CytoskeletonCell Migration and Adhesion

Team Members

Marta BechtelChristine HohmannCleo Hughes-DardenJohn NavaratnamKenneth SamuelDayalan SrinivasanErika Whitney

Facilitators

Randy PhillisMelissa 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

cellmigration & 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 B

To move the boat to the RIGHT

A. Remove anchor AB. Remove anchor B

extracellular matrix (ECM)proteins

adaptor complex

myosin II

direction ofmyosin pulling

actinfilament

Rho GTPases

cellmembrane

cytoplasm(inside)

extracellularspace

(outside)

Focal Adhesions:cellular anchors to the extracellular space

integrins

cutsactin

filaments

LIM kinase

cofilin

X

Focal Adhesions:cellular anchors to the extracellular space

cellmembrane

cytoplasm(inside)

Outside of Cellextracellular matrix (ECM)

proteins

adaptor complex

actinfilament

Rho GTPase

LIM kinase

3) integrins loseattachment!

2) lack of tensionalong actin!

1) Cutsactin

filamentsCofilin

myosin II

direction ofmyosin pulling

adaptor complex

actinfilament

Rho GTPase

LIM kinase

Cofilin

B- leading edge

A - trailing edge

Which side of the cell would you predict cofilin to be most active?

(A or B)

direction ofcell migration

What happens if cofilin cuts actin filaments at the “leading edge” of the cell?

A. Cell stops migrationB. Cell starts migrationC. 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 ECMB. Activation of LIM KinaseC. Elimination of Myosin II : Actin

interactionD. A, B, CE. 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 kinaseb. Rho GTPasec. 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) falseCofilin is active

Actin filaments are not cleaved

LIM kinase is inhibiting cofilin activity

Cells are able to migrate

Cofilin