies (chemotherapies) affect microtubule organization (mitotic spindle) required for cell division.
- Essential Cell Biology - Chapter 16 Cytoskeleton
- Molecular Biology of the Cell 4th ed. - IV. Internal Organization of the Cell Chapter 16. The Cytoskeleton The Cytoskeleton
- Molecular Cell Biology - Chapter 18. Cell Motility and Shape I: Microfilaments Cell Motility and Shape I: Microfilaments
- The Cell - A Molecular Approach - III. Cell Structure and Function Chapter 11 The Cytoskeleton and Cell Movement The Cytoskeleton and Cell Movement Signal Transduction and the Cytoskeleton