Tissue Architecture Flashcards
what are intermediate filaments resistant to?
stretching forces
what are the cytoskeleton filaments
- Intermediate filaments
- Microtubules
- Microfilaments
intermediate filaments
• Great tensile strength
• Found in cytoplasm of most animal cells
• Often anchored to plasma membrane at cell-
cell junctions
• Form mesh-like structure called nuclear
lamina
what is mutated in progeria
nucelar lamina
microtubles
• Crucial organization role in all eukaryotic cells • Long and stiff hollow tubes • Rapid assembly and disassembly • Extend from centrosome to cell periphery • Form mitotic spindle for chromosome segregation • Part of cilia and flagella
Role of γ−tubulin
nucleation of microtubules at - end
- anchor point for microtubules to grow from
taxol
binds and stabilizes microtubules
colchicine, colcemid
binds tubulin dimers and prevents their polymerization
vinblastine, vincristine
- binds tubulin dimers and prevents their polymerization
microfilaments
-Actin filaments (F-actin) – Twisted polymer of G-actin (globular) – Structural polarity • Present in all cell types • Many are unstable • Essential for cell movements
phalloidin
binds and stabilizes actin filaments
cytochalasin
-caps filament + ends preventing polymerization there
latrunculin
binds actin monomers and prevents polymerization
Extracellular Matrix and Basal Lamina
Components produced intracellularly and secreted
and aggregate
-Matrix which interacts with cells/tissues via
transmembrane proteins
-Composition and properties controlled and vary by
tissue type, location etc.
types of ECM proteins
- proteoglycans
- collagens
- multi-adhesive matrix proteins
ECM functions
- forming tissue boundaries
- determining biochem properties of EC environment
- controlling cell polarity, survival etc
- acts as reservoir for GF and binding of GF to receptor
- serve as ligand for signaling receptors
what is the Main structural protein in
ECM/connective tissue and basal
laminae
collagen
scurvy results from loss of what cofactor
ascorbate or iron
what makes up basement membrane
1) type IV collagen
2) laminin
3) fibronectin
ehlers-Danlos syndrome
-mutation in collegen or collegen 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
cell junctions
link cells to
neighboring cells,
focal contacts
link cells to
extracellular matrix, or basil lamina
types of cell junctions
1) anchoring
2) occluding
3) channel forming
4) signal relaying
adherin junction
type of anchoring junction
- cadherin (ca2+ dependent)
- catenin binds to actin
- role in metastasis (loss of E cadherin)
desmosomes
- type of anchoring junction
- cell to cell
- strength
- bind to intermediate filaments
hemidesmosomes
type of anchoring junction
- cell to ECM via basement membrane
- integrins bind to intermediate filaments
focal adhesions
type of anchoring junction
- cell to matrix
- integrins bind to actin
- imp in resisting sheer stree
tight junctions
- occludin and claudin bind to actin
- maintains conc gradient (keeps cell closed off)
gap junctions
- connexins bind to adaptors in other junctions
- small molecule transport between cells
major domains of CAMS
– Extracellular (binding to adjacent cell/matrix proteins – Transmembrane (links CAM to membrane) – Cytoplasmic (bind to cytoskeleton via linker proteins)
what are 4 major families of CAMs
1) cadherins
2) Ig superfamily
3) integrins
4) slectins
cadherin superfamily
-Ca2+ dependent adhesion molecule
– Important in formation of junctions
between cells (epithelial “sheets”)
classic cadherins
- interact with catenin
- associated with adherin junction
- linked to actin cytoskeleton
atypical cadherins
no interaction with catenin or link to actin cytoskeleton
what can serve as biomarkers for metastic tumors
cadherins
-epithelia to mesenchymal transition
Ig superfamily CAMS
Family of more than 25 Calcium-independent
transmembrane glycoproteins
• Immune cell interactions
-– Contain a variable number of
immunoglobulin-like domains
– Expressed on vascular endothelial cells
and bind to various integrin molecules
– Involved in recognition, binding, or adhesion
processes of cells
– Homophilic and heterophilc binding
selectins
Family of calcium dependent glycoproteins
– Bind to extracellular carbohydrates
– Play important roles in host defense mechanism
Increased presentation during local
inflammatory response
• WBC surface makers include carbohydrates
which act as ligands for selectins
• Low-affinity of selectins to ligands allows for
leukocyte “rolling” during leukocyte
adhesion cascade
what type of selectins are there
Include:
• Endothelial (E)-selectin
• Leukocyte (L)-selectin
• Platelet (P)-selectin
integrins
Couple the extracellular matrix to cell
cytoskeleton
-can activate signaling pathways
- cell - cell interaction via beta2 family
-Integrins on leukocytes allow for adhesion
and transmigration to sites of infection
