PhD The University of Hong Kong The University of Hong Kong, Hong Kong
Abstract: Neural crest cells (NCCs), a unique population of multipotent embryonic stem-like cells originating from the neural plate border (NPB), are fundamental to vertebrate development and give rise to diverse cell types including neurons, glia, melanocytes, and craniofacial structures. While the transcriptional network governing NC development is well-characterized, we previously identified an unexpected role for RhoGAP Deleted in liver cancer 1 (DLC1) in chick cranial NC formation. Here, using human induced pluripotent stem cells as a model system, we demonstrate that DLC1 isoforms play distinct, sequential roles in human NC development. By conducting detailed temporal expression analysis, we show that DLC1 isoform 2 is specifically expressed in NPB-like cells and early NCCs, while isoform 1 expression precisely correlates with NC specification markers. Functional studies reveal that knockdown of both isoforms significantly reduces expression of NPB and NC markers, while DLC1 isoform 2 overexpression maintains cells in an NPB state and isoform 1 overexpression promotes NC specification. These results establish that DLC1 isoform switching is essential for the NPB-to-NCC transition. Mechanistically, using mass spectrometry, we identified IGF2BP2 as a potential DLC1 interaction partner. RNA immunoprecipitation studies suggest that both DLC1 and IGF2BP2 could associate with FOXD3 mRNA, a key regulator of NC stem cell self-renewal. This association may be crucial for FOXD3 mRNA stabilization, as functional studies show that DLC1 knockdown reduces both FOXD3 expression and crestosphere size, while FOXD3 overexpression enhances NC self-renewal capacity. Together, these findings reveal a conserved role for DLC1 in NC development between human and chick and suggest a potential post-transcriptional regulatory mechanism controlling NC stem cell maintenance. This work provides new mechanistic insights into human NC development and may inform strategies for developing cellular therapies for treating NC-related diseases.
