Cytoskeleton
Cell Migration and Adhesion
Team Members
Facilitators
Marta Bechtel
Christine Hohmann
Cleo Hughes-Darden
John Navaratnam
Kenneth Samuel
Dayalan Srinivasan
Erika Whitney
Randy Phillis
Melissa Zwick
Background Information
• Class Level: Intermediate Cell Biology
• Student Homework Before Class:
- Complete a reading assignment
- Complete an on-line quiz
(please see handout for quiz)
Learning Goal & Outcome
Goal:
Understand the role of the cytoskeleton in cell
migration & adhesion.
Outcome:
Students will be able to predict the
effects of cytoskeletal changes on cell
migration & adhesion.
Why do cells move?
• Normal Tissue Development
• Wound Healing
• Normal Cell Function
Are there situations when cells move when
they should not?
Metastasis
A
To move the boat to the RIGHT
A. Remove anchor A
B. Remove anchor B
B
Focal Adhesions:
cellular anchors to the extracellular space
extracellular
space
(outside)
extracellular matrix (ECM)
proteins
integrins
cell
membrane
cytoplasm
(inside)
adaptor
complex
Rho
GTPases
actin
filament
direction of
myosin pulling
myosin II
cuts
actin
filaments
X
cofilin
LIM
kinase
Focal Adhesions:
cellular anchors to the extracellular space
Outside of
Cell
extracellular matrix (ECM)
proteins
3) integrins lose
attachment!
adaptor
complex
adaptor
complex
actin
filament
Rho
GTPase
actin
filament
LIM
kinase
myosin II
Cofilin
direction of
myosin pulling
Cofilin
2) lack of tension
along actin!
Rho
GTPase
1) Cuts
actin
filaments
LIM
kinase
cell
membrane
cytoplasm
(inside)
A - trailing edge
direction of
cell migration
B- leading edge
Which side of the cell would you predict
cofilin to be most active?
(A or B)
What happens if cofilin cuts actin filaments at the
“leading edge” of the cell?
A. Cell stops migration
B. Cell starts migration
C. Cell re-attaches to the Extracellular Matrix
(ECM)
Which of the following mimics the effect
of cofilin activity on cell-ECM adhesion:
A. Separation of Integrin from the ECM
B. Activation of LIM Kinase
C. Elimination of Myosin II : Actin
interaction
D. A, B, C
E. A and C
Homework
• Cilengitide is a drug that is thought to act by
interfering with the binding of specific integrin
proteins to extracellular matrix proteins.
• It has been shown to be effective in treating
breast cancer.
• Using the diagram for cell motility, how do you
think cilengitide may affect breast cancer cells?
Group (or homework) question # 2
Based on the model, you decide to use (interference)
RNAi to reduce the function of the following genes.
Predict the effects of each RNAi treatment on the
activity of cofilin.
Answer = “active” or “inactive”.
a. LIM kinase
b. Rho GTPase
c. Myosin II
Open ended discussion question
The actin filaments in the cytoskeleton are critical
for cell motility in normal and cancer cells. Conversion
of cofilin from inactive to active is regulated by
phosphorylation:dephosphorylation.
When cofilin is phosphorylated, it becomes
inactivated. What is a likely outcome of the following
on cell motility?
– Blocking cofilin Phosphorylation
– Enhancing cofilin Phosphorylation
– Blocking the activity of LIMKinase
When integrins bind to the ECM to the
leading edge of a mobile cell, which of
the following occur?
A) true, B) false
Cofilin is active
Actin filaments are not cleaved
LIM kinase is inhibiting cofilin activity
Cells are able to migrate
Cofilin