Axon Guidance Part 2

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What is the primary function of laminins in the extracellular matrix?

To provide structural support to the cell
To regulate cell-cell adhesion
To promote axon outgrowth (correct)
To control cell migration

What is the composition of integrins in nerve cells?

Homodimers of beta subunits
Heterodimers of a and b subunits (correct)
Heterotrimers of alpha, beta, and gamma subunits
Homotrimers of alpha subunits

What is the role of the intracellular domain of integrins?

To control cell proliferation
To interact with cytoskeletal components (correct)
To bind to extracellular matrix molecules
To regulate cell signaling pathways

What is the primary cue that guides retinal ganglion cell axons to the optic nerve head?

Laminins (A) Signup and view all the answers

What is the purpose of the cell adhesion assay in identifying NCAMs?

To identify cell adhesion molecules (D) Signup and view all the answers

What is the effect of antibodies to the cell surface on the aggregation of neurons in the presence of a NCAM?

They block the aggregation (A) Signup and view all the answers

What is the role of unc-5 receptor in axon growth?

Predominant role in axons that grow away from the midline (A) Signup and view all the answers

Which of the following molecules is involved in switching Sema3B repulsion?

SHH (A) Signup and view all the answers

What is the effect of active RhoGTP on growth cone morphology?

Causes growth cone collapse (A) Signup and view all the answers

What is the role of GEFs in the GTPase cycle?

Act as the 'on' switch (D) Signup and view all the answers

What is the consequence of binding of netrin to UNC-5-DCC heterodimers?

Growth cone repulsion (B) Signup and view all the answers

What is the role of DCC homodimers in netrin receptor signaling?

Induces growth cone attraction (B) Signup and view all the answers

What is the primary function of Ephrin A5 in the optic tectum?

Repulsion of RGC axons from the posterior region (D) Signup and view all the answers

Which of the following is a characteristic of Ephrin B?

It has a transmembrane domain and can undergo reverse signaling (C) Signup and view all the answers

What is the effect of Semaphorin on growth cones?

It causes growth cones to collapse and retract (B) Signup and view all the answers

What is the function of Sema5A around the optic nerve?

It repels RGC axons from the optic nerve (D) Signup and view all the answers

What is the consequence of ablating Slit-1 and Slit-2 expression?

Axons form an ectopic chiasm and wander outside of the optic nerve (D) Signup and view all the answers

What is the attraction cue for commissural neurons in the dorsal neural tube?

Netrin (B) Signup and view all the answers

What is the significance of the sequence in the 3’UTR of the mRNA in the regulation of EphA2 expression?

It regulates the localization of the mRNA in the growth cone (A) Signup and view all the answers

What is the effect of metalloprotease inhibitors on the response of neurons to Netrin-1?

They potentiate the responses of neurons to Netrin-1 (A) Signup and view all the answers

What is the role of Robo in the attractive response to Netrin-1?

It inhibits the attractive response to Netrin-1 (D) Signup and view all the answers

What is the result of treating spinal cord explants with a metalloprotease inhibitor and a low dose of Netrin-1?

There is neuron growth similar to that with a high dose of Netrin-1 (A) Signup and view all the answers

What is the effect of Slit-Robo signaling on the attractive response to Netrin-1?

It inhibits the attractive response to Netrin-1 (A) Signup and view all the answers

What is the role of the growth cone in the regulation of EphA2 expression?

It regulates the localization of the mRNA (A) Signup and view all the answers

What is the effect of Slit-induced activation of Robo on Cdc42 activity?

It decreases Cdc42 activity (B) Signup and view all the answers

Which of the following is NOT a mechanism by which intracellular concentrations of cAMP and cGMP regulate the axonal response to guidance cues?

Influencing the activity of tyrosine kinases (C) Signup and view all the answers

What is the consequence of asymmetric Robo activation on the cell surface in response to a gradient of Slit?

An intracellular gradient of Cdc42 activity driving repulsive migration (A) Signup and view all the answers

What is the role of local translation of receptors within the growth cone in axon guidance?

It is required for the responsiveness of axons to chemotropic cues (D) Signup and view all the answers

Which of the following is a difference between the effects of Netrin on DCC homodimers and DCC-Unc5 heterodimers?

The sign of the response to Netrin (B) Signup and view all the answers

What is the consequence of decreasing intracellular cAMP and cGMP levels on the response of Xenopus neurons to Netrin?

The neurons are repulsed by Netrin (B) Signup and view all the answers