ANHB3323 Lecture Notes - Lecture 18: Intermediate Filament, Cell Adhesion Molecule, Hemidesmosome
3 Jun 2018
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LECTURE EIGHTEEN: Cell-Cell/Cell-ECM Interaction
Cell Junctions in Epithelial Cells:
• Tight junctions → seals gap between epithelial cells
• Adherens junctions → connects actin filament in one cell with that in the
next cell
• Desmosome → connects intermediate filaments in one cell with that in
the next cell
• Gap junction → allows passage of small water soluble molecules from cell
to cell
• Hemidesmosome → anchors intermediate filaments in a cell to ECM
• Actin linked cell-matrix junction → anchors actin filaments in a cell to
ECM
Cadherins:
• Form diverse family of adhesion molecules
• Mediate hemophilic adhesion
• Always use the same binding domain
• Junctions are dependent on Ca2+ binding
• Cadherin-dependent cell-cell adhesion guides organization of developing
tissues
• Cadherin expression change is dynamic during development
• Use catenins to connect to actin filaments → happens via force feeling
Junctions:
• Tight junctions
o Contain strand of transmembrane adhesion proteins
o Proteins → claudin and occludin
• Gap junctions
o Connect both electrically and metabolically
o Channels directly connect cytoplasm of 2 cells
o Formed by 2 connexons that connect across intercellular space
o Small molecules and ions pass through → not proteins, nucleic
acids or organelles
Cell-ECM Adhesion:
• Mediated by integrin
• Heterodimer
o 24 alpha subunits
o 8 beta subunits
• Include hemidesmosomes
• Integrin defects are responsible for many genetic diseases
• Activated by intracellular signaling
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