Decoding Aberrant WNT/ROR Signalosome Assembly in Robinow Syndrome: Mechanistic Insights from Dishevelled Variants

Objective

WNT signalling pathways are evolutionarily conserved communication networks that control cell fate and tissue morphogenesis. While the canonical WNT/β-catenin pathway is well-studied, the non-canonical branch involving ROR receptors remains poorly understood, despite its critical role in development. Dysfunction of WNT/ROR signalling correlates with metastatic behaviour in cancer, neurological disorders and rare genetic diseases, most notably Robinow syndrome (RS). An essential step in this pathway is WNT ligand-induced activation of a receptor-bound signalling complex, termed the ‘signalosome’, assembled by the adaptor protein Dishevelled (DVL). However, the WNT/ROR signalosome component proteins and the mechanisms used to transduce its signals remain unclear. In preliminary work in the host lab, I have identified a RS-associated DVL1 frameshift mutation that drives aberrant signalosome formation. How this variant alters the molecular composition of the signalosome and disrupts downstream signalling remains unknown. This MSCA project will uncover the mechanisms by which RS mutations deregulate WNT/ROR signalosome function, advancing our understanding of pathway activation. In WP1, we will systematically characterise RS-associated DVL1-3 variants for their effects on signalosome assembly and signalling output using multiplexed WNT reporters and other tools, enabling the first comprehensive mechanistic analysis of these disease mutations. In WP2, we will map interactors involved in aberrant DVL assembly through proximity labelling proteomics and CRISPR-based screening, generating a high-confidence atlas of the WNT/ROR signalosome in health and disease. In WP3, we will dissect sequence motifs within the novel DVL C-termini that control assembly, revealing the molecular logic by which RS mutations rewire signalling dynamics. By uncovering how WNT/ROR signalling is disrupted in rare disease, this work will pave the way for therapeutic exploration of this pathway.