Lohraseb, I. | Search bioRxiv

bioRxiv2026

Trisomy 21 Impairs Development of Enteric Neural Crest-Derived Cells via SOD1-Mediated RET Dysregulation

Hirschsprung disease (HSCR) is a rare congenital disorder of the enteric nervous system (ENS), marked by the absence of enteric ganglia along variable lengths of the distal gastrointestinal tract, resulting in functional intestinal obstruction. Individuals with Trisomy 21 (Down syndrome) face a 50- to 100-fold increased risk of HSCR relative to the general population, yet the molecular basis of this susceptibility remains poorly understood. Here, we investigated this association using isogenic induced pluripotent stem cells (iPSCs) derived from a mosaic individual with Down syndrome, enabling direct comparison of Trisomy 21 and Disomy 21 cells within an identical genetic background following differentiation into enteric neural crest-derived cells (ENCDCs). Trisomy 21 ENCDCs exhibited reduced proliferative and migratory capacity and an impaired ability to differentiate into enteric neurons relative to Disomy 21 controls. These phenotypes were accompanied by decreased RET expression at both the transcript and protein levels, together with broad downregulation of the RET gene regulatory network, including GDNF, GFRA1, EDNRB, SEMA3C, and NRG1, and of cell cycle and DNA replication pathways. Strikingly, we identified SOD1, a chromosome 21-encoded antioxidant enzyme not previously linked to RET regulation, as a dosage-sensitive driver of this effect: SOD1 overexpression in disomic ENCDCs was sufficient to suppress RET, whereas shRNA-mediated knockdown of SOD1 in Trisomy 21 ENCDCs restored RET expression. Mechanistically, Trisomy 21 ENCDCs displayed markedly elevated catalase and a redox imbalance, and exogenous hydrogen peroxide recapitulated RET suppression in disomic cells, implicating oxidative stress as a mediator of RET downregulation. Collectively, these findings establish Trisomy 21 dosage effects as disruptors of RET-dependent enteric neural crest development and implicate SOD1-driven oxidative stress as a candidate mechanism, providing a framework for understanding the elevated risk of HSCR in Down syndrome.

cell biology↗

bioRxiv2025

Neural crest cell derived DKK1 modulates Wnt signalling in the second heart field to orchestrate cardiac outflow tract development

Heart morphogenesis is highly complex, and depends on the generation of diverse cell types which interact with each other in an orchestrated manner to remodel the primitive heart tube into a functional organ. Cardiac outflow tract formation critically depends on continued contribution of cardiac progenitor cells from the anterior second heart field to ensure proper growth of the outflow tract. Prior to entering the outflow tract, neural crest cells migrate in close apposition to the second heart field and may play important roles in regulating second heart field growth dynamics, however the molecular mechanisms by which neural crest cells interact with the second heart field have remained elusive. Here, we discover that neural crest cells are a primary source of Dickkopf1 (DKK1), a secreted Wnt signalling inhibitor, which modulates Wnt signalling activity in the second heart field to impose a balance between progenitor maintenance and differentiation. Further, we identify the ubiquitin ligase NEDD4 as a critical regulator of DKK1 levels, with disruption of Nedd4 activity leading to outflow tract defects. In the context of disease pathogenicity, we show a novel human congenital heart disease variant of NEDD4 has lost the ability to ubiquitinate DKK1, and is associated with heart defects in a mouse model of the genetic variant. Our findings point to an unexpected role for neural crest cells acting as a rheostat of Wnt signalling activity in cardiac progenitors, identifying a new molecular pathway underpinning correct outflow tract morphogenesis, and a new causative factor of congenital heart disease.

developmental biology↗