Superresolution microscopy reveals photoreceptor-specific subciliary location and function of Cep290

Abstract

Mutations in the cilium-associated protein CEP290 cause retinal degeneration as part of multi-organ syndromic ciliopathies or as retina-specific diseases. The precise location and the functional roles of CEP290 within cilia and, specifically, the connecting cilia (CC) of photoreceptors, remain unclear. We used superresolution fluorescence microscopy and electron microscopy (TEM) to localize CEP290 in the CC and in primary cilia of cultured cells with sub-diffraction resolution, and to determine effects of CEP290 deficiency. Radially, CEP290 co-localizes with the microtubule doublets and extends beyond them. Longitudinally, it is distributed throughout the length of the CC but is strictly confined to the very base of primary cilia in hRPE-1 cells. We found Y-shaped links, the ciliary sub-structures between microtubules and membrane, at the base of the transition zone in primary cilia of epithelial cells and throughout the length of the CC. Severe CEP290 deficiencies in mouse models did not prevent assembly of cilia or cause obvious mislocalization of ciliary components in early stages of degeneration. They did not lead to loss of the Y-shaped links but caused changes in their structures. These results point to photoreceptor-specific functions of CEP290 essential for CC maturation and stability following the earliest stages of ciliogenesis.

Durable vision improvement after a single treatment with antisense oligonucleotide sepofarsen: a case report

“…The largest compartments of photoreceptor cilia are outer segments which show extreme turnover by being rebuilt every 10 days 17 . All outer segment proteins must traffic through the ciliary transition zone where CEP290 is located 18,19 but synthesis and degradation rates of transition zone proteins are mostly unknown, and likely to be different between rod and cone photoreceptors. We now know that efficacy in the study patient was spatially located to the highly specialized foveal cone photoreceptors of the retina.…”

Compartmentalization of Photoreceptor Sensory Cilia

“…Overlapping localization of IFT88, IFT81, and BBS5 distribution across CC was also observed ( Figure 4C ), suggestive of IFT trains. Interestingly, CEP290, which is present at the base of the primary cilium, was present along the entire CC along with Y-links (Potter et al, 2020 ). These results have strengthened the notion that the entire length of the CC operates as the photoreceptor transition zone.…”

The connecting cilium inner scaffold provides a structural foundation to maintain photoreceptor integrity

“…We also inspected the distribution of the protein CEP290, known to localize along the CC in super-resolution microscopy (20), and Lebercilin (LCA5), a proposed FAM161A interactor (10), whose mutations have been linked to Leber congenital amaurosis, a retinopathy causing severe visual deficiency from the first year after birth (21,22). Consistently with our previous work, all three IS proteins were found in the central core region of centrioles, where the IS structure lies (16) (Fig.…”