BIOC 212 Lecture Notes - Lecture 23: Integrin, Morphogenesis, Hemidesmosome
29 May 2018
School
Department
Course
Professor
Cell Junctions & Cell Adhesion III
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Tight Junction-Associated Hereditary Diseases
• Few example of mutations in claudins associated to hereditary diseases
o Mainly associated with skin, kidney & gut
o Occludin-16: low Mg in blood since loss in urine, high Mg2+ and Ca2+ in
urine
• Skin is composed of epithelial cells (keratinocytes)
o Form same type of junctions as gut cells
o Loss of structure of epithelial layer due to claudin mutation
• Other examples leading to deafness, hypercalciuria, etc.
Anchoring Junctions
• Divided into two main classes depending on if connect to actin or intermediate
filaments
o Further subdivided for cell to cell vs. cell to ECM
• Why is it important to have anchoring junctions? Permanent-type (Not really
permanent, but more than other types of junctions)
o Cell is flimsy
• Cell does not have much rigidity
• Any type of blood flow or flow of digestive material, cell would be washed
away
• Need to be anchored to BM
o Transmission of force
o Tension bearing cytoskeleton
• Widely distributed in animal tissues
o Most abundant: muscle, heart, epidermis, epithelia
Anchoring Junction in Epithelium
• Basement membrane in yellow
o Line epithelial cell layers
o Illustrates how anchoring junctions join cytoskeletal filaments from cell to cell
• And from cells to ECM
Anchoring Junctions
• 2 principal protein classes
o Transmembrane adhesions proteins (green)
• Cytoplasmic tail, TM, extracellular domain
• One on each cells, interact with each other
• On other end, interact with adaptor proteins, which in turn interact with
cytoskeletal elements (plaque)
o Intracellular anchor proteins (blue)
