Factors controlling cardiac neural crest cell migration

Abstract

Cardiac neural crest cells originate as part of the postotic caudal rhombencephalic neural crest stream. Ectomesenchymal cells in this stream migrate to the circumpharyngeal ridge and then into the caudal pharyngeal arches where they condense to form first a sheath and then the smooth muscle tunics of the persisting pharyngeal arch arteries. A subset of the cells continue migrating into the cardiac outflow tract where they will condense to form the aorticopulmonary septum. Cell signaling, extracellular matrix and cell-cell contacts are all critical for the initial migration, pauses, continued migration, and condensation of these cells. This review elucidates what is currently known about these factors.

Figure 1

Diagram summarizing the origin and stages of cardiac neural crest migration and condensation in its targeted regions that will be discussed in the review. (Reprinted in modified form from Kirby, 2007 with permission.)

Figure 2

Illustration and explanation of the three rhombencephalic neural crest streams. Cranial is to the left in parts (A and B). (A) Transgenic zebrafish embryo expressing green fluorescence protein under the Sox10 promoter. The cranial, middle and caudal streams are marked. Gaps at rhombomeres 3 and 5 are indicated by arrowheads. The otocyst (O) is located adjacent to rhombomere 5. The eye is indicated by E. (B) Chick embryo electroporated with a green fluorescence protein-expressing plasmid. The three rhombencephalic streams are indicated as are the gaps (arrowheads). (C) Table indicating the origin, destination and fate of the three rhombencephalic streams.

Figure 3

Illustration of the circumpharyngeal ridge and its relationship to cranial nerves IX and X in an HH22 chick embryo. (A) Position of the arches and otocyst in an embryo electroporated with GFP-expressing plasmid in the neural tube. (B) Magnification of the caudal stream of cardiac neural crest in the same embryo showing the location of cranial nerves IX and X, the circumpharyngeal ridge (C) and arches 3, 4 and 6.

Figure 4

BMP receptor 1 (BMPR1) signaling is not needed for initial neural crest migration. (A) Whole mount chick embryo at HH14 stained for HNK1 a neural crest marker. The otocyst (o) is cranial to the caudal stream and cardiac crest can be seen in the circumpharyngeal ridge (c). (B) The same embryo shown in (A) showing the neural tube and cardiac crest labeled with dominant negative BMPR1-GFP. (C) Enlargement of (B) showing the cardiac crest (arrows) in the circumpharyngeal ridge.