BIOL 1F25 Lecture Notes - Lecture 14: Chemotaxis, Tx Network, Paravertebral Ganglia

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Outline of Lecture 14
Neural Crest Cells
I. Embryology and anatomy of NCCs
- Neural crest cells arise from dorsal ridge of neural fold and migrate to contribute
to a wide variety of tissues
- Major tissues formed by NCC include dorsal root ganglia, sympathetic chain
ganglia, parasympathetic nervous system (e.g. enteric ganglia), melanocytes (see
diagram p.6)
- Combination of BMP (from neural tube) and Wnt6 (ectoderm) signals cause
NCC fate
- NCC can migrate to anterior half of a somite, but not to posterior half due to
repellent ECM; this gives rise to segmented pattern of the peripheral nervous
system
- NCC cells migrate further to form DRG and SCG close to spinal cord (in
contrast, parasympathetic components are close to the tissues they affect)
II. Genes that control NCC development
- Quail grafts in chicks can be used to track fate of NCCs, since quail nuclei can
be distinguished from chick nuclei
- NCCs in trunk of body are a mixture of determined precursors and multipotent
cells
- NCCs in cranium express Hox genes characteristic of their A/P position which
control their fate, but Hox expr pattern is dependent on the environment
- NCC migration is guided by Steel factor chemoattractant (c-kit is receptor) and
ephrin chemorepellant
- Other genes are important in NCC development: endothelin-3 (and its receptor
EDNRB, a GPCR), Ret (a tyrosine kinase), and Pax-3 (txn factor)
III. Associated human disease
- Hirschsprung’s disease is characterized by a restricted descending colon due to
lack of innervation, and is associated with defects in 8 different genes including
Ret, EDN3, EDNRB
- Gain of function in RET (and developmental genes in general) can cause cancer
while loss of function causes developmental defects
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