1. By: London Seigle & Marlinda Reakes

2. Structure of Cytoskeleton  Long, twisted strands (criss-crossing)  A cellular, scaffolding structure  Found within the cytoplasm  Present in all cells  Eukaryotic and prokaryotic  Main fiber type: actin (made of up polymers)  Another type: microtubules (polymers made up of the protein tubulin)

3. Cow endothelial cell Microtubules

4. Functions  Maintains cell shape  Often protects cell  Enables cellular motion (using structures such as flagella, cilia, and lamellipodia)  Important role in intracellular transport (movement of vesicles and organelles)  Important in cell division  Dynamic to cellular structure

5. The Eukaryotic Cytoskeleton

6. Diseases  Dysfunction of the cytoskeleton results from mutations that alter the conformation and result in accumulation of the affected gene product  Cytoskeletal disruption initiates a cascade of events including mitochondrial dysfunction and oxidative stress that activates the DNA damage response  Neurodegeneration: underlying cause of cell death

7. Diseases cont.  Alzheimer's disease (AD)  Tauopathies  Parkinson's disease (PD)  Amyotropic lateral sclerosis (ALS)  Polyglutamine disease  These are the most common diseases known to the affect the cytoskeleton.

8. Alzheimer’s Disease(AD)  The genetic risk-factor: Apolipoprotein E  Mutations associated with amyloidal precursor protein(APP) and presenilins  Presenilins are membrane bound proteins that participate in the Notch-like cleavage of the APP protein within its b-amyloid region.  These proteins are involved with cell motility; however when these proteins are defected, it stimulates alterations in cytoskeleton.

9. Review Questions  1) What are the major fiber types made up of in the cytoskeleton? Explain what it is.  2) All of the following are functions of the cytoskeleton EXCEPT…  A. Maintains cell shape  B. Often protects cell  C. Enables cellular motion  D. Helps maintain the proteins in cytoplasm  E. None of these

10. References  www.wikipedia.com www.wikipedia.com  www.google.com www.google.com