CONTACT INFORMATION: LUISA IRUELA-ARISPE BSRB/ORH 445 PHONE# 310 - 794-5763 arispe@mbi.ucla

1. INTERACTIONS OF CELLS WITH THEIR ENVIRONMENT Lecture 1 January 7th, 2008 CONTACT INFORMATION: LUISA IRUELA-ARISPE BSRB/ORH 445 PHONE# 310 - 794-5763 arispe@mbi.ucla.edu

2. http://intranet.biolchem.ucla.edu/cm267a/index.htm Iruela-Arispe - 5 Lectures (MTWR M) Lecture Power-points Lecture Notes Required papers Previous Exams

3. Cells - Extracellular Matrix Interactions are critical to the structure and function of tissues

4. Functions of the extracellular matrix - Provides structural/mechanical support for cells and tissues - Provides signals for survival, morphogenesis/differentiation, migration, proliferation Properties of the extracellular matrix - Binds and modulates activity of growth factors - It is dynamic in nature - undergoes constant remodeling

5. Cells are surrounded by extracellular matrix - Migration requires selective binding and release of cell surface receptors

6. Two dimensional experiments can model the interaction of cells with specific matrix proteins

7. Chemical composition and physical organization of matrix proteins provides functional diversity to distinct tissue types COMPONENTS OF THE EXTRACELLULAR MATRIX Structural GLYCOPROTEINS FIBRILLAR PROTEINS GLYCOSAMINOGLYCANS AND PROTEOGLYCANS Catalytic MATRIX METALLOPROTEINASES ADAMS ADAMTS Inhibitors MMP INHIBITORS - TIMPS

8. Organization of Collagen Fibers in the Cornea - 90 degrees is responsible for the transparency of this tissue

9. Organization of Collagen Fibers in tendons - (parallel fibers) provides monodirectional resistance

10. Fibroblast • Responsible for synthesis and remodeling of the extracellular matrix in all connective tissue propers. • Scheme shows synthesis and extracellular processing of type I collagen.

11. 30 minutes 2 hours 24 hours 60 minutes How to study the biological relevance of the interaction of extracellular matrix to cells? binding and adhesion assays- migration assays- survival- differentiation / morphogenesis- loss and gain of function

12. Matrix proteins bind to different receptors which impose distinct: differentiation / proliferation /migration programs to the same cells

13. Glycosaminoglycans • Glycosaminoglycans (GAG) are polymers of repeating disaccharides of which one is always a hexosamine. GAG chains linked to a protein form proteoglycans. Hyaluronic acid

14. Heparan sulphate: a glycosaminoglycan that binds to growth factors

15. Interaction of growth factors with Heparan sulfate Enhanced affinity for Second FGF1 ligand Saccharide Conformational change + + + HS S domain FGF1 FGFR2 VEGF dimer S S K4 HGF/SF SP HS K3 K2 HS N K1

16. Question being adressed: How does branching morphogenesis occur? So-called regulatory proteins: - Stimulators (growth factors) - Inhibitors (Bmps and others) - Modulators (extracellular matrix)

17. Expression of fibronectin mRNA in branching morphogenesis of mouse embryonic salivary gland Submandibular glands from E12.5 Mesenchymal cells Epithelial cells Basement Membrane

18. Expression of fibronectin protein during branching morphogenesis, shown by staining with anti-fibronectin and imaging by confocal microscopy Dynamic balance between cell-cell adhesions and cell-matrix adhesions

19. Inhibition of branching by anti-fibronectin antibodies or by its corresponding receptors (specific integrins)

20. Effects of fibronectin siRNA and exogenous fibronectin on salivary branching morphogenesis

21. Local suppression of cadherin localization accompanying the formation of cell-matrix adhesions to cellular fibronectin in HSG epithelial cells Mesenchymal cells Epithelial cells Basement Membrane