Polycystic Kidney Disease in the Medaka (Oryzias latipes) pc Mutant Caused by a Mutation in the Gli-Similar3 (glis3) Gene

Abstract

Polycystic kidney disease (PKD) is a common hereditary disease in humans. Recent studies have shown an increasing number of ciliary genes that are involved in the pathogenesis of PKD. In this study, the Gli-similar3 (glis3) gene was identified as the causal gene of the medaka pc mutant, a model of PKD. In the pc mutant, a transposon was found to be inserted into the fourth intron of the pc/glis3 gene, causing aberrant splicing of the pc/glis3 mRNA and thus a putatively truncated protein with a defective zinc finger domain. pc/glis3 mRNA is expressed in the epithelial cells of the renal tubules and ducts of the pronephros and mesonephros, and also in the pancreas. Antisense oligonucleotide-mediated knockdown of pc/glis3 resulted in cyst formation in the pronephric tubules of medaka fry. Although three other glis family members, glis1a, glis1b and glis2, were found in the medaka genome, none were expressed in the embryonic or larval kidney. In the pc mutant, the urine flow rate in the pronephros was significantly reduced, which was considered to be a direct cause of renal cyst formation. The cilia on the surface of the renal tubular epithelium were significantly shorter in the pc mutant than in wild-type, suggesting that shortened cilia resulted in a decrease in driving force and, in turn, a reduction in urine flow rate. Most importantly, EGFP-tagged pc/glis3 protein localized in primary cilia as well as in the nucleus when expressed in mouse renal epithelial cells, indicating a strong connection between pc/glis3 and ciliary function. Unlike human patients with GLIS3 mutations, the medaka pc mutant shows none of the symptoms of a pancreatic phenotype, such as impaired insulin expression and/or diabetes, suggesting that the pc mutant may be suitable for use as a kidney-specific model for human GLIS3 patients.

Pkd1l1 complexes with Pkd2 on motile cilia and functions to establish the left-right axis

“…S2 in the supplementary material) and sequence comparison revealed a transposon insertion. Such insertions have been observed in the scaleless medaka mutant rs-3 (Kondo et al, 2001) and the PKD medaka mutant pc (Hashimoto et al, 2009). Collectively, we concluded that medaka pkd1l1 is the gene responsible for the abc mutant.…”

Novel GLIS3 mutations demonstrate an extended multisystem phenotype

“…The most severe clinical phenotype in a Saudi Arabian family kindred with consanguineous parents was caused by a single base insertion at nucleotide 2067 on GLIS3 (c.2067insC) that was predicted to result in a truncated protein with an altered C-terminal proline-rich domain, abolishing the DNA-binding capacity of GLIS3 to GLI response elements (GLI-REs) on the promoter region of target genes. Apart from the consistent presentation of neonatal diabetes and hypothyroidism, additional features included renal cystic dysplasia, likely to result from renal ciliary dysplasia early in renal embryogenesis (19,20) and progressive hepatic fibrosis culminating in cirrhosis. All three children from this Saudi Arabian family died between 10 days and 16 months from infection.…”

GLIS1–3 transcription factors: critical roles in the regulation of multiple physiological processes and diseases

“…1) suggesting that its primary cilium localization might be mediated by a similar mechanism. It is further interesting to note that GLIS3 interacts with SUFU, a protein that has been demonstrated to interact and co-localize with GLI proteins to the tip of the primary cilium [9, 10, 28, 166]. The ciliary localization of GLIS3 raises the question whether GLIS3 activity is under the control of an external signal that acts through a specific primary cilium-associated GPCR, as has been demonstrated for the hedgehog-GLI pathway [4, 155, 168].…”

“…GLIS homologs have been identified in all mammalian species, as well as Zebrafish , Medaka , Xenopus and Drosophila [10–12]. The GLIS homolog in Drosophila is referred to as gleeful ( gfl ) or lameduck ( lmd ).…”