Biology subjects

Dantas, T. J.

Publications and source records attributed to Dantas, T. J..

4 recordsLinked to original sources

bioRxiv2025

Removal of the Ciliary Gate Allows Axoneme Extension in the Absence of Retrograde IFT

The transition zone (TZ) is a selective barrier that maintains ciliary compartmentalization by controlling protein entry and exit. Cilia assembly requires the crossing of this barrier by intraflagellar transport (IFT) trains, scaffolded by IFT-A and IFT-B complexes, which move cargo bidirectionally using kinesin-2 and dynein-2 motors. In Caenorhabditis elegans, IFT-A loss abolishes retrograde transport, resulting in truncated cilia packed with IFT material. Here, we show that blocking TZ assembly prevents dynein-2 and IFT-B accumulation inside IFT-A-deficient cilia and partially rescues axoneme length. Single-particle imaging reveals that this rescue occurs without recovery of retrograde IFT. Instead, IFT particles exit cilia by passively diffusing through the disrupted TZ. Moreover, IFT-A/TZ double mutants shed ciliary extracellular vesicles (EVs) abnormally enriched in IFT components, providing a second clearance route. We conclude that TZ removal alters ciliary responses to retrograde transport defects, promoting diffusion and EV release to clear IFT machinery and facilitate axoneme extension. Highlights- TZ loss provides alternative routes for clearing IFT machinery stalled in IFT-A mutant cilia - Axoneme extension is possible without retrograde IFT when the TZ barrier is removed - Disrupted TZ enables exit of IFT particles by passive diffusion in retrograde IFT-deficient cilia - Excess IFT machinery is discarded in ciliary EVs when retrograde IFT and gating are compromised

cell biology↗

bioRxiv2024

CDR2 is a dynein adaptor recruited by kinectin to regulate ER sheet organization

The endoplasmic reticulum (ER) relies on the microtubule cytoskeleton for distribution and re-modelling of its extended membrane network, but how microtubule-based motors contribute to ER organization remains unclear. Using biochemical and cell-based assays, we identify cerebellar degeneration-related protein 2 (CDR2) and its paralog CDR2-like (CDR2L), onconeural antigens with poorly understood functions, as ER adaptors for cytoplasmic dynein-1 (dynein). We demonstrate that CDR2 is recruited by the integral ER membrane protein kinectin (KTN1) and that double knockout of CDR2 and CDR2L enhances KTN1-dependent ER sheet stacking, reversal of which by exogenous CDR2 requires its dynein-binding CC1 box motif. Exogenous CDR2 expression additionally promotes CC1 box-dependent clustering of ER sheets near centrosomes. CDR2 competes with the eEF1B{beta} subunit of translation elongation factor 1 for binding to KTN1, and eEF1B{beta} knockdown increases endogenous CDR2 levels on ER sheets, inducing their centrosome-proximal clustering. Our study describes a novel molecular pathway that implicates dynein in ER sheet organization and may be involved in the pathogenesis of paraneoplastic cerebellar degeneration.

cell biology↗

bioRxiv2023

Hot-wiring dynein-2 uncovers roles for IFT-A in retrograde train assembly and motility

Intraflagellar transport (IFT) trains, built around IFT-A and IFT-B complexes, are carried by opposing motors to import and export ciliary cargo. While transported by kinesin-2 on anterograde IFT trains, the dynein-2 motor adopts an autoinhibitory conformation until it needs to be activated at the ciliary tip to power retrograde IFT. Growing evidence has linked the IFT-A complex to retrograde IFT; however, its roles in this process remain unknown. Here, we used CRISPR/Cas9-mediated editing to disable the dynein-2 autoinhibition mechanism in Caenorhabditis elegans, and assessed its impact on IFT with high-resolution live imaging and photobleaching analyses. Remarkably, this dynein-2 "hot-wiring" approach reignites retrograde motility inside IFT-A-deficient cilia, without triggering tug-of-war events. In addition to providing functional evidence that multiple mechanisms maintain dynein-2 inhibited during anterograde IFT, our data uncover key roles for IFT-A in: mediating motor-train coupling during IFT turnaround; promoting retrograde IFT initiation; and modulating dynein-2 retrograde motility. Highlights- Hot-wiring mutations enable dynein-2 to undergo retrograde movement in IFT-A-deficient cilia - Disabling dynein-2 autoinhibition reveals that multiple mechanisms restrain dynein-2 activity during anterograde IFT - IFT-A promotes retrograde IFT initiation and efficient dynein-2 motility - IFT-A mediates dynein-2 coupling to retrograde IFT trains

cell biology↗

bioRxiv2021

WDR60-mediated dynein-2 loading into cilia powers retrograde IFT and transition zone crossing

The dynein-2 motor complex drives retrograde intraflagellar transport (IFT), playing a pivotal role in the assembly and functions of cilia. However, the mechanisms that regulate dynein-2 motility remain poorly understood. Here, we identify the Caenorhabditis elegans WDR60 homolog (WDR-60) and dissect the roles of this intermediate chain using genome editing and live imaging of endogenous dynein-2/IFT components. We find that loss of WDR-60 impairs dynein-2 recruitment to cilia and its incorporation onto anterograde IFT trains, reducing the availability of the retrograde motor at the ciliary tip. Consistently, we show that less dynein-2 motors power WDR-60-deficient retrograde IFT trains, which move at reduced velocities and fail to exit cilia, accumulating on the distal side of the transition zone. Remarkably, disrupting the transition zones NPHP module almost fully restores ciliary exit of underpowered retrograde trains in wdr-60 mutants. This work establishes WDR-60 as a major contributor to IFT and the NPHP module as a roadblock to dynein-2 passage through the transition zone.

cell biology↗