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Cytoskeleton - Locomotion

Explore the essential functions of the cytoskeleton in cellular movement, including determining cell shape, anchoring organelles, and more. Learn about microfilaments, microtubules, motor proteins, and their roles in cytoskeletal dynamics and locomotion.

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Cytoskeleton - Locomotion

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  1. Cytoskeleton - Locomotion Kohidai, Laszlo MD, PhD Med. habil., Assoc. Professor Dept. Genetics, Cell & Immunobiology, Semmelweis University http://gsi.semmelweis.hu Lecture ED 2015

  2. Main functions of cytoskeleton • Determines the shape of the cell • Anchores organelles • Movement of organelles • Tensile strength • Movement of chromosomes • Polarity • Motility

  3. Cytoskeleton • Microfilaments (actin) • Microtubuli (tubulin) • Intermedier filaments • Motor proteins • Actin and microtubule associated proteins

  4. Microfilaments Microtubuli Intermedier filaments

  5. SLIDING Globular proteins Ca2+ ATP Motor proteins Fibrillar proteins

  6. Microfilaments

  7. Polymerization of actin + ATP ADP Depolymerization - cytochalasin – inh. phalloidin - stabilizer ATP ADP Pi Polymerization - slow

  8. Actin - still in Prokaryots ! ((Ent et al. Nature 2001,413, 39)

  9. Other actin homologues ((Roeben A et al. J Mol. Biol2006, 358, 145)

  10. Comparison of homologues • Polymerization in both forms • Opposite chirality !!! ((Wickstead and Gull J Cell. Biol2011, 194, 513)

  11. Moving cytoplasm Stationary (cortical) cytoplasm Plasma membrane Actin filaments Cell-wall Chloroplasts Cyclosis • Transitional connections between actin and myosin • Ca2+, temperature- and pH-dependent (Lodish, H. et al. Mol. Cell Biol. 2000, 767)

  12. „Fountain” mechanism Ca2+-dep. requires ATP Mono- Poly- Lobo- podial Filo- Reticulo- Formation of pseudopodium stress-fibrillums integrins

  13. Cross-linking proteins of actin contractile bundle a actinin – in stress fibr. gel-like network filamin - cortex „tight” parallel bundle fimbrin – in filopodium

  14. Migrating keratinocyte 15 mm/sec Formation of lobopodium microtubuli actin-network

  15. - + Regulator proteins of actin polymerisation gCAP39 Severin Gelsolin Villin CapZ Tropomodulin  Cofilin Severin Gelsolin

  16. Actin polymerization – acrosomal-reaction (Lodish, H. et al. Mol. Cell Biol. 2000, 767)

  17. local actin polymerization • speed: 10 mm/min • high ability to transmit • in tissues Listeria monocytogenes actin (Fred Soo & Julie TheriotLaboratory

  18. Model of actin nucleation WASP = Wiscott-Aldrich syndr. prot.

  19. Structure of cortical region (Svitkina, TM, Borisy GG J. Cell Biol. 1999, 145, 1009)

  20. Myosin I. Arp2/3 Profilin - G-actin Filamin Integrin Actin – membrane links membrane F-Actin

  21. Profilin-mechanism Tb4 =thymosin b4 Proline-rich protein (Lodish, H. et al. Mol. Cell Biol. 2000, 767)

  22. Filamin – Membrane link filamin actin

  23. Structure of focal contact actin filament a actinin vinculin + paxillin talin integrin fibronectin

  24. Thrombocyte Glycophorin Ankyrin Spectrin tetramer Muscle Epithel A plasma membrane – cortex links ((Lux SE, 1979 Nature 281:426)

  25. E Electromagnetic field induces the transformation of cytoskeleton and formation of pseudopodia Adhesion plaque + + + - -

  26. ATP - ADP Pi Myosin head Ca2+-dependent phosphorylation and its effect on the 3D strcture light chain heavy chain a helix myosin I. 150 kD monomer myosin I I. 260 kD Head: - ATP-ase - motor dimer

  27. Distribution of myosines in the migrating Dyctiosteliumand in dividing cell myosin I. (green) myosin II. (red) (Fukui, Y. Mol. Cell Biol 2000, 785))

  28. + - Main types of interactions between the globular and fibrillar components of cytoskeleton membrane

  29. MT-blocked F-actin blocked Non-treated

  30. Microtubules

  31. Tubulin – still in Prokaryotes ! FtsZ Tubulin (Margolin Laboratory, University of Texas)

  32. Comparison of homologues • Polymerization in both forms • Monomers build helical structure vs. dimers build tubulus ((Wickstead and Gull J Cell. Biol2011, 194, 513)

  33. Polymerization of tubulin GTP Polymerization - fast GTP GTP GTP Protofilament (strait) GDP GDP GDP GDP Protofilament (curved) Depolymerization

  34. Nucleation Elongation Dynamics of microtubule-assembly - + incorporation balanced release

  35. Role of g-tubulin in nucleation (Wiease et al. Curr.Opin.Struct.Biol. 1999, 9, 250)

  36. Interphase cell centrosome Cilla Basal body Dividing cell spindle Neuron centrosome axon Microtubular systems in the cells -Centrosome - Cilia / flagellum - Mitotic system - Vesicular transport

  37. specific region of the cortex MTOC = Microtubulus organizing center g-tubulin ((Brinkley, B.R. Encyclop. Neurosci. 1987, 665)

  38. 24 nm a-bdimer Protofilaments alphatubulin betatubulin Network of microtubuli Fibroblast

  39. Cilia cilia flagellum Paramecium

  40. tubulin (13 ill. 11 protofilaments) A B dynein-arms nexin

  41. The arm moves toward the - pole Composition of dynein-arms ATP-independent binding ATP-dependent hydrolysis

  42. The role of dynein arms in beating of cilia Bending „Telescoping” Proteolysis

  43. Molecules composing the cilia more than 250 types of molecules • 70% a and b tubulin • dynein arms • outer - 9 polypeptides - ATP-ase • inner – composition varies • radial spokes - 17 polypeptides

  44. Microtubules of mitotic spindle and kinetochore

  45. Arrangement of actin during cell-division

  46. Intermedier filaments

  47. Crescentin

  48. intermedier filament i.e. vimentin microtubule = rupture actin filament Mechanical characterization of cytoskeleton components deformation force

  49. Role of intermedier filaments Buffer against external mechanical stress Tissue specificity Nucleus – lamines (lamina fibrosa) Epithel – keratin Connective tissue Muscles Neuroglia Neurones - neurofilaments }vimentin

  50. Structure of intermedier filamentums (Lodish, H. et al. Mol. Cell Biol. 2000, 767)

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