Abstract
Purpose: :
To investigate the function of inositol 5-phosphatase INPP5E in cilia development in the retina. Mutations of INPP5E cause Joubert Syndrome (MIM:213300), which is characterized by retinal degeneration, renal cysts, polydactyly, and mental retardation (Bielas, SL, et al. Nat Genet. 2009). Although INPP5E has been implicated in cilia development, its function in retina development is not known.
Methods: :
Using antisense morpholino oligonucleotides (MOs), knockdown of INPP5E was performed in zebrafish and rescue experiments were done using human wild type mRNA. Immunofluorescence of hTERT-RPE1 cells was performed to determine the subcellular localization of human INPP5E and ciliary markers.
Results: :
In zebrafish INPP5E morphants, embryos showed a dose-dependent phenotype of retinal degeneration, microphthalmia, and body axis asymmetry. The phenotypes were rescued by concomitant injection of human INPP5E mRNA. Kupffer vesicle cilia in the INPP5E morphants were markerly shorter than the wild type controls. Immunofluorescence experiments showed the co-localization of INPP5E, gamma tubulin, and Rab20 in the basal body in RPE and normal human fibroblasts.
Conclusions: :
Our data support an important role of INPP5E in ciliary development and maintenance and provide a novel animal model to examine the function of inositol phosphatases in retinal development.
Keywords: retinal degenerations: hereditary • proteins encoded by disease genes • photoreceptors