Cep164, a novel centriole appendage protein required for primary cilium formation
JOURNAL OF CELL BIOLOGY
Authors: Graser, Susanne; Stierhof, York-Dieter; Lavoie, Sebastien B.; Gassner, Oliver S.; Lamla, Stefan; Le Clech, Mikael; Nigg, Erich A.
Abstract
Primary cilia (PC) function as microtubule- based sensory antennae projecting from the surface of many eukaryotic cells. They play important roles in mechano and chemosensory perception and their dysfunction is implicated in developmental disorders and severe diseases. The basal body that functions in PC assembly is derived from the mature centriole, a component of the centrosome. Through a small interfering RNA screen we found several centrosomal proteins (Ceps) to be involved in PC formation. One newly identified protein, Cep164, was indispensable for PC formation and hence characterized in detail. By immunogold electron microscopy, Cep164 could be localized to the distal appendages of mature centrioles. In contrast to ninein and Cep170, two components of subdistal appendages, Cep164 persisted at centrioles throughout mitosis. Moreover, the localizations of Cep164 and ninein/Cep170 were mutually independent during interphase. These data implicate distal appendages in PC formation and identify Cep164 as an excellent marker for these structures.
Transient pupillary light reflex in CEP290- or NPHP5-associated Leber congenital amaurosis: Latency as a potential outcome measure of cone function
VISION RESEARCH
Authors: Krishnan, Arun K.; Jacobson, Samuel G.; Roman, Alejandro J.; Iyer, Bhavya S.; Garofalo, Alexandra V.; Heon, Elise; Cideciyan, Artur V.
Abstract
Mutations in photoreceptor cilium genes CEP290 and NPHP5 cause a form of Leber congenital amaurosis (LCA) which typically lacks rods but retains central cones. The current study evaluated the transient pupillary light reflex (TPLR) as an objective outcome measure to assess efficacy of ongoing and future therapies. Eleven eyes of six patients selected for retained cone function were tested with TPLR using full-field stimuli in the dark-adapted state. Stimuli were red or blue with 1 s duration and spanned a 6-log unit dynamic range. TPLR response amplitude was quantified at fixed times of 0.9 and 2 s after stimulus onset and TPLR latency was defined as the time to reach 0.3 mm constriction. Full-field stimulus testing (FST) and static perimetry were used to correlate subjective perception with objective TPLR parameters. TPLR and FST thresholds with both red and blue stimuli were abnormally elevated in patients to near -1.25 log phot-cdm(-2) consistent with the lack of rods. TPLR latencies were delayed on average but showed some differences among patients. Remnant extrafoveal vision was correlated with faster TPLR latencies. Our results support the use of a short TPLR protocol with full-field red stimuli of 0.7 log phot-cd.m(-2) or brighter as an objective and convenient outcome measure of cone function in CEP290- and NPHP5-LCA. The latency parameter of the TPLR would be expected to show a detectable change when an intervention modifies cone sensitivity in the extrafoveal region.