Neural Stem Cells Flashcards
What is another name for neural stem cells?
Neuroepithelial cells
What do NSCs asymmetrically divide into later?
One self-renewing NSC
One neurone
What else can neural stem cells generate?
Intermediate progenitors (transit amplifying cells)
Which can then either make neurones or glial cells
Give examples of glial cells
Oligodendrocytes
Astrocytes
Microglia
How long do stem cells live?
For the lifetime of the organism
Which germ layer does the nervous system develop from?
Ectoderm
Where do the signals come from that induce ectoderm to differentiate into neural plate?
Node or Organiser region = mesoderm derived
Where is the node/organizer region found?
Top of primitive streak
What signals from organizer/node induce neural tissue?
Fibroblast Growth Factor (FGF)
Transforming Growth Factor Beta (TGFb)
What happens to the neural plate later in development?
If folds up to form neural TUBE
Neural tube begins to extend forming anterior-posterior axis (head to tail elongation)
What can neuromesodermal progenitors (NMP) give rise to?
Spinal cord neural progenitors
Mesodermal progenitors
What are the two markers used to differentiate neural progenitors and mesodermal progenitors?
Sox2 marks neural progenitors
Brachyury (Bra) marks mesodermal progenitors
What is neurulation?
When neural plate folds to make neural tube
What gives rise to CNS?
Proliferative ventricular layer gives rise to the CNS
What gives rise to PNS?
Nerual crest cells migrate from dorsal neural tube and give rise to PNS
Including ganglia in the head and gut
Which part of the spine have cells doing the most proliferation?
The cells closest to the inner spine in the ventricular layer
Apical surface faces the centre of the neural tube
What do neural stem cells under go as they progress through cell cycle?
Interkinetic nuclear MIGRATION
Descibe where neural stem cells are as they go through the cell cycle
As they proliferate, move towards basal side of neural tube
When they differentiate = migrate outwards extending neural axis along the side
At S phase they reach the basal side, then return back to the apical side during G2
Finally returning to apical side at M phase
Axis of division is a specific was for asymmetrical division
Which zone are differentiated neurones found in?
Cortical plate / Marginal zone
What zone is expanded in humans?
Sub-ventricular zone
What regualtes NSC self-renewal?
Extrinsic signals such as, FGF, Wnt, IGF, and Notch pathway signals
What occurs in NSCs when Notch signalling is lost?
Cell cycle exit induced
AND
Premature neuronal differentiation
(in a wide range of animcal embryos and reigons of developing nervous system)
What mechanism does Notch signalling mediate?
Lateral inhibition
How does lateral inhibition work?
Neurons must decide whether to differentiate or stay undifferentiated based on the signals they receive from their neighbors.
Initially, neighbouring cells experience similar levels of Notch signalling.
When nascent neurons are in close proximity, they interact with each other. Nascent neurones express higher levels of Delta1, this increases Notch signalling in neighbouring cells
High Notch signalling represses neurogenin (proneural gene) = leading to reduced Delta1 expression.
Reduced Notch signalling in the newborn neuron and so increases levels of neurogenin and Delta1 in the nerones itself