L10 Cell Migration, Cell Maturation and Commitment

Question 1

What is the role of radial glial cells

Answer 1

maintain their contacts with both the ventricular and pial surface of the notochord.
-Form scaffolding for neurons to move along during migration.

Question 2

explain the “inside out” fashion of cortex layer development

Answer 2

• Young neurons end up in the most superficial areas. Old Neurons end up deeper..
• Astrotactin mediates this migration pattern.
• Reelin released by Cajal-retzius cells tells the neurons when and where to cease their migration.

Question 3

What are Cajal-Retzius cells and the reeler gene?

Answer 3

• Reeler Gene- codes for Reelin.
  
  • Reelin is the large extracellular matrix glycoprotein that regulates migration.
• Cajal-Retzius Cells- cells in the marginal zone of the cortex. Use reelin as migration signal for neurons to get off radial glial monorail

Question 4

do gnRH cells need radial glial cells?

Answer 4

No - they migrate into CNS from olfactory (nasal placode) pit to hypothalamus

Question 5

what is Kallmann’s syndrome

Answer 5

there is no GnRH migration - no smell (anosmia) and no sexual maturity (sterile)

Question 6

how does a neuron’s environment influence its function?

Answer 6

-Despite pre-determination of phenotype; a cell will fulfill the function needed wherever it is placed during development (the cell hasn’t “committed” yet).

Question 7

does neuronal location determine the NT type?

Answer 7

-A norandergenic cell will become a cholinergic one if cultured near myocardial cells.

Question 8

what is the role of leukemia inhibitory factor and its influence on neuronal cell phenotype

Answer 8

• Leukemia Inhibitory Factor- influences differentiation of cells in the immune system.
• More importantly, it helped cause the neural cells to change their phenotype based on their environment, like when they were put with cardiac tissue (the muscle cells released it).

Question 9

what is the role of PMP22 protein in peripheral myelination?

Answer 9

-Peripheral Myelin Protein- Schwann cells join molecules of this protein to produce myelin.

Question 10

describe schwall cell-neuron interactions and appropriate PMP22 expression

Answer 10

• PMP-22 is crucial for the Schwann cells to appropriately wrap themselves around a peripheral neuron. Without the proper expression of it, Charcot Marie Tooth disease results.

Question 11

describe the trembler mouse expierments and the importance of schwann cells

Answer 11

• Proved that myelination disorders are problems with the Schwann cells rather than the axons themselves
• When you graft in healthy Schwann cells to an affected mouse; myelination occurs.

Question 12

describe the role of PMP-22 in Charcot Marie Tooth Disease

Answer 12

• Aspartate is substituted in place of Glycine.

- Dysfunctional Peripheral Myelin Protein.

Question 13

describe the role of laminin and axonal growth

Answer 13

• Laminin- large molecule produced by Schwann cells to promote neurite extension and outgrowth.
• Synthesis is highest after neuronal injury.

Question 14

describe the role of netrin and axonal growth - motor vs. sensory

Answer 14

• Netrin- diffusible molecule produced by the floor plate that attracts the growing axon.
  
  • Specifically attracts neurons to the anterior commissure of the spinal cord.
  • Also aids in migration of the retinal ganglion cells.

Question 15

describe the role of nerve growth factor and the tyrosine receptor kinase activity

Answer 15

• Nerve Growth Factor- attracts extension of sensory and sympathetic neurons in the periphery.
  -Very little parasympathetic affect.
  -Induces the synthesis of NE by phosphorylating tyrosine hydroxylase and
  Dopamine-β-hydroxylase.
  -Mediated by retrograde transport to the developing nerve’s soma.