Elucidating the etiology for Schneckenbecken dysplasia, a rare disease, using a vetrebrate model system - Project Summary Schneckenbecken dysplasia (SBD) is a rare congenital disease characterized by severe skeletal dysplasia, caused by mutations in the nucleotide-sugar transporter gene, SLC35D1. SLC35D1 resides in the endoplasmic reticulum and facilitates transport of UDP-sugars for post-translational modification. UDP-sugars transported through SLC35D1 are crucial for biosynthesis of chondroitin sulfate, a proteoglycan in the extracellular matrix. In Slc35d1 knockout mice, chondrogenesis is disrupted and chondroitin sulfate chain length is decreased in chondrogenic regions. However, mechanistic insights into how changes in chondroitin sulfate chain length impair chondrogenesis are lacking for models of SBD and little is known about the developmental etiology. To address these knowledge gaps, we propose to use Xenopus tropicalis to generate CRISPR models of patient-specific variants of SBD to understand the underlying cause of aberrant chondrogenesis, with a specific focus on the neural-crest derived craniofacial cartilage. In the proposed aims, we will 1) uncover when neural crest (progenitors of facial skeleton) development is disrupted and assess how patient-specific SBD variants affect facial phenotypes and 2) determine how loss of Slc35d1 changes extracellular matrix composition and affects mechanical and biochemical inductive ques during chondrogenesis. This work will provide critical mechanistic insights into the role of the ECM in craniofacial development and establish tractable disease models for SBD which can be used for the development of therapeutic approaches for SBD.
