Neural Crest

Question 1

BMP levels

Answer 1

regulate nervous system formation

• low level=nervous system
• high level=ectoderm

Question 2

what surpressses BMP

Answer 2

near midline-noggin, chorddin, FGF

Question 3

Neural crset fomration step

Answer 3

become distinct from adhjacent ectoderm and neural tissue

begin migration

localize and differentiate

Question 4

Mapping neural crest fate

Answer 4

get quail cells, put in chick after remove that same part

let develop-see quail cells very different than chick

Question 5

what does rostral mean

Answer 5

cranial

Question 6

where does neural crest form

Answer 6

boundary where presumptive neural plat meets endoderm

• high levels of BMP on outside-epidermal
• the snail region have intermediate BMP
• neural plate-low bmp

Question 7

snail tf

Answer 7

results in neural crest formation

• turns on genes that limit boundary between neural tube and boundary
  
  • boarder specifer genes

Question 8

boarer specifier gene functions

Answer 8

w/ bmps induce additional TF’s that speicify neural crest as well as genes for migration
-simulate c-kit and c ret-these genes have long migratory pathways

Question 9

Iniitatin+ pathways of trunk neural crest migration

Answer 9

nueral crest much change epithelium to mesenchyme (EMT)

-lose 6b class of cadherins (mediate adhesion/in spot/belt desmosomes)-epi (tight pack) becomes mesenchyme (movable)

• Migrate into hyaluronic acid filed space
  
  • GAGs in joints/embryos

Question 10

steel factor+howw does neural crest move

Answer 10

produced in migratory pathways-c-kit receptor binds here
-hints at presence of ligand suggesting steel peptide is chemoattractant for receptor expressing cellls

-migratory pigment defects

ligand recepotr signalling system

Question 11

hetero c-kit phenotype

Answer 11

migratory pigment defects+blood/germ cell defects

white spot on forehead/tummy

Question 12

neural crest migration into gut

Answer 12

provides progenitors for enteric nervous system

Hirshbrungs disease-megacolon-deficeiny of enteric ganglia-cant excrete

Question 13

How do NC cells migrate through gut?

Answer 13

ligand receptor system
recepotor=c-ret-on neural crest cells
ligand-GDNF-in gut

if can’t make it through, cret/GDNF mutants-NC cells need reach posterior gut

Question 14

GDNF

Answer 14

chemoattractant of NC cells to colonize gut

GDNF production is activated sequentially in later time in more posterior gut
-gradient

Question 15

hirshbrings disease

Answer 15

Hirshbrungs disease-megacolon-deficeiny of enteric ganglia-cant excrete

NC cells don’t make through colon to end
-cret/GDNF mutants

Question 16

digeorge syndrome diagnosis, and etiology

Answer 16

cardiac/immune problems

low set, abnrmal ears

cleft pallete

defecits in several specific tissues
(pharyngeal and neurcal crest derivatives)
-represent failure of neural crest entering pharyngeal slits
-occur with large DNA deletion (same with mice/humans)

Question 17

T box gene family

Answer 17

encode TFs
-such as brachyury-involved in mesoderm formation-posterior structures

tbx1 is maps onto DGS region

• expressed in pharynx and not NC cells=probably cause for lack of NC migration signals into pharynx
• knockout in mice had lowset ears

Question 18

what regulates tbx1+ what does it regulate

Answer 18

SHH

targets peptides in FGF family
-loss of FGF family results in TGF like phenotype

Question 19

crk1

Answer 19

anotehr contributor to DGS

-absence of crk1 via KO stops TGF/FGF signalling

also leads to NC migration problems

probably part of ligand that will look for a receptor in pharngeal slit cells

Question 20

location of cork and tbx1

Answer 20

22q11-same spot!

Question 21

fetal alcohol syndrome diagnosis and effects

Answer 21

mentally regarded

small openings between eyed

low nose bridge

smooth upper lip

congenital heart disease

causes pop of rostral parts of embryo
-espeically in NC cells-

Question 22

what causes neural crest to deisperse/form

Answer 22

activation of sequenctial cascade of TFs started by specific BMP levels

Question 23

What control NC migration

Answer 23

speicfic ligand receptor systems-secreted ligands are chemoattractants

Question 24

alterations to nerual crest morphogenesis change

Answer 24

change in envrionemtn in which NC migrate (Tbx-1)

or efffect crest cell themselves (CrKL)

Question 25

teratogen xposure and effect on neural precursors

Answer 25

affects neural precursors and neural crest survival-leads to dev deficiencies

Question 26

LOOK AT HER SUMMARY-last slide

Answer 26

FOR ALL OF THE LECTURES