1. Molecular Cell Biology Intermediate Filaments Cooper

2. Introduction n Filaments 10 nm wide => “intermediate” n Present in Metazoa / Animals i.e. not Plants or Unicellular Organisms n Complex Gene Superfamily 70 in Human Genome n Specific Expression at Different Times and Places

3. Intermediate Filament Biochemical Properties In Vitro n Very stable. Little subunit exchange. n Very strong. Filaments do not break. MT’s strong but brittle Actin weak

4. Intermediate Filament Potential Functions In Vivo n Mechanical Strength of Cytoplasm n Help a Layer of Epithelial Cells Resist Shear Stress - Filaments Connect to Cell-cell Junctions n Hold Nucleus in Center of Cell

5. Intermediate Filament Structure & Assembly

6. Intermediate Filaments by EM: Filament Unraveling

7. Classes of Intermediate Filaments

8. Regulation of IF Assembly n Notoriously Stable No Nucleotide n Filaments Move Little Precursors Move More n Disassemble Somewhat during Mitosis Phosphorylation by Cyclin-depen Kinase

9. Vimentin Filaments in a Cultured Cell

10. Vimentin n All Cells in Early Development n Cage Around Nucleus n Interacts with Mt’s n Vimentin Knockout Mouse Initially normal at gross inspection Cultured cells have altered properties of uncertain significance

11. FRAP of Vimentin vs. Keratin in One Cell Left: Vimentin (Green) Right: Keratin (Red) 10 min time intervals

12. Dynamics of Keratin Particles in Periphery 11 micrometers over 10 minutes 18 micrometers over 10 minutes

13. Desmin n Expressed in Muscle n Elastic Elements to Prevent Over-stretching n Connects / Aligns Z lines n Knockout Mouse - Deranged Myofibril Architecture

14. Keratins n Expressed in Epithelia n Keratin Filaments Connect to Desmosome and Hemidesmosomes n Differentiation of Epidermis includes Production of Massive Amounts of Keratin n Provides Outer Protection of Skin n Composes Hair, Nails, Feathers, etc.

15. Density of Keratin Filaments in Outer Epidermis Layers

16. Keratin Mutations are Basis for Human Epidermal Diseases n Structure/Function Analysis of Keratin Assembly n Point Mutation in Terminal Domain Fails to Assemble n Mutant is Dominant, even in Low Amounts, in Cultured Cells and Mice

17. Epidermolysis Bullosa Simplex Wild-typeMutant

18. Keratins and EBS

19. Neurons n Neurofilament H, M, L Copolymer n Prevent Axon Breakage n Diseases with Clumps of Neurofilaments Superoxide dismutase model for ALS Clumps are secondary, not causative

20. Neurofilament Transport in Axons Photobleached Zone in the Middle

21. Neurofilament Transport in Axons Photobleached Zone in the Middle

22. Lamins n Square Lattice on Inner Surface of Nuclear Membrane n Present in Metazoans (Animals, not Plants or unicellular organisms) n Mitosis Breakdown Phosphorylation of A & C by Cyclin-depen Kinase B remains with Membrane n Mutations Cause Accelerated Aging Diseases Progerias - Dominant Mutations

23. EM of Nuclear Lamina Nuclear Pores

24. End