A nuclear form of Deleted in Liver Cancer 1 (DLC1) regulates neural crest specification in a RhoGAP independent manner

Abstract

Neural crest cells (NCCs) are a population of embryonic stem-like cells, which are transient and multipotent during vertebrate development. Abnormalities of neural crest development underlie many craniofacial diseases. The formation of NCCs is coordinately regulated by a gene regulatory network which involves a series of signaling events and transcriptional factor cascades. Our previous studies in chick embryos showed that Deleted in liver cancer 1(DLC1), a RhoGTPase-activating protein, is expressed in the neural plate border prior to the initiation of NC specifier genes expression. Functional studies revealed an appropriate level of DLC1 expression is required for the formation of NCCs. To further extrapolate the findings from chick to human, we use human induced pluripotent stem cells (iPSC)-derived NCCs as the cellular model to elucidate the role of DLC1 in NC development and craniofacial pathogenesis. Our results reveal that the onset of human DLC1 isoform 2 (DLC1-i2) (counterpart of chick DLC1) expression coincides with the expression of neural plate border markers, such as MSX1/2, PAX7, AP2α, and DLX5, followed by neural crest markers, including p75, Snail2, and FOXD3 during neural induction process. DLC1-i2 expression is stably maintained while expression of NC markers reach their peak. Subsequently, DLC1 isoform 1 (DLC1-i1) expression is initiated and remains high level as with neural crest markers. These results suggest that human DLC1-i2 has a conserved expression with its chick counterpart and may be related to the specification and/or multipotency of NCCs, while DLCI-i1 may play a role in the neural crest migration and differentiation process.