Adhesion in Epithelia BS31004 PDF

BS31004 Biochemistry and Cell Biology From Cells to Tissue: Cell Adhesion October 16th 2024 Inke Näthke [email protected] “Molecular Biology of the Cell” Alberts et al  Learning Objectives Cell Adhesion, from cel...

BS31004 Biochemistry and Cell Biology From Cells to Tissue: Cell Adhesion October 16th 2024 Inke Näthke [email protected] “Molecular Biology of the Cell” Alberts et al  Learning Objectives Cell Adhesion, from cells to tissue After this lectures you should be able to: Know different families of adhesion molecules and the structures they form, including other molecular components and their role Understand the differences and similarities between different cell adhesions: specific components, ligands, signaling principles, cytoskeletal links Understand the specific functions/roles of different adhesion structures/junctions in tissues, particularly epithelia Know and understand experimental evidence that helped to identify adhesion molecules, their interacting partners and mechanisms mediating their function Figures from: Molecular Biology of the Cell (© Garland Science, 2006 or 2008) and/or Molecular Biology of the Cell (© W. W. Norton & Company, 2022) Multicellularity requires – Strength in tissues – Communication between cells of tissues to coordinate allowing the entire organism to function as a whole >> Connections between cells that can relay information = mediate signals transmit force = physical link -> cell junctions  What is cell signalling?  What does cell signalling do? The environment sends information in the form of ‘signals’: Cell A tells Cell B that is is there by pushing it touching it Cell A tells Cell B to do something by secreting factors touching it/engaging a surface molecule -> causing changes in the behaviour of the receiving cell(s)  Epithelia line the cavities of organs … … and they produce >80% of all human cancers Functions of epithelia? Barrier Protection against: chemicals mechanical stress (stretching, abrasion) bacteria environmental pathogens Temperature/pH/radiation Control entry into & exit from body for: water nutrients Epithelia along the GI tract: examples of form and function Protection Protection Controlled entry & exit  How do these tissue layers provide protection? (ECM) Figure 19-1 Molecular Biology of the Cell (© Garland Science 2008 and Molecular Biology of the Cell (© W. W. Norton & Company, 2022)  Outside of the body Lateral membrane Figure 19-3 Molecular Biology of the Cell (© Garland Science 2008) Fig 19-2 Molecular Biology of the Cell (© W. W. Norton & Company, 2022)  Key components of a signalling pathway: Ligand/cue Receptor Transducer Effector Key components in adhesion: Adhesion or extracellular matrix molecules Adhesion molecule Plaque/linker proteins Signalling molecules (e.g. kinases) cytoskeleton Figure 19-4 Molecular Biology of the Cell (© Garland Science 2008; 19-3 Molecular Biology of the Cell (© W. W. Norton & Company, 2022)  2 1 3 Table 19-1 Molecular Biology of the Cell (© Garland Science 2008)  What are the adhesion molecules that form occluding/tights junctions? Where are the located? What do the adhesion molecules recognize on a neighbouring cell, i.e. what is their ‘ligand’? What are molecules associated with the cytoplasmic side of the adhesion molecules? Which cytoskeletal element are tight junctions connected to? What is their main function? How do we know this?  Occluding junctions: Tight junctions Figure 19-24 Molecular Biology of the Cell (© Garland Science 2008) 19-19 Molecular Biology of the Cell (© W. W. Norton & Company, 2022)  Occluding junctions: Tight junctions Glucose actively transported into cell from apical surface and diffuses out of cell at basolateral membrane Tight junctions act as diffusion barriers and confine the transport proteins at their appropriate membrane domains Tight junctions also prevent backflow of glucose from basal side of epithelium into the gut lumen Figure 19-23 Molecular Biology of the Cell (© Garland Science 2008) 19-18 Molecular Biology of the Cell (© W. W. Norton & Company, 2022)  Molecular architecture of the tight junction plate occludin claudin simplekin ZO2 ZO3 ZO1 atypical cingulin PKC ** rab3B/13 sec6/8 actin filaments Claudins and Occludins ZO proteins * = Signal mediators Figure 19-26a Molecular Biology of the Cell (© Garland Science 2008) 19-21 Molecular Biology of the Cell (© W. W. Norton & Company, 2022),  * Ceniz Zihni, Maria S. Balda & Karl Matter Journal of Cell Science (2014) 127, 3401–3413 doi:10.1242/jcs.145029  Ceniz Zihni, Maria S. Balda & Karl Matter Journal of Cell Science (2014) 127, 3401–3413 doi:10.1242/jcs.145029 Microbes/pathogens can hijack tight junctions for their own, nefarious purposes  Anchoring junctions Cell membranes are strengthened by presence of strong membrane- spanning structures