A single molecule approach to decipher assembly and entry of trains into C. elegans sensory cilia

Date

Nov 8, 2021

Time

4:15 PM - 5:45 PM

Speaker

Aniruddha Mitra

Affiliation

Department of Physics and Astronomy, and LaserLaB Amsterdam, Vrije Universiteit Amsterdam, The Netherlands

Language

en

Main Topic

Biologie

Other Topics

Biologie

Host

Stefan Diez

Description

Sensory neurons of C. elegans have signalling hubs called primary cilia, extending from dendritic endings, to sense and respond to the external environment. Cilia have a microtubule-based intraflagellar transport (IFT), which is essential for the growth and maintenance of the structure. The IFT proteins associated with cilia, have to be transported from the cell body to the cilia base, moving across the dendrites (10s of microns), where they assemble into IFT trains and cross a transition barrier to enter the cilia. By performing single-molecule fluorescence microscopy in the chemosensory neurons of C. elegans, we unravel that while motor proteins involved in IFT, kinesin-II, OSM-3 and IFT dynein, move diffusively from the cell soma to the cilia base, other proteins like IFT train proteins (CHE-11 and OSM-6) and ciliary transmembrane protein (OCR-2) are transported as packets in a directional manner. Single-particle tracking reveals that these packets show rich pausing dynamic, as they approach the cilia base, before docking at the cilia base. Further, we find that the IFT train proteins and IFT dynein pause at the base for a prolonged time, incorporating into IFT trains during the assembly process, before entering the cilia. In contrast, kinesin-II and OSM-3 are picked up by pre-packaged IFT trains, directly at the cilia base in case of kinesin-II and throughout the proximal segment of the cilia in case of OSM-3. Thus, using single-molecule live cell imaging in C. elegans, we illuminate how IFT proteins reach the cilia base, assemble into IFT trains and enter the cilia.

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Last modified: Nov 8, 2021, 3:09:58 PM