Loss of Sc5d Results in Cleft Palate Through Impaired Primary Cilium Formation and Pathogenic MicroRNAs

Objectives: Cleft palate is a common congenital birth defect with a complex etiology of contributions of both genetic and environmental factors. While increasing number of studies suggest a link between cellular metabolic aberrations and cleft palate, it remains largely unknown how cholesterol metabolism affects palate formation. SC5D is an enzyme crucial for cholesterol synthesis and its mutations cause lathosterolosis, characterized by craniofacial defects. In this study, we examined how loss of Sc5d resulted in cleft palate in mice.
Methods: Sc5d null mice were examined with histology, immunoblotting, RNA-seq, miRNA-seq, quantitative RT-PCR, and ChIP assays. All experimental data were analyzed using the Prism software (GraphPad), and p-value < 0.05 was considered to be statistically significant. The RNA-seq and miRNA-seq data were mapped to the mouse reference genome mm10 using HISAT2. R package DESeq2 (version 1.30.1) was used to identify differentially expressed genes and miRNAs.
Results: We found that the primary cilium, an antenna-like structure on the plasma membrane, was deformed in palatal mesenchymal cells in Sc5d mutant mice, resulting in compromised sonic hedgehog signaling, which is crucial for palate development. In addition, we found that several microRNAs were specifically upregulated and contributed to the cause of cleft palate in Sc5d mutant mice.
Conclusions: Our findings indicate that loss of Sc5d leads to cleft palate through a failure in primary cilium formation and abnormal miRNA expression.