that are tethered to the cytoskeleton They are common in tissues that are subjected to high amounts of mechanical stress (skin, muscle, heart) Anchoring junctions have two major components 1. Transmembrane protein (= adhesion protein) with an extracellular domain that interacts with either the Extra Cellular Matrix (ECM) or the extracellular domain of a partner-adhesion protein on another (neighbouring) cell PLUS an intracellular (cytoplasmic) tail that binds to one or more specific intracellular (signaling and/or structural/anchoring) protein 2. Intracellular proteins Bind the cytoplasmic tail of the adhesion protein and also other proteins, including the cytoskeleton, to create a physical and signaling link to cell interior Table 19-1 Molecular Biology of the Cell (© W. W. Norton & Company, 2022)  We can see them by electron microscopy Figure 19-17c, d Molecular Biology of the Cell (© Garland Science 2008)  CADHERINS Ca2+-dependent cell-cell adhesion (contain calcium binding sites) > dozen types Include classical, desmosomal, protocadherins Binding is homophilic; uses His-Ala-Val sequence Link directly to b-catenin proteins (all have “armadillo” repeats, important in cell signalling) Figure 19-11 Molecular Biology of the Cell (© W. W. Norton & Company, 2022) Figure 19-10 Molecular Biology of the Cell (© W. W. Norton & Company, 2022) Figure 19-12 Molecular Biology of the Cell (© W. W. Norton & Company, 2022)  Ex pe ri m en ta le v id en ce ? Table 19-3 Molecular Biology of the Cell (© Garland Science 2008) See also Figure 19-4 in MBoC 2022  E-cadherin expressed starting 8 cell stage Compaction in an early mouse embryo Figure 19-5 Molecular Biology of the Cell (© Garland Science 2008)  Antibodies against E-cadherin Control antibodies  Factors required to produce signals to polarize an epithelium © 2011 Baum and Georgiou Buzz Baum, and Marios Georgiou J Cell Biol 2011;192:907-917 Microbes/pathogens can hijack E-cadherin for their own, nefarious purposes Using E-cadherin as a receptor to gain cell entry Dash S., Duraivelan K., Smanta D., “Cadherin-mediated host–pathogen interactions”, Cellular Microbiology. 2021;23:e13316. https://doi.org/10.1111/cmi.13316 Microbes/pathogens can hijack E-cadherin for their own, nefarious purposes Producing toxins that disrupt E-cadherin structure and thus adherens junctions Dash S., Duraivelan K., Smanta D., “Cadherin-mediated host–pathogen interactions”, Cellular Microbiology. 2021;23:e13316. https://doi.org/10.1111/cmi.13316  Signaling components of junctions vary between species Figure 19-31 Molecular Biology of the Cell (© Garland Science 2008)  Desmosomes Figure 19-17a Molecular Biology of the Cell (© Garland Science 2008) 19-16 Molecular Biology of the Cell (© W. W. Norton & Company, 2022)  Desmosomes Connect intermediate filaments from cell to cell Components include: - desmosomal cadherins (desmogleins, desmocollins) - plakins (desmoplakin, plectin), - plakoglobin, plakophillin (armadillo-like proteins) - others specific for certain tissues, such as desmoyokin (stratified epithelia) Important in maintaining tissue integrity Figure 19-17b Molecular Biology of the Cell (© Garland Science 2008) 19-16b Molecular Biology of the Cell (© W. W. Norton & Company, 2022) Figure 19-18 Molecular Biology of the Cell (© Garland Science 2008) 19-17 Molecular Biology of the Cell (© W. W. Norton & Company, 2022)  Signaling from desmosomes * * * * * * Spindler & Waschke (2014) Cell Communication & Adhesion, 21: 77-84 DOI:10.3109/15419061.2013.877000  What are the two main anchoring junctions that mediate adhesion BETWEEN cells? What are the adhesion molecules that form them? What do the adhesion molecules recognize on a neighbouring cell, i.e. what is their ‘ligand’? What are other molecules associated with the cytoplasmic side of the adhesion molecules? Which cytoskeletal element are each of these anchoring junctions connected to? What is their main function? How do we know this?  Anchoring junctions Lateral membrane: Basal membrane: facing neighbouring cell facing substrate Cell - cell: bind through Cell-substrate: bind through CADHERINS INTEGRINS Homotypic binding to cadherin Bind to Extracellular matrix on neighbouring cell molecules Actin-attached = Actin-attached = adherens junctions focal contacts (dynamic) Intermediate filament- Intermediate filament attached = attached = desmosomes Hemidesmosomes (stable) Attachment to the Extracellular Matrix (ECM) via specialized junctions called Focal Adhesions is vital for development  EXAMPLES? Chemical signals Forces * Focal Signals for Adhesion Kinase survival, proliferation Figure 19-56 Molecular Biology of the Cell (© W. W. Norton & Company, 2022) Figure 19-48b Molecular Biology of the Cell (© Garland Science 2008)  Outside in signaling Figure 19-48a Molecular Biology of the Cell (© Garland