L6 GOK Flashcards
Neural patterning is ?
a biological process by which cells in the developing
nervous system acquire distinct identities according to their specific spatial
positions.
what is a major determinant of cell fate in the sc ?
Dorsal(D)-ventral(V) positioning
what does the roof plate secrete ?
whats does the floor plate secrete ?
roof - BMPs
floor - shh
what are morphgens ?
and examples ?
signaling molecules that elicits different cellular responses depending on its concentration
BMP & shh
where are the roof and floor plate located ?
roof = dorsally floor = ventrally
what does the absolute conc of a morphogen acting on a cell determine?
developmental fate
what is BMPs and shh’s gradients ?
BMPs = D/v shh = V/D
how do these gradients divid NPC?
subdivide neural progenitor cells into discrete domains
-> which then produce all subclasses of motor & sensory neurons
what do these opposing gradients led to the expression of ?
homeobox TFs
Nkx6.1 ventrally,
Pax6 medially,
Pax3/Pax7 dorsally
what does the V-D gradient of shh do to the basal plate ?
it partitions it into 5 discrete progenitor domains that wil generate 6 different classes of neurons
progen domains = V0,V1,V2,V3 and pMN
what do the motor neuron progenitors express ? (pMN)
Nkx6.1
what do the NP in other ventral domains become ?
interneurons
what do V3 neuron progenitors express ?
and what dont they express ?
express = nkx2.2
dont express = Pax6 and oligo 2
what do pMN express ?
and what dont they express ?
express = nkx6.1 and oligo 2
dont express = nkx2.2 and Irx 3
what does nkx6.1 turn on the express of ?
and what does this lead to ?
oligo2 = basic helix loop helix TF (bHLH)
oligo 2 induces motor neuron diffrin by activating Hb9 and Isl 1/2
what Ngn2 ? and whats it coexpressed with ?
its a gene for neural differentiation
coexpressed with - Oligo 2
are oligo 2 and Nkx6.1 coexpressed ?
yes
is NKx2.2 coexpressed with Oligo 2?
no, because Nkx2.2 is expressed in the most ventral domain where interneurons are expressed and oligo2 is involved in neuron diffrin
the D/V BMP gradient divides the alar plate into ?
two progenitor regions
most dorsal region = 2 progenitor domains = Class A dI1-dI3 interneurons.
intermediate region = 6 progenitor domains = Class B dI4-dI6 interneurons
what does BMPs dimers binding to their BMPr cause ?
to the recruitment and phosphorylation of
receptor-regulated smad proteins (Smad1/5)
when phosphorylated these complex with Smad-4
and translocate to the nucleus where they regulate
gene expression
What class of inter neurons neural diffrin is dependent on wnt/ Bmp signalling ? which class isnt ?
dependent = Class A dl1-dl3
independent = Class B dl4-dl6
Patterning of the dorsal sc inter neurons is dependent on what signalling ?
BMP/ smad
BMP/Wnt signalling turn on expression on which cell specific determinants of class A progenitors dl1-dl3
Olig3, Atoh1, Neurog1/2 & Ascl1
Oligo 3 is expressed by all Class A progenitors what does it repress ?
it represses Lbx1 to specify
dI1-dI3 interneurons.
Atoh1 = dI1; Neurog1/2 = dI2 & Ascl1 = dI3.
