1. Cell and Molecular Biology Fifth Edition CHAPTER 7 Part 2 Interactions Between Cells and Their Environment Copyright © 2008 by John Wiley & Sons, Inc. Gerald Karp

2. Integrins link ECM to cytoskeletons Focal adhesion (in vitro with actin) Hemidesmosomes (in vivo with keratin, IF) Out-side-in Normal cells (integrin dependent) and malignant cells (integrin independent)

3. Bullous pemphigoid Individual ’ s bp proteins (autoantibodies) present in these adhesive structures. These autoantibodies cause the lower layer of the epidermis to lose attachment to the underlying basement membrane. The leakage of fluid into the space beneath the epidermis results in severe blistering of the skin. Epidermis, GI, urinary tracts

4. 7.3 interactions of cells with other cells Cells can recognize the surfaces of other cells Interacting with some and ignoring others

5. Little was known about the nature of the molecules that mediate cell-cell adhesion until The development of techniques for purifying integral membrane proteins The isolation and cloning of genes that encode these proteins

6. Four distinct families of integral membrane proteins play a major role in mediating cell-cell adhesion Cell-cell adhesion molecules 1. Selectins 2. Certain members of IgSFs and integrins 3. Cadherins 4. Adherenes junctions and desmosomes: anchoring cells to other cells

7. 1. Selectins LEU-CAM1 (L-selctins) in vivo: lymphocytes homing A family of intergral membrane glycoprotein Bind to the oligosaccharides of other cells Possess a small cytoplasmic domain and a large extracellular segment Role of selectins in inflammation (P.263)

8. 2. Immunoglobulins and integrins Ig domains: 70-100 amino acids Most IgSF mediate lymphocytes and macrophages and target cells for immune response Calcium-independent cell-cell adhesion Some IgSF such as VCAM, NCAM and L1 mediate interaction between nonimmune cells i.e. nerve outgrowth, synapse formation, nervous development Deformed babies due to L1 mutation, water on the brain, mental retardation Integrins α4β1 binds to VCAM on blood vessels

9. 3. Cadherins Transmit signals from ECM to the cytoplasm Mediate Ca 2+ -dependent cell-cell adhesion E-cadherins, N-cadherins, P-cadherins

10. 4. Adherins junctions and desmosomes: anchoring cells to other cells Adhesive junctions (ca 2+ dependent): 1.adherens junctions 2.desmosomes 3.junctional complexes (tight junction and gap junction)