11. Tissue Architecture Flashcards
What are the 3 major components of the cytoskeleton?
Microfilaments:
- Actin (f-actin)
Microtubules:
- Tubulins
Intermediate filaments:
- Lamin
What are some of the purposes of the cytoskeleton?
Tissue Level:
- Muscle movement
Cellular Level:
- cell shape
- motility
- cell adhesion
- division
Sub-cellular Level:
- Organization
- Tensile Strength
- Chromosome segregation
- Cell polarity (top, bottom, side)
- Vesicular movement
What are the 4 important ways we can think of cytoskeletal elements?
- Dynamic
- Adaptable
- Stable
- Strong
Intermediate Filaments
- great tensile strength (rope like properties)
- found in cytoplasm
- often anchored to plasma membrane at cell-cell junctions
- form mesh-like structures called nuclear lamina
- cross-link filaments into bundles
- link to microtubules, actin filaments, and cell-junctions
What are the two classes of intermediate filaments?
Cytoplasmic:
- keratin filaments
- vimentin filaments
- neurofilaments
Nuclear:
- nuclear lamina, in all animal cells
What happens when there is faulty action of the nuclear lamina?
Increased cellular aging
Describe Microtubules
- long and stiff hollow tubes
- rapid assembly and disassembly
- create tracks to transport vesicles, organelles and other cell components
Describe the plus and minus ends of microtubules
(+): B-tubulin
- Growth
(-): a-tubulin
- Stability/Breakdown
What is the mechanism of action of Taxol?
binds and stabilizes microtubules
prevents cells from dividing and cells undergo apoptosis
What is the mechanism of action of Colchicine/Colcemid?
binds tubular dimers and prevents their polymerization
What is the mechanism of action of Vinblastine/Vincristine?
binds tubular dimers and prevents their polymerization
What is the function of y-tubulin?
y-tubulin forms a nucleus that attaches to the minus end and serves as an anchoring point from which to grow from
Describe Microfilaments
Actin filaments:
- twisted polymer of g-actin
- present in all cells
- essential for locomotion, phagocytosis, cell division, and contraction
What is the mechanism of action of Phalloidin?
binds and stabilizes actin filaments
What is the mechanism of action of Cytochalasin?
caps actin filament plus ends, preventing polymerization there
What is the mechanism of action of Latrunculin?
binds actin monomers and prevents their polymerization
What are the 3 types of extra cellular matrix proteins?
Collagen:
- main structural protein
- trimeric protein
- triple helix that forms fibers, sheets, or transmembrane structures
What are the main features of scurvy?
Loss of cofactor (ascorbate or iron)
- wounds re-open
- body falls apart
- loss of teeth
- pale skin
- sunken eyes
What are the main features of Ehlers-Danlos Syndrome?
Caused by a mutation in collagen or collagen synthesis genes
Mutations alter the structure, production, or processing of collagen or proteins that interact with collagen
Weakens connective tissue in the skin, bones, blood vessels, and organs
What is the purpose of the cell junction?
- cell junctions link cells to neighboring cells
- roles in cell migration, immune system function, wound healing, and tissue architecture
- involved in intracellular signaling pathways
What are the 3 domains of CAMs?
Extracellular
- binding to adjacent cell/matrix proteins
Transmembrane
- links CAM to membrane
Cytoplasmic
- bind to cytoskeleton via linker proteins
What are the 4 major families of Cell Adhesion Molecules? (CAMs)
- Cadherins
- Ig-Superfamily
- Integrins
- Selectins
Describe the Cadherin Superfamily
Ca 2+ dependent adhesion molecule
- E-cadherin (epithelial)
- N-cadherin (neural)
- VE-cadherin (vascular-endothelial)
- LI-cadherin (liver-intestine)
What is EMT?
Epithelia to Mesenchymal Transition
- increase in E-cadherin and decrease in N-cadherin
Describe the Ig Superfamily CAMs
Immune cell interactions/ hemophilic and heterophilic binding/ involved in recognition, binding, or adhesion processes of cells
- ICAM
- VCAM-1
- PECAM-1
- NCAM
- MAdCAM-1
Describe the Selection family
Calcium dependent glycoproteins, bind to extracellular carbohydrates, play role in defense mechanism during inflammatory response, leukocyte “rolling”
- E-selectin (endothelial)
- L-selectin (leukocyte)
- P-selectin (platelet)
Describe the Integrin family
- Couple the extracellular matrix to cell cytoskeleton
- Can activate the signaling pathway
- Cell-cell interaction via b2 family
15 a and 8 B subunits form over 20 heterodimeric integrins
