Using cryo-electron tomography for understanding function of the ciliary tip domain
Final Report Abstract
Cilia and flagella have fundamental motility, signaling, and sensory roles. Defects in the assembly and function of cilia can cause devastating human pathologies, which are collectively called ciliopathies. The ciliary tip serves as a critical region for the functionality and assembly of cilia, the microtubule-based organelles that extend from the surface of many eukaryotic cells. Nearly all human cells possess a primary cilium essential for intercellular signaling, while specialized motile cilia drive fluid flow or enable cellular movement. The distal tip is the exclusive site of ciliary growth and assembly, making it a focal point for understanding ciliary biology. Cilia are built from a microtubule-based axoneme, a highly ordered structure consisting of nine microtubule doublets (MTDs) surrounding a central pair (CP) in motile cilia. This architecture is fundamental to ciliary function, with components transported to the tip by intraflagellar transport (IFT) trains. Anterograde IFT trains, driven by kinesin-II motors, deliver cargo to the tip, while retrograde trains, powered by cytoplasmic dynein-1b, return to the cell body. The ciliary tip is where critical processes converge: the polymerisation and depolymerisation of microtubules during cilia assembly and disassembly, the turnaround of IFT trains, the unloading of IFT cargo, the assembly of these components into the axonemal structure, the release of ectosomes from the ciliary tip membrane. All these processes are key to the proper function of cilia, but how and who regulates them is largely unknown. Recent advances in microscopy and genome engineering have provided significant insights into the mechanisms at play at the ciliary tip. This report synthesizes findings from key studies, each focusing on different aspects of tip biology, including IFT turnaround, axoneme assembly, and tip protein engineering using CRISPR-Cas.
Publications
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Conversion of anterograde into retrograde trains is an intrinsic property of intraflagellar transport. Current Biology, 32(18), 4071-4078.e4.
Nievergelt, Adrian Pascal; Zykov, Ilia; Diener, Dennis; Chhatre, Aditya; Buchholz, Tim-Oliver; Delling, Markus; Diez, Stefan; Jug, Florian; Štěpánek, Luděk & Pigino, Gaia
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Efficient precision editing of endogenous Chlamydomonas reinhardtii genes with CRISPR-Cas. Cell Reports Methods, 3(8), 100562.
Nievergelt, Adrian Pascal; Diener, Dennis Ray; Bogdanova, Aliona; Brown, Thomas & Pigino, Gaia
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Protocol for precision editing of endogenous Chlamydomonas reinhardtii genes with CRISPR-Cas. STAR Protocols, 5(1), 102774.
Nievergelt, Adrian Pascal; Diener, Dennis Ray; Bogdanova, Aliona; Brown, Thomas & Pigino, Gaia
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Tubulin tyrosination/detyrosination governs the spatial segregation of intraflagellar transport trains on axonemal microtubule doublets. openRxiv.
Chhatre, Aditya; Stepanek, Ludek; Nievergelt, Adrian Pascal; Alvarez, Viar Gonzalo; Diez, Stefan & Pigino, Gaia
