The structure and distribution of the cross‐striated fibril and associated membranes in guinea pig photoreceptors

Spira, Arthur W.; Milman, Gordon E.

doi:10.1002/aja.1001550304

Cited by 43 publications

(31 citation statements)

References 17 publications

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“…A dominant anatomical structure located in the photoreceptor inner segment is the ciliary rootlet, which is a large cytoskeleton-like arrangement extending from the basal body to the axon terminal (Cohen, 1960; Sjostrand, 1953; Spira and Milman, 1979). The mammalian ciliary rootlet is primarily composed of the protein rootletin, which forms parallel homodimers that organize into elongated polymers (Yang et al, 2002).…”

Section: Structure-functional Organization Of Photoreceptorsmentioning

confidence: 99%

Protein sorting, targeting and trafficking in photoreceptor cells

Pearring

Salinas

Baker

et al. 2013

Progress in Retinal and Eye Research

176

175

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Vision is the most fundamental of our senses initiated when photons are absorbed by the rod and cone photoreceptor neurons of the retina. At the distal end of each photoreceptor resides a lightsensing organelle, called the outer segment, which is a modified primary cilium highly enriched with proteins involved in visual signal transduction. At the proximal end, each photoreceptor has a synaptic terminal, which connects this cell to the downstream neurons for further processing of the visual information. Understanding the mechanisms involved in creating and maintaining functional compartmentalization of photoreceptor cells remains among the most fascinating topics in ocular cell biology. This review will discuss how photoreceptor compartmentalization is supported by protein sorting, targeting and trafficking, with an emphasis on the best-studied cases of outer segment-resident proteins.

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Section: Structure-functional Organization Of Photoreceptorsmentioning

confidence: 99%

Protein sorting, targeting and trafficking in photoreceptor cells

Pearring

Salinas

Baker

et al. 2013

Progress in Retinal and Eye Research

176

175

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“…In cross section it displays the peripheral arrangement of nine pairs of microtubules with the central pair typical of motile cilia absent [Dowling and Gibbons, 1961], In some species a prominent filamentous struc ture referred to as a rootlet fibril descends from the basal body of the connecting cilium [Uga et al, 1970;Cohen, 1972], In the guinea pig this fibril extends as far as the synaptic terminal [Spira and Milman, 1979]. The function of this fibril, although believed to be structural, is speculative, as it does not appear in all species and is not obvious in the sheep.…”

Section: Discussionmentioning

confidence: 99%

Retinal Photoreceptor Fine Structure in the Domestic Sheep

Braekevelt¹

1983

Cells Tissues Organs

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The structure of the photoreceptors of the domestic sheep has been investigated by light and electron microscopy. In the sheep retina the photoreceptors are readily differentiated and adequately described by the classical terminology of rods and cones. Rods are more numerous then cones. They appear as tall slender cells measuring 45–50 µm in length and 2–3 µm in diameter with inner and outer segments of the same diameter. Rod nuclei are located at all levels of the outer nuclear layer. The rod synaptic ending is small and rounded with two to three invaginated (ribbon) synaptic sites. Cone cells are shorter than rods, measuring only 30–35 µm in total length. The cone inner segment is wider than the outer segment which tapers distally. Cone nuclei are located adjacent to the external limiting membrane and are more vesicular than rod nuclei. Cone synaptic endings are larger spherules with ten to twelve (ribbon) synaptic sites. Both rods and cones also display supperficial synaptic regions. An unusual form of apparent degeneration is noted in cone photoreceptors. This involves a disorganization and loss of the outer segment and a progressive distal movement of the nucleus through the inner segment towards the retinal epithelial layer. The structure and ratio of rods and cones remains similar in both the tapetal and nontapetal regions of the fundus.

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“…Although motile cilia are tiny in comparison, they may also be subjected to mechanical strain imposed by vigorous ciliary beating. An additional role in the proper positioning or anchoring of cellular organelles is implicated by the association of photoreceptor rootlets with membranebound saccules, endoplasmic reticulum (ER), Golgi membranes, and mitochondria (19,24). Finally, a role for rootlets in intracellular protein transport has also been suggested (4).…”

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confidence: 99%

“…The outer segment is linked to the cell body, the inner segment, through a thin bridge called the connecting cilium (3). In a photoreceptor, the rootlet appears as a very thick striated filament that traverses the entire cell body all the way to the synaptic terminal (17,19,26). In epithelial cells bearing motile cilia, rootlets appear as robust subapical filamentous networks.…”

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confidence: 99%

The Ciliary Rootlet Maintains Long-Term Stability of Sensory Cilia

Yang

Gao

Adamian

et al. 2005

Molecular and Cellular Biology

148

158

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The striated ciliary rootlet is a prominent cytoskeleton originating from basal bodies of ciliated cells. Although a familiar structure in cell biology, its function has remained unresolved. In this study, we carried out targeted disruption in mice of the gene for rootletin, a component of the rootlet. In the mutant, ciliated cells are devoid of rootlets. Phototransduction and ciliary beating in sensory and motile cilia initially exhibit no apparent functional deficits. However, photoreceptors degenerate over time, and mutant lungs appear prone to pathological changes consistent with insufficient mucociliary clearance. Further analyses revealed a striking fragility at the ciliary base in photoreceptors lacking rootlets. In vitro assays suggest that the rootlet is among the least dynamic of all cytoskeletons and interacts with actin filaments. Thus, a primary function of the rootlet is to provide structural support for the cilium. Inasmuch as photoreceptors elaborate an exceptionally enlarged sensory cilium, they are especially dependent on the rootlet for structural integrity and long-term survival.The ciliary rootlet originates from the proximal ends of basal bodies, the centriole-related structure that anchors the cilia, and extends proximally toward the cell nuclei (5, 25). Prominent rootlets are associated with sensory cilia of photoreceptor cells and motile cilia, such as those lining the respiratory tract, oviduct, and brain ventricles. The retinal photoreceptor elaborates a single enlarged distal cilium known as the outer segment. The outer segment is packed with photosensitive membranous disks and specializes in phototransduction. It is among the largest of all mammalian cilia, spanning approximately 25 m in length and more than 1 m in diameter. The outer segment is linked to the cell body, the inner segment, through a thin bridge called the connecting cilium (3). In a photoreceptor, the rootlet appears as a very thick striated filament that traverses the entire cell body all the way to the synaptic terminal (17,19,26). In epithelial cells bearing motile cilia, rootlets appear as robust subapical filamentous networks.

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The structure and distribution of the cross‐striated fibril and associated membranes in guinea pig photoreceptors

Cited by 43 publications

References 17 publications

Protein sorting, targeting and trafficking in photoreceptor cells

Protein sorting, targeting and trafficking in photoreceptor cells

Retinal Photoreceptor Fine Structure in the Domestic Sheep

The Ciliary Rootlet Maintains Long-Term Stability of Sensory Cilia

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