Science 2008)  Inside out signaling *Focal Adhesion Kinase Figure 19-49 Molecular Biology of the Cell (© Garland Science 2008) David S. Harburger, and David A. Calderwood J Cell Sci 2009;122:159-163 © The Company of Biologists Limited 2009  Different integrins for different cells and ECMs Table 19-3 Molecular Biology of the Cell (© Garland Science 2022)  Fibronectin (ECM) F-actin Figure 19-74 Molecular Biology of the Cell (© Garland Science 2008) 19-50 MBoC 2022  Phospho-Tyrosine = Focal adhesion F-actin Figure 19-52a Molecular Biology of the Cell (© Garland Science 2008) 19-60 Molecular Biology of the Cell (© W. W. Norton & Company, 2022)  Focal Adhesion Kinase = FAK The dynamic assembly and disassembly of focal adhesions is important for migration and cell spreading Figure 19-52b,c Molecular Biology of the Cell (© Garland Science 2008)  What are the adhesion molecules that form focal adhesions? Where are they located? What do the adhesion molecules recognize i.e. what is their ‘ligand’? What are other molecules associated with the cytoplasmic side of the adhesion molecules? Which cytoskeletal element are focal adhesions connected to? What is their main function? How do we know this?  Hemi-desmosomes Figure 19-57 Molecular Biology of the Cell (© Garland Science 2022) Hemidesmosomes are crucial for normal skin function. What do you think would happen if they were defective? Skin blistering diseases are caused by defects in hemidesmosomal components (tissue lectures)  Directly communicating junctions Gap junctions functional Gap junctions inhibited Figure 19-37 Molecular Biology of the Cell (© Garland Science 2008) Figure 19-35 Molecular Biology of the Cell (© Garland Science 2008) 19-23 Molecular Biology of the Cell (© W. W. Norton & Company, 2022) Figure 19-33 Molecular Biology of the Cell (© Garland Science 2008) 19-24 Molecular Biology of the Cell (© W. W. Norton & Company, 2022)  Gap junctions are composed of ‘Connexins’ Large family of proteins, some tissue specificity Six connexins (approx 30kD) associate to form one ‘connexon’ Each connexin has 4 a-helices that span the membrane Many forms of connexin exist, allowing different properties of gap junctions in different tissues Mutations in connexins cause diseases/defects in the nervous system, skin, and ear (deafness) Figure 19-25 Molecular Biology of the Cell (© Garland Science 2022)  Gap junction closure is regulated by calcium  Functions of gap junctions Passing of electrical signals Sharing of small molecules and electrolytes Reduces effect of fluctuations in concentration Protection from calcium damage If cell is damaged there is an increase in the concentration of calcium, which can be damaging. Gap junctions close to prevent damage to other cells Gap junctions are connected to signalling networks Kurtenbach, S., Kurtenbach, S., Zoidl, G. (2014) Frontiers in Physiology 5:82 DOI: 10.3389/fphys.2014.00082  What is a directly communicating junction? What are the adhesion molecules that form them? What do the adhesion molecules recognize on a neighbouring cell, i.e. what is their ‘ligand’? What are other molecules associated with the cytoplasmic side of the adhesion molecules? What is their main function? How do we know this?  Summary Cells in tissues have specialised contact zones Enable stable/dynamic physical contact & communication (signals) Act as receptors and transmit information (chemical, mechanical) by connecting to other cells & ECM Note: adhesion does not just occur at classical cell junctions. Non- junctional mechanisms also exist, especially in non-epithelial cells (immune cells) Similar to 19-2 Molecular Biology of the Cell (© W. W. Norton & Company, 2022) The following slides contain additional information particularly about signaling events. They are included for those who are interested in more detailed information. The publications that they were taken from are listed on each slide. Ceniz Zihni, Maria S. Balda & Karl Matter Journal of Cell Science (2014) 127, 3401–3413 doi:10.1242/jcs.145029  Ceniz Zihni, Maria S. Balda & Karl Matter Journal of Cell Science (2014) 127, 3401–3413 doi:10.1242/jcs.145029 © 2011 Baum and Georgiou Buzz Baum, and Marios Georgiou J Cell Biol 2011;192:907-917 More signaling to and from desmosomes Spindler & Waschke (2014) Cell Communication & Adhesion, 21: 77-84 DOI:10.3109/15419061.2013.877000 David S. Harburger, and David A. Calderwood J Cell Sci 2009;122:159-163 © The Company of Biologists Limited 2009 David S. Harburger, and David A. Calderwood J Cell Sci 2009;122:159-163 © The Company of Biologists Limited 2009  Biochemistry David S. Harburger, and David A. Calderwood J Cell Sci 2009;122:159-163 © The Company of Biologists Limited 2009  Biochemistry David S. Harburger, and David A. Calderwood J Cell Sci 2009;122:159-163 © The Company of Biologists Limited 2009