Transcript No Slide Title

Last Class
1. ECM components: glycosaminoglycans (GAGs) and fibrous
proteins
a. GAGs: Hyaluronan; Chondroitin sulfate and dermatan sulfate;
Heparan sulfate; Keratan sulfate
b. Fibrous proteins: collagen, elastin, fibronectin, laminin
2. basal laminae, neuromuscular junction
3. Cell-ECM interaction, ECM degration
4. ECM receptor, integrins
• Cell Junctions, CellCell Adhesions
CrossSection View of Intestine Wall
*
***
*
*
*
*
Tight Junctions
Claudins,
Occludins
ZO Proteins
Tight Junctions as barriers to solute diffusion
Electron-dense tracer is added in the apical (B) and
basal sides of the cells (C).
Tight Junctions Structures
Freeze-fracture EM
Models for Tight Junctions
Claudin and occludin
Anchoring Junctions
Connecting cytoskeletons
Two Classes of anchoring junctions
Anchoring junctions
1. Adherens junctions (cell-cell)
2. Desmosomes (cell-cell)
3. Focal adhesions and hemidesmosomes
(cell-ECM)
Adherens Junctions
Adherens Junctions
Folding of an epithelial sheet to
form an epithelial tube
Desmosomes
Desmosomes
Focal Adhesion
hemiDesmosomes and desmosomes
Gap Junctions
Size of molecules allowed to pass
Gap Junctions
Gap Junctions in EM
Regulation of Gap Junctions
Rabbit retina and dopamine treatment
Switch between rod and cone photoreceptors
Lucifer yellow injection
Gap Junctions Functions
1. Rapid communication between neighboring cells,
e.g. cardiomyocytes need synchronized actions
2. Communication beyond nerve system, e.g.
hepatocytes beyond sympathetic nerves need to
be informed to produce glucose from glycogen
3. Embryogenesis, form specific tissue with
coupled group of cells
Summary of cell junctions
Summary of cell junctions
Cell-Cell Adhesions
Cell to Tissue mechanism
A Simple Model
Cell to Tissue mechanism
A More Complex Model
Cell adhesion molecules
(CAM)
Cell-cell Adhesion
cadherins
Cell-cell Adhesion
Regulation of cadherins
The distribution of E-cadherin (ectoderm) and
N-cadherin (neural tube) in Chick embryo
Three mechanisms of
cell-cell adhesions
Cadherin-dependent Cell
Sorting
Cadherins are linked to
actin filaments
Adherens Junction Formation
movie
Selectin-mediated cell-cell adhesion (blood
cell rolling)
E-selectin, L-selectin, P-selectin
White Blood Cell Rolling and
Adhesion
Movie
Neural cell adhesion
molecule (N-CAM),
intercellular adhesion
molecule (ICAM)
Calcium-independent
Immunoglobulin (Ig)
superfamily
Summary Diagram
non-junctional adhesion proceeds junctional adhesion
Summary
1. Junctions: Occluding Junctions, Anchoring Junctions,
Communicating Junctions
2. Occluding Junctions: Tight Junction
3. Anchoring Junctions: adherens Junction
4. Communicating Junctions: Gap Junction
5. Cell-Cell Junction: adherens junction, cadherins
Overview of the Cell
• Membrane structure and components, membrane proteins, carrier
proteins, channel proteins
• Signaling transduction, ligand-receptor interactions, ion-channels,
GPCRs, RTKs, molecular switches (kinase, GTPases), molecular
complex formation and signaling integration, signaling desensitization,
• GPCR, GPCR signaling: cAMP, Calcium (CaM Kinase as memory
molecule)
• RTK, RTK signaling: Ras, PI3K (PLC, Akt, Rac)
• Protease mediated signaling: NF-kB
• Cytoskeleton: microtubules, actin, intermediate filament
• Regulation of microtubules and actin
• Molecular motors: myosin (Sliding Acto-Myosin filaments), kinesin
• Cell migration and its relationship with actin filaments
• Extracellular matrix: GAG, fibrous proteins (collagen, elastin,
fibronectin, laminin)
• Basal laminae, cell-ECM interaction, integrins, cell-cell adhesion (tight
junction, adherens junction, gap junction), cadherins