The retinal photoreceptors possess specialized sensory cilia critical for phototransduction while the nonphotoreceptor cells typically exhibit simpler primary cilia or lack them altogether. This dichotomy in ciliary architecture underpins the functional specialization of retinal cell types, but how this dichotomy arises and is maintained remains elusive. This study explores the role of the transcription factor Foxn3 in establishing and maintaining this divergence. We generated retina-specific Foxn3 conditional knockout (Foxn3CKO) mice, which show that Foxn3 is essential for repressing ciliary gene expression in nonphotoreceptor cells, such as bipolar and amacrine cells. Foxn3CKO mice exhibit significant reductions in electroretinogram b-wave amplitudes and oscillatory potentials, indicating functional impairments in inner retinal neurons. Loss of Foxn3 leads to ectopic ciliary gene expression and abnormal ciliogenesis in nonphotoreceptor neurons, without affecting retinal cell specification and differentiation. Single-Cell RNA Sequencing, chromatin profiling, and transcription assays reveal that Foxn3 directly binds to and represses the promoters of ciliary genes and their transactivators, including Foxj1 and Rfx family members. Our data together highlight Foxn3 as a key transcriptional repressor that may function to ensure the proper ciliary architecture of retinal neurons by preventing nonphotoreceptor neurons from adopting photoreceptor-like ciliary features and provide insights into the molecular mechanisms governing retinal development and ciliopathies.

We assessed the preliminary safety of a recombinant adeno-associated virus serotype 8 vector carrying the native human LCA5 cDNA (OPGx-001) in LCA5-associated Leber congenital amaurosis (LCA5-LCA), a congenital blindness. This phase 1b/2a trial (NCT05616793) is a nonrandomized, single ascending, dose-escalation study. Three subjects with LCA5-LCA (ages 19, 26, and 34 years old) received uniocular subretinal injections of 1E10 vector genome per eye of OPGx-001. There were no serious adverse events related to OPGx-001 or the procedure. Retinal microstructure by spectral-domain optical coherence tomography showed no major changes in retinal lamination of the treated central retina compared with the contralateral control. Efficacy was detectable in these severely affected patients by subjective and objective methods at 1-month post-treatment and persisted for at least 12 months. Chromatic full-field stimulus testing showed improvements in cone-mediated vision averaging ∼1 log10 unit. Objective pupillometry confirmed perceptual results. Improvements were associated with better performance on a virtual reality orientation and mobility test. Visual acuity returned to baseline or improved in the treated eyes of all participants. The favorable safety profile and efficacy outcomes pave the path for enrolling milder phenotypes with careful dose escalation.

CEP162, a 162-kDa centrosome protein, is a crucial centrosomal adapter, mediating cell differentiation and polarization. CEP162 maintains mitosis by dynamically stabilizing microtubules. CEP162 promotes the transition zone (TZ) assembly in the basal body through interaction with CEP131, CEP290, and axoneme microtubules as well as the distal centriole. TZ ensures the normal distribution of soluble proteins between the cytoplasm and cilia. It also facilitates retinal development and sperm flagellar motility. However, fluctuations in TZ permeability caused by abnormal expression of CEP162, including truncated mutations and naturally occurring mutations, lead to cilia abnormality and dysfunction in ciliogenesis through the regulation of intraflagellar transport, resulting in retinal degeneration and infertility. LncRNAs can induce SNP events in the CEP162 transcript by altering alternative splicing. Naturally occurring mutations are closely linked to retinal ciliopathy and diabetic retinopathy. This review summarizes the latest research progress to better understand the biology and pathophysiology of CEP162 and the clinical manifestations caused by CEP162 variants.

The human photoreceptor function is dependent on a highly specialised cilium. Perturbation of cilial function can often lead to death of the photoreceptor and loss of vision. Retinal ciliopathies are a genetically diverse range of inherited retinal disorders affecting aspects of the photoreceptor cilium. Despite advances in the understanding of retinal ciliopathies utilising animal disease models, they can often lack the ability to accurately mimic the observed patient phenotype, possibly due to structural and functional deviations from the human retina. Human-induced pluripotent stem cells (hiPSCs) can be utilised to generate an alternative disease model, the 3D retinal organoid, which contains all major retinal cell types including photoreceptors complete with cilial structures. These retinal organoids facilitate the study of disease mechanisms and potential therapies in a human-derived system. Three-dimensional retinal organoids are still a developing technology, and despite impressive progress, several limitations remain. This review will discuss the state of hiPSC-derived retinal organoid technology for accurately modelling prominent retinal ciliopathies related to genes, including RPGR, CEP290, MYO7A, and USH2A. Additionally, we will discuss the development of novel gene therapy approaches targeting retinal ciliopathies, including the delivery of large genes and gene-editing techniques.

Primary cilia are sensory organelles that extend from the cellular membrane and are found in a wide range of cell types. Cilia possess a plethora of vital components that enable the detection and transmission of several signaling pathways, including Wnt and Shh. In turn, the regulation of ciliogenesis and cilium length is influenced by various factors, including autophagy, organization of the actin cytoskeleton, and signaling inside the cilium. Irregularities in the development, maintenance, and function of this cellular component lead to a range of clinical manifestations known as ciliopathies. The majority of people with ciliopathies have a high prevalence of retinal degeneration. The most common theory is that retinal degeneration is primarily caused by functional and developmental problems within retinal photoreceptors. The contribution of other ciliated retinal cell types to retinal degeneration has not been explored to date. In this review, we examine the occurrence of primary cilia in various retinal cell types and their significance in pathology. Additionally, we explore potential therapeutic approaches targeting ciliopathies. By engaging in this endeavor, we present new ideas that elucidate innovative concepts for the future investigation and treatment of retinal ciliopathies.