Gene therapy rescues cilia defects and restores olfactory function in a mammalian ciliopathy model

Abstract

Cilia are evolutionarily conserved microtubule-based organelles that are crucial for diverse biological functions, including motility, cell signaling and sensory perception1. In humans, alterations in the formation and function of cilia manifest clinically as ciliopathies, a growing class of pleiotropic genetic disorders2–4. Despite the substantial progress that has been made in identifying genes that cause ciliopathies, therapies for these disorders are not yet available to patients. Although mice with a hypomorphic mutation in the intraflagellar transport protein IFT88 (Ift88Tg737Rpw mice, also known as ORPK mice)5 have been well studied, the relevance of IFT88 mutations to human pathology is unknown. We show that a mutation in IFT88 causes a hitherto unknown human ciliopathy. In vivo complementation assays in zebrafish and mIMCD3 cells show the pathogenicity of this newly discovered allele. We further show that ORPK mice are functionally anosmic as a result of the loss of cilia on their olfactory sensory neurons (OSNs). Notably, adenoviral-mediated expression of IFT88 in mature, fully differentiated OSNs of ORPK mice is sufficient to restore ciliary structures and rescue olfactory function. These studies are the first to use in vivo therapeutic treatment to reestablish cilia in a mammalian ciliopathy. More broadly, our studies indicate that gene therapy is a viable option for cellular and functional rescue of the complex ciliary organelle in established differentiated cells.

Hedgehog signaling regulates ciliary localization of mouse odorant receptors

“…To address whether the reduction in ciliary OR accumulation affected the function of OSNs, we analyzed the S100 calcium binding protein A5 (S100A5) that is transiently expressed to high levels in odorant-stimulated OSNs and that requires intact olfactory cilia to be expressed (22,23). In concordance with reduced olfactory transduction in vismodegib-treated mice we found that the number of S100A5-positive OSNs was reduced in vismodegib-treated mice compared with controls (Fig.…”

Heterotrimeric Kinesin-2 (KIF3) Mediates Transition Zone and Axoneme Formation of Mouse Photoreceptors

“…Chlamydomonas mutants lacking IFT88 are viable but do not form flagella (14), and zebrafish Ift88 mutants never develop photoreceptor outer segments (15). Germline deletions of IFT88 are embryonically lethal (14,16), and hypomorphic mutations (Tg737 orpk mice) cause complex ciliopathies affecting multiple tissues including photoreceptors, kidney, and olfactory neurons (17)(18)(19)(20). IFT88 was shown by pulldowns to be associated with rhodopsin, GC1, and a chaperone termed mammalian relative of Dna-J (MRJ) suggesting that outer segment transmembrane proteins are IFT cargo (21).…”

Centrin 2 Is Required for Mouse Olfactory Ciliary Trafficking and Development of Ependymal Cilia Planar Polarity

“…Cilia dysfunction causes a wide range of human diseases collectively called ciliopathies. Disruption of olfactory cilia causes anosmia (inability to perceive odors) or dysosmia (reduced sensitivity to odors; Kulaga et al, 2004;Tadenev et al, 2011;McIntyre et al, 2012), whereas ependymal cilia dysfunction leads to impaired CSF flow and hydrocephalus (Lechtreck et al, 2008;Tissir et al, 2010;Wilson et al, 2010).…”