A functional and therapeutic investigation of ciliopathy proteins and ciliopathies

This thesis aims to investigate new functions for ciliopathy proteins and identify candidates for therapeutic application. The ciliopathies form a class of genetic diseases whose aetiology lies in the primary cilium. Over 30 genes have been identified as mutant in ciliopathies and their proteins localise at the primary cilium. When mutated they can cause kidney disease, obesity, polydactyly, and retinal degeneration. In this project, I have studied craniofacial dysmorphology related to Bardet-Biedl syndrome (BBS) in humans, mice, and zebrafish, and shown there to be consistent midfacial flattening and hypoplasia. Bbs8, a causative gene of BBS, has a key role in neural crest migration and possibly in cell migration in general. This accounts for the frequent observation of Hirschsprung’s disease, a gut immotility disorder, in BBS. I identified new roles for BBS and other ciliopathy proteins in Sonic hedgehog (Shh) signal transduction and showed that they are important in the downstream processing of the transcription factor Gli3. I modelled ten different ciliopathy genes in the zebrafish and identified specific ciliary phenotypes, such as laterality randomisation, otic vesicle anomalies, and kidney cysts. Administration of two drugs, Rapamycin and Roscovitine, were sufficient to rescue formation of kidney cysts and restore the filterative capacity of the kidney. This paves the way for studies in mouse models and, ultimately, in humans, where no treatment for ciliopathic renal disease exists. I examined whether FTO, a gene associated with obesity in the general population, functioned in ciliary processes. I provided some evidence that its protein was involved ciliary processes and glucose homeostasis. I also showed that fto interacted with its neighbouring ciliary gene, ftm, in the zebrafish. I performed similar interaction studies to show that a non-synonomous SNP in a gene associated with lipid accumulation in C. elegans had deleterious effects on protein function, explaining its high degree of association in BBS patients.