Cytoskeleton and Response to Mechanical stress Flashcards
What are the cytoskeleton components?
Microtubules, microfilaments, intermediate filaments
What is the most important role of the cytoskeleton?
Internal organization (cell shape)
What are the largest structural elements?
Microtubules
What are the smallest structural elements?
Microfilaments
What structural element is between these?
Intermediate fibers
What is the function of microtubules?
Cellular movement (Cilia, Flagella)
Maintenance of nerves & axons
Spatial orientation in cytosol
Do microtubules have a solid center?
No. Formed by protofilaments with a hollow center
What are protofilaments?
Tubulin (alpha-beta heterodimer)
What tubulin isoform does the brain use?
5-alpha, 5-beta
Where are microtubules found in relation to the cell?
Periphery
What are MAPs?
Microtubule Associated Proteins
Bind along wall of microtubule and regulates growth and interaction with other filaments
Where are non-motor MAPs found?
Brain
Control microtubule organization
What are motor MAPs?
Drive tansport of vesicles/organelles
What MAP factors regulate Axons and Dendrites?
Axons - Tau (Alzheimers)
Dendrites - MAP2
What is the main function of microfilaments
Contractile fibers of muscle (actin)
Microvilli
What is G Actin? F-Actin?
G-Actin: Individual Actin
F-Actin: Polymerization of G-Actin
Which actin is muscle specific?
alpha-actin
What are microspikes?
Cell surface extensions that aid in cell movement
What are actin binding proteins? What do they do?
Myosin
Stabilizes filaments & generates force
What is the function of intermediate filaments?
Most stable
Tension-bearing
Least soluble
Acts as scaffold to support cytoskeleton
How many classes of intermediate filaments are there?
6
What is Class I & II Intermediate filaments?
Epithelial cells
What is class 3 intermediate?
Muscle, glial, connective tissue
What is class 4 intermediate?
Nerve cells
What is class 5 intermediate?
All cells
What is class 6 intermediate?
Embryonic nervous system
Why do changes/adaptation occur in cytoskeleton?
Mechanical stress like structure, metabolism, gene expression
What is tensegrity?
Use tension (pull) and compression (push) to provide support
What structural elements provide the tension?
Microfilaments (cables)
What structural elements provide elasticity?
Intermediate filaments (cables)
What structural elements provide Compression?
Microtubules (Pillars)
How does cytoskeleton transmit stress?
From 1 point to the rest of the structure so that tension bearing forces align with the stress
What is an example of cytoskeleton changes due to mechanical stress?
RBCs passing through capillary and becoming temporarily distorted
Mechanical Gated Ion channel is opened by mechanical pressure
How are cells signalled to adapt?
ECM recognizes stress and signals for change
Regulation of nuclear access by altering pore size
Cytoskeleton & ECM can confirmationally change so they go to signalled site
