Neural Crest Flashcards
What are 5 key features of neural crest cells?
- Formed along the entire length of the neural tube, from its most dorsal region
- undergo an epithelial to mesenchymal transformation (EMT) to migrate
- differentiate into a large range of cell types
- form specific migratory streams
- migration directed by attraction (chemotaxis) and repulsion mediated by proteins (like ephrins)
What determines our facial appearance?
the differential growth of neural crest cells
What molecule is necessary for the dissociation of E-cadherins?
Slug
Why to neural crest cells need to dissociate their E-cadherins?
In order to undergo epithelial and mesenchymal transformations and become migratory.
What are the 4 main regions of the neural crest?
- Vagal and sacral
- produce 500 mil ganglia in the gut needed for digestion - Trunk
- form somites 7 - tail, melanocytes, and sensory neurons of the dorsal root ganglia (this forms the lateral spinal cord) - Cranial
- form facial bones and sensory neurons - Cardiac
- somites 1-3, make the outflow tract of the heart and the 3rd, 4th, and 6th pharyngeal arches.
What are 5 derivatives of the neural crest?
- Peripheral nervous system - glial and Schwann cells
- Endocrine and peraendocrine (never asked about)
- Pigment cells - melanocytes (epidermal pigment, not iris)
- Facial cartilage and bones - facial and anterior ventral skull bones and cartilage
- Connective tissue - smooth muscle
What causes the specific migratory streams of neural crest cells?
The attraction to chemotaxis and the repulsion of ephrins
What attracts neural crest cells to the colon?
Glial-derived neutrophic factor (GDNF) which is made by the gut
What disease is caused by the absence of Glial-derived neutrophic factor (GDNF)?
Hirschsprung’s disease
What are the two pathways for the trunk neural crest cells?
- Ventral Pathway - migrate first through the sclerotome to become dorsal root ganglia, sympathetic ganglia, and the adrenal medulla
- Dorsolateral Pathway - migrate after to become melanocytes
Where is there more migration of neural crest cells on the sclerotome? Anterior or posterior?
Anterior, sets up spinal segmentation and motor neuron formation. (high [ephrin])
What’s the difference between the anterior and posterior sclerotome cells?
- The anterior sclerotome cells have ephrin receptors (EPH, an RTK) that bind to the ephrins (mem. bound ligands) on the posterior sclerotome cells, this causes a repulsion (like grabbing an electric fence) and creates segmentation.
- The anterior cells remain in the neural crest and become the dorsal root ganglia
Are motor axons going to form with the anterior or posterior sclerotome cells?
Anterior, they also contain EPH so they are repelled by ephrin
How is the MITF transcription factor activated to allow expression of melanoblasts?
- A stem cell factor binds to Kit (an RTK on neural crest cells) and phosphorylates adaptor protein SOS which is bound to GEF
- GEF phosphorylates the GDP on Ras to GTP, then follows the following phosphorylation cascade
- Raf
- MEK
- ERK, then goes into the nucleus, binds and phosphorylates MITF to allow transcription.
What is the purpose of expressing melanoblasts?
prevent neural crest cell apoptosis and they are precursors for melanocytes
