Wnt3a regulates the development of cardiac neural crest cells by modulating expression of cysteine-rich intestinal protein 2 in rhombomere 6

The cardiac neural crest is a subpopulation of neural crest cells (NCCs) that originates from the dorsal neural tube and later migrates to the heart and pharyngeal arch (PA), where they contribute to distinct aspects of cardiogenesis and PA patterning. Wnt family members have been implicated in general neural crest induction; however, the molecular mechanisms underlying the specification of distinct cell types such as cardiac NCCs remain unclear. Here, we have identified cysteine-rich intestinal protein 2 (crip2), a gene encoding for a LIM domain-containing protein, as a novel marker for cardiac NCCs in zebrafish. We observed a dynamic expression pattern for crip2, with expression being detected in the premigratory NCCs in rhombomere 6 (r6), migrating NCCs, ventricular cardiomyocytes, and aortic vessels in PAs 3 to 6. Interestingly, expression of wnt3a was detected in regions of the dorsal neural tube encompassing r6, and reduction of wnt3a led to disrupted expression of crip2 in r6, abnormal migration of NCCs, and defective cardiac function, as well as PA development. Furthermore, these phenotypes could be recapitulated by reduction of crip2 and rescued by overexpression of crip2. In summary, our data suggest a specific role for Wnt3a in the development of cardiac NCCs. We propose that this function of wnt3a in r6 is partially mediated by crip2 expression in the premigratory cardiac NCCs, which subsequently affects cardiac function and PA patterning.