Zebrafish <em>arl6ip1</em> Is Required for Neural Crest Development during Embryogenesis

<div><h3>Background</h3><p>Although the embryonic expression pattern of ADP ribosylation factor-like 6 interacting protein 1 (Arl6ip1) has been reported, its function in neural crest development is unclear.</p> <h3>Methods/Principal Findings</h3><p>We found that knockdown of Arl6ip1 caused defective embryonic neural crest derivatives that were particularly severe in craniofacial cartilages. Expressions of the ectodermal patterning factors <em>msxb</em>, <em>dlx3b</em>, and <em>pax3</em> were normal, but the expressions of the neural crest specifier genes <em>foxd3</em>, <em>snai1b</em>, and <em>sox10</em> were greatly reduced. These findings suggest that <em>arl6ip1</em> is essential for specification of neural crest derivatives, but not neural crest induction. Furthermore, we revealed that the streams of <em>crestin-</em> and <em>sox10-</em>expressing neural crest cells, which migrate ventrally from neural tube into trunk, were disrupted in <em>arl6ip1</em> morphants. This migration defect was not only in the trunk neural crest, but also in the enteric tract where the vagal-derived neural crest cells failed to populate the enteric nervous system. We found that this migration defect was induced by dampened Shh signaling, which may have resulted from defective cilia. These data further suggested that <em>arl6ip1</em> is required for neural crest migration. Finally, by double-staining of TUNEL and <em>crestin</em>, we confirmed that the loss of neural crest cells could not be attributed to apoptosis.</p> <h3>Conclusions/Significance</h3><p>Therefore, we concluded that <em>arl6ip1</em> is required for neural crest migration and sublineage specification.</p> </div>