A Centriole-less Pericentriolar Material Serves as the Base of C. elegans Sensory Cilia
Abstract/Contents
- Abstract
- Cilia are complex sensory and motile organelles found on almost all cells of the body. Sensory cilia act as the cell’s antennae, detecting and managing external signals. Perturbation of cilia related genes leads to a large scope of diseases, ciliopathies, such as retinal degeneration and polycystic kidney disease. While the assembly of cilia by basal bodies, which are re-purposed centrioles, is shared among unicellular organisms and animal cells, in the nematode Caenorhabditis elegans basal bodies are necessary for ciliogenesis, but are degraded upon cilia maturation. This raises the question of how ciliary microtubules are maintained in the absence of the basal bodies from which they are templated. We used CRISPR-generated endogenously tagged alleles to assess the localization of centrosomal proteins. Surprisingly, although the base of cilia lacks an association with centriole proteins or the PCM protein SPD-2/CEP192, SPD-5, ZYG-9/XMAP-215 and the conserved microtubule nucleating γ-tubulin ring complex (γ-TuRC) localize to this region. We named this previously unidentified structure the “centriole-less PCM.” Confocal microscopy revealed distinct subdomains of the centriole-less PCM, with a subset of proteins localizing closer to the ciliary axoneme and others localizing closer to the dendrites, a region nucleating the assembly of dynamic microtubules into the cell body, confirming that the base of cilia is a microtubule organizing center (MTOC). Using tissue-specific degradation, we tested the role of SPD-5 at the base of cilia at different time points in development. Degradation of SPD-5 after cilia maturation did not grossly impact cilia structure or function. However, degradation of SPD-5 during ciliogenesis perturbed cilia structure, suggesting that SPD-5 is required to maintain the axoneme in the absence of a canonical basal body. Moreover, SPD-5 is necessary for γ-TuRC localization at the ciliary base and nucleating dynamic microtubules into the cell body of the neuron. Unlike at the centrosome, the localization and regulation of SPD-5 appears to be independent of mitotic kinases. The presence of a RFX-type transcription factor binding site in the promoter region of SPD-5 indicates a pressure to maintain its expression in ciliated neurons. Thus, I propose that, in the absence of a canonical basal body, SPD-5 maintains the cilia structure while also recruiting the γ-TuRC, which imparts MTOC function to the centriole-less PCM.
Description
| Type of resource | text |
|---|---|
| Date created | June 2020 |
Creators/Contributors
| Author | Eskinazi, Sani | |
|---|---|---|
| Primary advisor | Feldman, Jessica Lynn | |
| Advisor | Stearns, Tim | |
| Degree granting institution | Stanford University, Department of Biology, 2020 |
Subjects
| Subject | biology |
|---|---|
| Subject | cilia |
| Subject | basal body |
| Subject | MTOC |
| Subject | Pericentriolar material |
| Subject | neuronal microtubules |
| Subject | C. elegans |
| Genre | Thesis |
Bibliographic information
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- This work is licensed under a Creative Commons Attribution Share Alike 3.0 Unported license (CC BY-SA).
Preferred citation
- Preferred Citation
- Eskinazi, Sani, Stearns, Tim, and Feldman, Jessica Lynn. (2020). A Centriole-less Pericentriolar Material Serves as the Base of C. elegans Sensory Cilia. Stanford Digital Repository. Available at: https://purl.stanford.edu/bx446qq5867
Collection
Undergraduate Theses, Department of Biology, 2019-2020
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- sanie@stanford.edu
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