| Summary: | The development of key structures within the mature vertebrate hindbrain requires the migration of neural crest (NC) cells and motor neurons to their appropriate target sites. Functional analyses in multiple species have revealed a requirement for the transcription factor gastrulation-brain-homeobox 2 (Gbx2) in NC cell migration and positioning of motor neurons in the developing hindbrain. In addition, loss of <i>Gbx2</i> function studies in mutant mouse embryos, <i>Gbx2</i><sup>neo</sup>, demonstrate a requirement for <i>Gbx2</i> for the development of NC-derived sensory neurons and axons constituting the mandibular branch of the trigeminal nerve (CNV). Our recent GBX2 target gene identification study identified multiple genes required for the migration and survival of NC cells (e.g., <i>Robo1, Slit3, Nrp1</i>). In this report, we performed loss-of-function analyses using <i>Gbx2</i><sup>neo</sup> mutant embryos, to improve our understanding of the molecular and genetic mechanisms regulated by <i>Gbx2</i> during anterior hindbrain and CNV development. Analysis of <i>Tbx20</i> expression in the hindbrain of <i>Gbx2</i><sup>neo</sup> homozygotes revealed a severely truncated rhombomere (r)2. Our data also provide evidence demonstrating a requirement for <i>Gbx2</i> in the temporal regulation of <i>Krox20</i> expression in r3. Lastly, we show that <i>Gbx2</i> is required for the expression of <i>Nrp1</i> in a subpopulation of trigeminal NC cells, and correct migration and survival of cranial NC cells that populate the trigeminal ganglion. Taken together, these findings provide additional insight into molecular and genetic mechanisms regulated by <i>Gbx2 </i>that underlie NC migration, trigeminal ganglion assembly, and, more broadly, anterior hindbrain development.
|
|---|
