Neural Crest development Flashcards
Tell me where the multipotent stem cells arise from and how they are able to move to their destined location?
- Originate in the dorsal region of the developing neural tube
- Neural crest cells leave the CNS
- Migrate the dorsal neural tube to the periphery of the embryo
- Multipotent stem cells: Give rise to a multitude of cell types
Where do neural crest cells arise from and tell me about their ‘birth’ to the point where they are able to migrate
(A) Neural crest cells undergo an epithelial-to-mesenchymal transition from the dorsal most portion of the neural tube
(B) The neural crest cells can be seen as a collection of mesenchymal cells above the neural tube
(C)
- The neural crest specifies at the border of the neural plate
- and subsequently localizes at the apex of neural folds,
- then neural crest cells delaminate at the point of neural tube closure,
- and finally migrate out of ectodermal tissues
What forms the bone and cartiledge and also contributes to the cranial nerves?
The cranial neural crest migrates into the pharyngeal arches and the face to form the bones and cartilage of the face and neck. It also contributes to forming the cranial nerves
What forms the parasympathetic nerves of the gut and refer to the name and somite number?
The vagal neural crest (near somite’s 1-7)
and the sacral neural crest (posterior to somite 28)
form the parasympathetic nerves of the gut
What number somites does the cardiac neural crest cells arise near and what are they critical in?
The cardiac neural crest cells arise near somite’s 1 through 3;
they are critical in making the division between the aorta and the pulmonary artery (sometimes there is overlap in these regions)
Tell me what the Neural crest cells form and at what somite number this occurs at
Neural crest cells of the trunk (from about somite 6 through the tail) make sympathetic neurons and pigment cells (melanocytes),
and a subset of them (at the level of somite’s 18-24) forms the medulla portion of the adrenal gland (this gland sits on top of kidney and is involved in many endocrine functions such as the release of adrenaline)
Regions of the chick neural crest
What is the hox genes role in this?
Hox gene attenuate (reduce effect of) development potential
What are the two migratory pathways in neural crest cell migration?
Tell me where the cells travel in each of these pathways
Ventral and dorsolateral
Vental: cells travel ventrally though the anterior scleotome
Dorsolateral: Cell travel between the epidermis and the dermis
In neural crest cells that migrate via the ventral pathway, what do they contribute to?
- Sympathetic and parasympathetic ganglia
- adrenomedullary cells
- dorsal root ganglia
In neural crest cells that migrate via the dorsolateral pathway, what do the cells become?
Pigment- producing melanocytes
What do somites arise from?
Sclerotome
What does neural crest cell delamination (delamination is a separation into layers) coincide with?
Neural crest delamination coincides with the separation of neural and surface ectoderms and their fusion at the midline
In the mechanism of neural crest cell migration, what unique adhesion proteins are expressed and where?
- surface ectoderm (E-cadherin)
- neural tube (N-cadherin)
- premigratory neural crest (cadherin-6B)
During neural crest cell migration, what do high levels of BMP and intermediate amount of Wnt do?
High levels of BMP, and intermediate amounts of Wnt (both epidermal) upregulate expression of Snail-2 (and Zeb-2) in the premigratory neural crest cells
What does SNAIL-2 do in this domain where neural crest cell migration is occurring?
Snail-2 proteins repress N-cadherin and E-cadherin in this domain
Whats RhoA and Rac1?
Two members of the family, Rac1 and RhoA, can show opposite behaviors and spatial localisations, with RhoA being active toward the rear of the cell and regulating its retraction during migration, whereas Rac1 is active toward the front of the cell.
Tell me about the contact inhibition of locomotion
- “kiss and run” process this is known as where the cells touch then move straight apart
- Reorganise actin and actomyosin network and this helps the cells start their migration
What does the collective migration of neural crest cells require and what is this mediated by?
Requires some amount of cell-to-cell adhesion, which is mediated by a low-level N-cadherin expression (blue receptors)
During neural crest cell migration, what do the cells sense that helps steer migration?
- Repulsion and attraction tell cells to stay in given environment or to move on to their right location, this guides neural crest cells during their migratory path
- Gradient diffusive manner and generally they are morphogenes
Tell me about the “chase and run” model for chemotactic cell migration. Mention any proteins when necessary
A ventrally positioned placode (blue cells) attracts the leading edge of the cranial neural crest stream via SDF1 (CXCL12)-CXCR4 signaling (the “chase”).
The cranial neural crest contacts the placode, triggering contact inhibition that pushes the placode forward (the “run”)
What yields forward migratory movement of both placodal and cranial neural crest cells?
(A) A ventrally positioned placode (blue cells) attracts the leading edge of the cranial neural crest stream via SDF1 (CXCL12)-CXCR4 signaling (the “chase”). The cranial neural crest contacts the placode, triggering contact inhibition that pushes the placode forward (the “run”)
(B) Internal molecular events and resulting cellular behaviors that yield forward migratory movement of both placodal (blue) and cranial neural crest (red/yellow) cells
For the chase and run model give example(s) for the chemorepellants and chemoattractants expressed by the placode cells
Chemorepellents: Semaphorins/ ephrins
Chemoattractant: SDF1
