A Histone2BCerulean BAC transgene identifies differential expression of Phox2b in migrating enteric neural crest derivatives and enteric glia

The mammalian enteric nervous system (ENS) derives from migratory enteric neural crest- derived cells (ENCC) that express the transcription factor Phox2b. Studies of these enteric progenitors have typically relied on immunohistochemical (IHC) detection. To circumvent complicating factors of IHC, we have generated a mouse BAC transgenic line that drives a Histone2BCerulean (H2BCFP) reporter from Phox2b regulatory regions. This construct does not alter the endogenous Phox2b locus and enables studies of normal neural crest (NC) derivatives. The Phox2b-H2BCFP transgene expresses the H2BCFP reporter in patterns that recapitulate expression of endogenous Phox2b. Our studies reveal Phox2b expression in mature enteric glia at levels below that of enteric neurons. Moreover, we also observe differential expression of the transgene reporter within the leading ENCC that traverse the gut. Our findings indicate that the wavefront of migrating enteric progenitors is not homogeneous, and suggest these cells may be fate-specified before expression of mature lineage markers appears.