1. Cell adhesion Adhesion molecule signaling Mechanotransduction
Cell motility

2. Cell adhesion molecules
Immunoglobulin-like
Cadherin
Integrin
Selectin
Dystroglycan

3. Integrins Alpha/Beta heterodimers Closed/Open/Ligated states
Couple cytoskeletal and extracellular conformations
Focal complex
Insideout
Ousidein
Xiao et al., 2004

4. Integrin signaling Survival Focal Adhesion Kinase PTEN/SHP PI-3K
Src/Grb2, Crk
RhoGAP
PTEN/SHP
Phosphatase and tensin homolog on chromosome 10
PIP3->PIP2
PI-3K antagonist

5. Integrin signaling: motility
Juliano 2002

6. Cadherins Cell-cell adhesion Catenin signaling
Adherens junction
Desmosome
Catenin signaling
p120 RhoGAP
b Transcription factor
a Cytoskeletal linker
Differentiation/development
Tissue aggregation
Juliano 2002

7. Cadherin Signaling
Cadherin/catenin signaling interacts with traditional growth factor receptors, incl wnt/frz/dsh and HGF/c-Met
Juliano 2002

8. Immunoglobulin-like Ubiquitous class, CAM
Several extracellular Ig like domains
Not antibodies
Short cytoplasmic tail
Associates with ankyrin/ spectrin cytoskeleton
MAP kinases
Function
Developmental guidance
Immune cell response
Juliano 2002

9. Mechanotransduction Mechanical conformational change
Force
Deformation
Opposition of internal and external forces
CAM-matrix adhesion
CAM-cytoskeleton adhesion
Deformability of series structures

10. Elastic Domains EGF Fibronectin (FN) Immunoglobulin (Ig)
Complement like
EGF
Complement like Ig
CN3D, UIUC Theoretical and computational biophysics group

11. Mechanical conformational changes
Mechanical energy disrupts H-bonding
Modular elasticity
nm stretch
100%+ strain
pN force
Gao et al., 2002 PNAS

12. Cell growth-substrate interaction
Substrate chemistry
Ligand matching
Integrin/CAM mediated differentiation
Substrate mechanics
Improved differentiation on elastic substrates
Fewer stress fibers on softer materials
Yeung et al 2005

13. Motility Motility vs. contraction Polymerization systems
Actin
Tubulin
Filament – motor systems
Actin-myosin
Microtubule-kinesin/dynein

14. Structural reorganization
Motion of focal adhesions (white) and surrounding gel (red) in corneal fibroblasts. Petroll et al 2003

15. Crawling Pseudopodia Actin filament dynamics Lammelapodia Filopodia
Directional polymerization
Treadmilling
Photolabel actin
monomers
Cell moves relative to actin
2 minutes

16. Actin: polymerization dependent motion
Disk shaped
Adenine nucleotide binding
ATPase activity
Nucleotide exchange
Promoted by Profilin
Inhibited by Cofilin
Filament formation
Barbed/Pointed end
Myosin S-1 “decoration”
ADP maturation

17. Actin filament polymerization
Asymmetric exchange of monomers
Myosin fragment

18. Filament regulation Exchange proteins Monomer recycling Profilin
PROmotes filament growth towards barb
Nucleotide exchange factor
Cofilin
ADP-Actin binding
Filament repair
Monomer recycling
Cofilin disassembles ADP-actin
Profilin regenerates ATP-actin

19. Monomer recycling Facilitates “treadmilling” Membrane extension
Profilin carries ATP-actin to leading edge
ATP-ADP conversion as filament matures
Cofilin disassembles ADP-actin

20. Rho family GTPases GTP dependent cofactors, like Ga subunits
Rho Kinase, mDia,
Components of shape-dependent processes
Motility, cell cycle, phagocytosis
Heasman & Ridley 2008

21. Rho family GTPases Rho Rac cdc42 Stress fibers, integrin, selectin
Lamellipodia, growth factors
cdc42
Filopodia, cytokines
Constitutively active cdc Rac Rho
Normal cell

22. Rho family signaling diversity
cdc42
Rac
Rho
WASP
IRSp53
mDia2
PAK
WAVE
mDia2
PAK
RhoK
LIMK
LIMK
ARP2/3
ARP2/3
formin
MLCK
MLP
coflin
coflin
myosin
Actin
branching
Actin
polymerization
Actin
turnover
Actin
polymerization
Actin
turnover
Lamellipodia
Stress fiber
Filopodia
Filopodia

23. Microtubule Regular array of a/b dimers Spontaneous tube formation
Polar

24. Motor Proteins
Myosin-actin
Kinesin-tubulin
Dynein-tubulin

25. Motor step cycle
One head
Two head “Hand-over-hand”

26. Motor step systems Myosin Kinesin AM AMT AMDP AMD MT MDP M MD T P D
Shape Changes
“Weak”
Binding
“Strong”
Myosin T P D
MtK1
MtK1T
MtK1DP
MtK1DK2
MtK2
Kinesin P K1
K1T
MtK1DPK2D
MtK1DPK2 Mt
“Weak”
Binding K2
“Strong”
Binding K2
Shape Changes T

27. Kinesin/Dynein motility
Vesicular transport
Kinesin
Toward +
Away from nucleus
Dynein
Toward –
Toward Nuc
0.1-1 um/s

28. Myosin motility Cytoplasmic streaming (plants) Muscle
Transport of ER along actin tracks
60 um/s
Muscle
Specialized bipolar myosin filaments
Opposing motion in adjacent actin filaments
1-10 um/s

29. Highly ordered filaments
Crystalline polymerization facilitates molecular interaction
Maximize density of force generating elements
Double-headed Myosin
“J” structure on filament surface
Woodhead et al 2005

30. Regulation of force (smooth muscle)
Thick filament regulation
Regulatory myosin light chain phos
Myosin light chain kinase (MLCK)
Calmodulin
Slow, sustained

31. Regulation of force (striated muscle)
Thin filament regulation
Steric availability of actin
Tropomyosin
Troponin I,C,T
Cooperative
Rapid
Weak myosin binding
Strong myosin binding
Actin
Tropomyosin